Search

• Weathering of TTG in an island arc environment formed the protolith of Sidaolazihe Formation. • The emplacement age of Sidaolazihe Formation was constrained as 2565 ± 5.9 Ma and metamorphosed at 2475.6 ± 9 Ma. • A nearly isobaric cooling (IBC) anticlockwise P-T paths with three stages were determined. The Archean supracrustal rock series in the Laojinchang area of Jilin Province, China provide valuable insights into the Precambrian geological evolution of the North China Craton. This study presents new results on petrography, geochemistry, mineralogy, isotope geochronology and phase equilibrium modeling of the Laojinchang granulite facies metamorphic rocks. The protolith ages of garnet two-pyroxene granulite and amphibolite from Sidaolazihe Formation, and two-pyroxene granulite from Laoniugou Formation are 2565 ± 5.9 Ma, 2512 ± 17 Ma, and 2509.2 ± 8.6 Ma, respectively, with the metamorphic age recorded by amphibolite being 2475.6 ± 9 Ma. New geochemical data indicates that TTGs (tonalite-trondhjemite-granodiorite) weathering in an island arc environment formed the protolith of argillaceous gneiss of Sidaolazihe Formation. Basaltic andesite, formed under an island arc environment, was the protolith of garnet two-pyroxene granulite of Sidaolazihe Formation; while calc-alkaline basalt was the protolith of amphibolite from the same formation and two-pyroxene granulite from Laoniugou Formation. All these Archean supracrustal rocks exposed in the Laojinchang area have recorded nearly isobaric cooling (IBC) anticlockwise P-T paths with distinct prograde, peak and post-peak stages. The peak P-T conditions reached granulite facies, suggesting a heat source from underplated magmas. A tectonic model involving an island-arc setting is proposed for the evolution of these Neoarchean supracrustal rocks in Laojinchang area. [ABSTRACT FROM AUTHOR]

• Phosphatized stromatolites occurrences were controlled by depositional settings. • Depositional settings are more associated with currents and shallow environments. • The dolomitization model is associated with evaporated seawater and basinal brines. • Dolomitization and early phosphogenesis are intimately linked. • REY patterns support a restricted environment and continental influence on seawater. During the Precambrian − Cambrian transition, the occurrence of phosphogenesis and the rise in atmospheric oxygen levels are closely linked to the proliferation of life. However, the mechanisms associated with these phenomena and their underlying causes are not well understood. The Irecê Basin represents the remnants of intracratonic marine environments that document the Neoproterozoic sea flooding of West Gondwana. This study presents an integrated analysis of sedimentary facies and chemostratigraphy through high-resolution sampling of pristine limestones and dolomites from the Salitre Formation in east-central Brazil. The aim is to explore the relationship between environmental settings and phosphatized stromatolites by combining detailed facies descriptions with isotopic and geochemical data. A total of fifteen lithofacies types are identified and grouped into seven major facies associations. These associations reveal a depositional stacking pattern defined by flooding surfaces and transgressive–regressive cycles, allowing for the division of the Salitre Formation into two depositional sequences. The basal sequence includes sedimentary phosphorite deposits intimately associated with widespread dolomitization levels at the top. Here, we describe a combination of two major processes for the dolomitization model of the Salitre Formation, with a contribution of evaporative environment settings related to a sabkha, and the influence of a meteoric mixing zone. Furthermore, three stages of phosphogenesis have been identified, with two of them interpreted as early diagenetic deposition associated with stromatolites and early cementation, and the last one associated with a late stage of phosphogenesis. The combined analysis of REY patterns, 87Sr/86Sr ratios, and geochemical results suggests a significant continental influence on both dolomitization and phosphogenesis. The identification of depositional settings and stratigraphic patterns for these deposits is crucial for the understanding of phosphogenesis during the Ediacaran, which may have been influenced by the continentalization of the marine environments forced by the intracratonic marine setting and the tectonic evolution at the end of the Neoproterozoic Era. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Union Tin Member comprises pyroclastic rocks and shale-dominated sediments. • It is intercalated within the rhyolitic rocks of the Rooiberg Group. • The shale unit formed within a shallow-marine sedimentary environment. • The episodic emplacement of the Rooiberg Group led to a downsagged basin. • This basin represents the surface expression of a deep-seated large magma reservoir. The Union Tin Member, comprising a succession of pyroclastic and shale-dominated sedimentary rocks associated with the 2.05 billion-year-old Bushveld Large Igneous Province (LIP), is well-exposed particularly in the Union Sn field located 150 km north of Pretoria, South Africa. The Union Tin Member is a laterally extensive (>200 km-wide) marker horizon situated between the rhyolitic Kwaggasnek and Schrikkloof formations of the Rooiberg Group. The shale unit exhibits low total organic carbon (TOC) contents (168 ± 70 ppm) along with a narrow range of δ13C values (−27.7 ± 1.7 ‰) and δ15N values mostly around 0 ‰, resembling characteristics typical of marine shales. These siliciclastic sedimentary rocks were deposited in a shallow-marine sedimentary environment subjected to sea-level fluctuations, suggesting widespread submergence of the Kaapvaal Craton despite ongoing LIP magmatism. The whole-rock compositions, particularly rare earth elements (REE), Th, Sc, Zr, Ni, V and TiO 2 , indicate a provenance dominated by the underlying Rooiberg Group, which may also include the Paleoproterozoic Transvaal Supergroup, Archean tonalite-trondhjemite-granodiorite (TTG) suites and greenstones. Variable enrichments of the shale in Sn, Li, Cs, W and U are primarily associated with chlorite, sericite, illite and hematite. Notably, the rhyolites, immediately underlying and overlying the Union Tin Member, are similarly altered to a mineral assemblage dominated by the Fe-Al-Mg-bearing phases with relative enrichments especially in Sn. Alteration is linked to large-scale Sn-bearing hydrothermal fluids derived from the Lebowa Granite Suite. The periodic emplacement of extensive volcanic rocks of the Rooiberg Group is likely to have resulted in a downsagged >200 km-wide basin underlain by the Transvaal Supergroup. The deposition of the Union Tin Member within this basin could potentially represent the surface expression of a deep-seated, exceptionally large magma reservoir suggested to have contributed to the formation of the entire Bushveld LIP. [ABSTRACT FROM AUTHOR]

• The studied granitic gneisses show diverse geochemical characteristics. • The protoliths of gneisses have not experienced notable fractional crystallization. • The Xiaoqinling experienced a post-collisional extension in the early Paleoproterozoic. Although the early Paleoproterozoic global magmatism appears to be rare, the Taihua Complex within the Xiaoqinling terrane of the southern Trans-North China Orogen (TNCO) contains abundant evidence for magmatic and tectonic activities during this period. In this contribution, we present whole-rock geochemical and Sr-Nd isotopic data for the gneisses from the Taihua Complex within the Xiaoqinling terrane to investigate their petrogenetic processes, geodynamic setting, and provide a better understanding of the tectonic evolution in the southern margin of the TNCO. Based on their patterns of geochemical characteristics, the studied samples can be broadly subdivided into three groups. The Group-1 and −3 gneisses have relatively low Sr/Y ratios, and negative Eu anomalies, indicating plagioclase was a residual phase during partial melting, which requires relatively low pressure conditions. The majority of the samples in these groups have negative whole-rock εNd(t) values, indicating the magma source was mainly ancient crust. However, these Group-2 gneisses have moderate to high Sr/Y ratios, and high Mg#, which may related to mantle-melt interactions. This study shows that the protoliths of studied gneisses from the Taihua Complex within the Xiaoqinling terrane were probably formed by either partial melting of pre-existing arc lower crust or partial melting of the delaminated thickened lower crust and then interacted with the mantle components in a post-collisional extension tectonic regime, which is consistent with the global tectonic regime at this time. [ABSTRACT FROM AUTHOR]

• New localities in Canadian Cordillera bearing a −12‰ carbon isotope excursion. • Isotope conglomerate tests require syn-depositional origin of excursion. • Elemental analyses suggest the presence of an early-diagenetic fluid. • Excursion matches Wonoka and Gametrail Formations; we interpret to be Shuram CIE. • First deep-water record of Shuram on western margin of Laurentia. The Ediacaran Old Fort Point Formation in the southern Canadian Cordillera records a large, highly negative carbon isotope excursion, with a minimum in the δ 13 C values of marine carbonates of –12‰. Carbon isotope excursions are often interpreted to be broadly synchronous and to reflect shifts in the δ 13 C value of marine dissolved inorganic carbon, possibly reflecting either fluctuations in the global proportion of organic matter burial, or post-depositional diagenesis. As diagenesis can create large discrepancies between the original δ 13 C carb value of the sediment and what is preserved today, it is essential to determine to what extent diagenesis has impacted these records. We measured carbon and oxygen isotopes on eight stratigraphic sections (n = 360), carbonate clasts from debris-flow deposits from the Old Fort Point Formation (n = 968), and major and trace elemental abundances (n = 249). We used these geochemical datasets to investigate whether local processes leverage a larger control on carbon and oxygen isotopic values rather than global processes. We argue that the carbonate strata with the lowest δ 13 C carb values (∼ –12‰) are now calcitic but were neomorphosed from an aragonite precursor in a fluid-buffered, early diagenetic environment conducive to dolomite growth. Additionally, the recovery of the expressed excursion is preserved in carbonates that underwent early-marine diagenesis under more sediment-buffered conditions, with its geochemistry closer to the aragonite precursors. Tremendous variability, up to 17‰, is observed in δ 13 C carb values of clast populations from individual breccia horizons found in the in-fill of submarine paleocanyons, filled with material from underlying carbonates of the Temple Lake and Geikie Siding Members. The presence of such a large range of clast δ 13 C carb values requires an early acquisition of the observed Old Fort Point Formation δ 13 C carb values (pre-brecciation and submarine canyon incision) and precludes late-stage burial diagenesis. Moreover, despite disagreement with previously published geochronological constraints, we propose that the carbon isotope excursion recorded in the Old Fort Point Formation is equivalent to the widely studied Shuram excursion, the most negative carbon isotope excursion recorded in Earth history, and thus further geochronological work in the southern Canadian Cordillera is needed to test this proposition. [ABSTRACT FROM AUTHOR]

• Comparative geochemical and AMS study of three subswarms of 2.08 Ga dyke swarm. • Multiple magma pulses from a common source generating the 3 subswarms. • Revealing spatial variation in geochemistry and emplacement in a radiating swarm. • Inferences towards multiple concentric magma chamber around a central domal uplift. • Emplacement of 2.08 Ga dyke swarm to be the precursor to Proterozoic Cuddapah Basin. The ca. 2.08 Ga Devarabanda mafic dyke swarm in the eastern Dharwar craton exhibits a spectacular radiating geometry spanning 167˚. This study focuses on unravelling the intra-swarm variability in geochemistry and emplacement systematics across its three distinct sub-swarms designated as SS-1, SS-2 and SS-3, trending N, NW, and NE, respectively. Through an integrated study that includes whole rock geochemistry, anisotropy of magnetic susceptibility (AMS), and available geochronology and gravity data, we identify shared differentiation trends across all the sub-swarms, suggesting a common genetic linkage. While crustal influence is evident, the SS-3 displays relatively primitive geochemical signatures, the other two sub-swarms signify more highly differentiated pulses, indicating multiple magma pulses in the ca. 2.08 Ga dyke swarm. AMS analyses reveal lateral magma flow for SS-3, while vertical injection feeds the other two sub-swarms. Based on this study, we propose the role of a mantle plume for the formation of the three sub-swarms; SS-3 formed from a shallow crustal magma chamber during the pre-rift phase, due to a central domal uplift. Subsequently, SS-1 and SS-2 were emplaced at a later rift phase, where SS-2 was emplaced along a pre-existing NW-trending rift, and SS-1 formed during active rifting and crustal thinning. Evidence supporting an older NW-trending rifting event in the region corresponding to the SS-2 exposures was observed from available gravity data. The presence of discrete crustal magma reservoirs, separate for each sub-swarm, surrounding the domal uplift, explains the intervening dyke-poor areas, and suggests the formation of an apical graben as a precursor to the Proterozoic Cuddapah basin. [ABSTRACT FROM AUTHOR]

• Ca. 3.75 Ga gneiss developed a gneissosity prior to ca. 3.3 Ga. • Ferroan, calc-alkaline ca. 3.3 Ga granitoids formed by remelting of Eoarchean crust. • Ca. 3.3 Ga granitoids were intruded by ca. 2.7 granite and by 2.5 Ga granitic dyke. • The magmatic history of the Saglek Block is similar to that of the SW Greenland. The Saglek Block in the Nain Province of northeast Canada is part of the North Atlantic Craton. It comprises Archean gneisses that record magmatic and metamorphic ages between ca. 3.9 and 2.5 Ga. In this study, a grey banded gneiss from Maidmonts Island records an age of 3.72 Ga, which is equated with Uivak I gneisses reported from across the Saglek Block, and contains 3.8 Ga xenocrysts. These rocks were deformed and metamorphosed prior to the intrusion of augen gneiss protoliths on both Maidmonts and Mentzel islands that record U-Pb zircon ages of 3.33 Ga. These rocks are composed of ferroan calc-alkaline granite and granodiorite and were likely generated by partial melting of pre-existing quartzo-feldspathic crust, as attested by the presence of ca. 3.8 Ga xenocrysts. Such augen gneiss was previously classified as ca. 3.6 Ga 'Uivak II gneiss', a term we argue should now be abandoned. The final magmatic events recorded on Maidmonts and Mentzel islands took place in the Neoproterozoic with the emplacement of granitic stocks at ca. 2.72 Ga, and sills and dykes at ca. 2.57 Ga. This sequence of magmatic events from the Eoarchean to Neoarchean is very similar to that recorded in the Itsaq Gneiss Complex of southwest Greenland, where, based on the Hf signature, it has been suggested that a change in tectonic environment resulted from the initiation of subduction at ca. 3.2 Ga. Although Lu-Hf and Sm-Nd isotopic signatures from the ca. 3.33 Ga gneisses have been interpreted in the literature as due to partial melting of Hadean mafic crust, alternatively, they can be generated by partial melting of Eoarchean continental crust in a continental arc setting. We argue this is more consistent with the non-TTG geochemistry of the augen gneisses. [ABSTRACT FROM AUTHOR]

[Display omitted] • Clay mineralogy reflects climatic conditions before, during and after the Sturtian Snowball Earth glaciation. • Detrital and diagenetic illite is common across all three climatic intervals. • Predominance of detrital chlorite in the glaciogenic tillites plus weak chemical weathering of source rocks is consistent with strong continental erosion by melting ice sheets. • Detrital clay minerals modulated nutrient supply to marginal seawater across the Sturtian Snowball Earth glaciation. Recent evidence from marine sedimentary rocks suggests that clay minerals were important in the supply of bioessential nutrients to seawater at the end of the Sturtian Snowball Earth glaciation that occurred ∼ 717–660 million years ago. However, little is known about the identity of these clay minerals, their abundance and distribution in the pre-glacial, glacial and post-glacial deposits. Here, high resolution petrographic scanning electron microscopy-energy dispersive x-ray spectroscopy, combined with bulk and < 2µ clay-size fraction X-ray diffraction mineralogical analysis and trace and major element geochemistry, point to dominant enrichment of illite in shallow marine platform sediments preserved across Sturtian Snowball Earth facies on Islay and the Garvellachs Island, Scotland. The glacial till is enriched with detrital chlorite, while pore-filling authigenic kaolinite is observed in the pre-glacial and post-glacial greenhouse facies, but scarce in the glaciogenic tillites. Discriminant binary plots of Th/Sc vs Zr/Sc ratios, indicative of insignificant modification of primary sediment composition by hydraulic sorting and recycling processes, together with chemical weathering indices, point to moderate to intense chemical weathering of the pre-glacial and post-glacial source rocks. Low Chemical Index of Alternation (CIA) values, coupled to the distinct chlorite composition of the glacial till, is consistent with mechanical tillage of continental landmass by the terminal Snowball melting ice sheets. The moderate to intense chemical weathering indices in the pre- and post-glacial deposits correspond with greenhouse conditions of elevated atmospheric CO 2 content and temperature. Overall, the predominantly detrital origin of the clay minerals implies enhanced post-glacial nutrient supply bound to clay minerals in lower pH river water during transportation, followed by release in higher pH saline seawater. [ABSTRACT FROM AUTHOR]

• The volcanic rocks formed in an arc setting at 756-740 Ma. • The late Tonian arc in the Wuyi domain was part of a major arc system in the West Cathaysia terrane. • The Wuyi arc system was different from the arc system along the western margin of the Yangtze Block at the late Tonian. • The West Cathaysia terrane was distinct from the southeastern margin of the Yangtze Block and they were not amalgamated until after the late Tonian. The late Tonian tectonic setting of the West Cathaysia terrane in South China is highly controversial and is key to better understanding the timing of amalgamation between the Yangtze Block and the West Cathaysia terrane and the positions of these two terranes in Rodinia and Gondwana. A detailed field-based study was conducted on the petrology, zircon U-Pb geochronology and Lu-Hf isotopes, and whole-rock geochemistry of a series of Neoproterozoic meta-volcanic and meta-sedimentary rocks in the Wuyi domain in the northeastern West Cathaysia terrane. The results indicate that the meta-volcanic rocks formed in an arc setting at 756-740 Ma, and the meta-sedimentary rocks were developed in an arc-related basin with single zircon age peaks of 765-728 Ma. We propose that the late Tonian arc in the Wuyi domain was part of a major arc system in the West Cathaysia terrane. An arc setting for the West Cathaysia terrane is distinct from the continental rift setting for the southeastern margin of the Yangtze Block at the time, supporting an interpretation that the two terranes were not amalgamated until after the late Tonian and occupied separate positions in Rodinia. [ABSTRACT FROM AUTHOR]

• This work explores the roles of depositional and diagenetic processes that operated on an Archean carbonate platform. • Micro-analytical techniques (scanning XRF and LA-ICP-MS) were employed to investigate those controls on geochemistry. • Samples with proxies indicating the presence of free oxygen are the least diagenetically altered. • Rare earth elements and minor elements, e.g. Sr, Ba and Mn, were mobile during dolomitization. • The extent of diagenetic alteration was not apparent using only visual and microscopic examination. A plethora of proxies has been developed over the preceding two decades in attempts to investigate the geochemistry of the Archean ocean–atmosphere system, and in particular oxygen levels. Unfortunately the necessary parallel investigations of the effects that localized ocean chemistry and diagenesis can have on Archean sediments have commonly not kept pace. We used micro-analytical techniques (LA-ICP-MS and XRF scanning), to distinguish the effects of changes in water composition during precipitation and diagenesis on marine limestone precipitates at the margin and interior of a 2.8 Ga carbonate platform (Mosher Carbonate, Steep Rock Group) in western Superior Province, Canada. Platform margin meter-scale hybrid giant domes consist of centimetric interlayered couplets of (1) Sr-rich crystal fan fabric and cuspate fenestral microbialite, both with pronounced negative Ce-anomalies, and (2) net-like fenestral microbialite, rich in diagenetic cement with diminished concentrations of Sr and lacking negative Ce anomalies. The elevated Sr in the crystal fan fabric and cuspate fenestral microbialite is a general sign of less diagenetic alteration, as is preservation of millimeter-scale chemical differences. XRF mapping revealed that samples that otherwise appear pristine from a second site on the platform rim, near a zone of alteration in the limestone, have ferroan dolomite-filled micro-fractures with Mn flooding of the surrounding calcite and lack Ce anomalies. Platform interior silicified and ferroan dolomitized columnar stromatolites have some calcite laminae, but exceptionally low Sr contents indicate that they formed by dedolomitization. In several horizons REE patterns identical to those of offshore iron formation, replacement of calcite by iron carbonate, and the presence of iron oxides all suggest that short term flooding of the platform by offshore seawater episodically introduced ferroan dolomitizing fluids. Overall, these data indicate a restricted marine environment subject to periodic flooding by offshore waters that caused seafloor diagenetic alteration and precipitation of iron hydroxides. In this system the least altered limestone was the lithotype most likely to retain evidence of free oxygen. Samples with abundant phreatic cement and/or Mn alteration associated with micro-fractures were liable to have experienced REE mobilization. Detailed studies that integrate both depositional and diagenetic information are critical for the correct interpretation of geochemical data from sedimentary rocks. [ABSTRACT FROM AUTHOR]

• Calcite bodies (CBs) consistently appear within a marble band of the UHT granulite facies metamorphic terrain of the Highland Complex (HC) in Sri Lanka. • The trace element and isotopic compositions of the CBs show distinctions from typical mantle-derived carbonitites, but indicating crustal sources. • These findings suggest that the CBs should be derived from the crustal anatexis of marble. • The UHT metamorphism, along with the presence of CO 2 -rich fluids, likely facilitated the crustal anatexis of marble. The special calcite bodies (CBs) exposed within the ultrahigh temperature (UHT) granulite facies terrain in the Balangoda area of Sri Lanka preserve shreds of evidence for the generation of crust-derived carbonatite in the crust. The CBs are exclusively made up of massive calcites and appear as concordant bands extending tens of meters or as meso -scale isolated pockets hosting the massive dolomitic marble band. Various sizes of mafic and calc-silicate enclaves occur as rotated or tilted structures within the CBs. The contact between the CBs and the host marble is texturally and mineralogically gradational, while the contact between the enclaves and the CBs is sharp. The large-ion lithophile elements and rare earth element contents of the CBs show enrichment compared to the host marble, while depletion compared to typical carbonatites. Furthermore, the Sr content and C-O isotope values in CBs differ from those found in known carbonatites, hydrothermal carbonates, or metasomatic carbonates. We suggested that the crustal anatexis of marble should be hypothesized as the possible mechanism for the origin of the CBs. Microtexural evidence of the calcite grains shows indications of the melting of the host marble. The release of CO 2 -rich fluids from the collision and thrusting of HC over VC, or related metamorphic events, likely lowered the solidus of carbonates, triggering crustal anatexis of marble during UHT granulite facies metamorphism. The generated low viscous carbonate melt may have moved rapidly, resulting in a low degree of mixing of silicates and fragmentation and dislocation of enclaves. The results of the present study reflect the existence of anatexis of carbonates under extreme crustal conditions and provide a better understanding of the sources, migration paths and reservoirs of the carbon recycling processes. [ABSTRACT FROM AUTHOR]

• BIFs ores formed in a hydrothermal-related volcanic submarine environment. • BIFs deposited from seafloor hydrothermal fluids in partially oxidized seawater. • A mantle plume model explains the formation of the late Neoarchean Qian'an BIFs in NCC. The Neoarchean Qian'an BIF deposit in eastern Hebei, eastern North China Craton has attracted extensive attention of study in the last decades, but the genesis, e.g., Fe sources, metallogenic mechanism, as well as tectonic attributes of the BIFs remains highly disputed. Based on field investigations, microscopic observations and geochemical analysis, this study tries to unravel the source characteristics of ore-forming materials in the Qian'an deposit. The results show that the chemical compositions of the BIF ore samples are mainly composed of TFe 2 O 3 and SiO 2 , with minor Al 2 O 3 and TiO 2. The total trace element contents of the samples are relatively low. The PAAS-normalized REE distribution patterns of the ores show LREE depletion and HREE enrichment, with robust positive anomalies of Eu, Y and La. These characteristics indicate that the BIFs are attributed to dominant chemical precipitation originated from paleo-ocean with obvious volcanic hydrothermal contributions and minor clastic input. Their positive to no Ce anomalies and positive δ56Fe magnetite values unveil that the iron was precipitated at low oxygen fugacity. These results, in collaboration with evidence from previous lithological, structural geology, metamorphic P-T paths, geochemistry, geochronology and numerical modeling studies, support a mantle plume model to explain the complicated tectono-thermal processes, and the sources of BIFs in Eastern Hebei, eastern North China Craton. [ABSTRACT FROM AUTHOR]

• Late tectonic Archaean granites reflect the final melting and stabilisation of cratons. • Experimental studies show that melting TTG to form granite is implausible. • TTG sources need to be more potassic than expected to produce a granite melt. • Potassic TTGs are not primary melts of a basaltic source. • Potassic TTGs are melts of a silicified basalt/ crustally contaminated source. Late- to post-tectonic high-K granites are found in many Archaean cratons and are thought to be the product of a major, crustal-scale melting event in the underlying TTG crust leading to the stabilisation of the craton. However, despite the TTG melting model being an obvious explanation for the origin of late-Archaean high-K post-tectonic granites, experimental studies show that TTGs are insufficiently fertile to produce large volumes of potassic granites. This is the late Archaean granite paradox. Here we argue that the paradox can be resolved if the TTG protolith is more potassic than might be expected from a straightforward partial melt of an Archaean basalt. We propose that a likely fertile protolith for late Archaean granites is TTG crust which has incorporated a partial melt of older felsic crust during its emplacement. This hypothesis is validated with a case study from the Neoarchaean rocks of the Zimbabwe Craton. This paradox reflects a more fundamental problem when considering the origin of Archaean TTGs, for the 'enriched' basaltic protolith invoked in many models of TTG genesis is not abundant in Archaean terrains, nor should it be if the basaltic protolith is a melt of primitive or depleted mantle. This means that fertile, K-rich, TTGs are not simply the product of the melting of a basaltic protolith, but involve an additional process. Three models of TTG petrogenesis are discussed which might lead to K-enrichment in the melt – the hydrothermal potassic enrichment of the basaltic protolith and the influences of fractional crystallisation and/or crustal contamination on the TTG magmas. We conclude that to produce a sufficiently fertile, K-rich TTG source in the Zimbabwe Craton the contribution of a melt phase from older TTG crust is most consistent with the major and trace element and isotopic geochemistry. [ABSTRACT FROM AUTHOR]

The Duanfangxi appinite suite sourced from the asthenospheric mantle during the tectonic exchange from subduction to post-subduction in ca. 890–865 Ma. This tectonic translation recorded a complete Wilson Cycle in the northern margin of the Yangtze Block, indicated the staring construct of South China Craton. The new data for the Duanfangxi appinite suite suggests that the South China Craton was a collage of the main body of Rodinia during the early Neoproterozoic. [Display omitted] • The Duanfangxi appinite suite sourced from the asthenospheric mantle. • The Duanfangxi appinite suite recorded a complete Wilson Cycle in the northern margin of the Yangtze Block. • This new data suggests that the South China Craton link with the main body of Rodinia during the early Neoproterozoic. Appinite rock suites generally consist of bimodal mafic–silicic hornblende-bearing igneous rocks, mostly generated by post-subduction processes along ancient convergent plate margins. In this study, we investigated the Neoproterozoic Duanfangxi appinite rock suite from the south Kongling terrane, South China, which is key to understanding the tectonic evolution of the Yangtze Block and for the reconstruction of its association with Rodinia. Based on field observations, mineralogical and whole-rock geochemical analyses, the appinites are divided into the early Zhaibao and Yazikou and the late Taipingxi sub-series. Zircon U–Pb dating constrains the age of formation of the early Zhaibao and Yazikou and the later Taipingxi sub-series to 890–870 Ma and 870–865 Ma, respectively. The three successions are characterised by high hornblende, biotite, and Mg calc-alkaline compositions, and low Th, Nb, and Zr content. While the early sub-series is rich in large-ion lithophile elements, the late sub-series is enriched in high-field-strength elements. Collectively, the geochemical composition of the three rock units is typical of arc-related rocks, with slightly positive to negative ε Hf (t) values spanning 11.5 to –14.8 for the Zhaibao and –1.2 to –18.1 for the Yazikou sub-series, indicating an asthenospheric mantle source that interacted with subducted slab-derived fluids and hydrous melts. Together, the appinite suites suggest a switch from subduction to a post-subduction depositional setting between 890–865 Ma. Our results, supported by previous lines of evidence, indicate that formation of the northern margin of the Yangtze Block was associated with a complete Wilson cycle during the late Mesoproterozoic to early Neoproterozoic. [ABSTRACT FROM AUTHOR]

• The ca. 2.0 Ga Tiepu quartz monzonites are syn -collisional alkaline rocks. • The Tiepu quartz monzonites were derived from a mature crustal materials metasomatized lithospheric mantle. • The eastern part of Yangtze Craton had westward subducted beneath the western microcontinent during the ca. 2.0 Ga arc-continent collision. The Paleoproterozoic tectonic evolution of the Yangtze Craton associated with the assembly of the supercontinent Columbia is still greatly debated. In this study, we conduct an integrated study of zircon U–Pb ages and Hf–O isotopic compositions, as well as whole-rock major and trace elements and Sr–Nd isotope compositions for Tiepu alkaline quartz monzonite intrusion in the Hong'an orogen, northern Yangtze Craton. Zircon U–Pb dating yields intrusion age of 1993 ± 10 Ma for the Tiepu quartz monzonite, suggesting that it belongs to syn -collisional magmatism. The quartz monzonites have intermediate SiO 2 (53.52–60.38 wt%), but relatively high K 2 O (4.30–8.53 wt%), MgO (2.97–4.48 wt%), Cr (65.4–113 ppm), and Ni (49.2–87.4 ppm) contents and Mg# (43.7–54.9) values. They belong to alkaline series and are characterized by enrichment of large ion lithophile elements (LILEs) but depletion of high field strength elements (HFSEs). The quartz monzonites show ε Nd (t) of –7.27 to –3.82 and zircon ε Hf (t) of –9.8 to –8.6 and δ18O values of 6.63–6.99 ‰. These geochemical features suggest that the quartz monzonites were derived from an enriched lithospheric mantle source that had been metasomatized by mature crustal materials. The syn -collisional alkaline magmatism along with the ca. 2.0 Ga Huangtuling HT-HP granulites to the east provides further support for the westward subduction of the eastern part of the Yangtze Craton beneath the western microcontinent during the ca. 2.0 Ga arc-continent collision. [ABSTRACT FROM AUTHOR]

[Display omitted] • We focus on the oldest tin deposit in China using geology, geochemistry and geochronology methods; • Mineralization occurred between 851–844 Ma, corresponding to rift setting; • Sn-bearing granite is identified as originating from the reworking of Paleo- to Mesoproterozoic metasedimentary crust; • A high degree of differentiation is pivotal in facilitating the formation of tin-bearing granites; • This study highlights the significance of a metasediment-derived source and highly evolved, reduced, or ilmenite-series granitic magma in controlling the formation of granite-related Neoproterozoic tin mineralizations. The scarcity of Precambrian tin deposits in China has drawn significant interest to their formation. The Chahe tin deposit (26 Mt @ 0.38 % Sn), one of the oldest in China, provides a valuable opportunity to investigate the key factors controlling the development of such deposits. Situated along the western margin of the Yangtze craton in southwestern China, this deposit exhibits diverse mineralization types, including greisen cassiterite mineralizations located on top of the granitic cupola, skarn-cassiterite-axinite-quartz veins, and cassiterite-sulfide veins at the granite-limestone contact, and structurally controlled occurrences within siliciclastic metasedimentary rocks along secondary faults. Extensive U-Pb dating reveals that both barren and tin-bearing granites associated with the deposit share similar ages, ranging from 851 ± 4 Ma to 848 ± 4 Ma. These ages closely match, within error, the cassiterite U-Pb age of 843–853 Ma and the rutile U-Pb age of 859 ± 27 Ma for greisen veins/veinlets hosted in granite. Additionally, a cassiterite U-Pb age of 844 ± 9 Ma has been identified in the cassiterite–axinite–quartz veins hosted in the skarn. These findings provide direct evidence for the spatial, temporal, and genetic association of tin mineralization with Neoproterozoic Mosuoying granites. The granites in the region are categorized as peraluminous calc-alkali granites, characterized by high FeO, Ga/Al ratios, and zircon saturation temperatures, indicative of A-type granite features. In comparison to regional contemporaneous granites, the barren and tin-bearing granites exhibit high Rb/Ba and Rb/Sr ratios, variable ε Hf (t) values (–17.8 to + 3.1), and two-stage Hf model ages (T DM2) spanning from 2.6 to 1.5 Ga. These characteristics indicate a common source and origin through the reworking of Paleo- to Mesoproterozoic metasedimentary crust in response to the breakup of the Rodinia supercontinent. Simultaneously, they display low whole-rock Fe 2 O 3 /FeO and zircon Ce4+/Ce3+ ratios, consistent with those observed in typical Sn-bearing ilmenite-series granites globally. Notably, the tin-bearing granites manifest a highly fractionated nature, evident in their REE distribution patterns with a pronounced tetrad effect, as well as lower Nb/Ta and Zr/Hf ratios for twin elements. In summary, this study emphasizes the significance of a metasediment-derived source and the presence of highly evolved, reduced, or ilmenite-series granitic magma in the development of highly fractionated A-type granites associated with Neoproterozoic tin mineralization. These findings provide insights into the crucial factors controlling Neoproterozoic tin metallogenic events, shedding light on metallogenic processes and systematic exploration strategies for tin in Precambrian terranes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Quartz from different source rocks distinct geochemical features related to specific CL properties. • A statistically valid correlation exists between CL properties and geochemical features in detrital quartz. • A significant change on provenance during Marwar sedimentation is identified based on detrital quartz. • Combining detrital quartz and zircon could be effective in tracing specific sources and relative contribution. Quartz as one of the most stable minerals in sedimentary processes, is widely distributed in clastic sedimentary rocks, making it a potential provenance tracer in the source-to-sink system. In this study, internal morphology and trace element geochemistry of detrital quartz from the Marwar sandstones in NW India were utilized to decipher the source lithologies. Quartz from various source rocks displays distinctive trace element characteristics that correspond to specific cathodoluminescence properties. Phenocrystic quartz in hypabyssal and volcanic rocks is characterized by higher Li (>10 ppm), Al (>90 ppm), and Ti (>60 ppm) contents, medium to bright blue cathodoluminescences, and visible zoning. Quartz in plutonic rocks, especially diorite, contains a lower abundance of trace elements. It exhibits dark brownish red, violet to blue cathodoluminescence, and is marked by dark streaks, patches, and partial healing fractures. Pegmatitic quartz with the lowest Li (0.03 ppm) and the highest Ge (1.38 ppm) contents, displays brown to dark blue cathodoluminescences. Gneissic quartz with the highest Fe (3.98 ppm) and a moderate abundance of other trace elements, exhibits non-luminescence or dark brown to dark blue cathodoluminescence, occasional dark streaks, and healing fractures. Quartz in migmatites generally shows a lower trace elements abundance, non-luminescence, or dark brown to dark blue cathodoluminescence. A robust statistical correlation between the cathodoluminescence properties and trace element characteristics is discernible in the detrital quartz grains through the entire stratigraphy of the Marwar Supergroup, shedding light on the lithological and compositional make-up of the provenances. This study identifies that the early sedimentation in the Marwar basin was predominantly fed by detritus from the Neoproterozoic Malani Igneous Suite and Paleoproterozoic granitoids, whereas the younger strata document a marked increase in contributions from the older Aravalli Craton basement. Our findings demonstrate the utility of quartz trace element geochemistry and internal morphology as effective tools for provenance analysis in source-to-sink systems. Moreover, detrital quartz and zircon in combination can be effectively used in tracing the specific source and quantifying relative contributions from different source rocks that could be applied to provenance studies elsewhere. [ABSTRACT FROM AUTHOR]

• Post-Marinoan marine cements in Central Flinders Ranges record oxic conditions. • Regional transition from red to green shales appears to show Fe2+/Fe3+ redoxcline. • Earliest Ediacaran shales and carbonates show evidence of an oxygenation event. The first appearance of animals during the Ediacaran is arguably related to an increase in oceanic oxygenation during this time. However, there is considerable ambiguity in the global record of Ediacaran oxygenation, making it difficult to assess the potential links between oxygen and metazoan evolution. Here, we examine the earliest Ediacaran Nuccaleena Formation cap dolomite and basal Brachina Formation of the Adelaide Superbasin, South Australia, to determine the redox landscape in which these units were deposited. Red shales are present at the base of the Brachina Formation (lower Moolooloo Siltstone Member) over much of the Adelaide Superbasin but these transition laterally into green shales in the north, correlating with a facies transition into a deeper water setting. Fibrous dolomite cements within sheet cavities of the Nuccaleena Formation cap dolomite display evidence of a primary marine origin. Cathodoluminescence microscopy and laser ablation ICP-MS trace element analysis of these marine dolomite cements indicates a transition from an oxic environment in the south (with low Fe, Mn, and a Ce anomaly) to an anoxic (ferruginous) setting in the north (with high Fe, Mn and no Ce anomaly). This cap carbonate trace element geochemistry is spatially consistent with the overlying red to green shale transition in the basal Brachina Formation. Together, these data suggest the existence of a deep-water chemocline in this basin, separating an oxic upper water column from a ferruginous deeper water mass. This oxic interval directly post-dates the end-Cryogenian Marinoan Glaciation and is synchronous with an earliest Ediacaran oxygenation event previously described from South China. This evidence from the Adelaide Superbasin provides direct evidence for an earliest Ediacaran oxic water mass penetrating to a substantial paleodepth. The synchronous development of oxic intervals in both Australia and South China supports the notion of a globally developed oceanic oxygenation event and is consistent with the hypothesis that Ediacaran continental margin settings were periodically bathed in oxic water, conducive to the evolution of metazoans. [ABSTRACT FROM AUTHOR]

• Petrography, geochemistry, zircon U-Pb on Archean granitoids from the Chaillu inlier. • The granitoids include TTGs, sanukitoids, and potassic granites. • TTG magmatism between 3.02 and 2.92 Ga. • Coeval TTGs, sanukitoids, and potassic granites between 2.91 and 2.82 Ga. We present new geochemical and geochronological data for Mesoarchean to Neoarchean plutons of the Chaillu inlier of the Congo Craton that demonstrate an evolution of magma sources in relation with crustal growth. Four distinct plutonic suites were newly identified: (1) sodic low medium/high-pressure tonalite-trondhjemite-granodiorite, (2) Mg–K-rich monzogranite to monzodiorite (sanukitoids), (3) K-rich monzogranite–syenogranite, (4) K-rich granodiorite–monzogranite with medium/high-pressure TTG-like signatures. The TTGs are metaluminous to slightly peraluminous, silica-rich magmatic rocks (SiO 2 > 67.5 wt%) with high contents of Na 2 O (3.5 < Na 2 O < 6.2 wt%), and low contents of ferromagnesian oxides, and K 2 O contents (K 2 O < 2.6 wt%). The sanukitoids (s.l.) are metaluminous to slightly peraluminous, with a large range of silica contents (53 < SiO 2 < 69 wt%), high Mg# (42–74) and potassic with variable K 2 O contents (1.2 < K 2 O < 5.0 wt%). The high-K granites are slightly peraluminous, with high silica contents (SiO 2 > 67.7 wt%), low amounts of ferromagnesian oxides, and a clear potassic signature, with K 2 O contents (2.5 < K 2 O < 4.7 wt%), and K 2 O/Na 2 O ratios higher than 0.55. The zircon U–Pb dating results indicate that: i) TTGs emplaced between 3012 ± 16 Ma and 2840 ± 9 Ma; ii) sanukitoids between 2853 ± 14 Ma and 2832 ± 9 Ma; and iii) are K-rich biotite granites between 2893 ± 11 Ma and 2847 ± 16 Ma. Two main well-defined periods are identified: i) one of TTG-type magmatism between 3.02 and 2.92 Ga; and ii) one of sanukitoid-TTG-biotite granite-type association between 2.91 and 2.82 Ga. Such temporal evolution from TTG-domination through coexisting sanukitoids (s.l.) – TTGs – biotite granites during the late-Archean in the Congo Craton resembles other Archean cratons, such as the Dharwar, North China, Karelian, Superior Province, Pilbara, Kaapvaal, São Francisco and Amazonian. [ABSTRACT FROM AUTHOR]

• New petrographic and geochemical results of the Bingo alkaline-carbonatite complex. • First emplacement age of the Bingo ijolite using U-Pb titanite geochronology. • First direct age-dating of tropical lateritization via U-Pb geochronology of pyrochlore. This study presents petrographic, whole-rock geochemical, stable isotope (C-O) and U-Pb geochronological data for a suite of carbonatite, nepheline syenite and ijolite from the Bingo complex. The Bingo alkaline-carbonatite complex is located within the western branch of the East African Rift System (EARS) in the Democratic Republic of Congo (DRC). The carbonatites are petrographically classified into calcite and magnetite-calcite carbonatite but have similar geochemical compositions. The ∑REE vary from 960 to 2400 ppm and the La N /Yb N ratios fall within the spectrum of 20 to 145. Calcite stable isotope compositions, δ13C (V-PDB) (−3.51 to −3.87 ‰) and δ18O (V-SMOW) (+12.12 to + 13.70 ‰), plot within the primary igneous carbonatite field and therefore reflect carbonated mantle melts. Based on similarity of geochemical trends between the carbonatite and the alkaline silicate suite, such as negative anomalies in Th, Ta, Pb, Zr, Ti and positive anomalies in Ba, Sr, La and Nb, we suggest that carbonatite and alkaline rocks could have been generated from a carbonated mantle source through extensive fractional crystallization and liquid immiscibility processes. U-Pb titanite dating of the ijolite suggests an emplacement age of 861.5 ± 7.0 Ma during the Neoproterozoic era, consistent with carbonatite magmatism elsewhere along the western branch of the EARS (i.e., Lueshe and Upper Ruvubu Alkaline Complex). This timing is associated with the initial break-up stages of the Rodinia supercontinent, a significant geological event recorded in central Africa during the Neoproterozoic. Additionally, in-situ U-Pb pyrochlore dating of the carbonatite indicates an age of 48.13 ± 0.80 Ma, coupled with a low (radiogenic) 207Pb/206Pb ratio of 0.1554. We discuss three potential interpretations of this anomalous U-Pb age. Firstly, it could represent a primary magmatic crystallization age, implying carbonatite magmatism during the Eocene. A second interpretation is that the age indicates resetting of the U-Pb system due to hydrothermal alteration of the pyrochlore. Thirdly, the pyrochlore could have recrystallized during intense tropical weathering (lateritization). The first and second interpretation are deemed unlikely given the apparent petrogenetic and geochemical relationship between the silicate and carbonatite suites, as well as the fact that this age would predate any recorded rift activity within the western branch of the EARS. Furthermore, the low 207Pb/206Pb ratio points to a highly radiogenic reservoir that is incompatible with a magmatic-hydrothermal source. We thus consider the third option of supergene recrystallization of pyrochlore most likely, possibly from Nb, U and Pb rich fluids released from the overlying weathering profile. As such, supergene pyrochlore might offer a novel approach to determine the absolute age of tropical weathering affecting carbonatites. [ABSTRACT FROM AUTHOR]

• Craton-wide structural and geochemical data from main Yilgarn Craton shear zones. • Syn-orogenic shear zones reflect pulses of Neoarchean synmagmatic transpression. • Syntectonic granitic magmatism from upper-mantle and lower-crustal sources. • Synorogenic magmatism played a major role in shaping Yilgarn lithosphere. • Syn-orogenic shear zones played critical role in development of mineral systems. Between the Neoarchean and the early Proterozoic, plate tectonics was gradually established on our planet. How this transition took place, and what kind of geodynamic paradigm dominated before, is a matter of debate, and systematic multidisciplinary studies help improving our understanding of such a transitional period of Earth's evolution. The Yilgarn Craton of Western Australia exposes upper-crustal granite–greenstone terranes that are juxtaposed along large-scale, Neoarchean shear zones, which mainly developed during the 2730 – 2660 Ma Yilgarn Orogeny. By combining structural, microstructural and geochemical data, we present here a systematic study of the main shear zones occurring in the best-exposed, northwestern half of the craton. Our structural data demonstrate that large granitic magma sheets were emplaced during shearing. Although these shear zones exhibit a variety of fabrics that developed over a wide range of temperatures, all preserve memory of at least one stage of shearing at near-solidus temperatures. Our results allow tracing a c. 100 Myr-long tectonomagmatic evolution of this portion of the Archean crust, with implications for lithosphere rheology, crustal evolution, and mineral systems. The major synorogenic structures can be interpreted as inclined transpressional shear zones, along which the bulk of the 3D deformation was efficiently partitioned between greenstones and crystallizing granitic sheets within the shear zones, with the latter accommodating large amounts of orogen‐parallel strain through suprasolidus viscous flow. The positive feedback between protracted magmatism and transpression promoted the extraction and upward transfer of syntectonic magma originated between the uppermost mantle and the mid-crust, as demonstrated by our geochemical dataset. This synkinematic mode of granitic magma transfer contrasts fundamentally to the diapiric mode that was dominant during the lithospheric extension phase that pre-dated the Yilgarn orogeny. Our study suggests that the shear zone system studied here likely played a major role in controlling magma/fluid pathways throughout the late Archean lithosphere, therefore playing a critical role in controlling the development of near-surface mineral systems. [ABSTRACT FROM AUTHOR]

• A new robust U-Pb baddeleyite age of 1385 ± 5 Ma for Virei dyke swarm, Angola. • A new 1385 Ma paleomagnetic pole for Congo-São Francisco (CSF) craton. • A refined Nuna model with SW Congo / W Siberia cratonic connection at 1700–1500 Ma. The location of the Congo-São Francisco (CSF) craton, one of the largest cratons in Proterozoic paleogeography, has been poorly constrained for the supercontinent Nuna interval (ca. 1800–1300 Ma). Initial models of Nuna suggested that the CSF craton was part of the Atlantica continent, together with Amazonia, West Africa, and perhaps Río de la Plata, as a separate continental block from other Nuna constituents. In other Nuna models the CSF craton has been placed adjacent to Baltica and Siberia, the core of Nuna, based mainly on ages of mafic magmatism and sparse paleomagnetic data. Through a geochemical, geochronological and paleomagnetic study of the WNW-trending Virei mafic dykes, which extend outward from the Mesoproterozoic Kunene Igneous Complex in southwest Angola, we provide a U-Pb baddeleyite age of 1385 ± 5 Ma, geochemical signatures, and a robust Mesoproterozoic paleomagnetic pole to test the CSF craton's placement within Nuna. Including our new pole with quality-filtered poles from the other cratons during the Nuna interval, we propose a refined Nuna model with (1) southwest Congo / west Siberia cratonic connection at 1700–1500 Ma, (2) proximity of Amazonia and West Africa cratons, and (3) connection of southwest Congo craton with northwest West Africa at 1380 Ma. Our proposed 1500–1380 Ma reconstructions are further supported by matching large igneous province (LIP) records from these crustal blocks. The new 1385 Ma Virei pole, when considered relative to an earlier CSF pole at ca. 1500 Ma, requires substantial azimuthal rotation (∼85°) of CSF in the intervening time interval. To accommodate both the matching LIP records and paleomagnetic data from CSF and neighboring cratons in Nuna, we propose an interval of transform motion near the supercontinent's periphery prior to more widespread mid-Mesoproterozoic supercontinental breakup. [ABSTRACT FROM AUTHOR]

• The tholeiitic-komatiitic meta -mafic rocks were formed at ca. 3.3 Ga. • They were formed by partial melting of a depleted mantle associated with mantle plume activity. • The NCC underwent a substantial juvenile crustal growth event during the Paleoarchean. The geodynamic regime that governed the crustal evolution of Earth during the early Archean remains intensely debated. The North China Craton (NCC) preserves a geological history spanning 3.8–2.5 Ga, particularly in the Anshan area, making it an ideal natural laboratory for probing the formation and evolution of the NCC and its associated geodynamic regime. Here, we document new geochronology, geochemistry, and zircon Hf-O isotope data from newly discovered Paleoarchean meta -mafic rocks in the Anshan area. Based on their whole-rock geochemistry, these unit can be divided into tholeiitic and komatiitic series. Of which, the komatiitic rocks are characteristic by high MgO contents (up to 20.6 wt%). Zircon U-Pb dating shows that all meta -mafic rocks formed contemporaneously, with crystallization ages of ca. 3.3 Ga. Most of the studied meta -mafic rocks display radiogenic zircon Hf isotopes, with T DM 1 ages ranging from 3592 to 3346 Ma and ε Hf (t) values from −1.94 to + 3.49. They also exhibit mantle-like zircon δ18O values (+4.92 ‰ to + 5.98 ‰). These zircon Hf-O isotope data indicate that the protoliths of the ca. 3.3 Ga meta -mafic rocks originated from the partial melting of a depleted mantle without significant crustal contamination. Furthermore, the parental magmas of the komatiitic rocks and some of tholeiitic rocks were generated from 20 % and 5–10 % partial melting of spinel-lherzolite, respectively, whereas other tholeiitic rocks were the result of a low degree (1–5 %) of partial melting of spinel-garnet lherzolite. The ca. 3.3 Ga tholeiitic-komatiitic rocks were most likely formed in an intraplate rifting setting, associated with a mantle plume. [ABSTRACT FROM AUTHOR]

• The lower part of the Fengjiawan Formation contains abundant stromatolitic dolostones that possess well-preserved primary structures. • The depositional environment was an open shallow marine associated with a passive continental margin setting. • The stromatolitic dolostones are characterized by suboxic environment with minimal detritus contamination and weak post-depositional alteration. • Multiple depositional factors contributed to the growth and excellent preservation of the stromatolite-dominated microbialites. Stromatolites in the lower part of the Early Mesoproterozoic Fengjiawan Formation in the southern North China Craton (NCC) contain abundant microbial dolostones with well-preserved primary structures. This study comprehensively investigates the macromorphological, petrographical, mineralogical, and geochemical characteristics of these pure stromatolite-dominated microbialites for the first time. The results reveal diverse macromorphological structures distributed from the bottom to the top as conical (lower intertidal to upper subtidal zones), hemispherical domal (lower supratidal zone), spherical domal (upper to middle intertidal zone), and more abundant columnar (upper to middle subtidal zone) stromatolites. The mineral composition of these stromatolites indicates that they are pure dolostones, predominantly consisting of dolomite (avg. 94.24 wt%). These stromatolite-dominated microbialites were subjected to minimal detrital contamination and weak post-depositional alteration as documented by different geochemical multiproxy evaluations. This indicates that they have effectively retained the composition of the seawater in which they were initially formed. Geochemical indicators, such as Y/Ho, La/La*, Gd/Gd* and Ce/Ce* strongly suggest deposition of the stromatolites in an open shallow marine environment characterized by a passive continental margin setting. Different elemental ratios, such as Ce/Ce*, Mo EF , U EF , Mo EF /U EF , imply the stromatolites formation under a suboxic redox environment, where the photosynthesis of cyanobacteria likely played a significant role in the slight oxygenation of the seawater during their formation. These oxygenation levels decreased as water depth increased, with more nutrient supply promoting from deeper waters. The formation and growth of the stromatolite-dominated microbialites were significantly influenced by various depositional conditions, including sea level fluctuations, biological processes, suboxic redox environment, low detritus contamination, and weak post-depositional alteration. These conditions all contributed to the excellent preservation of the Fengjiawan Formation stromatolites, providing valuable insights into deep time microbial carbonates. [ABSTRACT FROM AUTHOR]

• Paraná Basin exhibits a mixture between quartzose detritus and mafic contributions. • The Ribeira Belt is the primary sedimentary source for the pre-Carboniferous strata. • The Iapó Formation received contributions from Archean plagioclase-rich sources. A provenance study through petrography, whole-rock geochemistry, and zircon U-Pb-Th and Lu-Hf systematics suggests that the lowermost strata of the Paraná Basin (460–380 Ma) record a recycled orogen provenance with mixing trend between mature polycyclic quartzose detritus and mafic/intermediate contributions. Sources with felsic compositions are indicated by the Lower Paraná Group, as it is suggested by the relative enrichment of Zr/Y, Th/Sc, and Y/Sr ratios. Meanwhile, the Iapó Formation received additional contributions from Archean mafic/intermediate plagioclase-rich sources (Eu* = 0.81). The Tonian juvenile (900–800 Ma) detrital zircon population from the Pre-Carboniferous strata with εHf(t) ranging from +3 to +11, in additional, late-Tonian population with an important crustal component (εHf(t) ranging from −12 to −8), provide evidence that the Ribeira Fold Belt constitutes the primary sedimentary source for the lowermost strata. Juvenile early-Tonian (950–900 Ma) and middle-Tonian (810–750 Ma) detrital zircon population suggests an additional provenance derived from the São Gabriel Domain, located at the southern border of the basin. Late-Ediacaran to early-Cambrian detrital zircon population suggest sources from the Eastern Pampean Range whereas a restricted detrital zircon population younger than 500 Ma with εHf(t) signatures ranging from 3 to −32, is consistent with a provenance from the Famatinian magmatic arc and associated rocks. In contrast to the detrital zircon population from the Pre-Carboniferous strata, the Itararé Group (∼310 to 298 Ma) reveals juvenile Ordovician sources (εHf(t) ranging from −2 to +2) and a restricted population encompassing both evolved and juvenile sources with a "Grenvillian" signature. [ABSTRACT FROM AUTHOR]

• Geochemical subdivision of mafic-intermediate volcanic rocks based on immobile element ratios. • Blake River Group geochemical diversity is mostly caused by crustal interaction with TTG-like contaminant. • VMS deposits in the Blake River Group show a potential relationship with crustal assimilation. • Composition of mafic to intermediate volcanic rocks has potential for VMS vectoring. Volcanogenic massive sulfide (VMS) deposits, prevalent since the Archean, constitute a well-explored ore deposit type. Nonetheless, the factors contributing to variations in fertility among volcanic centers, assemblages within greenstone belts, or entire greenstone belts remain unclear. For instance, the Blake River Group (BRG) of Ontario and Quebec, Canada, hosts almost half of the total VMS tonnage of the entire Abitibi greenstone belt, yet represents less than 10 % of its map surface. This study utilizes a large dataset (n = 2271) of whole-rock geochemistry for mafic to intermediate volcanic rocks to understand the BRG petrogenesis, and its implications for VMS endowment in the Abitibi. Principal Component Analysis shows that Ti, Th, and Yb are the primary contributors to the dataset's variation. This yields a two-ratio diagram (Th/Yb versus Zr/Ti) revealing seven geochemical groups with coherent map patterns referenced as tholeiitic basalts, tholeiitic intermediate rocks, medium-Th basalts, transitional intermediate rocks, high-Th basalts, calc-alkaline intermediate rocks and low-Zr basalts. A least altered subset of the data is used to analyze major element patterns. BRG mafic to intermediate magmas show variable degrees of Fe-Ti enrichment/depletion during their evolution, with simultaneous Al 2 O 3 depletion or lack thereof. Utilizing a single parental mafic tholeiitic magma, the Magma Chamber Simulator enables the modeling of major and trace element compositions for each geochemical group. Fractional crystallization (FC) models with variable initial water contents can explain the range of the tholeiitic basalt and tholeiitic intermediate compositions. Assimilation fractional crystallization (AFC) models successfully replicate most of the geochemical groups using a TTG average composition for the assimilant. While mafic-intermediate host rock geochemical signatures are not the sole factor influencing VMS endowment in volcanic belts, regional analysis reveals that the vast majority of volcanic rocks in geological formations bearing VMS deposits in the BRG are crustally contaminated lacking tholeiitic geochemical groups. Conversely, poorly endowed formation consistently contain samples from these groups. Moreover, the Bousquet formation, which hosts several world-class gold-rich VMS deposits, displays the highest rates of crustal assimilation, further suggesting that petrogenesis of mafic-intermediate volcanic rocks is linked to VMS metallogenesis in the BRG. [ABSTRACT FROM AUTHOR]

• Metapelites of the Fenzishan Group were formed in a back-arc basin of an active continental margin. • Three age groups of detrital zircon: ∼ 3019–2816 Ma, 2761–2610 Ma and ∼ 2261–2128 Ma. • The minimum depositional age of metapelite precursor is ∼ 2261 – 2128 Ma. • Apatite U-Pb age ∼ 1923 – 1893 Ma reflects to the post peak collisional metamorphism. • Metapelites record the UHT metamorphism, showing an anticlockwise P-T path. Metapelites from the Fenzishan Group of the Zhengjiapo banded iron formation (BIF) iron mine studied have undergone high-pressure and ultrahigh-temperature (UHT) metamorphism. The rocks occur in the Changyi metallogenic belt that belongs to the Jiaobei terrane, Jiao-Liao-Ji Belt, North China Craton. P-T estimates using pseudosection modeling, mineral compositio isopleths and two-feldspar geothermometry of observed mesoperthite and antiperthite intergrowth textures of Bt-Grt-Mag-Amp gneisses, three different metamorphic stages were obtained: A prograde stage M1 at ∼ 600–610 °C/5.5–6.1 kbar, a peak metamorphic stage M2 at ∼ 899–1062 °C/8.6–9.15 kbar, an early retrograde stage M2́at 780–792 °C/8.6–9.15 kbar and a retrograde decompression stage M3 at 466–493 °C/4.5–5.8 kbar. Thus an anticlockwise trajectory can be defined indicating that granulite facies UHT-metamorphic peak conditions have been reached, followed by fast cooling during rapid exhumation. Geochemical characteristics of the metapelites indicate that the Fenzishan Group of the Zhengjiapo BIF iron mine was formed in a back-arc basin system of an active continental margin in a convergent/collisional geological setting.. Magmatic U-Pb ages (LA-ICP-MS) of detrital zircon from metapelites are ∼ 3096 – 2816 Ma and 2761 – 2610 Ma, indicating a source of the Archean basement which delivered clastic material for pelitic protolith. A zircon age of ∼ 2261 – 2128 Ma constrains the minimum depositional age of the metapelitic precursor, while an apatite U-Pb age of ∼ 1923 – 1893 Ma dating demonstrates a metamorphic age of ∼ 1923 – 1893 Ma, is indicated to represent a late Paleoproterozoic post peak metamorphic event that corresponds to the collision of the Jiao-Liao-Ji orogenic belt. [ABSTRACT FROM AUTHOR]

• SIMS U-Pb zircon analyses display the Fanjingshan leucogranite formed at ca. 812 Ma. • W-Sn dominant mineralization is temporally and genetically linked with granitic magmatism. • The Fanjingshan leucogranites produced by crustal remelting marked the latest stage of the Jiangnan Orogeny. The Jiangnan Orogen in China host large volumes of Neoproterozoic igneous rocks and is a well-preserved Neoproterozoic orogenic belt in the South China Block. A series of W–Sn mineralization occurrences and ore deposits are spatially related to Neoproterozoic granites in the orogen. However, the geochronology and petrogenesis of the host Neoproterozoic granites and associated W–Sn mineralization in the western Jiangnan Orogen remain poorly understood. In this study, the U–Pb ages of zircon, cassiterite, and apatite, and the geochemistry of minerals and whole rock of the Fanjingshan (FJS) leucogranites, which are located along the western margin of the Jiangnan Orogen, were used to re-evaluate the Neoproterozoic magmatism that occurred in response to the orogeny and the mechanism of W–Sn mineralization. The FJS leucogranites consist mainly of strongly peraluminous tourmaline–muscovite granites. The leucogranites have a characteristic magmatic and hydrothermal mineral assemblage, including cassiterite, tourmaline and fluorite. Zircon U–Pb dating indicates the leucogranites were emplaced at ca. 812 Ma, which is consistent with apatite U–Pb age. Cassiterite U–Pb dating yields an age of ca. 810 Ma, suggesting the mineralization was coeval with the crystallization of the FJS leucogranites. In multi-element variation diagrams, all samples display sea-gull-shaped rare earth element patterns with significant negative Eu anomalies. The whole-rock geochemical data suggest the leucogranites originated by muscovite dehydration melting of a metasedimentary source. Extensive fractional crystallization and magmatic–hydrothermal interactions, as inferred from extremely low rare earth element contents, low Nb/Ta and Zr/Hf ratios, and a large tetrad effect, lead to the W–Sn enrichment and crystallization of ore minerals, such as cassiterite and scheelite. The compositions of muscovite, apatite, cassiterite and tourmaline, along with the occurrence of quartz veins, also provide information on the nature of the magmatic–hydrothermal processes and mineralization. Our data and those for other S-type granites (840–800 Ma) in the western Jiangnan Orogen, suggest that magmatic–hydrothermal processes had a key role in W–Sn mineralization. The Neoproterozoic FJS leucogranites likely formed in an extensional setting during the final stage of orogenesis. [ABSTRACT FROM AUTHOR]

[Display omitted] • Northern Chah-Farsakh is hosted by Neoproterozoic-early Cambrian mafic (basaltic andesitic)-siliciclastic rocks. • Leaching of the footwall volcanic rocks are the primary sources of metals in this deposit. • The Northern Chah-Farsakh Cu-Zn deposit is a well-preserved mafic-siliciclastic type (Besshi-type) VMS deposit. Northern Chah-Farsakh is the first seafloor VMS described in the Torud-Chahshirin metallogenic belt of Iran. The deposit is hosted by Neoproterozoic-Early Cambrian mafic (basaltic andesitic)-siliciclastic rocks in volcano-sedimentary basin. The evolution of the ore-bearing basin is governed by the Proto-Tethys Oceanic crust subduction beneath the Central Iranian microcontinent. Three ore facies can be distinguished based on the ore textures studies: stringer zone ore facies, massive-replacement ore facies, bedded ore and distal facies. Pyrite, chalcopyrite, magnetite and sphalerite are the main minerals, together with minor amounts of pyrrhotite, bornite, tetrahedrite and tennantite. Textures include laminated, banded, replacement, massive, and vein-veinlet texture. There is a distinct metal zonation in the massive sulfide orebody; Gold, Ag, and Zn contents increase vertically from the stringer to the bedded ore facies; Cu and Co increase in the massive ore facies, and Pb is highest in the stringer zone. Ore mineralization in the Northern Chah-Farsakh deposit has emplaced in two stages. The fine-grained ore bands (stage 1) which are intricately interlayered with host rock beds, exhibit sedimentary structure such as laminae and bedding are consistent with a syn -sedimentary origin. Coarser-grained stage 2 ores have massive and vein-veinlet textures that are considered to form by replacement during sub-seafloor fluid flow. Based on SEM-EDS analysis, significant compositional variations were observed in the Py-1b grains. Py-1b is enriched in Pb compared to Py-1a. The elemental distribution map shows that the chalcopyrite (Cpy-2) minerals in Northern Chah-Farsakh deposit do not have variable composition and are homogeneous. Fluid inclusions in quartz minerals rom the footwall stringer zone have trapping temperatures between 203 and 500 °C with salinities (3.39–16 wt% NaCl equiv.) higher than modern seawater. Fluid inclusion studies suggest that the ore-forming fluids were derived from seawater. High level of Se in the massive ore facies of the Northern Chah-Farsakh supports the formation of mineralization from a high-temperature hydrothermal fluid. The Northern Chah-Farsakh Cu-Zn VMS deposit typify the mafic-siliciclastic type (Besshi-type), where the majority of the host stratigraphy is composed of a mafic flow-volcaniclastics and sedimentary rocks. [ABSTRACT FROM AUTHOR]

[Display omitted] • - Ediacaran sediments in the northern Tarim display abrupt provenance changes from bidirectional to single resource. • - Northern margin of the Tarim block was involved in protracted subduction process during the Neoproterozoic. • - Back-arc rift basin in the northern Tarim eventually evolved into a passive margin with the opening of the Southern Tianshan Ocean. In the Neoproterozoic era, the breakup of the Rodinia supercontinent had a profound impact on different aspects of Earth; yet, the precise driving mechanism behind this event has been a source of ongoing controversy. The Tarim block, as a crucial component, presents an opportunity to gain valuable insights into the breakup process through its tectonic-sedimentary evolution history and dynamic background. However, the comprehension of basin evolution is limited due to the presence of an ambiguous prototype basin during the late Neoproterozoic and its intricate interconnections with surrounding blocks. In this contribution, we integrate detailed field observations, U-Pb dating of detrital zircon and rutile, and trace element analysis of detrital rutile to elucidate the source-to-sink relationships and the tectonic setting of Ediacaran sedimentary strata in the Aksu area (northern Tarim block, China). Detrital zircon age spectra exhibit consistent distributions with ages between ∼ 850 and ∼ 600 Ma and between ∼ 2100 and ∼ 1800 Ma. Rutile age groups however exhibit an abrupt transition between the lower member of the Sugatbrak Formation and the succeeding upper member to the Qigebrak Formation in the basin, with ages between ∼ 1800 and ∼ 900 Ma and nearly identical to those between ∼ 2100 and ∼ 1800 Ma. Calculated Zr-in-rutile temperatures and Cr-Nb compositions imply that the majority of the detrital rutiles were sourced from amphibolite facies metapelites, with an abrupt transition from amphibolitic schist to amphibolite-granulite facies for the ∼ 1800 Ma group grains. Provenance tracing shows that the detrital sediments of the lower Sugatbrak Formation are sourced from both the Central Tianshan and the Tarim blocks, and that the overlying strata have a single source in the Tarim block. A corresponding change from syn -rift detrital facies to a shallow-marine environment in on a passive continental margin is suggested in terms of depositional setting. In light of prior published evidence from petrology, geochronology and paleomagnetism, we propose that the Neoproterozoic northern Tarim margin was affected by a protracted subduction zone retreat. Associated back-arc spreading eventually was responsible for the opening of the southern Tianshan Ocean and rifting of the Central Tianshan block from the Tarim block in the late Ediacaran. This development ultimately prevented detrital material from the Central Tianshan block from reaching the northern Tarim depocenters as the latter evolved into a passive continental margin. [ABSTRACT FROM AUTHOR]

• Sedimentology and geochemical analysis were performed for the inter-diamictite black sediments in the Ediacaran Talisayi Formation. • The inter-diamictite sediments were formed during a short-lived partial deglaciation with enhanced weathering. • The inter-diamictite sediments were deposited under a benthic environment with microbial mat substrates. • Diverse organic-walled microfossils were found in inter-diamictite sediments. • The inter-diamictite sediments represent isolated shallower refugia during a major glaciation. The Ediacaran glaciation has garnered considerable attention for its potential biological impact because it witnesses the birth of complex animals. Many researchers question whether large-scale regional or even global glaciations, represent critical barriers to the evolution of macroscopic animals. So how did complex animals survive during a major glaciation? One possible explanation is the existence of isolated shallower refugia or ice-free oases. However, the sedimentary evolution of such ice-free oases and how they could support the survival of complex life forms are not yet fully understood. This study focuses on the inter-diamictite black sediments in the Ediacaran Talisayi Formation of NW China (Yili block), which may represent a habitable ice-free oasis during the Gaskiers glaciation. The sedimentary facies and geochemical analyses indicate that these deposits were formed in oxygenated and photic shallow glacier lake environments with highly developed microbial mat substrates, it was formed during a short-lived partial deglaciation with enhanced weathering. And diverse organic-wall microfossils were found within the inter-diamictite black sediments. Furthermore, based on the growth habits of modern microbial algal mats, a paleontological clock can be established to estimate the duration of partial deglaciation, which may have lasted only for thousands of years. The ice-free oasis formed during this period could potentially harbor complex ecosystems, providing valuable ecological and temporal windows for the evolution of complex animals. [ABSTRACT FROM AUTHOR]

• Sedimentation of BIFs in the Girar and Mauranipur belt occurred in the Mesoarchean. • Sedimentation of BIFs in the Babina belt occurred in the Neoarchean. • There was availability of free oxygen at least since the Mesoarchean. • BIFs had inputs from seawater, hydrothermal sources and pre-existing crust. In this study, we present major and trace element concentrations, U-Pb zircon geochronology as well as neodymium isotopic compositions of the banded iron formations (BIFs) from the Bundelkhand Craton, India. The study aims to constrain the source characteristics, depositional age and evaluate the paleoenvironmental implications of the Meso-Neoarchean seawater from which the BIF precipitated. The presence of a 2898 ± 26 Ma rounded zircon grain in the Girar BIFs indicates their maximum depositional age, which is consistent with the reported age of the metabasalts (2989 ± 190 Ma). Bearing in mind the errors, we consider the age of the studied BIFs to be ca. 2850 Ma. The BIFs from Mauranipur are associated with 2810 Ma dacite and formed at the same time. They have zircon with ages of 2718 ± 22, 2573 ± 66, 2070 ± 29 and 1934 ± 39 Ma. The BIFs from Babina are associated with 2540 Ma felsic volcanics and can be considered of the same age. Our study shows that the sedimentation of BIF in the Girar and Mauranipur greenstone belts took place in the Mesoarchean between ca. 2850 and 2810 Ma, respectively, and in the Babina greenstone belt in the Neoarchean at ca. 2540 Ma. A positive correlation between TiO 2 and Zr, Al 2 O 3 and Zr, Zr and Th/U, Y and Zr, Ni and Cr, as well as Hf and Zr, may suggest a detrital component to the BIF derived from terrigenous mafic and felsic sources. The PAAS-normalized REE patterns of the Bundelkhand BIFs are characterized by depleted LREEs, positive La, Eu, Y anomalies and Y/Ho ratios mostly ranging between 18 and 47. The studied BIFs are broadly similar to worldwide BIF occurrences at the time with the exception of the Mauranipur BIFs, which show elevated MnO concentrations (0.92 to 4.82 wt%). The studied BIF samples from the Bundelkhand Craton display a wide range of εNd(t) ranging from −6.57 to + 4.12. The broad range of isotopic values along with the above-noted geochemical signatures suggest that the BIF from the Bundelkhand Craton had significant inputs from submarine hydrothermal sources as well as pre-existing continental crust. The elevated manganese concentrations in BIFs from Mauranipur may imply the availability of free oxygen in seawater on the Bundelkhand Craton during the Mesoarchean. [ABSTRACT FROM AUTHOR]

• Three episodes granitic magmatism at ca. 1420 Ma, ca. 900 Ma and 780–750 Ma were identified in drill cores from the Qaidam basin. • Ca. 1.8–1.1 Ga, 1.0–0.9 Ga and 850–750 Ma three tectonic-thermal events of the Qaidam block correspond to the fragmentation of Columbia and the assembly and breakup of Rodinia. • The Qaidam block and Tarim craton likely constituted a unified block, and located at interior of Columbia but peripheral of Rodinia during Meso–Neoproterozoic. As a micro-continent lying at the junction of the North China, Yangtze, and Tarim Cratons in northwest China, the composition and tectonic-thermal history of the Qaidam Block not only are crucial for determining its tectonic attribute and relationships with surrounding cratons, but also can provide key constraints on convergence, fragmentation, and paleogeographic reconstruction of Columbia and Rodinia. In this study, systematic petrology, geochemistry, and zircon U–Pb–Hf isotope analyses were conducted on newly discovered Meso-Neoproterozoic granitic rocks from drill cores in the Qaidam basin and three stages granitic magmatism at ca. 1420 Ma, ca. 900 Ma and 780–750 Ma are yielded. The ca. 1420 Ma granitic rocks exhibit characteristics of highly fractionated I-type granites, with high Yb but low Sr contents, low Sr/Y and La/Yb ratios, high zircon saturation temperatures (774–831 ℃), and positive ε Hf (t) values (–0.04 to +11.35) with T DM2 values of 2178–1468 Ma, suggesting that they were mainly derived from the ancient crust with mantle magma input under an extensional setting. The ca. 900 Ma granitic rocks have high A/CNK values (1.01–1.21) and variable zircon ε Hf (t) values (–1.93 to + 6.58) with T DM2 ages between 1402 and 1910 Ma, indicating they are S-type granites formed by partial melting of sedimentary rocks in thickened crust. The ca. 780–750 Ma granites have high Zr + Nb + Ce + Y contents, 10000* Ga/Al ratios, and crystallization temperatures (mean = 808 ℃), belonging to the A 1 -type granite formed in a continental rift setting. Combined with the previous researches, the Meso-Neoproterozoic tectonic-thermal events in the Qaidam Block can be divided into three stages, 1.8–1.1 Ga, 1.0–0.9 Ga and 850–750 Ma, corresponding to the fragmentation of Columbia, and the assembly and breakup of Rodinia, respectively. Comparing the Qaidam Block with the surrounding blocks and the major cratons in Columbia and Rodinia, it is considered that the Qaidam Block was splited from the Tarim Craton and they may have occupied an interior position in Columbia but a peripheral position in Rodinia, connecting to the India and East Antarctica. [ABSTRACT FROM AUTHOR]

• The most ancient source rock in South China was evaluated comprehensively. • A spatial distribution pattern of interglacial Datangpo Formation has been established. • The OM enrichment of the Datangpo Formation is associated with hydrothermal activity and terrigenous nutrients. The organic-rich Datangpo Formation was deposited between Sturtian and Marinoan glaciations during the Cryogenian in South China. As a set of source rocks with great petroleum exploration prospect, it is important to understand how the glacial ocean transformed into a favorable condition for organic matter (OM) accumulation for evaluating its hydrocarbon potential. Here, the organic and inorganic geochemical data were tested, and the lithological and geochemical data were compiled to study the spatial distribution and OM enrichment of Datangpo Formation. The Datangpo Formation is a set of good quality (average total organic carbon (TOC) content = 1.83 %), sapropelic OM type (light organic carbon isotopes (δ13C org) and overmature source rocks (average solid bitumen Raman spectroscopy equivalent vitrinite reflectance (R equ) = 4.28%). The areas of thickest source rock are located in the Xiushan and Tongren, and spatial distribution was controlled by rift activity and the erosion by the Marinoan glaciation instead of the remnant glacial topography of the Sturtian glaciation. The OM enrichment of Datangpo Formation was controlled by anoxic/euxinic water condition, high sedimentary rate, and high productivity. The primary productivity in interval Ⅰ and Ⅱ was promoted by hydrothermal nutrients continued since late Sturtian glaciation and few terrigenous nutrients, and terrigenous nutrients of continental weathering during greenhouse period, respectively. [ABSTRACT FROM AUTHOR]

• TTGs were formed by melting of garnet-amphibolite in a subduction–related setting. • Granitic vein intruded into TTG gneisses was formed by in–situ anatexis of the TTGs. • Tarim Craton was composed of discrete terranes before the late Paleoproterozoic. The Archean–Paleoproterozoic basement rocks, exposed in the Xingdi region of the Quruqtagh Block, provide a great opportunity to characterize the early crustal evolution of the Tarim Craton and reconstruct the Columbia supercontinent. Here we report zircon U–Pb ages, Lu–Hf isotope compositions, and bulk-rock geochemical data of orthogneisses and granitic veins from the Xingdi region of the Quruqtagh Block in the northeastern margin of the Tarim Craton. The orthogneisses formed in the late Neoarchean to early Paleoproterozoic (2504 ± 33 Ma, 2419 ± 24 Ma and 2450 ± 27 Ma), and were metamorphosed in the late Paleoproterozoic (1789 ± 43 Ma and 1748 ± 35 Ma). The orthogneisses have relatively high Sr (312–710 ppm) contents, and low Y (5.3–13.8 ppm) and Yb (0.46–1.10 ppm) contents, resulting in high Sr/Y (32–118) and La/Yb (17–64) ratios that are characteristics of adakites. The relatively high Mg# (49–55) and depleted zircon Hf isotope characteristics (positive εHf(t), with T DM2 of ca. 2.5–2.8 Ga) indicate that the orthogneisses crystallized from partial melting of garnet-bearing amphibolite in a subduction environment. The granitic veins that intrude the orthogneisses formed during the late Paleoproterozoic (1760 ± 25 Ma), which is roughly contemporaneous with the metamorphic ages of the orthogneisses; the granitic veins are characterized by extremely high SiO 2 (>80 %), enrichments in Rb, Ba and U, and depletions in Nb and Ta. It is inferred that the granitic veins formed by in situ anatexis of the orthogneisses during the late Paleoproterozoic. Based on the zircon ages with Hf isotope compositions, it is evident that the continental crust in the Xingdi region of the Tarim Craton largely formed between 2.5 and 2.8 Ga and was reworked at ca. 1.8 Ga; this evolutionary history is similar to that of the Dunhuang Block. Comparison of the Paleoproterozoic tectono-thermal events in the different terranes of the Tarim Craton, it is suggested that the Tarim Craton is composed of discrete terranes that detached from different ancient cratonic nuclei prior to the late Paleoproterozoic, and assembled within the Columbia supercontinent respectively. [ABSTRACT FROM AUTHOR]

• Calc-alkaline shoshonitic lamprophyre at Dharwar craton-Southern Granulite terrane boundary. • U-Pb titanite SHRIMP-II dating yielded a Tonian age of 820 ± 15 Ma. • Sr and Nd isotopes suggest the derivation from an enriched lithospheric mantle source. • Involvement of large-scale rifting, associated with the break-up of Rodinia, • Implications for India-South China Block paleoposition during Neoproterozoic. We present petrology, U-Pb titanite geochronology, bulk-rock and Sr-Nd geochemistry of an undeformed and unmetamorphosed shoshonitic lamprophyre (spessartite) from the Mysuru area (Halaguru- Harohalli alkaline province) located approximately 80 km north of the tectonic contact between the Western Dharwar Craton and the Southern Granulite Terrane, southern India, to understand its origin and to evaluate its geodynamic significance. The lamprophyre shows a typical porphyritic-panidiomorphic texture with amphibole phenocrysts. Clinopyroxene occurs only as xenocrysts with feldspar, apatite, titanite and titano-magnetite confined to the groundmass. Amphibole mineral composition classifies them as pargasite and tremolite, and the groundmass is essentially constituted of alkali feldspar. High whole-rock Mg# (56–65), Ni + Cr (245 to 730 ppm), a lack of correlation between SiO 2 and Rb/Sr as well as ɛNd (i) indicates that crustal contamination experienced by the lamprophyre magma is limited. U-Pb titanite (n = 18) SHRIMP-II dating yielded a Neoproterozoic Tera-Wasserburg concordia age of 820 ± 15 Ma (MSWD = 5.9). Whole-rock derived 87Sr/86Sr (i) (0.70425–0.70530) and ɛNd (i) (-6.3 to −4.3) suggest origin of the lamprophyre from an enriched lithospheric mantle source. Paleoproterozoic depleted-mantle model ages of ca. 1.8 Ga suggest the existence of a long-lived enriched mantle which correspond to the timing (ca.1.9–1.7 Ga) of widespread mafic dyke swarms' emplacement in the Dharmapuri-Agali-Tiruvannamalai domain in the Salem block at the northernmost portion of the Southern Granulite Terrane. The Tonian emplacement age of the studied lamprophyre is synchronous with several co-spatial Neoproterozoic (i) alkaline complexes ± carbonatite ± lamprophyre from the northern part of the Southern Granulite Terrane, and (ii) other mafic alkaline dykes of the Halaguru-Harohalli alkaline province from the southern part of the Eastern Dharwar Craton. Our results highlight the importance of this lamprophyre dyke, present close to the'Fermor Line' as well as near the boundary between Eastern and Western Dharwar Cratons, which provides a rare opportunity to understand its spatio-temporal link with alkaline dykes of the Southern Granulite Terrain. Our findings also help understand the role of repeated large-scale rifting, associated with the Rodinia break-up, leading to the generation of a wide spectrum of Tonian-Cryogenian alkaline magmas in southern Indian Shield. The new age data also have implications for the configuration of India's paleoposition during the Neoproterozoic and support the idea that South China Block-India were located on the periphery of Rodinia or were already detached from the supercontinent. [ABSTRACT FROM AUTHOR]

• Pembine Ophiolite (USA) is a rare Paleoproterozoic (c. 1900 Ma) ophiolite. • The mafic volcanic rocks progress from MORB-like to boninitic up stratigraphy. • This evolution is identical to that observed for < 250 Ma Tethyan ophiolites. • Plate tectonics at c. 1900 Ma was not dissimilar to the modern Earth. Orogenic ophiolites are a hallmark of Phanerozoic plate tectonics, containing igneous lithologies that provide constraints on fundamental tectono-magmatic processes. The c. 1900Ma Pembine Ophiolite (Wisconsin, USA) is associated with the Penokean Orogen and represents a rare example of a proposed Paleoproterozoic ophiolite. The Penokean Orogen shares broad characteristics with Phanerozoic (<541 Ma) orogens, but the origin of the Pembine Ophiolite remains unclear, with the mafic volcanic rocks interpreted as representing either an intra-oceanic arc or continental back arc setting. To test these hypotheses, we present the results of petrography, bulk-rock geochemistry and mineral chemistry for a suite of 34 Pembine rocks, as well as U-Pb zircon geochronology for two samples. Based on trace elements established as immobile in the studied rocks, we demonstrate that mafic volcanism progressed (up-stratigraphic-section) from mid-ocean ridge-like to boninitic. The chemical evolution is identical to that observed in < 250 Ma ophiolites in the Himalayan–Alpine Orogen, which record forearc spreading during the nascent stages of subduction in the Tethys Ocean. We interpret the Pembine Ophiolite as forearc lithosphere formed during subduction initiation and obducted to the margin of the Superior Craton during the Penokean Orogeny. The processes responsible for forming (and preserving) this example of a Paleoproterozoic ophiolite may not have been dissimilar to those operating on the Phanerozoic Earth. [ABSTRACT FROM AUTHOR]

• The newly identified Yunnongfeng intrusion in the southwestern margins of the Yangtze Block is formed at ca. 782.5–763 Ma. • They originated from metasomatized mantle source enriched by subducted slab fluids, and sediment melts and underwent remarkable fractional crystallization. • Neoproterozoic magmatism in western margins of Yangtze Block formed in persistent oceanic-crust subduction and back-arc basin setting. • Sediment-melt react with lithospheric mantle would form K-enriched mafic-intermediate intrusive rocks. The study of K-enriched intrusive rocks is essential for deciphering mantle metasomatism beneath active continental arcs. In this contribution, high-precision zircon U–Pb–Hf isotope, whole-rock geochemistry, Sr–Nd isotope, and mineral chemistry analyses were performed to evaluate the petrogenesis and geodynamic system of the Yunnongfeng intrusion on the southwestern margin of the Yangtze Block. The Yunnongfeng intrusion consists of a high-K to shoshonitic rock assemblage with variable lithology from gabbro-diorite to granite. Zircon U–Pb dating gives concordant crystallization ages of ca. 782.5 ± 3.8 Ma for gabbro-diorite, ca. 774 ± 4.1 and 776 ± 4.1 Ma for diorite, ca. 770 ± 4.7 Ma for quartz monzonite, ca. 763 ± 3.4 Ma for quartz syenite, and ca. 764 ± 16 Ma for granite. These samples also show similar Sr–Nd, and Lu–Hf isotopic compositions, implying a common magma source. The similar crystallization age and regular variation of major and trace element contents suggest that these rocks were formed through fractional crystallization of cogenetic primitive mantle magmas. The enriched εNd(t) (−5.7 to − 5.1) and εHf(t) (−6.7 to − 1.2) values, high Rb/Y and Th/La ratios, slight Nd–Hf decoupling, and high-K and Th contents demonstrate that their lithospheric mantle source was enriched by slab-related fluid and sediment-related melt. The samples also exhibit remarkable enrichment in large-ion lithophile elements and depletion in high-field-strength elements, indicative of subduction-related arc magmatism. Taking into account previous studies, we suggest that the western margin of the Yangtze Block experienced a long-term subduction process during the Neoproterozoic, and the Yunnongfeng intrusion formed in an extensional back-arc basin. Based on the K-enriched mafic–intermediate rocks from the western margin of the Yangtze Block commonly show high K 2 O/Na 2 O, Rb/Sr, low Ba/Rb ratios, and enriched εNd(t) values, our study, coupled with numerous previous reports, proposes that the K-enrichment resulted from the breakdown of phlogopite, owing to subduction-related sediment melt reacting with peridotite in the mantle source area. [ABSTRACT FROM AUTHOR]

• Ca. 1.94–1.85 Ga collision-related granitic magmatism were identified in the Cuoke Complex; • A late collisional or an early post-collisional setting at 1.94–1.89 Ga, followed by a post-collisional setting at 1.85 Ga. • The convergence of the Yangtze Block occurred during the Nuna supercontinent assembly. The Paleoproterozoic tectonic evolution of the southwestern Yangtze Block has been ambiguous due to the scarce preservation of geological records, confusing the history of the entire Yangtze Block in the Nuna supercontinent. We here report an integrated study involving petrology, whole-rock geochemistry, zircon U-Pb geochronology and Hf-Nd isotopes of the recently identified late Paleoproterozoic granitoids from the Cuoke Complex in the southwestern Yangtze Block. LA-ICP-MS zircon U-Pb dating reveals three episodes of granitic magmatism at ca. 1.94 Ga, 1.89 Ga, and 1.85 Ga. Geochemically, the ca. 1.94 Ga albite granites (AGs) and ca. 1.89 Ga and 1.85 Ga monzogranites (MGs) exhibit features of I-type granite, while the ca. 1.85 Ga AGs display characteristics of A-type granite. The zircon ε Hf (t) values range from −13.0 to −8.1 for the 1.94–1.89 Ga granitoids and from −8.9 to −7.2 for the ca. 1.85 Ga granitoids, with two-stage model ages of 3.3–3.1 Ga and ca. 3.0 Ga, respectively, indicative of their derivation from remelting of Mesoarchean crustal materials. The relatively low heavy rare earth elements (HREEs) (e.g., Yb < 1.9 ppm) and Y (<18 ppm) contents, and moderately negative Eu anomalies of the ca. 1.94–1.89 Ga granitiods suggest they may have been produced in a late collisional or earliest post-collisional setting. The ca. 1.85 Ga AGs and MGs were probably formed in a post-collisional setting indicated by their high HREE (e.g., Yb > 1.9 ppm) and Y (>18 ppm) contents and strongly negative Eu anomalies. Combined with available data, we provisionally divided the tectonic evolution of the southwestern Yangtze Block into four stages: 1) ca. 2.01 Ga subduction, 2) ca. 1.97–1.95 Ga metamorphism associated with collision events, 3) ca. 1.94–1.89 Ga late collisional or earliest post-collisional stage, and 4) ca. 1.85 Ga post-collisional extensional stage. The subduction and collision of the southwestern Yangtze Block initiated slightly later than the northern part, but their near-synchronous tectonic process since ca. 1.97 Ga suggest they may have collaged together at that time. The ca. 1.94–1.89 Ga and ca. 1.85 Ga late collisional to post-collisional granitic magmatism likely recorded the convergence of discrete Archean rock provinces of the Yangtze Block during the Nuna supercontinent assembly. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ediacaran-Cambrian series of Cap de Creus studied through Nd isotopic sources. • Eastern Pyrenees series (Cap de Creus) show Nd model ages ranging 1.4–1.6 Ga. • Coeval series from different Iberian terranes show contrasted Nd isotopic sources. • These data suggest different original locations along the Gondwana margin. • Isotopic tracers are a useful tool to check the provenance in paleoreconstructions. The North African margin of Gondwana formed by subduction and accretion during Ediacaran to Cambrian times. Sections of this active margin were incorporated during the late Paleozoic to the Variscan and Appalachian orogens. In the Variscan realm, these sections define in some regions a Cadomian basement comprising thick metasedimentary series associated with coeval subduction-related magmatic rock dated in the range 650–500 Ma. In the Cap de Creus Massif (Eastern Pyrenean domain), the Cadomian metasedimentary rocks formed from sediments derived from mixed felsic and intermediate/mafic sources, intruded by granitoid and minor mafic igneous rocks. These series were formed in a peri -Gondwanan volcanic arc setting, like other Cadomian series described in the SW of the Iberian Massif, such as Serie Negra Group of the Ossa Morena Complex. However, the Nd model ages of the Cap de Creus metasedimentary samples range from 1431 to 1620 Ma and are younger than those of their SW Iberia equivalents. This result can be interpreted as an indication of an eastern location in the Ediacaran - Cambrian peri -Gondwanan magmatic arc. Furthermore, the Cadomian series in the Central Iberian Zone have even younger Nd model ages than those of SW and NE Iberia. We present two end-member paleogeographic models consistent with reconstruction of the initial location of the Cap de Creus Massif and its relations with other domains (Ossa Morena Complex and Central Iberian Zone) in this sector of the North African Gondwanan margin. [ABSTRACT FROM AUTHOR]

[Display omitted] • Pre-, syn-, and post-collisional plutons in a multi-intrusion batholithic system. • Juvenile Tonian island arc remnants preserved as roof pendants and mega-xenoliths. • Ediacaran pre-collisional tonalites/granodiorites as main bodies of the orogenic core. • Syn-collisional garnet-bearing leucogranites formed as crustal melts at 575–560 Ma. • Post-collisional undeformed A-type granites intruded at 500 Ma. High-grade metamorphism, extensive partial melting, and polyphase deformation often obliterate records of pre-collisional stages in ancient orogens, making it hard to unravel Precambrian accretionary events. In western Gondwana, the high-grade core of the Araçuaí-Ribeira Orogenic System (AROS) comprises pre-collisional rock-assemblages largely disrupted, overprinted, and remelted by collisional and post-collisional tectono-metamorphic and igneous events, hampering reconstructions of its accretionary history. Detailed studies reveled remnants of an Early Tonian (860–840 Ma) island arc, forming km-size roof-pendants and mega-xenoliths within the composite Caxixe batholith, in the boundary zone between the Araçuaí and Ribeira orogens. We further characterize the Caxixe batholith and surrounding plutons, showing that the main stage of magmatism is composed of pre-collisional orthogneisses, partially migmatized and crystallized between ca. 607–580 Ma, thus, much later than the Tonian island arc records. Those Ediacaran granitic rocks represent intrusions of calc-alkaline magmas with elemental geochemistry and isotopic (εHf(t): −6 to −10, whole-rock εNd(t): −4.9 to −9.5, and 87Sr/86Sr(i): 0.706–0.711) data correlated with the continental-margin Rio Doce arc. This contrasts with signatures indicative of a mantle source εHf(t) = +10 to + 14, εNd(t) = +0.9 to + 6.4, and 87Sr/86Sr(i) = 0.698–0.704) of the Early Tonian arc remnants. Intruding the pre-collisional granitic plutons, garnet-bearing leucogranites dated at ca. 575 Ma and a mafic intrusion of ca. 560 Ma mark the transition from the syn-collisional to late-collisional stages. Post-collisional, non-deformed, A-type granites with the most evolved isotopic signatures (εHf(t): −22; εNd(t): −5.6 to −13.2) intruded at ca. 500 Ma, ending the long-lasting orogenic history documented in the region. Our results demonstrate that a basement composed of an early Tonian juvenile arc docked with a continental margin and hosted several intrusions of an early Ediacaran continental-margin magmatic arc that, in turn, were intruded by collisional and post-collisional magmas from the Late Ediacaran to Cambrian, finally forming the main plutonic masses of the Araçuaí-Ribeira Orogenic System (AROS) core, during the complex history of western Gondwana assembly. [ABSTRACT FROM AUTHOR]

• A significant early Neoproterozoic magmatic event developed in the CTB. • The early Neoproterozoic magmatic event in the CTB formed in an active continental margin environment. • The CTB and other microcontinents located along the northern Tarim during the early Neoproterozoic and constituted the active continental margin during circum-Rodinia subduction. • The CTB constituted the active continental margin during circum-Rodinia subduction. As an important ancient continental constituent of the Central Asian Orogenic Belt (CAOB), the Central Tianshan Block (CTB) is indispensable to improving our understanding of the early evolution and architectural framework of this orogenic belt. Here, we present new zircon U–Pb ages and Hf isotopes, as well as bulk-rock geochemistry, for amphibolite, gneissic granite, and augen granite from several localities in the CTB. Zircon U–Pb ages of ten samples demonstrate that the protolith of the amphibolite, gneissic granite, and augen granite formed in the early Neoproterozoic (from 905.9 ± 4.8 Ma to 940.0 ± 4.5 Ma). Geochemically, the early Neoproterozoic amphibolite is depleted in Nb, Ta, P, and Ti, but enriched in light REE (LREE) and large ion lithophile elements (LILE), similar to arc-related basalt. The gneissic granites from the Shardland area and the Alatage area, and gneissic granites and augen granites from the Xingxingxia area are enriched in SiO 2 , Na 2 O + K 2 O, LREE, and LILE, and depleted in heavy REE (HREE) and high field strength elements (HFSE), exhibiting an I-type granite affinity. Zircons from the amphibolite in the Shardland area exhibit positive ε Hf (t) values of +1.7 to +4.9 and T DM1 model ages of 1.27–1.39 Ga, indicating that the protolith crystallized from a mantle-derived magma. Zircons from the gneissic granites in the Shardland area, the Alatage area and the Xingxingxia area have ε Hf (t) values that range from –5.9 to +7.3 and T DM2 model ages of 1.33–2.17 Ga, indicating that the granites may have been derived from partial melting of ancient continental crust that contained compositionally variable juvenile material. These new results, combined with previous studies, indicate that early Neoproterozoic magmatic rocks are well-developed throughout the CTB and formed along a subduction-related continental arc. The CTB and other microcontinents of the southwestern CAOB may have been located proximal to the northern margin of the Tarim Craton during the early Neoproterozoic, thereby representing the active continental margin of the circum-Rodinia subduction–accretion system. [ABSTRACT FROM AUTHOR]

• We contribute 38 new U–Pb ages to the data-poor north-eastern Albany–Fraser Orogen; • Low sample volumes are used to meaningfully investigate concealed basement geology and the location of major Archean–Paleoproterozoic terrane boundaries; • A new and previously unrecognised felsic igneous suite is defined—the Moonyoora Suite (ca. 2030–2010 Ma); • Zircon U–Pb magmatic ages and Lu-Hf analyses indicate that the inception of Biranup Zone extension and magmatism on the southern margin of the Yilgarn Craton began ca. 200 Myr earlier than previously documented; • Emplacement of the Moonyoora Suite occurred at the start of a widespread extensional regime across the West Australian Craton, and a period of increased mafic magmatism globally. Uranium–lead zircon geochronology, zircon lutetium–hafnium isotope analyses and whole-rock geochemistry are used to investigate concealed basement geology and the location of Archean–Paleoproterozoic terrane boundaries in the northeastern Albany–Fraser Orogen (AFO). We identify a new major component of the AFO, and the first compelling evidence for ca. 2030–2010 Ma A-type felsic magmatism in western Australia. Prior to this study, the oldest rocks in the AFO that formed by extension and reworking of the southern Yilgarn Craton margin had protolith emplacement ages of ca. 1810–1800 Ma; our results extend this record by ca. 200 Myr and provide new insights into the crustal and tectonic evolution of the AFO. This phase of magmatism marks the start of a long-lived and widespread Paleoproterozoic extensional regime that prevailed across the West Australian Craton (WAC) for ∼ 400 Myr. Extension in the WAC was coeval with localised magmatism, volcanism and volcano-sedimentary basin formation in the North and South Australian cratons. Globally, our findings also correlate with the onset of prolonged extension and the generation of a vast tract of oceanic crust around the periphery of Nuna. We posit a petrogenetic link between ca. 2030–2010 Ma felsic rocks in the AFO and age–isotope-equivalent ultramafic–mafic rocks in the eastern Yilgarn Craton that are located along-strike and are interpreted to reflect a possible far-field and late-stage magmatic expression of the ca. 2060–2055 Ma Bushveld superplume. [ABSTRACT FROM AUTHOR]

• The Kangilleq Formation documents Paleoproterozoic subaqueous, basaltic volcanism. • The Kangilleq Formation is correlative with the Bravo Lake Formation of Baffin Island. • It records the initiation of an extension in an intracontinental backarc. • Initial extension and volcanism recorded in the OIB-like rocks of the Umiammakku member. • Followed by the eruption and deposition of the E-MORB-like rocks of the Kangiusap member. Mafic volcanic rocks of the Paleoproterozoic Kangilleq Formation of the Karrat Group of West Greenland represent a submarine mafic volcanic sequence, erupted and deposited on the Rae craton of Greenland. The formation ranges from <100 m-thick to ∼500 m-thick, and consists of mafic volcaniclastic rocks, pillow lavas and massive basalt lavas that have undergone greenschist facies metamorphism, yet preserve primary volcanic textures such as pillows, drainage cavities, lobes, flow banding, autoclastic breccias, hyaloclastite, scoria and layering. Rocks of the Kangilleq Formation overlie the Archean Qeqertarssuaq Complex and are interleaved with and overlain by the ca. 1950 Ma Nûkavsak Formation. Based on detailed (1:200) mapping and high-precision geochemistry, rocks of the Kangilleq Formation are subdivided into the Kangiusiap and Umiammakku members. The Kangiusiap member is dominated by mafic, scoria-rich breccias, has sulfide mineralization, and is bound at the bottom and top by the Nûkavsak Formation. This member has subalkaline, transitional to tholeiitic, mid-ocean ridge basalt (MORB) to back arc basin basalt (BABB) signatures with a Nd-isotope value similar to the depleted mantle at 1.88 Ga. The Umiammakku member is dominated by pillow lavas, with subordinate amounts of massive lavas and volcaniclastic rocks, overlies the Qeqertarssuaq Complex and is overlain by, and interleaved with, the Nûkavsak Formation. It is alkaline with characteristics similar to modern ocean island basalts and Nd-isotopic values slightly lower than the depleted mantle at 1.88 Ga. The rocks of the Kangilleq Formation represent non-arc suites or suites that have only minor subduction zone or crustal input, and display geochemical signatures similar to basalts found in modern intracontinental back arc settings. Lithofacies, bedforms, internal stratigraphy, and the identification of synvolcanic faults, suggest it is the product of volcanic eruptions during incipient rifting within a back arc setting, and seafloor mass wasting events at fault scarps related to rifting. Based on the geological characteristics and its petrogenetic and tectonic history, the Kangilleq Formation is interpreted to be correlative with the Bravo Lake Formation of the Piling Group of northeastern Canada and records incipient rifting of the southern margin of the Rae craton in the Paleoproterozoic. [ABSTRACT FROM AUTHOR]

• A multi-proxy study suggesting important constraints on the evolution of the Chattisgarh basin. • The petrology and geochemistry of individual sandstone type from each formation of the basin have been reported in details. • Petrology and geochemistry of sandstones from the basin indicate passive marginal tectonic setting, weak to intense palaeoweathering, and semi-arid to humid palaeoclimatic condition at the source, and granites and gneisses of Dongargarh Granitoids and Baya Gneissic Complex as the basin fill source. • Chattisgarh basin originated as an intracratonic rift basin that evolved into a passive margin basin during the Mesoproterozoic. • The basin is correlatable with other Mesoproterozoic basins of Peninsular India, as well as with other global basins related to the Columbia-Rodinia Supercontinent cycle. Depositional processes and stratigraphic evolution of the Chattisgarh basin exhibit a synergistic relation between sedimentation and tectonics. To interpret the sedimentation history and basin evolution, multiproxy approach including field studies, petrography, geochemical, and multivariate statistical analyses of the sandstones of Chandarpur and Raipur groups is employed. The study provides a detailed analysis of the time-connoted petrography and geochemistry of the sandstone units from each formation of the Chandarpur-Raipur sequence of Chattisgarh basin. The sandstones grade from immature wacke through submature arkose to mature quartzarenite from the bottom up the section. These sandstones are broadly characterized by felsic provenance, arid-humid palaeoclimate, and weak-intense palaeoweathering at the source. The assemblage of wacke-arkose-sublitharenite of the basal Lohardih Formation is characteristics of fan delta environment and represents initiation of rifting and basin formation stage. Subarkoses from the younging up sequence of Lohardih-Chaporadih-Kansapathar formations reflect prograding shelf environment that represents craton interior field of the continental block provenance and passive marginal tectonic setting, indicating gradual stabilization of the basin. Quartzarenites from Kansapathar Formation and stratigraphically younger Devsagar Member of Charmuria Formation also represent broadly similar provenance and tectonic setting indicating stable craton interior provenance in a passive marginal setting. Petrographic and geochemical analyses of some of the Kansapathar-Devsagar sandstones suggesting recycled orogen provenance, however, may be attributed to the orogenic activity and/or role of younger bimodal volcanic rock during rejuvenation of multistage basin opening faults. Rifting stage was followed by subsidence stage as indicated by the presence of black limestone capping the sandstone successions. Initiation of basin formation ∼1400 Ma and sedimentation can be correlated with the late-stage fragmentation of the supercontinent Columbia. The basin probably closed ∼1000 Ma during the assembly of the next supercontinent Rodinia. It is estimated that ∼87% of the 2.2-km-thick sedimentary succession in the eastern Chattisgarh basin, were already deposited within this time frame (∼1405 and ∼1007 Ma). The basin is correlatable with other Mesoproterozoic basins of Peninsular India like Vindhyan, Cuddapah basins, as well as with basins like Xiong'er rift basin of North China Craton, Espinhaco basin of eastern Brazil, that are related to the Columbia-Rodinia Supercontinent cycle. [ABSTRACT FROM AUTHOR]

• Deep-seated crustal xenoliths from Yangyuan represent the ancient lower crust. • Multiple thermal events are uncovered in the lower crust beneath Yangyuan. • An evolutional heterogeneity is identified in the lower crust beneath the central–northern part of the TNCO. Deep-seated crustal xenoliths captured by volcanic rocks play a rare opportunity in understanding the composition and evolution of the lower continental crust. Here, we present mineral chemistry, whole-rock major and trace elements and Sr–Nd isotopes, and in-situ zircon U–Pb ages and Hf isotope data for a suite of granulite and biotite gneiss xenoliths entrained in the Oligocene basalts from the Yangyuan county in the central part of the Trans North China Orogen (TNCO) with aims to decipher the composition and evolutionary history of the lower crust beneath this area. Calculated equilibrium temperatures (841–933 °C) and pressures (9.7–14.3 kbar) suggest an origin of the Yangyuan granulites from the lower crust. The dominantly Archean–Proterozoic zircon ages and low Mg# values (29.0–68.4) of the Yangyuan crustal xenoliths indicate that they represent the ancient crust and the fractional crystallization plays a key role during the protolith formation. Furthermore, the zircon U–Pb–Hf isotopes data reveal multiple thermal events, including two main peaks of crustal growth at ∼2.7 Ga and ∼2.5 Ga, ∼1.85–1.80 Ga and the Phanerozoic accretion and reworking of the lower crust beneath Yangyuan. In addition, a comparison study of crustal xenoliths from Yangyuan, Nangaoya and Hannuoba areas demonstrates that the lower crust beneath the central–northern part of the TNCO experienced as a whole the Neoarchean crustal growth, Paleoproterozoic metamorphism and Phanerozoic magmatic underplating. More importantly, the absence of U–Pb age peak of ∼1.95 Ga and Hf model age peaks of ∼3.9–3.8 Ga, ∼2.9–2.8 Ga, ∼2.2–2.1 Ga and ∼700–600 Ma in Yangyuan shows a heterogeneous evolution of the lower crust beneath the TNCO, which could pave the way for a more comprehensive picture of the crustal evolutional history beneath the North China Craton. [ABSTRACT FROM AUTHOR]

• A continuum of Paleoproterozoic heritage, seen in Nd model ages, from N to S in the Bushmanland Domain (BD), with the Buffels River shear zone simply a regional discontinuity. • The southern BD (SBD) has a greater juvenile component than the northern BD (NBD), becoming more dominant post-1.10 Ga. • Orthogneisses derived from crustal magmas with subduction-influenced signatures with mixed Meso- to Paleoproterozoic model ages. The SBD Koperberg Suite derived from low degrees of melting of enriched SCLM, but at deeper levels than those of the NBD. • The paragneisses derived from largely reworked, mixed Meso- to Paleoproterozoic felsic to intermediate sources. • Paragneisses derived from largely reworked, mixed Meso- to Paleoproterozoic felsic to intermediate sources. • SBD Koperberg Suite derived from low degrees of melting of enriched SCLM, but at somewhat deeper levels than NBD Koperberg magmas. • D 2 deformation constrained to ~ 1.11-1.09 Ga, with peak M 3 metamorphism at ~ 1.05-1.02 Ga. The timing of tectonomagmatic events and petrogenesis of ortho- and paragneisses within the high-grade southern Bushmanland Domain (SBD) of the Namaqua Metamorphic Province is, largely, poorly constrained. U-Pb age dating and whole rock lithogeochemistry of the rocks of the upper granulite facies Kliprand dome provide constraints with regards to the evolution of the SBD during the 1.2–1.0 Ga Namaquan Orogeny. The SBD has a greater juvenile component, particularly added between ∼1.1 and 1.02 Ga, compared to the northern Bushmanland Domain (NBD). This is reflected in marginally younger T DM model ages (1.60–1.95 Ga) than for the NBD (∼1.9–2.4 Ga), and higher ε Nd(t) values for magmatic rocks, particularly for the late- to post-tectonic Spektakel Suite (SS), concentrated in the SBD. The ∼1.06 Ga Klein Lieslap Charnockite of the SS was derived from reworking of radiogenic Paleoproterozoic arc crust, but has a large juvenile depleted component compared to that of the ∼1.19 Ga Grootberg Gneiss of the syn-tectonic Little Namaqualand Suite. SBD mafic magmas were derived from low degrees of partial melting of subduction-influenced enriched subcontinental lithospheric mantle. The pre-tectonic ∼1.17 Ga Oorkraal Suite shows limited crustal contamination of mantle-derived melts. The post-tectonic ∼1.05 Ga Koperberg Suite was derived from deeper mantle melting than that in the NBD, but shows less crustal contamination. The supracrustal Kamiesberg Group was derived from mixed, reworked Meso- to Paleoproterozoic crust that showed a more dominant depleted component compared to that in the NBD. Incongruent anatexis of the paragneisses gave rise to crosscutting garnetiferous quartzofeldspathic segregations, notably the strongly peraluminous ∼1.07 Ga Ibequas Leucogranite. D 2 deformation, at ∼1.11–1.09 Ga, resulted in penetrative foliation. D 3 deformation, related to the development of a sub-vertical foliation in the limbs of F 2 folds, is constrained to ∼1.07–1.06 Ga, between emplacement of the Ibequas Leucogranite and the Koperberg Suite. Peak granulite facies M 3 metamorphism occurred at ∼1.05–1.02 Ga. These age constraints are similar to those of the NBD reflecting a synchronous tectonomagmatic and kinematic history. The SBD represents a deeper crustal level with a greater mantle influence than the NBD. [ABSTRACT FROM AUTHOR]

• Trace elements, isotopes, TOC and iron speciation data of the Bambuí basin. • Changes in the geochemical proxies were caused by tectonic restriction of the basin. • Oxygenation in the post-glacial period was superseded by anoxia after restriction. • Basin restriction suppressed biological evolution and emergence of Cambrian fauna. Neoproterozoic marine systems are associated with major paleoecological changes that took place in the Ediacaran and during the Ediacaran-Cambrian transition. During this timespan, the Bambuí basin located on east Brazil held a peculiar paleoenvironmental scenario. Due to its intracratonic evolution, the basin was partially disconnected from neighboring open marine systems. This setting raises a very interesting opportunity to understand how an isolated Neoproterozoic marine system evolved in contrast with typical (globally connected) open marine systems. To understand the paleoenvironmental changes that took place in the Bambuí basin, we investigate the pre-glaciogenic deposits of the Carrancas Fm and the post-glaciogenic mixed (shale-carbonate) successions of the Bambuí Group. Through the analysis of iron speciation, TOC, trace element and C-O isotope systematics, our study suggests a very complex environmental evolution. Firstly, our samples are marked by strong contamination of detrital continental material that can be related to an increased bioproductivity on both the Carrancas Fm. and lower Bambuí group stratigraphic units, and provenance data show that all studied sediments probably shared common source areas. Iron speciation data, Ce anomalies and RSE enrichments shows that lower Bambuí Group stratigraphic units were likely deposited in an open marine scenario featuring high bioproductivity in shallow waters and euxinic incursions in predominant anoxic/ferruginous bottom waters. On the other hand, upper Bambuí stratigraphic units register a marine evolution in a restricted scenario, where anoxic ferruginous conditions probably reached surface waters. Finally, our data show that the lack of oceanic connection prevented the re-supply of marine sulfate, RSE, bionutrients and ultimately of dissolved oxygen which may have decreased biological activity and probably hindered biological evolution, preventing the rise of a typical modern-like Cambrian ecosystem. In this sense, our data suggest that oceanic connectivity and proper re-supply of inorganic marine input were important features in the development of complex life in the Ediacaran-Cambrian environment. [ABSTRACT FROM AUTHOR]

We present ten new ID-TIMS U-Pb baddeleyite ages for late Neoarchean to Paleoproterozoic dyke swarms cutting Archean gneisses of the Hopedale block (North Atlantic craton, NAC). An age of 2505 ± 4 Ma for a NNE-trending pyroxenite dyke represents the first date for extension-related mafic magmatism of this antiquity in the Labrador portion of the NAC. Four samples of N-S to NNE-trending Kikkertavak dykes yield ages between 2238 ± 6 Ma and 2216 ± 2 Ma, defining a minimum age range and distribution for this extensive swarm. A single NNE-trending dyke is dated at 2169 ± 13 Ma, representing a new magmatic event at this age in Nain Province, but is equivalent in timing to the well-known Biscotasing dykes in the southern Superior craton. Three NW-trending dykes (termed Ellen Island dykes) yield ages of 2051 ± 6 Ma, 2051 ± 1 Ma and 2050 ± 2 Ma, and represent part of a newly-recognized but important swarm in southern Nain craton. The 2.05 Ga dykes better define a vast radiating fan of dykes that include Kangâmiut and MD3 dykes of southern West and South-West Greenland, respectively. A U-Pb baddeleyite age of 1800 ± 4 Ma has been obtained for a fourth, NW-trending ("Ussiranniak Lake") dyke, which also represents a newly-revealed mafic magmatic event, both in the Labrador and Greenland portions of the NAC. The results presented here are unique for Labrador, but invite comparison with other Neoarchean and Paleoproterozoic mafic dykes elsewhere in the North Atlantic craton and other Archean cratons (e.g., Superior, Kola-Karelia, Zimbabwe). Multiple precise age matches, dyke geochemistry, and dyke geometries for several swarms allow a preliminary level testing of possible reconstructions involving the North Atlantic and eastern Superior cratons. [ABSTRACT FROM AUTHOR]