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[Display omitted] • Subduction slab break-off occurred at ∼835 Ma in the southwestern JNO. • Final assembly of the Yangtze and Cathaysia blocks is before ∼810 Ma. • Southwestern JNO occupied a deep-water area of the Nanhua Rift Basin. • The SCB was located at the periphery of Rodinia in the Neoproterozoic. The Neoproterozoic Jiangnan Orogen (JNO) marks the consolidation of the South China Block, sparking ongoing debates on its early to mid-Neoproterozoic tectonic evolution. In this study, we have gathered detrital zircon data from the southwestern JNO, presenting new detrital zircon U-Pb ages alongside trace element data from the mid-Neoproterozoic Banxi Group and Sinian System within this region. Our objective is to illuminate the early to mid-Neoproterozoic tectonic evolution within the southwestern JNO through a comprehensive detrital zircon analysis. The obtained dating results derived from detrital zircons reveal maximum depositional ages of ∼733 Ma and ∼713 Ma for Mobin Formation (Banxi Group) and Jiangkou Formation (Sinian System) sedimentary rocks, suggesting a proximal source, possibly originating from magmatic rocks within the southwestern JNO. Within the paleo-geographic context, it is plausible that these samples were deposited within the deep-water expanse of the Nanhua Rift Basin. Trace element analysis of detrital zircons within the southwestern JNO highlights distinctive fluctuations, delineating three crucial time points (∼885 Ma, ∼835 Ma, and ∼810 Ma): the beginning of early Neoproterozoic subduction of the South China Ocean towards the Yangtze Block beneath the southwestern JNO, the subduction slab rollback, and the Nanhua rifting initiation. The discernible shifts in detrital zircon age distributions within these sedimentary rocks serve as robust validation for the proposed model and crustal reworking. We then propose that the southwestern JNO was in a lull of magmatism before ∼885 Ma, then transitioned to a convergent setting around 885–835 Ma, subsequently subduction slab rollback after ∼835 Ma. The time of final assembly of the Yangtze and Cathaysia blocks in the southwestern JNO is no later than ∼810 Ma. This transformative period (∼810–720 Ma) witnessed the development of a rift basin concurrently with the accumulation of deep-water deposits within the southwestern JNO. [ABSTRACT FROM AUTHOR]

• The alkaline pluton of Balda, located at the boundary of the geological domains of Northwestern Cameroon and Mayo-Kébbi, underwent tectonic deformation subsequent to its emplacement. • The pluton was emplaced at 732.7 ± 7.5 Ma in a syn -orogenic extensional context of a back-arc basin. • The deformation is related to the continental collision of the NW Cameroon and Mayo-Kébbi domains and resulted from a sinistral simple shear-dominated transpressive tectonic regime, dated to around 680 Ma. Located on the border between the NW Cameroon and Mayo-Kebbi domains in northern Cameroon, the Balda pluton is a deformed alkaline granite. Due to its unique location and geological features, it holds crucial information for understanding the evolution of the Central African Orogenic Belt (CAOB), which remains poorly understood. This multidisciplinary study combines field data, microscopic observations, Anisotropy of Magnetic Susceptibility (AMS), and U-Pb zircon dating to constrain the geodynamic evolution of the CAOB. The Balda pluton is a NNE-SSW elongated pluton consists mainly of aegirine-riebeckite granite and leucogranite. It displays diverse magnetic susceptibility values (Km) spanning from 0.19 x 10-3 to 21.98 x 10-3. Notably, 93 % of the Km values exceed 5 × 10-4SI, indicating a prevalence of mixed paramagnetic and ferromagnetic mineralogy (such as magnetite-rich). This observation is supported by microscopic examinations and K-T curves. An analysis of AMS unveils high P% values (2.8 to 58.7 %, with a mean of 15 %) and prevalent oblate magnetic fabrics (68 %). The magnetic foliation generally aligns with the field foliation and has steep dips ranging from NNE to NE or from SSW to SW and magnetic lineations exhibit shallow plunges (<35°) from SSW to SW. Microscopic analysis reveals high-temperature, solid-state deformation microstructures, indicating post-emplacement deformation processes and the presence of kinematic markers consistent with sinistral shear. Zircon grain analysis reveals two distinct types: "bright" and "dark." These types differ in both their appearance under cathodoluminescence and their chemical composition. Bright zircons yield a U-Pb age of 732.7 ± 7.5 Ma, interpreted as the pluton emplacement age. Dark zircons are younger (ca. 680 Ma), suggesting a later tectono-metamorphic or alteration event. The integration of these results in a larger geodynamic context suggests that the Balda pluton formed within a syn -orogenic extensional back-arc basin. This emplacement was followed by significant post-emplacement deformation characterized by sinistral simple shear-dominated transpression likely related to the continental collision (ca. 680 Ma) of the NW Cameroon and Mayo-Kébbi domains. [ABSTRACT FROM AUTHOR]

• Two distinct LREE-rich mineralizing events in the Central Grenville province (Quebec) • LREE-rich pegmatite derived from anatectic melting of metaigneous rocks. • Source of anatectic melts is not critical for the genesis of LREE-rich pegmatites. The source of the melt forming rare-metal granitic pegmatites in high-grade metamorphic orogenic belts is debated and is interpreted to be either (i) the product of magmatic differentiation of a large volume of granitic melt or (ii) the anatectic product of local crustal rocks. The Haut-Saint-Maurice region of the Grenville Province, Canada is of special interest to this controversy as it hosts alkaline plutonic rocks and granitic pegmatite dykes associated with significant light rare earth element (LREE) mineralization. This study focuses on the richest known LREE-bearing granitic pegmatite dyke (up to 2.7 wt% REE) of the region, named Blanchette-1. Zircon U-Pb analysis on the LREE-rich Blanchette-1 granitic pegmatite, and on nearby intrusive rock belonging to the LREE-rich Toad alkaline intrusive suite, returned ages of 1061 ± 7 Ma and 982 ± 5 Ma, respectively. The 80 Myr gap between these dates suggests no genetic link between the two LREE mineralization types. Zircon Lu-Hf and trace element analyses are integrated with micro-XRF and electron microprobe analysis of amphibole and biotite from the LREE-rich Blanchette-1 granitic pegmatite, two genetically related granitoid dykes, and from the Toad alkaline intrusive suite to investigate their potential sources and the processes controlling the LREE content of these rocks. Zircon in the three dykes record a high proportion of inheritance from ∼ 1100 Ma to ∼ 1450 Ma, a linear increase of the εHf (t) from ∼+3 to ∼+13 through time, and Hf model ages from ∼ 1300 to ∼ 1500 Ma, strongly supporting a pre-Grenvillian, crustal, metaigneous origin of the melt that formed the granitic dykes. This inferred metaigneous source for the LREE-rich pegmatites in the Haut-Saint-Maurice region contrasts with the metasedimentary source proposed for the LREE-rich pegmatite dykes located in the Lac Okaopéo region suggesting that the nature of the protolith (metaigneous vs metasedimentary) is not a critical factor for the genesis of either suite of LREE-rich pegmatite dykes. Finally, the recorded LREE, Th, and Zr enrichments in the Blanchette-1 granitic pegmatite resulted from the differentiation of the Cl- and F-rich anatectic melt during ascent through the crust and subsequent disequilibrium crystallization of allanite, zircon, and thorite crystals in discrete zones of the pegmatite dyke. [ABSTRACT FROM AUTHOR]

• Zircon ages reveal that the Helanshan shear zones developed at ca. 1904–1826 Ma. • Orogen-parallel shear zones in the Khondalite Belt occurred at ca. 1.90–1.82 Ga. • The Khondalite Belt suffered polyphase deformation (D 1 -D 3) at ca. 1.97–1.82 Ga. • The Khondalite Belt recorded a protracted (>100 Myr) orogeny in the Orosirian. The Khondalite Belt has been regarded as a Paleoproterozoic collisional orogen in the northwestern North China Craton, but the geochronological framework of polyphase deformation in the Khondalite Belt still remains unclear, particularly the timing of orogen-parallel ductile shearing. In this study, we conducted field-based structural analysis and LA-ICP-MS zircon U-Pb geochronology on the Helanshan ductile shear zones (HDSZ) in the Khondalite Belt. The results show that three pre-kinematic leucocratic dykes have been reworked by the shear zones and yielded magmatic zircon ages of 1934 ± 13 Ma, 1924 ± 5 Ma and 1920 ± 24 Ma. Two syn -kinematic leucocratic dykes appeared along the mylonitic foliations and were dated at 1887 ± 21 Ma and 1871 ± 28 Ma. A post-kinematic leucocratic dyke cut the mylonitic foliations and gave a crystallization age of 1816 ± 28 Ma. These emplacement ages of shear zone-related dykes constrain the development of the HDSZ at some time between ∼ 1920 Ma and ∼ 1816 Ma. Meanwhile, zircon overgrowth rims from three intrusions that suffered the shear deformation exhibited metamorphic ages of 1904 ± 11 Ma, 1840 ± 13 Ma and 1826 ± 31 Ma. Similar metamorphic ages of 1901 ± 7 Ma, 1888 ± 8 Ma and 1849 ± 29 Ma were also obtained from high-temperature felsic, pelitic and calcitic mylonites. These results further unravel that the HDSZ most likely developed at ca. 1904–1826 Ma. Additionally, we have summarized available deformation-related geochronological data in the Khondalite Belt, and proposed that this belt underwent three major phases of deformation (D 1 -D 3) in the Orosirian. D 1 mainly produced overturned to recumbent isoclinal folds F 1 , penetrative transposition foliations S 1 and mineral lineations L 1 at ca. 1.97–1.93 Ga. Subsequently, D 2 dominantly resulted in tight to open upright folds F 2 at ca. 1.93–1.90 Ga. Later, D 3 generated a series of NE- to E-trending orogen-parallel ductile shear zones at ca. 1.90–1.82 Ga. Together with multiple high-grade metamorphism and magmatism, the D 1 -D 3 deformation recorded a complex protracted orogeny (>100 Myr) in response to the collision between the Yinshan and Ordos blocks. [ABSTRACT FROM AUTHOR]

• Three units make up the Piedra Alta Terrane: arc-related igneous basement, intra-arc basins and late intrusive granites. • U-Pb ages in zircon restrict the formation of the three units that make up the PAT to the Rhyacian. • Largely predominant positive εHf (T) values attest to the juvenile nature of PAT's crustal segment. • The development of the PAT is related to the evolution of an intraoceanic magmatic arc. This work delves into the intricate Paleoproterozoic geological setting of Uruguay, focusing on the Rio de la Plata Craton (RPC) and its prominent constituent Piedra Alta Terrane (PAT). The PAT constitutes the core of the RPC, characterized as a complex geological entity that encompasses a granite-migmatite basement, metamorphic belts, granite intrusions, and Proterozoic magmatism. To the west, it interfaces with the Transbrasiliano-Kandi tectonic corridor, bounded by the Late-Neoproterozoic Pampia Terrane. The PAT s southeastern boundary extends to Sierra de Tandil and perhaps to Sierra de La Ventana, demarcating its limits with Phanerozoic rocks of the North Patagonian Massif. The Sarandí del Yí shear zone defines the eastern limit of the PAT. Despite varied interpretations of the Piedra Alta Terrane's significance, it is important to note that consensus prevails regarding its four major associations: a granite-gneiss-migmatitic basement complex, three volcanosedimentary belts of low to medium metamorphic grade, diverse late igneous intrusions, and extensional Statherian magmatism (1.79 Ga), represented by tholeiitic gabbroic dikes. In this study, a novel tectonic model for the PAT evolution emerges, supported by an extensive zircon dataset comprising new U-Pb ages, Hf isotopes, and trace element geochemistry. The analytical core involves U-Pb analyses on zircon for dating igneous rocks and establishing the provenance and maximum age of deposition of metavolcanosedimentary sequences. Lu-Hf isotopic analyses on the same zircon crystals provide petrogenetic insights, revealing episodes of crustal growth and minor recycling. Trace element geochemistry and zircon εHf(t) data further accentuate these findings, hinting at mantle source enrichment due to subduction within an intraoceanic magmatic-arc arc setting. [ABSTRACT FROM AUTHOR]

• This is the first discovery of Paleoproterozoic nepheline syenite in Trans-North China orogen. • The rock has experienced metamorphism at 1.87 Ga following its crystallization at 1.89 Ga. • It was derived from mafic continental crust under high-pressure condition. • It indicates continental subduction at 1.9 Ga during assembly of North Craton craton. Subduction of continent is known as a feature of modern plate tectonics, and it is still unclear whether such a process also occurred in the early Precambrian. Despite of ultra-high pressure metamorphism of terrestrial rocks as a proxy of continental subduction, magmatism produced during continental subduction is also a potential alternative. The North China craton is well-known for the occurrence of 1.9 Ga retrograde eclogite, which was likely originated from the subducting oceanic crust along the Trans-North China Orogen (TNCO). Here a nepheline syenite (the Aohu pluton), the first of the kind from the TNCO, is discovered in Yunzhong Mts. It comprises nepheline (∼20 vol%), albite (50–55 vol%), K-feldspar (5–10 vol%), biotite (∼10 vol%), and calcite (∼5 vol%), with minor accessory minerals. No associated mafic or silicic rocks are outcropped in the pluton. SHRIMP zircon U-Pb analyses yield a crystallization age of 1893 ± 13 Ma and a metamorphic overprinting of 1871 ± 17 Ma. The rocks have medium SiO 2 contents (51.9–58.9 wt%), low MgO (0.6–1.6 wt%) and Mg# (24–34), but high Al 2 O 3 (20.0–22.9 wt%) and extremely high K 2 O + Na 2 O contents (10.0–13.6 wt%; Na 2 O/K 2 O = 1.3–2.6). They are enriched in light rare earth elements (REEs) and large ion lithophile elements, but relatively depleted in heavy REEs and high field strengthen elements. They have extremely low compatible elements (e.g., Ni and Cr). They show high (87Sr/86Sr) i ratios (0.706–0.707) but low ε Nd (t) values (−5.3 to −6.0; Nd T 2DM = ca. 2.7 Ga). Their zircon in-situ ε Hf (t) values have a wide range (0 to −5.7; Hf T 2DM = 2.5–2.85 Ga). The absence of mafic component and the extremely low-Mg feature, as well as their trace element patterns and initial Sr-Nd isotopes being compatible with melts derived from the Archean mafic crustal enclaves in the region, support a continental crust origin for the Aohu nepheline syenite. Based on comparison and modeling, we suggest that its generation was most likely under ultra-high pressure condition. It is thus proposed that continental subduction (into the mantle) might have occurred in the TNCO during the Paleoproterozoic. [ABSTRACT FROM AUTHOR]

• Closure of the Ediacaran-Cambrian ocean between the OMAS and Africa. • Multiple metamorphic events in the Central Ribeira belt. • Tectonic setting of two superposed basins: The Costeiro and Búzios basins. The Ribeira Belt represents a deeply eroded orogen which exposes rocks from the different stages of magmatic arcs and associated metasedimentary basins. This contribution focus on the last collisional episode between the Outer Magmatic Arc System (OMAS) and the Cabo Frio Terrane (Angola craton). The OMAS represents a long-lived magmatic arc that collided against the Inner Magmatic System (IMAS) at ca. 590 Ma (M1 metamorphism), and against the Cabo Frio Terrane at ca. 530 Ma (M2 metamorphism). The nature of the magmatism recorded in the first collisional episode, and the subduction polarity of the second is a current topic of debate. New U-Pb age and Lu-Hf analyses in zircon grains from units close to the contact are presented to propose a tectonic model for the closure of the oceanic space between the OMAS and the Cabo Frio Terrane. The results in combination with published data suggest that the metasedimentary rocks of the São Fidélis Group are in a back-arc position of the OMAS and were affected by both the M1 and M2 metamorphic episodes, reflected by the presence of metamorphic zircons with ages between ca. 592–553 Ma and 543–533 Ma. The orthogneiss of the Tinguí Complex intrusive in the back-arc metasedimentary units yielded a crystallization age of 578 ± 9 Ma, coeval with the syn -collisional stage M1. A younger metamorphic overprint at 529 ± 7 Ma was also detected (syn -M2). The orthogneiss of the Região dos Lagos Complex (Cabo Frio Terrane) rendered a crystallization age of 1968 ± 26 and a M2 metamorphic overprint at 522 Ma. Zircon analyses from folded leucosomes in the orthogneiss also indicated a crystallization age of 523 ± 10 Ma, which constrain the time of folding after thrusting. Undeformed post-collisional granitoids and pegmatites yielded crystallization ages between 496 and 499 Ma, closing the tectonic evolution of the belt with the orogen collapse. Our results corroborate with terrane accretion model for the Central Segment of the Ribeira Belt. [ABSTRACT FROM AUTHOR]

[Display omitted] • Summarized how big data can be applied in Precambrian research. • Conjoint analyses using big geochemical data reveal NCC formation and evolution. • Revealing magma cycle indicates NCC involved supercontinent cycle since Archean. • ML-based crust thickness reconstruction highlights arc subduction in NCC formation. • Spatio-temporal analyses suggest prolonged accretion in Precambrian NCC development. The enigmatic nature of the Precambrian era poses ongoing challenges for researchers seeking to uncover its secrets. With the exponential growth of scientific data, there exists a vast repository of information through which these mysteries can be explored. However, this data is often derived from fragmented investigations of geological phenomena within specific disciplinary domains and limited spatiotemporal boundaries, resulting in untapped potential for extracting undiscovered knowledge. To address this limitation, the field of big data science provides a foundation for multidisciplinary research on the geological evolution of the Precambrian. By harnessing the power of large-scale data integration and analysis, valuable insights into this pivotal era in Earth's history can be revealed. This paper offers a comprehensive overview of big data types in geoscience and elucidates common analysis methods. Through a case study focused on the North China Craton (NCC), we demonstrate the application of conjoint analysis to a dataset comprising rock and mineral geochemistry data. Employing local singularity analysis and wavelet analysis on zircon age frequency and Hf isotopic time series, we reveal a persistent long-term periodicity of 800–500 million years since 3.5 billion years ago. This finding indicates a co-evolution between the NCC and the global supercontinent cycle dating back to the Archean period. To investigate the formation of the NCC, we employ machine learning-based crustal thickness evolution reconstruction, which highlights arc formation during subduction as the primary factor, with regional mantle activities playing a secondary role in the convergence. Combining spatio-temporal evolution analysis of magmatic intensity and εHf(t) values, we infer that the development of the NCC primarily resulted from a prolonged process of accretion targeting the Eastern Block (the primary continent nuclei) through the incorporation of diverse arc massifs. This examination of the NCC serves as an example of how data collection, processing, and utilization can enhance our understanding of formational and evolutionary processes, signaling a paradigm shift in Precambrian research driven by the integration of big data. [ABSTRACT FROM AUTHOR]

• In the Ontario gneiss belt, Nd isotope boundaries can be identified in the field. • These isotope boundaries provide the best constraint on major crustal structures. • Spatial control from Nd isotope mapping complements age control from U-Pb dating. • Detrital zircon Hf model ages rather than U-Pb ages yield crustal extraction ages. With the increasing availability of U-Pb-Hf isotope analysis of zircon suites, does whole-rock Nd isotope analysis still have a role to play in mapping Precambrian gneiss terranes? I answer this question by examining the Ontario Gneiss Belt of the Grenville Province, and show that Nd isotope mapping still has a vital role to play in studies of Precambrian crustal evolution. Although U-Pb-Hf isotope analysis of detrital zircons can provide large suites of crystallization ages and epsilon Hf values, the poor spatial control of these data means that precise geographical control of crustal structure from Nd isotope mapping is still important. I demonstrate this for several regions of the Ontario Gneiss Belt, including northern Algonquin Park, western Lake Nipissing and Georgian Bay. In all these regions, mapping complex geographical patterns of crustal formation ages allows detailed documentation of large-scale crustal structure. Only with such an accurate understanding of crustal structure can accurate models of tectonic evolution be constructed in a complex, deeply exhumed orogenic belt such as the Grenville Province. [ABSTRACT FROM AUTHOR]

• We identified a previously unknown ∼2.9 Ga magmatic event in Eastern Hebei, which may challenges the long-held view that granitic gneisses in Eastern Hebei Province, though diverse in composition, type and origin, were emplaced and crystallized in a rather short period of magmatic activity. We report the results of a comprehensive isotopic investigation of zircons from metamorphosed orthogneisses from Caochang village in the Zunhua Complex, Eastern Hebei, North China Craton (NCC). A detailed investigation of the internal structures of these zircons combined with SIMS U–Pb and ICP-MS Lu-Hf zircon analyses, as well as a whole-rock geochemical study, revealed a previously unknown ∼2.9 Ga magmatic event in Eastern Hebei. The identified Mesoarchean gneisses are mainly felsic gneisses and amphibolites. Amphibolites with positive εNd(t) values were derived from the depleted mantle, with some crustal contamination during ascent. Zircon Hf isotopes indicate that the high-silica gneisses originate from the high-temperature mixing of mafic magma derived from a depleted mantle source and the subsequent felsic magma derived from the melting of ancient crustal materials, with the subsequent high degree fractional crystallization of the parental magma. Some of the 2.9 Ga felsic gneisses may record an anatectic event at 2.5 Ga. The widespread ancient inherited and detrital zircons (>2.6 Ga) and the existence of Mesoarchean rocks imply a possible ancient continent in Eastern Hebei. It may also imply that the Mesoarchean era (especially at 2.9 Ga) represents another important magmatic event in the eastern block of the NCC. The identification of 2.9 Ga rocks indicates that the magmatic history of Eastern Hebei is far more complex than previously thought. [ABSTRACT FROM AUTHOR]

Highlights • New geological, geochronological and geochemical data from Cryogenian rocks in the Yukon provide needed geological context to critical dates constrain the onset of the Sturtian glaciation. • Onset of the Sturtian glaciation is constrained between 716.9 ± 0.4 and 717.4 ± 0.2 Ma. • Major unconformities developed throughout northwest Laurentia between the end of the Sturtian glaciation at 660 Ma and the end of the Marinoan glaciation at 635 Ma. • Stratigraphic sections in the Yukon should be considered in defining the base of the Cryogenian Period. Abstract Cryogenian strata of the Windermere Supergroup were deposited in tectonically active basins throughout the North American Cordillera from Alaska to Mexico. The Windermere Supergroup of Yukon, Canada, hosts key geochronological constraints on the start of the Cryogenian Period and the onset of the Sturtian Snowball Earth glaciation at ca. 717 Ma. A 57-million-year duration for the Sturtian glaciation has been suggested by correlations of the glacigenic Rapitan Group in Yukon with equivalent strata in the Mackenzie Mountains of Northwest Territories, where it is overlain by organic-rich argillaceous carbonate of the ca. 660 Ma Twitya Formation; however, syn-depositional faulting and large lateral facies variation complicate these stratigraphic correlations. Here we describe Cryogenian strata of the northern Wernecke Mountains, Yukon, where correlations with the Rapitan and Hay Creek groups of the Mackenzie Mountains have been previously established. These units are then traced south across Cryogenian structures to the southern Wernecke Mountains and west through the Hart River inlier to the Coal Creek and Tatonduk inliers of the Ogilvie Mountains in order to construct a new regional stratigraphic framework. The Coal Creek inlier preserves volcanic rocks in the Mount Harper Group and the Eagle Creek Formation of the Rapitan Group, for which we provide new U-Pb CA-IDTIMS zircon ages. We further formalize the glacigenic Cryogenian Eagle Creek Formation. Together, the new correlations and geochronological data allow us to more precisely integrate geological data from northwest Canada with the rest of the Cordillera and beyond. Particularly, these data refine the onset of the Sturtian glaciation in northwestern Canada to between 716.9 ± 0.4 and 717.4 ± 0.2 Ma and demonstrate that syn-sedimentary tectonism resulted in unconformities throughout northwest Laurentia between the end of the Sturtian glaciation at 660 Ma and the end of the Marinoan glaciation at 635 Ma. These unconformities confound correlations throughout the Cordillera by commonly preserving only one of the two Cryogenian glacial deposits. [ABSTRACT FROM AUTHOR]

Highlights • Amphibolitic rocks from the Paleoproterozoic Erdaowa Group are tholeiitic basalts and basaltic andesites. • The igneous protoliths were derived from the partial melting of the lithospheric mantle with minor crustal contamination. • The REE and trace element patterns suggest that the igneous protoliths have affinities to continental marginal arcs or island arcs. • The Erdaowa Group were most likely developed on an active continental margin arc or an island arc. • Pb/Pb ages of amphibolitic rocks further confirm the previous collisional time between the Yinshan and Ordos blocks, and demonstrate besides high-grade metamorphic rocks, the low- and medium-grade rocks from the Khondalite Belt were also involved in collision. Abstract A currently popular model regards the Khondalite Belt in the North China Craton as a typical continent–continent collisional belt along which the Yinshan and Ordos blocks amalgamated to form the Western Block at ∼1.95 Ga. Although this model is fully supported by the geological data of high-grade metamorphic rocks from the belt, it remains unknown whether it is consistent with the low- to medium-grade units in the belt. One of such low- to medium-grade units from the Khondalite Belt is the Paleoproterozoic Erdaowa Group that consists of low-grade schists, quartzites, amphibolitic rocks, calc-silicate rocks, marbles and minor meta-conglomerates, of which amphibolitic rocks can provide important insights into understanding the tectonic setting and timing of collision of the Yinshan and Ordos blocks along the Khondalite Belt. The Erdaowa amphibolitic rocks can be divided into two groups of which Group1 is assigned to tholeiitic basalts, whereas Group 2 belongs to basaltic andesites, but they both experienced the fractional crystallization of the primary magma that was derived from the partial melting of the lithospheric mantle with minor crustal contamination. Such partial melting of the lithospheric mantle most likely occurred in a subduction zone as evidenced by their REEs and trace elements characterized by depletions in high field strength element (HFSE), Ti, P, Nb and Ta, suggesting that their igneous protoliths have affinities to continental marginal arcs. Metamorphic zircons from two amphibolitic rock samples yield Pb/Pb ages of 1941 + 14 Ma and 1910 + 9 Ma, similar to those metamorphic ages obtained for high-grade pelitic granulites from the Khondalite Belt. This confirms that the Yinshan-Ordos collision occurred at 1.95–1.90 Ga, and provides direct evidence for the involvement of low- and medium-grade rocks during the collision. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Detrital zircon ages constrain transition from Cadomian orogen to passive margin. • This transition spanned about 50 M.y. • Curved geometry of the West African margin and subduction zone played a key role. • The transition was driven by oblique ridge–trench interaction. • Slab pull of the Iapetus Ocean followed. Abstract The Avalonian–Cadomian belt formed as a collage of accretionary complexes, island arcs, and sedimentary basins along the northern margin of Gondwana during the Neoproterozoic times. One of the enigmatic issues is how and when this active margin evolved to a passive margin in the southern realms of the Rheic Ocean during late Cambrian to early Ordovician. This issue is addressed here using U–Pb detrital zircon dating of key stratigraphic sections in the Teplá–Barrandian unit, Bohemian Massif. The new ages constrain the base of the Davle volcanic arc to 608 ± 6 Ma, 591 ± 6 Ma, and 590 ± 4 Ma and its termination to 563 ± 7 Ma. The lower part of the overlying Příbram–Jince continental basin was deposited between 512 ± 5 and 511 ± 3 Ma. These brackets define a time span of about 50 M.y. for the geodynamic transition from Cadomian subduction, accretion, and arc magmatism to a passive margin and lithospheric extension. In our model, a major role is assigned to a presumably curved geometry of the adjacent West African continental margin, which consisted of the outboard Armorican–Saxothuringian portion at an angle to the inboard Iberian–Barrandian portion. We suggest that during oblique subduction, ridge–trench collision and slab break-off occurred in the former at ca. 540 Ma, while subduction/accretion continued in the latter and was terminated by a major pulse of sediment accretion at around 527 Ma and ridge subduction at ca. 524–520 Ma. Finally, the tectonic regime in the Cadomian arc and accreted upper crust switched to extension associated with crustal remelting to produce intraplate magmatism and development of continental basins with short-lived marine transgressions between ca. 512 Ma and ca. 488 Ma. The continued extension led to rifting and basaltic volcanism, directly linked to the diachronous opening of the Rheic Ocean. We conclude that the prolonged transition from active to passive margin in the Cadomian belt was driven two principal geodynamic causes: first by oblique oceanic subduction and ridge–trench interactions, bearing many similarities to modern Cordilleran-type active margins, and then by the far-field slab-pull force of the subducting Iapetus Ocean. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Araçuaí-Ribeira orogenic system (AROS). • Rhyacian-Orosirian orogenic systems (ROOS). • First isotopic Hf signatures for ROOS in AROS. • Brazil-Africa links in Palaeoproterozoic time. Abstract Assembled during the Rhyacian-Orosirian boundary, the Congo-São Francisco palaeocontinent remained linked by a continental bridge from ca. 2 Ga to the Atlantic Ocean opening in the Cretaceous. To the south of that bridge, precursor basins and orogenic outcomes encompassed by the Neoproterozoic-Cambrian Araçuaí-Ribeira orogenic system (AROS) and its African counterparts, developed. The AROS discloses reworked basement units, like the Juiz de Fora, Pocrane and Quirino complexes, which are key units to retrieve the Palaeoproterozoic history of the Congo-São Francisco palaeocontinent. This paper presents new U-Pb ages, and the first Lu-Hf in zircon signatures from those complexes. All magmatic zircon grains show Rhyacian and Orosirian ages, ranging from c. 2250 Ma to c. 1850 Ma. The best Concordia ages range from 2184 ± 9 Ma to 2080 ± 19 Ma. Hf in zircon and whole-rock Sm-Nd data disclose mantle-related signatures for both, the Pocrane and Juiz de Fora complexes, suggesting igneous protoliths with no or very few involvement of continental crust, similarly to juvenile magmatic arcs. Conversely, Hf in zircon data for the Quirino complex show an evolved signature compatible with a magmatic arc developed on a continental older crust with Archaean components. Together with a thorough compilation on Rhyacian-Orosirian orogenic systems (ROOS), our data allow us to envisage links within the Congo-São Francisco palaeocontinent, comprising orogens characterised by mostly evolved isotopic signatures and zircon inheritance. They are grouped into the: (i) W-ROOS, including the Mantiqueira complex, the west segment of the Eastern Bahia belt, intrusions in the south Gavião and Porteirinha blocks, and parts of the Mineiro belt; and (ii) E-ROOS, comprising the Quirino complex, basement rocks of the Cabo Frio tectonic domain, the coastal Eastern Bahia belt, and, in Africa, Eburnean and Kimezian complexes, as well as the western Angola shield. Assembled between the W-ROOS and E-ROOS, an orogenic system with prominent juvenile to moderately juvenile isotopic signature (JU-ROOS) includes the Juiz de Fora and Pocrane complexes, and the Buerarema complex at the central segment of the Eastern Bahia belt. [ABSTRACT FROM AUTHOR]

• U–Pb data from fast pulse LA-ICP-MS is equivalent with conventional U–Pb analysis. • Provenance of the largely unexposed Yeneena Basin revealed. • Exotic sources support a transcontinental transport system across Rodinia. Over ten thousand detrital zircon U–Pb analyses on thirty four samples were undertaken using a fast pulse laser ablation protocol from the Neoprotoerozoic rocks of the largely unexposed Yeneena and northwestern Officer Basins in Western Australia. In addition, conventional laser ablation detrital zircon U–Pb geochronology was carried out on three of the samples. A comparison of the two datasets demonstrated that no statistical significant difference was observed in the detrital zircon spectra between the two techniques. The results of the detrital zircon analyses reveal that after an intial pulse of material dominated by Archean detritus the sediment are dominated by Mesoproterozic sources. This indicates that there is little variation in source materials within and between the identified formations. The major age peaks coincide with magmatic rock ages from within Australia. The results indicate that either the Palaeoproterozoic and Mesoproterozoic terranes remained sources throughout the deposition of the Yeneena and northwestern Officer Basins during the Neoproterozoic, or that recycling of zircons occurred within a quasi-closed system for the duration of sedimentation. The remaining 10 % of grains are difficult to reconcile with magmatic suites of any significant volume within Australia. However, when considering the broader palaeogeographic context at the time the sediments are inferred to have been deposited, rocks from Dronning Maud Land and the Kalahari Craton can supply grains of appropriate ages and are consistent with the known paleocurrent directions. This work demonstrates that there is no significant disadvantage in the application of the fast pulse technique when applied to the collection of U–Pb detrital zircon datasets for the purpose of detrital zircon fingerprinting. However, there is a large upside related to the significant amount of data that can be collected for a given amount of time compared to other more conventional techniques. [ABSTRACT FROM AUTHOR]

• Combination of dating techniques improves accuracy of determination. • Spurious detrital zircon dates post-dating crystallization found by LA-ICP-MS. • LA-ICP-MS studies should routinely chemically abrade zircon prior to analyses. • The oldest Paleoproterozoic glacial event is dated to 2423.1 ± 1.0 Ma. • Anoxic atmospheric settings from the Koegas Subgroup are dated to 2451.5 ± 2.5 Ma. The Transvaal Supergroup, on the Kaapvaal Craton in South Africa, is widely accepted as one of the best-preserved sedimentary archives to constrain planetary-scale environmental changes during the late Archean and early Proterozoic, yet the sedimentation age for certain stratigraphic intervals remains poorly constrained. To improve the temporal control on some of the first-order global changes recorded in these rocks, we carried out U-Pb analyses of detrital zircon populations from several clastic and volcano-clastic sedimentary units of the Transvaal Supergroup. We applied the Chemical Abrasion-Isotope Dilution-Thermal Ionization Mass Spectrometry (CA-ID-TIMS) technique on detrital and volcanic zircon populations that had been previously screened using the Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) technique. We report new maximum depositional age estimates for the Pannetjie (2456.6 ± 7.0 Ma), the Heynskop (2451.5 ± 2.5 Ma), the Makganyene (2423.1 ± 1.0 Ma) and the Hekpoort formations (2248.0 ± 1.1 Ma). A ca. 2.25 Ga-old cluster of LA-ICP-MS analyses in the Makganyene Formation was identified to be spurious, since it was completely removed during the chemical abrasion. Thus, we speculate that circulation of hydrothermal fluids and associated Pb-loss from a radiation-damaged lattice during the emplacement of the much younger Hekpoort Formation or possibly the Ophthalmia Orogeny, recorded in Western Australia, may have reset the U-Pb system of this zircon population. This implies that the accurate maximum depositional age of the Makganyene Formation is ca. 2.42 Ga instead, which denotes the age of the oldest glacial event of global extent during the Paleoproterozoic. Therefore, we suggest that the combination of both dating techniques is essential to ensure accurate maximum depositional age constraints for ancient detrital sedimentary rocks. Additionally, our data provides temporal constraints on a period characterized by major fluctuations in atmospheric oxygen. Finally, and supporting the complex nature of the Paleoproterozoic, linkages between widespread glaciations and atmospheric oxygen fluctuations remain to be explored. [ABSTRACT FROM AUTHOR]

In this contribution, we carry out an integrated study of petrology, whole-rock geochemistry, as well as zircon morphology, trace element, U–Pb and Lu–Hf isotopes for granitic gneisses and leucogranites from the Yudongzi complex, a poorly studied Archean outcrop in the northwestern Yangtze Block. The granitic gneisses have the TTG affinity characterized by relatively high Na 2 O/K 2 O and Sr/Y ratios, and fractionated REE pattern with relatively high LREE but low HREE concentrations. Zircon grains in the granitic gneisses show magmatic cores and metamorphic rims. U–Pb dating on zircon core of four granitic gneiss samples yielded their formation ages as 2660–2632 Ma with a weighted average of 2650 ± 21 Ma (MSWD = 1.6; n = 4). Their average ε Hf (t) values range from −0.6 to 0.5 and two-stage model ages from 3.20 to 3.10 Ga, suggesting that the granitic gneisses were likely generated by remelting of thickened Mesoarchean proto-mafic crust. The metamorphic zircon rims have relatively high Th/U ratios and identical Hf isotope compositions to their corresponding cores, indicating that the rims were formed via solid-state recrystallization process. The metamorphic zircons recorded a metamorphic event at ca. 2.5 Ga. U-Pb dating and Lu-Hf isotopes on magmatic zircons from a leucogranite sample revealed a magmatic event at 2477 ± 18 Ma. The recognization of the 2.65 Ga TTG magmatism and the 2.48 Ga intercrustal remelting event in the Yudongzi complex demonstrates the widespread Neoarchean magmatism in the Yangtze Block. Combined with the age spectra of previous detrital zircons, we show that the Yangtze Block has experienced a major tectonothermal event in the late Archean. The Yudongzi complex has a distinct crustal evolution history compare with the Paleoarchean continent nucleus in the eastern part of the Yangtze Block, suggesting that the continent nucleus might have subjected to lateral growth by accretion processes. [ABSTRACT FROM AUTHOR]

Continental rifts are tectonic zones where substantial material and heat can be transferred from the asthenospheric mantle into the crust. Because of their high thermal gradients, they were hypothesized as a setting for regional high-temperature (HT)/low-pressure (LP) metamorphism. However, the cited example is located in an intracontinental setting, where not only the compressional regime was prominent during collisional orogeny but also the envisaged continental rift failed to run into rupture. This led to ambiguous identification of the continental rift in intraplate regions and thus rejection of this hypothesis. In the present study, we identify for the first time typical HT/LP metamorphic rocks that show the occurrence of both andalusite and sillimanite in a Neoproterozoic continental rift zone. Andalusite O isotopes confirm the continental rift setting, and comparison with zircon O isotopes supports the metamorphic origin of aluminosilicates. Pseudosection calculations indicate that the HT/LP metamorphism occurred at 1.0–3.5 kbar and 560–660 °C. U-Pb dating of metamorphic titanite yields ages of ca. 750 Ma for the HT/LP metamorphism, consistent with the peak age of Rodinia breakup. Premetamorphic protoliths show bimodal lithochemistry and arc-like geochemical signatures, suggesting that they are rift magmatic rocks. These rocks would be produced during the development of continental rifting on a Grenvillian accretionary orogen that formed due to the Rodinia assembly. The continental rifting is coupled with stretching of the thinned orogenic lithosphere, accounting for the high heat flow from the asthenospheric mantle into the upper crust for the HT/LP metamorphism at shallow depths. Heat flow estimates from crustal Th, U and K contents are significantly lower than that from peak mineral assemblages, indicating that the anomalously high heat flow from the asthenospheric mantle did occur in the continental rift. Therefore, continental rifts are an important site for high thermal gradients and thus for regional HT/LP metamorphism. [ABSTRACT FROM AUTHOR]

The Columbia (Nuna) supercontinent existed from approximately 1.9 Ga to 1.3 Ga. Laurentia was part of Columbia, and the western edge of Laurentia (current coordinates) was likely proximal to a large landmass during parts of this interval. Here, we present detrital zircon ages of a Paleoproterozoic sedimentary succession in northern Yukon, Canada, that bear on the evolution of Columbia. The sedimentary succession is preserved as clasts within 1.60 Ga hydrothermal megabreccias. Analyses of detrital zircon reveal abundant 1.78–1.68 Ga zircon with evolved Hf isotope values (−16.1 < εHf(t) < +1.4). Sm-Nd isotope analysis on clasts yields εNdi from −5.3 to −5.5 and model ages from 2.4 to 2.2 Ga. The detrital zircon age distribution is strikingly similar to those from sedimentary megaclasts in the ca. 1.59 Ga Olympic Dam Breccia Complex on the Gawler Craton of Australia. The whole rock Sm-Nd ratios are consistent with derivation from the Gawler Craton. We propose that the sedimentary material contained in both breccia complexes was derived from an overlap assemblage deposited on Australia and Laurentia at ca. 1.6 Ga. This model supports a previous hypothesis that the Gawler Craton was connected to northwestern Laurentia at ca. 1.6 Ga, and that these regions shared a single hydrothermal province that is recognized in northwestern Laurentia as the Wernecke Breccia and in the Gawler Craton as the Olympic Dam Breccia Complex and associated IOCG deposits. The sedimentary overlap succession was deposited after collision between Australia and Laurentia. Australia was subsequently translated southward along the Laurentian margin, placing the Gawler Craton next to southwestern Laurentia and the Mt. Isa Inlier adjacent to northwestern Laurentia by 1.5 Ga. [ABSTRACT FROM AUTHOR]

We present new LA ICP-MS U-Pb-Hf detrital zircon data from Neoproterozoic sedimentary basins located along the south-western margin of the Siberian Craton. In the Yenisey Ridge (the Taseeva basin), siliciclastic sedimentary units contain abundant 2.7–2.5 Ga, 2.0–1.75 Ga and 0.95–0.57 Ga detrital zircon populations, whereas for the Prisayan Uplift slightly different detrital zircon ages of 3.0–2.5 Ga, 2.2–1.8 Ga and 0.95–0.65 Ma are common. Mid Neoproterozoic sandstones were deposited in a rift setting or along a rifted cratonic margin facing a back-arc basin, whereas the immature to submature upper Ediacaran to Lower Cambrian fluvial successions were probably deposited in the foredeep setting, at the expense of proximal Neoproterozoic igneous suites and the underlying metasedimentary basement. A range of εHf values from −10 to +14 indicates intense mixing between juvenile and evolved magma components in a continental arc setting at ca. 950–570 Ma. Geological evidence, persistent input of detrital zircon material derived from ancient crustal units of western Siberian cratonic margin and evolution of Hf isotopic compositions suggest that the Neoproterozoic arc system of the Yenisey Ridge and, partly, Sayan orogens developed along the active margin of Siberia. In the Neoproterozoic, the arc system probably extended along the periphery of Rodinia into the Taimyr orogen of northern Siberia and Valhalla orogen of north-eastern Laurentia. [ABSTRACT FROM AUTHOR]

The lutetium–hafnium (Lu–Hf) isotope record, typically measured in zircon crystals, provides a major tool for the study of crustal growth and differentiation. Interpretations of Hf isotope datasets use an evolution array defined by source 176 Lu/ 177 Hf. However, the very process that drives crustal differentiation to produce such arrays – partial melting – is precisely that which may modify the trajectory of the array due to variable degrees of anatexis allied with the differing compatibilities of Lu and Hf in residual minerals. Further, Lu/Hf estimates derived from the composition of present-day continental crust may be inappropriate for modelling Archaean crustal evolution, where different geodynamic styles and magmatic sources prevailed. Using an approach combining phase equilibria, and trace element and isotopic modelling, we quantify the effects of partial melting of both a modern (N-MORB) and Archaean (C-F2) mafic source on melt Lu/Hf. Melting N-MORB shows that the 176 Lu/ 177 Hf of the melt, which modelling predicts to be between 0.015 and 0.022, is sensitive to the degree of melting. This difference results in a variation of 4.5 epsilon units/billion years. By contrast, anatexis of C-F2 yields melts with 176 Lu/ 177 Hf ∼0.009 that are less affected by the degree of melting. Remelting TTG yields K-rich granitic melts (TTG + G) with 176 Lu/ 177 Hf ∼0.005. Thus, a partial melting event imposes a greater control on the resulting crustal reservoir Lu/Hf than the degree of melting. Archaean continental crust has a lower Lu/Hf than that of the average mid to upper continental crust, and therefore a lower 176 Lu/ 177 Hf (here 0.005–0.009) is appropriate to modelling its Hf isotopic evolution. There has been a secular change in average crustal Lu/Hf, with the median Lu/Hf of Proterozoic and Phanerozoic magmatic rocks being higher than that of Archaean TTG + G. We show that an enriched Archaean mafic source (C-F2) with a Lu/Hf ratio of ∼0.12 may produce TTG continental crust with a 176 Lu/ 177 Hf approaching that calculated in real rocks worldwide. [ABSTRACT FROM AUTHOR]

The c.3.0–2.9 Ga Pongola Supergroup located on the south-eastern margin of the Kaapvaal Craton preserves some of the most pristine Archean successions but the timing of volcanic and sedimentary processes, and sediment sources remain relatively poorly known. Combined zircon U-Pb ages and Hf isotope data of sandstones from the Nsuze and Mozaan Groups are presented from key locations of the Northern, Central and Southern Domains of the 270 km long belt. These data indicate important lateral and temporal variations and therefore changes in source areas. The basal Pongola sedimentary rocks (Mantonga Formation) in the Northern Domain were derived from the c.3.4 Ga basement, and also most likely from reworked Moodies Group sedimentary rocks of the Barberton greenstone belt. Zircon detritus in Nsuze and lower Mozaan Groups sandstones shows similar age-Hf isotope spectra, and a remarkable overlap with data from magmatic and (meta)sedimentary rocks of the southeastern Kaapvaal craton. The data point to a proximal source for Nsuze sandstones in the Northern Domain and a different provenance for the Southern Domain sandstones. A possible signature of the extensive 3.10–3.07 Ga Mpuluzi granite is seen only in the Nsuze sandstones and basal Mozaan of the Central Domain. The data indicate for the first time that Cr-rich sandstones of the Ndikwe Thrust Segment of the Southern Domain were deposited at <2.92 Ma, and therefore belong to the uppermost Mozaan Group. Furthermore, they reveal a significant switch in provenance from the lower to upper Mozaan Group from a reworked Archean basement towards a more juvenile hinterland with εHf t  = +0.9 to +6.3 between 3.07 and 2.92 Ga; similar to the source previously reported for the Central Rand Group of the Witwatersrand Basin. The juvenile zircon detritus in the upper Mozaan Group requires sources as far as the Pietersburg and/or Kimberley Blocks, which became amalgamated to the central block of the Kaapvaal Craton at 2.97–2.87 Ga, but perhaps also a source outside of the present day Kaapvaal Craton, and possibly as far as the Pilbara Craton. [ABSTRACT FROM AUTHOR]

A number of Precambrian terranes are distributed in the Tibetan Plateau, including the Lhasa, Sibumasu, Qiangtang, Qaidam, Qilian and Tianshuihai terranes. These terranes exhibit distinct features in rock associations and tectonothermal history. They are important for understanding the evolution of the Tethys Ocean and the assemblage and breakup of the Precambrian supercontinents. In this contribution, we identify a Precambrian terrane at the southeastern section of the Pamir Syntax and we name it as Mazar terrane. Systematic zircon U-Pb dating shows that the basement, mainly composed of metamorphic bimodal volcanic rocks and gneiss/schist, deposited at ca.2.5 Ga and was overprinted by ca.2.0 Ga amphibolite-facies metamorphism. The Neoproterozoic granitic intrusions into the basement, emplaced at 840–835 Ma. Geochemistry of the granitic intrusions defines two distinct types of granitic rocks, including the trondhjemite-tonalites and granodiorites. The sodic trondhjemite- tonalites show TTG-like or adakitic signatures such as enrichment of LREE and LILEs, depletion of HREE and HFSE, resulting in their high Sr/Y and (La/Yb) N ratios. The granodiorites exhibit typical signatures of the calc-alkaline I-type granites. Both trondhjemite-tonalites and granodiorites have coupled unradiogenic whole-rock Nd and zircon Hf isotope compositions. εNd(T) and εHf(T) values of the trondhjemite- tonalites range from −9.5 to −8.7 and from −14 to −10, respectively. The granodiorites have slightly more radiogenic Nd-Hf isotope compositions with εNd(T) values ranging from −5.5 to −4.4 and εHf(T) values ranging from −10 to −7. According to elemental and isotope signatures of the granitic intrusions, the trondhjemite-tonalites were derived from partial melting of a mafic crust at depth ≥30 km with a garnet amphibolite residue whereas the granodiorite was formed by partial melting of a mafic crust at a shallower level and mantle-derived magma could be involved in the genesis of the granodiorite. In line with their geochemistry and the fact that the granodiorite is slightly younger than that of the trondhjemite-tonalites, we propose that those granitic intrusions were most likely formed in an extensional environment, and that they could be part of the earliest igneous activity related to the initial breakup of the Rodinia supercontinent. Our study, in combination with previous works, suggests that the Mazar terrane, as well as the Qilian, Qaidam, Tianshuihai terranes, is most likely continental fragments drifted from the Yangtze Block during the breakup of the Rodinia supercontinent. [ABSTRACT FROM AUTHOR]

The subsurface Beetaloo Sub-basin of the McArthur Basin, Northern Territory, Australia, comprises a succession of shallow-water, dominantly marine, clastic sedimentary rocks that formed in the main depocentre of the Mesoproterozoic Roper Group. This group contains the oldest commercial hydrocarbons known, whose presence has been linked to changing nutrient flux controlled by a changing provenance. LA-ICP-MS detrital zircon U–Pb age data presented here provide new age constraints on the upper Roper Group and reveal spatial and temporal provenance variations illustrating the evolution of the basin and its margins that are linked to a major provenance change caused by the coeval collision of the combined South Australian Craton/North Australian Craton with the West Australian Craton. The maximum depositional ages of the Bessie Creek Sandstone and the Velkerri Formation of the Roper Group are constrained to 1386 ± 13 Ma and 1308 ± 41 Ma, respectively, whereas the overlying Moroak Sandstone has no younger detrital zircons, so its maximum depositional age is also constrained as 1308 ± 41 Ma. The Kyalla Formation was deposited after 1313 ± 47 Ma, and two, as yet, informally defined and ungrouped latest Mesoproterozoic to Neoproterozoic sedimentary units, the lower and upper Jamison sandstone, have maximum depositional ages of 1092 ± 16 Ma and 959 ± 18 Ma, respectively. Large detrital zircon age datasets (of 1204 near-concordant analyses) indicate that zircons from the Maiwok Subgroup were originally sourced from Palaeoproterozoic and earliest Mesoproterozoic rocks. These are consistent with derivation from the surrounding exposed basement. Detrital zircon age variations up-section suggest a systematic temporal change in provenance. The oldest formation analysed (Bessie Creek Sandstone) has a major source dated at ca. 1823 Ma. Rocks of this age are common in northern basement exposures. Samples from the overlying Velkerri Formation, show derivation from a ca. 1590 Ma source, consistent with rocks exposed in Queensland, or the Musgrave Province. The Moroak Sandstone and the Kyalla Formation show progressively more ca. 1740 Ma detritus, which we suggest likely reflects new sources in the Arunta Region to the south. We suggest that the provenance variation initially records exposure and denudation of western Queensland rocks at ca. 1400 Ma due to rifting between Laurentia and the North Australian Craton. From then until at least ca. 1320 Ma, the increased ca. 1740 Ma detritus suggests uplift of the Arunta Region that we interpret as reflecting collision between the southern North Australian Craton and the West Australian Craton as ca. 1300–1400 Ma. This tectonically-controlled provenance change is interpreted to have included erosion of nutrient rich arc-rocks that may have caused a bacterial bloom in the Roper Seaway. The Jamison sandstone and overlying Hayfield mudstone represent a marked change in provenance and were deposited after the Musgrave Orogeny, representing a newly-recognised siliciclastic basin that may have formed a shallow, long wavelength foreland basin to areas uplifted during the Musgrave Orogeny. [ABSTRACT FROM AUTHOR]

Deformed and metamorphosed mafic to ultramafic intrusive rocks are common along and adjacent to the Snowbird Tectonic Zone, a major Paleoproterozoic structure separating the Rae and Hearne cratons. On the Rae side of this major lithospheric structure, we investigated a series of mafic bodies that intrude high-grade paragneiss and are associated with Ni–Cu ± PGE mineralization. By linking field observations, geochronology and metamorphic petrology, our results indicate Archean (∼2.63 Ga) crystallization ages for these mafic intrusions over a minimum along-strike extent of ∼500 km and a later high-temperature (∼820 °C and ∼7.5 kbar), Paleoproterozoic metamorphic overprint at t  < 1.94 Ga. The youngest reproducible ages of detrital zircon from the host paragneiss indicate a maximum depositional age of ∼2.73 Ga for the paragneiss. These results indicate that the sedimentary rocks hosting the mineralized mafic intrusions are older than the mixed siliciclastic and carbonate sedimentary units previously described along the Snowbird Tectonic Zone (<2.07 Ga). Furthermore, in two localities (Thye and Yotin-Shagory lakes, in Northwest Territories and northern Saskatchewan), zircon from both the mafic and pelitic samples exhibit an unusual within-run fluctuation in the lead isotope signal during SHRIMP analysis, suggesting inhomogeneous redistribution of radiogenic Pb within the crystal lattice. Redistribution is interpreted to have occurred during the ∼1.94–1.90 Ga tectonometamorphic event. This behaviour, documented only in ∼10 (Ultra)High-Temperature localities worldwide, has not been observed in the other two studied localities (Currie and Axis lakes in northern Saskatchewan), suggesting either i) a different metamorphic history or ii) different re-crystallization processes occurring during the Paleoproterozoic high-temperature evolution (or a combination of the two). Our data indicate that (U)HT metamorphism and the absence of a fluid/melt phase are not a requirement for lead redistribution in zircon. [ABSTRACT FROM AUTHOR]

The North China Craton (NCC) is one of the oldest cratons in the world that preserves the records of many important geological events in the early evolution of the Earth. However, the early Precambrian tectonic evolution history of the NCC is still controversial. Here we report Paleoproterozoic leucogranites, garnet granites and granulites in the Fengzhen area that constitutes a junction between the Khondalite Belt and the Trans-North China Orogen (TNCO). The leucogranites have high SiO 2 content (75–85 wt%), and magmatic zircon U-Pb age of 2199 ± 3 Ma. Their zircons have slightly various εHf (t) values (−0.45 to 1.41) with T DM model ages of 2.5–2.6 Ga. The granites show strong LREE enrichment with La/Yb cn ratio of 12–176, and have high initial Nd isotope (ε Nd(t) = 3.5–4.5). Most of them display positive Eu anomaly, excluding fractional crystallization contribution on the high Si feature. The leucogranite was produced by melting of Late Archean felsic TTGs (tonalite–trondhjemite–granodiorite) and addition of juvenile crust. Magmatic zircons yield the garnet granite age of 2002 ± 3 Ma. The zircons show various εHf (t) values (−5.8 to 7.1) and T DM model ages (2.1–2.6 Ga). Low initial ε Nd(t) isotope value (−4.2 to −8.3) was determined in the granites. The granulites are high pressure metamorphic rocks with a peak pressure of 12.0 ± 0.8 kbar, and have similar metamorphic age of 1967 ± 10 Ma to the garnet granites. This indicates that the Fengzhen area underwent 2-Ga inter-continental orogeny, in which the melting of sedimentary rock formed the garnet granites. Similarly, sodic TTG melting to form K-rich leucogranites also needs high pressure. However, the leucogranite age is obviously older than the peak metamorphic timing of continent–continent collision. This implies that the Fengzhen area may have underwent arc-continental collision at 2.2 Ga. [ABSTRACT FROM AUTHOR]

The formation and tectonic evolution of the Jiangnan orogenic belt in South China have been debated in the context of plate subduction-collision versus mantle plume. Here we present new results from petrology, whole rock geochemistry, zircon U-Pb chronology and Hf isotopes, on three magmatic suites ranging in composition from felsic to mafic from the Jiuling terrane of the central Jiangnan orogenic belt in the southeastern margin of Yangtze Block. Suite 1 including meta-diorites and meta-basites are dated at 849.9 ± 4.9, 848.8 ± 4.5 and 846.3 ± 3.5 Ma. The meta-diorites and some of the meta-basites display enrichment of LREE, Rb and K and depletions of Nb, Ta and Ti anomalies, with distinctive geochemical features of continental arc setting. The εHf(t) values of zircons from meta-diorites range from 0.17 to 6.10. The other meta-basites have LREE depleted REE patterns, similar to N-MORB and intra-oceanic island arc settings, suggesting a fore-arc environment. Suite 2 consists of foliated granitoids dated at 816.8 ± 4.2, 814.6 ± 3.6, 812.5 ± 3.5 and 810.3 ± 3.5 Ma, with the A/CNK values >1.1, and are classified as post-collisional granites in the Rb/(Y + Nb) diagram. Zircon grains from the granitoids show εHf(t) values in the range of −1.99 to 8.49 and Hf model ages of 1835–1041 Ma. Suite 3 is composed of meta-diabase dated at 792.1 ± 2.8 Ma, with zircon εHf(t) values of 8.46–13.83. This suite shows E-MORB REE patterns, and plot within continental rift field. Their zircon Hf model ages mainly clustered at 1046–811 Ma, indicating magma sourced through partial melting of early Neoproterozoic lithosphere mantle. These data suggest that the three Neoproterozoic Jiuling magmatic suites in the Jiuling terrane correlate with (1) the continental arc, fore-arc, (2) collision and (3) continental rift settings in the interval from 850 Ma to 790 Ma. These tectonic settings are consistent with a geodynamic process from the oceanic subduction beneath the Yangtze Block (850 Ma), collision between Cathaysia and Yangtze Blocks (820 Ma) and intracontinental rift (790 Ma). This tectono-magmatic cycle in the Jiangnan orogenic belt is >200 Ma later than the global Grenville orogeny in response to Rodinia supercontinent assembly, and challenges some of the existing models. [ABSTRACT FROM AUTHOR]

Abundant porphyritic granites, including Grt-bearing and Bt-bearing porphyritic granites, and flesh-red porphyritic granites, as various scale batholiths are widely distributed within the Jiao-Liao-Ji belt (JLJB), which extends for a distance of at least 1000 km, rather than being limited to sporadic outcrops in southern Liaoning and Jilin as stated in previous studies. On the basis of morphology, CL and BSE zoning patterns, and mineral inclusions of dated zircon and monazite grains from samples of various porphyritic granites, the grains exhibit evident magmatic zones with distinct cores and rims and preserve felsic mineral inclusions of Qtz + Kfs + Pl + Qtz ± Ap in both domains. The magmatic zircon cores and rims from 18 dated samples yielded two distinct weighted mean age groups, from 1872 ± 9 to 1866 ± 7 Ma and 1851 ± 14 to 1842 ± 10 Ma, with age peaks at 1869 ± 1.7 and 1848 ± 2.4 Ma, respectively. Similarly, the magmatic cores and rims of monazites from 10 dated samples also showed two distinct weighted mean age groups, from 1870 ± 3 to 1864 ± 2 Ma and 1851 ± 6 to 1842 ± 12 Ma, with age peaks at 1868 ± 0.8 and 1847 ± 1.2 Ma, respectively. The numerous U-Pb age data of both zircons and monazites revealed that the JLJB experienced a major episode of granitic magmatism in the Paleoproterozoic with initial emplacement timing of melts at ∼1.87 Ga and crystallisation end timing of melts at ∼1.84 Ga as represented by the magmatic cores and rims of the zircons and monazites, respectively. A combined study of whole-rock geochemistry and zircon Lu-Hf isotopic analyses revealed that the three types of porphyritic rocks are enriched in HREE, Zr, Nb, Ga, and Y and are depleted in V, Cr, and Ni, and that most have high TFeO/MgO ratios and Zr-saturation temperatures of ∼850 °C, which is suggestive of an affinity with A-type granite. Moreover, the dominant ε Hf (t) values of the magmatic zircons range from −4.8 to +3.3, which is consistent with those of the 2.2–2.1 Ga calc-alkaline meta-granites in the JLJB. Considering the high contents of garnet, Al-rich paragneiss enclaves, and ∼1.92 Ga inherited metamorphic zircons in the granites, these porphyritic rocks were most likely derived from the partial melting of the 2.2–2.1 Ga calc-alkaline meta-granites with abundant involvement of Al-rich pelitic granulites from the basement of the JLJB. As the result of a newly combined study of traditional geothermobarometers and phase equilibria modelling together with geochronological U-Pb dating, a precise clockwise P-T-t path with a subsequent near isothermal decompression process has been well determined in the HP-MP granulite facies metamorphic rocks in the JLJB. Thus, the following sequence of events can be inferred. Abundant ∼2.2–2.1 Ga granitic rocks and voluminous Paleoproterozoic sedimentary rocks were subducted to lower crustal depths and underwent a peak HP-MP granulite facies metamorphism at 1950–1900 Ma. These granulite facies rocks were exhumed to middle crustal levels and experienced a post-peak MP-LP granulite facies metamorphism at 1875–1840 Ma. The retrograde rocks continued to be exhumed to shallow crustal levels at 1830–1800 Ma and were finally overprinted by late amphibolite facies retrogression. The numerous magmatic zircons and monazites from the various porphyritic granites record a distinct Paleoproterozoic granitic magmatic event with two evident age peaks of ∼1.87 Ga and ∼1.84 Ga, which are completely consistent with the post-peak MP-LP granulite facies metamorphism (1875–1840 Ma), representing an anorogenic magmatic association formed in an extensional setting possibly resulting from mantle upwelling and lithospheric thinning and resulting in the violent partial melting of ∼2.2–2.1 Ga meta-granites along with abundant Al-rich pelitic granulites. Considering these data in combination with previous whole-rock geochemistry and age data, it can be stated that similar porphyritic granites are not only limited to the entire JLJB but are also widely distributed in North and South Korea. Thus, it can be concluded that the ∼1.87–1.84 Ga porphyritic granites, together with massive rapakivi granites, Kfs-megacrysts, and porphyritic monzogranites, as products of an anorogenic granitic magmatic event, may have widely formed in both the JLJB and Korean Peninsula in an extensional and thinning tectonic setting. [ABSTRACT FROM AUTHOR]

The supergiant Olympic Dam Cu-U-Au-Ag deposit is hosted by the Olympic Dam Breccia Complex within a ca. 1.59 Ga granite. The breccia complex is largely granite-derived but also includes volcanic clasts and domains of bedded clastic facies. Recently discovered quartz-rich sandstone has a provenance that included Paleoproterozoic and Archean units represented by zircon populations centered at ca. 2.4 Ga and ca. 1.7 Ga. The texture, detrital and cement mineralogy, and distribution of detrital zircon ages in the quartz-rich sandstone closely match those in sandstone of the Pandurra Formation deposited in the regionally extensive intracratonic Cariewerloo Basin (ca. 1.44 Ga). The age of authigenic apatite (1.44 ± 0.02 Ga) in the brecciated quartz-rich sandstone is equivalent to the minimum depositional age of the Pandurra Formation. We conclude that the quartz-rich sandstone is a remnant of the Pandurra Formation, that the Pandurra Formation originally extended across the Olympic Dam Breccia Complex, and that it was incorporated by tectonic activity at least 150 myr after initial formation of the breccia complex. Furthermore, we speculate that oxidized U-bearing fluids from the overlying Cariewerloo Basin may have interacted with the Olympic Dam U resource, consistent with mounting evidence for substantial post-1.59 Ga remobilization and probable addition of U. [ABSTRACT FROM AUTHOR]

There are different viewpoints on metamorphic and anatectic zircons recording ages of 2.45–2.48 Ga or even younger in some areas of the North China Craton where both late Neoarchean and late Paleoproterozoic tectono-thermal events are well developed. These are: 1) partial resetting of the U-Pb isotopic system in the late Neoarchean zircons, 2) metamorphism lasting from the late Neoarchean to the earliest Paleoproterozoic, and 3) earliest Paleoproterozoic metamorphism as separate different event. Western Shandong Province is an area where the late Neoarchean tectono-thermal event is widely developed but the late Paleoproterozoic event has not been identified. This provides an opportunity to understand the geological processes around the Archean-Proterozoic boundary. Based on a field study, we carried out SHRIMP U-Pb zircon dating on seventeen samples of ∼2.5 Ga old metamorphic and anatectic rocks, including tonalite, trondhjemite, granodiorite, gabbro, quartz diorite, granite and paragneiss with primary emplacement or depositional ages of 2.52–2.68 Ga. Anatectic zircons show some textural and compositional features: a) Homogenous or blurred oscillatory zoning, b) high U contents and low in Th/U ratios (commonly <0.3), c) rare idiomorphic morphologies, and d) commonly containing inherited (xenocrystic) cores. We conclude that the strong late Neoarchean event is widespread in western Shandong and is limited between ∼2.50 and 2.54 Ga. In contrast, apparent 2.45–2.48 Ga metamorphic zircon ages in some other areas of the North China Craton may be the result of overprinting and partial recrystallization of Neoarchean metamorphic zircons during the late Paleoproterozoic event. The Archaean rocks of western Shandong can be divided into three belts, namely Belts A, B and C from the northeast to the southwest. The difference between Belts A and B in ∼2.5 Ga metamorphic and anatectic intensity may indicate that the former was elevated to a higher crustal level compared with the latter at the end of the Neoarchean. [ABSTRACT FROM AUTHOR]

U-Pb detrital zircon age and trace element data from a Devonian sandstone sample of the Beacon Supergroup provide new evidence for 1450 Ma zircon sources in Antarctica. These grains yield a dominant 1450 Ma (Mesoproterozoic, Calymmian) age probability peak with U/Th ratios suggesting they primarily formed from magmatic processes, also consistent with the presence of grains with oscillatory zonation. Determination of zircon parent rock types using trace element proxies reveals that the zircon grains are likely predominantly derived from granitoid rocks, with subsidiary, yet significant contributions from mafic and alkaline igneous rocks. These results are consistent with a ca. 1440 Ma (Mesoproterozoic, Calymmian) granitoid glacial erratic and similar aged detrital zircon found elsewhere in the Transantarctic Mountains that suggest a continuation of the trans-Laurentian A-type granitoid belt into Antarctica and, therefore, a 1400 Ma SWEAT-like reconstruction of the continental landmasses. [ABSTRACT FROM AUTHOR]

We have targeted the southern side of the Dronning Maud Land (DML) mountains in search of moraine material that might reveal the geology in the ice-covered region of the East Antarctic polar plateau. Nine samples of unconsolidated moraine material, carried by the northward flowing East Antarctic ice sheet to the southern side of the DML escarpment, were collected and processed for U-Pb zircon analyses. The analyses resulted in ca. 1100 new U-Pb zircon spot ages between ca. 2000 and 500 Ma. The oldest, Palaeoproterozoic rocks come from the easternmost localities with a probable source region between the Sør Rondane Mountains and Dome Fuji. The samples have major Stenian and early Tonian age peaks. Early Tonian rocks are well known from the SW Terrane in the Sør Rondane Mountains and characterise the major Tonian Oceanic Arc Super Terrane (TOAST). Stenian ages are far less common in the outcropping region. Although Stenian ages are common in both the Maud Province of western-central DML as well as in the Rayner Complex, our samples differ with respect to composition and/or isotope geochemistry; they are juvenile, subduction-related and resemble an early phase of oceanic arcs that was so far unknown in this region. In the westernmost sample, the oldest age peak is ca. 800–720 Ma with possible counterparts in the Schirmacher Oasis. All samples show a protracted Late Neoproterozoic/Early Palaeozoic metamorphic overprint, accompanied by igneous addition, most likely related to the East African-Antarctic Orogen. This overprint appears most intense in clasts collected from the westernmost locality, lasted for ca. 150 Ma and an eastward younging of metamorphic ages is observed. The new moraine samples together with previous outcrop studies reveal that this region has undergone two major phases of oceanic arc/terrane accretion; the first one from ca. 1100 to 900 Ma is probably related to accretion tectonics outboard of Rodinia, the second one from ca. 850 to 580 Ma occurred as a result of ocean closure and finally Gondwana amalgamation. No significant old components are found, but the high proportion of Late Neoproterozoic/Early Palaeozoic ages confirms that the East African-Antarctic Orogen transects DML and East Antarctica. [ABSTRACT FROM AUTHOR]

• Correlation of profiles of the Volyn LIP using zircon CA-ID-TIMS analysis. • Discovery of younger than 567 Ma felsic phase of Volyn volcanism. • Constraining ages of glaciations older and younger than basalt flows. • Constraining ages of Redkino-Kotlin boundary and Podillya Ediacaran biota. • Correlating Podillya Ediacaran with the felsic phase of Volyn volcanism. Combined single zircon crystal CA-ID-TIMS U-Pb dating, micropaleontological study, and quantitative XRD analysis were used to correlate sections of the Podillya-Moldova Ediacaran succession with sections of the Volyn Large Igneous Province (Volyn LIP). Five U-Pb zircon ages were obtained from Volyn LIP rocks, and four from three distinct Podillya bentonite horizons. Biostratigraphic determinations were made for one section in Volyn, and two sections in Podillya. It was concluded that Volyn LIP activity had two phases. A first phase of mafic and felsic magmatism was characterized by eruption of numerous basalt lava flows, and lasted from c. 580 to 567 Ma; a second phase of pyroclastic felsic magmatism, with no lavas, lasted from 567 to c. 545 Ma. The two phases can be distinguished in the quantitative mineral composition of rocks from the Kobryn 1K borehole in western Belarus. In the central area of the Volyn LIP, near Brest, rocks of the felsic phase were removed by erosion before deposition of the Kotlin subgroup. The Podillya Ediacaran succession, from the top of the Hrushka formation to the top of the Kalyus beds, (i.e. the Mohyliv-Podilsky group), hosts soft-bodied organisms. This succession corresponds to the felsic phase of the Volyn LIP. The age of the Redkino-Kotlin subgroup biostratigraphic boundary, at the base of the Nagoryany formation, is constrained at 555–545 Ma, close to the end of the Volyn LIP activity. The newly discovered glaciation in Volyn is dated as c. 567 Ma. The period of development of kaolinitic paleosols on top of the Volyn LIP effusive rocks is dated at c. 570–550 Ma. [ABSTRACT FROM AUTHOR]

[Display omitted] • New data on interbedded metavolcanic rocks inform the origin of DFB complexes. • Metamorphic complexes of the DFB Central Sector show two unrelated magmatic events. • Elemental and isotope data indicate an Andean-type magmatic arc at 800–770 Ma. • New U-Pb zircon ages reveal Passo Feio metavolcanic protoliths of 580 ± 2 Ma. • The volcano-sedimentary complexes have a common late-orogenic evolution at 580 Ma. The geochemical and isotopic signatures of magmatic events preserved in deformed metavolcano-sedimentary sequences may inform about geological setting and original basin stratigraphy. This paper discusses elemental and isotopic geochemical literature data on metavolcanic rocks interleaved with highly-deformed metasedimentary rocks from the Dom Feliciano Belt central sector, southernmost Brazil: the high-grade Várzea do Capivarita, and the lower greenschist to amphibolite facies Porongos and Passo Feio complexes. We also provide new geochemical data for seven samples and two U-Pb zircon determinations. REE patterns, together with geochronological data, permit to sort the dataset into three main groups: i) Group 1 - LaN/YbN ≈ 10, Eu/Eu* = 0.38 to 0.86; ii) Group 2 - LaN/YbN = 12 to 44, no Eu anomaly, and iii) Group 3 - negative Eu anomaly (Eu/Eu* ≈ 0.70), but higher LREEs absolute values (LaN/YbN ≈ 22), and rare basic metavolcaniclastic rocks (Bmvc). New U-Pb zircon analyses of two Passo Feio acidic metavolcanic rocks yield a crystallization age of 580 ± 2 Ma (2σ). Group 1 samples account for a magmatic event at 800–770 Ma in the Várzea do Capivarita and Porongos (Cerro da Árvore sequence) complexes. They represent a magmatic association produced from subduction-related sources, with crustal contribution shown by 87Sr/86Sr (790 Ma) > 0.715 and ƐNd (790 Ma) from −5 and −11 (up to –22). Groups 2 and 3 account for a magmatic event at ca. 600 to 580 Ma in the Passo Feio and western Porongos (Capané sequence) complexes. Groups 2 and 3 rocks are interpreted to have been sourced from subduction-related enriched mantle without major crustal contamination, with 87Sr/86Sr (580 Ma) = 0.7035–0.7050 and ƐNd (580 Ma) > -10. For the basic metavolcanoclastic sample (Bmvc), the data suggest mantle-derived origin without significant contribution of subduction-related sources, possibly indicating multiple sources for this newly-described and not yet fully understood Ediacaran magmatism. Our comparative study leads to the novel conclusion of a shared tectonic evolution between the Passo Feio Complex and the western Porongos Complex at ca. 600–580 Ma. They also corroborate a shared tectonic evolution between the Porongos Complex and Várzea do Capivarita Complex at ca. 800–770 Ma, as reported by previous authors. [ABSTRACT FROM AUTHOR]

• The Sassandra-Cavally domain is located across the Paleoproterozoic and the Archean teranes. • Rocks consist of migmatitic gneisses, metasediments and a granitic intrusion. • U-Pb ages obtained on zircon span from the Mesoarchean to the Paleoproterozoic. • Hf compositions show mixed crustal growth processes at 3328–2812 Ma and 2213–2088 Ma. Crustal evolution in the south West African Craton is dominated by a significant input of juvenile material into the crust at ca. 2.1 Ga and it remains unclear how much of the Paleoproterozoic continental mass was influenced by the presence of pre-existing Archean crustal domains. The Sassandra-Cavally (SASCA, Côte d'Ivoire) domain is strategically located east of the Sassandra shear zone at the transition of the Paleoproterozoic and Archean terranes of the Leo-Man shield. Combined U-Pb and Lu-Hf isotopic analyses by LA-(MC-)ICP-MS were acquired on zircon grains extracted from migmatitic gneisses, metasedimentary rocks and a granitic intrusion. The migmatitic gneisses, yield Archean ages between ca. 3330 and 2810 Ma with ε Hf ranging from −9.4 to + 3.3 and a metamorphic age at 2076 ± 6 Ma. They are tentatively interpreted as orthogneisses extracted from the mantle during the Paleoarchean and reworked substantially in the Mesoarchean. Detrital zircon grains from metasedimentary units adjacent to the Archean migmatitic gneisses yield ages ranging from ca. 2213 to 2088 Ma with ε Hf ranging from + 0.0 to + 5.5, indicating derivation from juvenile Paleoproterozoic source rocks. A granite intrusion was dated within uncertainty of the metamorphic age at 2084 ± 6 Ma. It exhibits a hybrid isotopic signature with ε Hf forming two distinct clusters between −4.9 and −8.5, and between + 2.2 and + 6.5 for inherited zircon grains dated between ca. 2343 to 2100 Ma. The near continuous U-Pb age record from this early Mesoarchean event to the Neoarchean is associated with constant initial 176Hf/177Hf suggesting for an ancient lead loss event at ca. 2800 Ma or a prolonged period of zircon dissolution/precipitation and/or crystallization. This early period is followed by peaks of zircon dates highlighting crustal extraction during the Eoeburnean (ca. 2250 to 2150 Ma) and Eburnean orogenies (ca. 2140 to 2100 Ma). The absence of detrital zircon of the ages similar to those of migmatitic gneisses (∼3200–2800 Ma) in Paleoproterozoic metasediments suggests their deposition distal from the Archean terranes followed by a tectonic assemblage of the SASCA domain during the later stages of the Eburnean orogeny. [ABSTRACT FROM AUTHOR]

[Display omitted] • Transition from stable (S-type granites, - ε Nd) into stretched continental margin(I-type granitoids, + ε Nd) • Linkage of NW India, Seychelles, SE Pakistan, E-Oman indicates Tonian continent to volcanic arc transect. • Constitution of a volcanic arc at ca 1 Ga. • 130 my of cordilleran-type continental arc setting along Neoproterozoic NW Indian continent. • Episodic magmatic activity at 840 Ma, 825 Ma and 770 Ma. Here we introduce a new model for a Tonian active continental margin in the Neoproterozoic western foreland of the Delhi Fold Belt of NW India. This study gives indication for a transition from continental crust into an active arc setting prior to emplacement of the volcano-plutonic Malani Igneous Suite. Erinpura Granites (890 to 860 Ma) are exposed in a large area west of the Delhi Fold Belt in NW India. The Erinpura Granites are S-type (ε Nd −10 to −3) whereas granites, granodiorites and gabbros exposed in the westernmost basement outcrops (Bhinmal, Harsani) are I-type granitoids and show positive Nd ratios (ε Nd + 4 to + 6). These intrusions are derived from crustal melting with a lithospheric component and affinity to a subduction setting, as can also be inferred from trace element ratios. Our study places the Bhinmal granite as youngest intrusion in this setting (U-Pb analyses of zircon 794 ± 17 Ma and titanite 793 ± 19 Ma). High temperature linear solid-state fabrics in the granites indicate intrusion and deformation during crustal extension. After uplift and exhumation bimodal dykes and granites of the Malani Igneous Suite (770–750 Ma) intruded into this older crust (pre-Malani basement). An evolutionary model for a Tonian active continent margin is established by integrating data from Nagar Parkar in East Pakistan and Neoproterozoic basement inliers in East Oman. The data indicate 130 Myr of ongoing subduction (900 to 770 Ma) along the continental margin. Magmatic activity is identified as episodic with three major pulses starting at ca. 840 Ma, ca. 825 Ma and ca. 770 Ma. High temperature melting constitutes the last Tonian magmatic pulse (Malani Igneous Suite) attributed to roll-back of the subducting slab. The implications for Neoproterozoic plate tectonic reconstructions are discussed. [ABSTRACT FROM AUTHOR]

We report high-precision geochronological, structural and geochemical data from a series of mafic–ultramafic bands and lenses hosted in orthogneiss of the remote Archaean Thrym Complex of southeast Greenland. These rocks primarily comprise mafic granulite and ultramafic rocks, which locally host orthomagmatic Ni-Cu-PGE sulfide mineralisation that consists of pyrrhotite, pyrite, pentlandite and chalcopyrite. In situ SHRIMP analyses on zircon grains from a representative mafic granulite sample yield an age of 2859 ± 6 Ma, which is interpreted as the crystallisation age for the protolith of the mafic granulite. A younger 2744 ± 9 Ma zircon is interpreted to represent peak metamorphism associated with the Skjoldungen Orogeny. On the basis of zircon textural features, whole rock geochemistry and cross-cutting field relationships between the ultramafic rocks and the mafic granulite, it is possible to conclude that emplacement and crystallisation of the Ni-Cu-PGE mineralised peridotite and pyroxenite of the Thrym Complex took place at lower crustal levels (∼25–40 km depth), synchronously with the granulite facies conditions that prevailed at the base of the Skjoldungen Orogen. Occurrences of Ni-Cu-PGE mineralisation in the high-grade metamorphic terrains of the Thrym Complex are extremely significant, because they shed light on ore forming processes that happen at the base of the continental crust. Therefore, outcomes from this study suggest that the current exploration search space for Ni-Cu-PGE sulfide mineralisation, which is largely constrained to upper and middle crustal settings, could be significantly expanded to exhumed deeper crustal level terrains of high metamorphic central orogenic complexes. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Dantazi Complex of the North Hebei Terrane in the northern North China Craton. • Late Neoarchean diversified granitoids were derived from crust-mantle interactions. • These crust-mantle dynamic processes developed in a continuous retreat arc setting. The Dantazi Complex in the North Hebei Terrane is located in the middle segment of the northern North China Craton, and plays a crucial role for understanding the early Precambrian crustal evolution of the craton. The Dantazi Complex is composed mainly of late Neoarchean tonalites-trondhjemites-granodiorites, potassic granites, sanukitoid granodiorites-monzodiorites and quartz syenites, which were emplaced by Paleoproterozoic gabbroic stocks. SHRIMP and LA–ICP–MS zircon dating analyses have revealed that the Neoarchean diversified granitoids of the Dantazi Complex were formed in ∼2.52–2.47 Ga, and preserved ∼2.60–2.53 Ga inherited/captured zircon ages. All these rocks experienced early metamorphism and deformation at ∼2.40 Ga, later granulite facies metamorphism at ∼1.80 Ga, and alterations at ∼1.73 Ga. Whole-rock chemical characteristics and Sm–Nd–Lu–Hf isotopes indicate that (1) The ∼2.52 Ga tonalites-trondhjemites-granodiorites were derived from partial melting of juvenile mafic crust; (2) the ∼2.51 Ga sanukitoid monzodiorite-granodiorite series came from slab-mantle interaction with different melt/rock ratios; (3) The ∼2.50–2.47 Ga potassic granites were generated by intracrustal recycling of metagreywacks that sourced from the mixture between juvenile and ancient crustal materials; and (4) The ∼2.50 Ga quartz syenites were originated from fractional crystallization of mantle-derived magmas. These petrogenetic processes reveal that the subduction-related crust-mantle interaction is the key reason for the diversity of late Neoarchean granitoids in the Dantazi Complex. Regional comparison indicates that the Precambrian North Hebei Terrane show distinct structure in the chronology and lithological assemblages from other basement terranes in the trans-North China Orogen and Western Block, implying that they were formed in different crust-mantle dynamic systems. Therefore, the Precambrian North Hebei Terrane was probably an independent micro-continental block at least until the early Paleoproterozoic. In the Archean crystalline basement range of the North Hebei–West Liaoning–East Hebei, from NW to SE, the magmatic crystallization ages gradually became older, and the granitoid assemblages transformed from sodium-rich to potassium-rich, the spatio-temporal evolution of chemical composition and lithological assemblages further indicates that the North Hebei Terrane was most likely developed in an arc environment with continuous retreat subduction caused by the slab roll-back. [ABSTRACT FROM AUTHOR]

• New in situ detrital zircon analyses are reported for the Winnipeg River terrane. • Eo-Paleoarchean detrital ages and their Hf compositions suggest local sources. • The Eo-Paleoarchean data overlaps with two other terranes in the Superior Province. • These three terranes may have comprised a once contiguous proto-cratonic nucleus. Metasedimentary rocks within Archean cratons can preserve a record of early cratonic crustal evolution and later metamorphic events. However, interpreting this record is difficult where the metasedimentary rocks have undergone amphibolite-granulite facies metamorphic overprinting and migmatization. In the Western Superior Province, migmatitic metasedimentary rocks represent a dominant supracrustal component in several terranes, including, from north to south, the English River, Winnipeg River, Wabigoon and Quetico terranes. Here we present zircon U-Pb-Hf isotope data for three metasedimentary rocks and one augen gneiss from the Mystery Lake dome in the Winnipeg River plutonic-gneiss terrane using in-situ techniques and large zircon populations. The augen gneiss contains zircon that has overlapping U-Pb-Hf isotope systematics with the ca. 3250 Ma gneissic basement of the terrane. The detrital zircon grains from the metasedimentary rocks have age populations at ca. 3750 Ma, 3600 Ma, 3500 Ma, 3400 Ma, 3300–3100 Ma, 3050 Ma, 2950–2900 Ma, 2850–2800 Ma, and 2800–2745 Ma, with metamorphic zircon between approximately 2745 Ma and 2550 Ma. The paucity of exposed Eo-Paleoarchean rocks in adjacent terranes suggests that the source rocks were derived from within the Winnipeg River terrane. The age and Hf isotope systematics of Eo-Paleoarchean detrital zircons from the Winnipeg River terrane overlap with zircon data from the Hudson Bay and Minnesota River Valley terranes on the northern and southern margins of the craton, respectively. The evidence suggests all three plutonic-gneiss terranes have preserved similar Eo-Paleoarchean geological histories, supporting the hypothesis that they were derived from a contiguous proto-craton. [ABSTRACT FROM AUTHOR]

• There are abundant carbonate clasts in the terminal Cryogenian Nantuo Formation. • These clasts were thought to have derived from Mesoproterozoic Shennongjia Group. • Petrographic and C-O isotope data are inconsistent with a Shennongjia Group source. • These clasts are likely from the Wujiatai Formation or a now eroded carbonate unit. Glacial diamictites of the Cryogenian Nantuo Formation of the Yangtze Craton of South China record major environmental transitions during the Marinoan glaciation. Although the provenance of the siliciclastic materials in the Nantuo Formation have been constrained via detrital zircon analysis, the source areas for the abundant carbonate clasts within the formation have yet to be determined. Given that the Mesoproterozoic Shennongjia Group is the only major extant pre-Cryogenian sedimentary carbonate succession in South China, it has been proposed as a source of the Nantuo dolostone clasts in the northern Yangtze Craton and may have been a major supplier of Cryogenian carbonate clasts across the entire Yangtze Craton, but this speculative provenance has not been tested or formally investigated. To test this hypothesis, δ13C and δ18O values of 18 clasts collected near Yichang, Hubei Province were analyzed along with petrographic examination to determine lithology, diagenetic alteration, and relationship to the Shennongjia Group carbonates. Our data show that the δ18O and δ13C values of these clasts are distinct from and thus unlikely sourced from the Shennongjia Group. Therefore, the Shennongjia Group cannot be the sole source of Nantuo carbonate clasts. Instead, we propose the Nantuo carbonate clasts in the study area were derived from either (1) pre-Marinoan carbonate successions in South China that were lost due to erosion or (2) another craton (e.g., the Indian Craton) adjacent to the Yangtze Craton during the Cryogenian. Given that paleogeographic and detrital zircon provenance analysis suggest separation between the Yangtze Craton and the Indian Craton in the Cryogenian Period, we favor the former origin, and that the Shennongjia Group is not the exclusive source of carbonate clasts from the Nantuo Formation. [ABSTRACT FROM AUTHOR]

• IN-SIMS zircon analysis yields a ca. 2.1 Ga age for Chipman and Kazan dike swarms. • Geochemical data suggests an asthenospheric-source for the STZ LIP swarms. • The STZ LIP underwent contamination by Neoarchean metasomatized lithosphere. • New data indicate that STZ dike swarms may be 2.1 Ga, and extend for > 800 km. • The STZ LIP formed during incipient rifting of a coherent Rae-Hearne boundary. • The STZ was reactivated during Hudsonian orogenesis from 1.98 to 1.80 Ga. IN-SIMS (in-situ secondary ionization mass spectrometry) micro-zircon geochronology resolves the age of the Chipman and Kazan mafic dike swarms exposed along the central segment of the Snowbird Tectonic Zone (STZ), the geophysically defined feature separating the Rae and Hearne subprovinces of the western Churchill Province. Long-considered syn -kinematic with respect to Paleoproterozoic transpressional deformation, the primitive composition of the STZ Large Igneous Province (LIP) and granulite grade metamorphic overprint has made establishing crystallization ages difficult. In-situ U-Pb isotopic analysis of micro-zircon yielded scattered and discordant results, except for four zircon crystals, which yielded a weighted mean of 2113 Ma +/- 22 (n = 8 analyses; MSWD: 0.46). This age is similar to other mafic complexes in the western Churchill Province including the Griffin Gabbro sills interpreted to have formed during opening of the Manikewan Ocean. Nd isotopic analyses of Kazan dikes paired with geochemical data suggest that the Chipman and Kazan dikes were asthenospherically-derived but contaminated by a metasomatized lithospheric root. At ca. 2.1 Ga, the STZ was the site of intracratonic extension within a coherent Rae-Hearne crustal block (Snowbird LIP Phase I). Existing data suggests that subsequent tectonism led to focused dextral transpression along the trace of the dike swarm and attests to a long-lived interplay of preexisting weaknesses and deformation. [ABSTRACT FROM AUTHOR]

• Meta-mafic rocks in this study experienced multiple metamorphism of the late Neoarchean and the late Paleoproterozoic. • The garnet-bearing mineral assemblages were formed during the late Paleoproterozoic rather than the Neoarchean. • The Neoarchean metamorphic event of Jiaobei terrane occurred in garnet-absent low pressure P-T conditions. Interpretations of high-grade terranes recording more than one episode of metamorphism can often be problematic due to the difficulties in assigning the metamorphic conditions to the time of metamorphism. The Jiaobei terrane as a typical Precambrian metamorphic terrane in the North China Craton (NCC) records multiple high-grade metamorphic events. Resolving the timing and features of each metamorphic event can cast light on the above issue and also play a key role in understanding the geological evolution of the Jiaobei terrane and the NCC. This study reports paired U-Pb dating with in-situ trace elements and oxygen isotope compositions of metamorphic zircons in meta -mafic rocks from the Qixia area of Jiaobei terrane. The zircons develop core-rim structures with both of them exhibiting metamorphic features. Zircon rims, although widely developed, are mostly too thin for in-situ age dating. LA-ICPMS as well as SIMS zircon U-Pb analysis of zircon cores yielded metamorphic ages of ∼ 2500 Ma, whereas the rims yielded 207Pb/206Pb ages of 1915–1717 Ma. The rare earth elements (REE) patterns and δ18O values measured in the Paleoproterozoic metamorphic zircon rims are distinct from those measured in the Archean cores. Distinct features of the cores and rims imply that the garnet-bearing (high-pressure) mineral assemblages were formed during late Paleoproterozoic metamorphic event and absent during the Neoarchean event. These new geochronological data further confirm that the Jiaobei terrane records both the late Neoarchean metamorphism and the late Paleoproterozoic tectonic thermal event. Also, our study argues for the existence of global subduction network geological records in the NCC during Paleoproterozoic, rather than during Neoarchean. The influence of the overprinted late Paleoproterozoic metamorphism should be fully considered when estimating P-T conditions of the earlier tectonothermal event (Neoarchean metamorphism). [ABSTRACT FROM AUTHOR]

• Detrital zircon age spectra analyses suggest that the Quanji Group and the overlying Neoproterozoic rocks in the OLT may have different source provenances. • The Great Unconformity in the OLT and NCC consists of two or three discrete unconformities. • These unconformities may have been caused by multiple tectonic activities rather than a single, global synchronous one. The Great Unconformity that separates the early Cambrian sandstones from the Proterozoic metamorphosed sedimentary rocks has been recognized in many blocks on Earth. However, whether it represents a globally synchronous event or a composite of a series of diachronous events, and its formation mechanism remain largely unknown. In this study, we carry out detrital zircon U-Pb analyses for seven samples collected from the Paleoproterozoic Quanji Group and the overlying Neoproterozoic strata in the Olongbuluke terrane (OLT) of Northwest China. The results show that apart from age populations of ∼ 1.8–2.0 Ga and ∼ 2.2–2.5 Ga for all samples, additional ∼ 1.55–1.65 Ga age population occurs in sample from the Zhoujieshan Formation, and more scattered age populations ranging from ∼ 0.75 to ∼ 1.7 Ga are present in samples from the Heitupo and Hongtiegou formations. The ∼ 1.8–2.0 Ga and ∼ 2.2–2.5 Ga zircons correlate well with the magmatic and metamorphic events in the OLT basement, indicating their local provenances, while other zircons were possibly derived from the North China craton (NCC) or other adjacent blocks. Combined with published paleontological, stratigraphic, and geochronological data, the present study supports previous inference that the OLT had a close paleogeographic affinity to the NCC during late Paleoproterozoic to Neoproterozoic. New zircon U-Pb ages indicate that the Heitupo Formation was deposited later than ∼ 750 Ma, and the underlying Hongzaoshan Formation was deposited at ∼ 1.66 Ga, implying a huge break between them. Whereas the duration of the sedimentary break between the Heitupo Formation and the overlying Hongtiegou Formation is uncertain, biostratigraphic data suggest that a break of ∼ 30 Myr may exist between the late Ediacaran Zhoujieshan Formation and the overlying early Cambrian Xiaogaolu Group. The occurrences of these multiple unconformities in OLT are comparable to those in NCC, indicating that the Great Unconformity is represented by a series of lengthy denudations during the Proterozoic-early Cambrian in both the OLT and NCC, which may result from multiple tectonic activities in these two blocks. [ABSTRACT FROM AUTHOR]

• Abundant zircon xenocrysts were captured by the late Paleozoic (<342 Ma) Maping diamondiferous kimberlites. • Xenocrystic zircon peak ages at ∼2.9 Ga, ∼2.6 Ga and ∼2.0 Ga are older than the Neoproterozoic outcrops. • Highly evolved Archean basement may exist beneath the southern Yangtze Block. • The basement underwent complex crustal growth at 2.6–2.5 Ga and reworking at 3.0–2.6 Ga. • Newly identified ∼2.0 Ga metamorphic event was probably linked to the assembly of the Nuna/Columbia supercontinent. Crustal zircon xenocrysts from mantle-derived magmatic rocks have the potential to probe the deep crust. Here we present integrated U–Pb dating and Hf-isotope analyses of zircons from a Paleozoic diamondiferous kimberlite dike in the Maping area of Zhenyuan County (southeastern Guizhou Province), with implications for the tectonothermal evolution of unexposed continental crust beneath the southern Yangtze Block, South China. All zircons (n = 236) show a wide range of U–Pb ages between Mesoarchean and middle Carboniferous. Among them, 96 zircons with 90–110% concordance yield concordant ages from 2942 ± 8 Ma to 342 ± 2 Ma, and form major age peaks at ∼2.9 Ga, ∼2.6 Ga and ∼2.0 Ga. The overwhelming majority of zircons are dominated by Mesoarchean–Paleoproterozoic U–Pb ages regardless of their concordance degrees. The zircon populations mainly consist of magmatic zircons, with minor metamorphic grains (Th/U < 0.10). The youngest magmatic zircon (Th/U = 0.43) with a well concordant 206Pb/238U age of 342 ± 2 Ma (M1-16) is interpreted as the maximum emplacement age of the Maping diamondiferous kimberlites. Most zircons with pre-eruption ages are considered to be xenocrysts, and they may be derived from the deep-seated continental crust through which kimberlite host magmas have passed. Their U–Pb ages and Hf isotopic compositions suggest the possible existence of a highly evolved Archean basement beneath the southern Yangtze Block, South China, which is much older than its known surface rocks. A lot of magmatic zircon xenocrysts reveal complex Precambrian crustal evolution in the southern Yangtze Block. These processes involved the important growth of continental crust at 2.6–2.5 Ga, and in the meantime, crustal reworking could be intermittently proceeding at 3.0–2.6 Ga. In addition, a group of xenocrystic zircons are identified to be of metamorphic origin, indicating that the proposed Archean basement beneath the southern Yangtze Block likely experienced a metamorphic event around 2.0 Ga. This geologically significant episode is consistent with the well-developed coeval metamorphism in other places of the Yangtze Block (e.g., Kongling Terrane), which has been considered to link to the assembly of the Paleoproterozoic Nuna/Columbia supercontinent. Our zircon data implies that the unexposed Archean basement beneath the southern Yangtze Block was affected by multiple thermal activities. [ABSTRACT FROM AUTHOR]

[Display omitted] • Limpopo Belt Central Zone consists of two terranes (T1, T2) of distinct origin. • T1 was connected to the Zimbabwe Craton between 3.4 and < 2.9 Ga as indicated by detrital zircons. • T2 comprises an oceanic realm < 3.05 Ga which became successively accreted to the Kaapvaal Craton. • Final closure of the oceanic realm resulted in T1-Zimbabwe-Kaapvaal Craton collision at 2.62 Ga. • Post-collisional sandstones of the Central Zone and Kaapvaal Craton have different provenances. There are ongoing debates about the nature and timing of Kaapvaal-Zimbabwe Craton accretion. A critical role in this discussion plays the Central Zone (CZ) of the Limpopo Belt, which represents a polymetamorphic gneiss terrane limited by the Kaapvaal Craton to the South and the Zimbabwe Craton to the North. Uncertainties mainly result from complex field relationships, the lack of age data, and the complexity of investigated zircon grains. In this study we present new results of combined U-Th-Pb and Lu-Hf isotope analyses of zircon grains from quartzite, granitoid, and metabasite samples from different areas of the CZ. These data indicate that the oldest lithologies are mafic rocks which were emplaced at 3.35–3.29 Ga from near-chondritic mantle source. They also reveal that quartzite precursors throughout the CZ were deposited during two major sedimentary cycles, with quartzite-I members between 3.36 and 2.64 Ga, and quartzite-II between 2.55 and 2.04 Ga, and that the detritus was supplied from distinct sources. Detrital zircon grains of quartzite-I were delivered from Eo- to Mesoarchean granite-gneiss terranes, affected by magmatism between 3.92 and 2.90 Ga, and characterized by hafnium model ages (T DM) between 4.40 and 3.30 Ga. In contrast, zircon grains of quartzite-II stem predominately from Neoarchean granitoids, which intruded between 2.73 and 2.62 Ga, and mostly show T DM of 2.88 ± 0.06 Ga (n = 8) or 3.09 ± 0.10 Ga (n = 4). Comparison with published age-εHf t data and spatial relationships suggest quartzite-I being sourced mainly from the Zimbabwe Craton, which was connected to parts of the CZ since the Paleoarchean, and quartzite-II from granitoids of an independent Neoarchean terrane (with T DM 3.1–2.9 Ga), which was derived from the same mantle source as the crust of the adjacent Pietersburg Block (northern Kaapvaal Craton). All data in combination provide evidence that the CZ of the Limpopo Belt hosts a composite terrane that comprises relics of (1) Zimbabwe Craton-related crust, and (2) a south-to-north developing accretionary system of granite-greenstone terranes younger than 3.1 Ga, which finally collided with the Zimbabwe Craton at ca. 2.62 Ga. [ABSTRACT FROM AUTHOR]

[Display omitted] • Zircon U-Pb data constrain emplacement of mafic–ultramafic suite at ca. 3.2 Ga. • Magmatism within a subduction metasomatised mantle wedge. • Mesoarchean subduction-accretion and amalgamation of ancient continental nuclei. Archean mafic–ultramafic rocks provide important clues on the tectonic and crust building processes in the early Earth. The Western Dharwar Craton (WDC) and the Karwar Block (KB) in southern Peninsular India preserve some of the oldest records of craton building processes in the Archean Earth. The tectonic affinity of the Karwar Block that lies at the western periphery of the WDC remains uncertain. Here we present the results from an integrated study of a mafic–ultramafic rock suite from this block using petrology, whole-rock geochemistry, and zircon U–Pb and Lu-Hf data. These rocks occur as deformed and dismembered units within basement granitic gneiss. The primary igneous minerals such as pyroxene and plagioclase show variable degrees of alteration. The rocks show negative Nb anomalies and prominent Pb enrichment. The uniform enrichment of Th and U over Nb-Ta indicates the influence of metasomatic fluids in the mantle wedge. The geochemical data indicate that these rocks were derived from basaltic magmas generated within a subduction metasomatised mantle wedge in an intra-oceanic arc setting without any significant crustal contamination. U-Pb isotope analysis of zircon grains from the metapyroxenite shows upper intercept ages of 3172 to 3213 Ma and weighted mean ages of 3170 to 3203 Ma. A metagabbro sample yielded upper intercept age of 2792 Ma and the 207Pb/206Pb spot ages in another sample range up to 3202 Ma. Zircon U-Pb data suggest that the mafic–ultramafic suite formed at ca. 3.2 Ga and were overprinted by 2.7 Ga thermal event. The εHf(t) values are all positive and range between 0.73 and 6.02, suggesting that the magma was derived dominantly from Mesoarchean juvenile (depleted mantle) sources. We propose a tectonic model that involves a subduction-accretion stage followed by suturing of the ancient continental nuclei. [ABSTRACT FROM AUTHOR]

[Display omitted] • High pressure metamorphism at peak temperatures up to 900 °C and pressures up to 9.5–10 kbar. • Major, trace and REE geochemistry confirm subduction-related arc magmatism. • Magma derived from both juvenile and reworked Paleoarchean sources. • Maturation of ensialic crust and intrusion of underplated mafic magmas. Lower crust mafic granulites are key components in understanding the formation and growth of the continental crust. Here we investigate the mafic granulites and associated rocks from the Paleo-Mesoarchean Coorg Block in southern India with a view to gain insights into the crust-mantle dynamics and the subduction–accretion‐collision history. We present petrology, mineral chemistry, conventional thermobarometry and computed pseudosections, whole‐rock geochemistry including major, trace element, and rare earth element (REE), and zircon U–Pb and Lu-Hf isotopes to trace the magmatic evolution and metamorphism of these rocks. The petrological features, mineral chemistry data and phase equilibria modelling suggest that the rocks underwent HP metamorphism at peak temperatures up to 900 °C and pressures up to 9.5–10 kbar along a clockwise P–T path followed by near isobaric cooling. Zircon U–Pb data from the mafic granulites place the peak emplacement time of the protolith at 3.1 Ga with a minor group of younger zircons indicating a post-collision thermal event at 2.7 Ga. Zircon REE patterns suggest the involvement of continental crust components in the magma source. Zircon Lu-Hf analysis yield positive εHf(t) values from 0.5 to 4.1 with model ages (T DM) of 3.3 Ga for rocks from the northern margin of the block and the bordering Mercara suture zone while samples from the southern margin display slightly older (3.4 Ga) ages. Our data indicate that the parent magmas were derived from both juvenile and reworked Paleoarchean sources. The mafic granulites record Mesoarchean subduction-related magmatism and crust building in the Coorg block. Our study contributes to the understanding of geodynamic processes and continent formation in the Early Earth. [ABSTRACT FROM AUTHOR]

• Comprehensive compilation of U-Pb and Lu-Hf spot analyses in zircon. • Various basement fragments in southern South America share pre-Brasiliano similarities. • They record a long-lived Archean to Early Neoproterozoic crustal growth. • They have more similarities with African blocks than with the Rio de la Plata Craton. • Possible connections have implications for pre-Brasiliano reconstructions. The amalgamation of southwestern Gondwana during the late Neoproterozoic Brasiliano/Pan-African orogenic cycle involved the tectonic interaction of the Congo, Kalahari and Rio de la Plata cratons, together with numerous smaller basement fragments scattered throughout South America. A comprehensive review of U-Pb and Lu-Hf spot analyses in zircon provides new insights on the pre-Brasiliano crustal growth of the main tectonic domains of the southern South American Platform from the Archean to the early Neoproterozoic. The results highlight similarities between five basement fragments, from south to north: the Nico Pérez Terrane, Tijucas Terrane, Camboriú Complex, Luis Alves Terrane and Curitiba Terrane. Whereas these units have variable characteristics, especially concerning differing degrees of tectonic reworking in the late Neoproterozoic, they share similarities in their geological evolution. They were all originally accreted in the Archean, as evidenced by Hf T DM model ages and zircon inheritance, and later experienced intense orogenic reworking during the Rhyacian and Orosirian. The Paleoproterozoic record is diverse and indicates a complex episodic evolution instead of a single orogenic event. Conspicuous diachronic magmatic events took place locally in the Late Paleoproterozoic and Mesoproterozoic, interrupting an otherwise relatively stable tectonic setting until the Neoproterozoic. The Archean origin and strong crustal signatures of the main Paleoproterozoic units distinguish these terranes from the Rio de la Plata Craton, evidencing instead stronger affinities with African crustal blocks such as the Congo and Kalahari cratons. This relationship has implications for the geodynamic reconstruction of southwest Gondwana that extend into the early Neoproterozoic, as it contextualizes the genetic link between the main Tonian events in the region, namely the formation of the São Gabriel Terrane and the emplacement of the magmatic protoliths of the basement of the Punta del Este Terrane. They can be understood as marginal and within-plate manifestations of an accretionary orogen, respectively. The basement of the Punta del Este Terrane has signatures compatible with the recycling of ancient crust through the mixture of mantellic magmatic input with the partial melting of Archean or Archean-derived Proterozoic lithosphere, a process that likely took place multiple times from the Paleoproterozoic onwards in the region. [ABSTRACT FROM AUTHOR]

[Display omitted] • Zircon xenocrysts have low-δ18O and high-εHf(t) values. • Zircon xenocrysts were generated from high temperature altered gabbroic rocks of subducted oceanic slab. • This paper provides new evidence for Paleoproterozoic oceanic slab subduction in the Trans-North China Orogen. The Trans-North China Orogen (TNCO) is suggested to form under a transition from subduction to collision from 2500 Ma to ∼ 1850 Ma, and the Taihua TTG gneiss in the Xiong'ershan district is thought to have formed in an Andean-type continental arc setting or island arc setting during this geological event. However, to date, the geochemical record of the subducted oceanic slab is still lacking. This study focuses on Hf-O isotopic analyses of zircon xenocrysts from the Qi189 hornblende monzogranite, Qiyugou Au orefield, TNCO. The results reveal that zircon xenocrysts with ages from 2304 Ma to 1934 Ma generally have low-δ18O values from 2.66‰ to 3.83‰ and high-εHf(t) values from 2.7 to 7.8. These zircon grains were generated from remelting of high-temperature altered gabbroic rocks of the subducted oceanic slab during the transition from compression to extension. In this paper, we present new evidence for Paleoproterozoic oceanic slab subduction in the TNCO. [ABSTRACT FROM AUTHOR]

Abstract: The Southern Ethiopian Shield (SES) in the central East African Orogen lies at the junction of Neoproterozoic (880–550Ma) largely greenschist-facies juvenile crust of the Arabian-Nubian Shield in the north and more metamorphosed and remobilized older crust of the Mozambique Belt to the south. The SES exposes a polycyclic sialic gneissic basement (represented by the Alghe Terrane in this study) with interleaved ophiolitic–volcano–sedimentary (Kenticha, Megado, and Bulbul) terranes. U–Pb zircon SHRIMP and LA-ICP-MS dating of 8 igneous and metamorphic intermediate and felsic bodies in the eastern SES yield Neoproterozoic crystallization ages: 847±11, 855±14, 732±5, 665±8, 657±6, 560±8, and 548±8Ma. From these and previously published ages, we infer 4 principal magmatic episodes: 840–890Ma (Late–Tonian–Early Cryogenian), 790–700Ma (Cryogenian), ∼660Ma (Moyale Event), and Pan-African (630–500Ma; Ediacaro-Cambrian). Neoproterozoic zircon xenocrysts (941, 884, 880, 863, 762, 716 and 712Ma) confirm the dominance of Neoproterozoic crust in the study area. One sample of undeformed granite from the Alghae Terrane has abundant Archean zircons and may be a ∼550Ma melt of ∼2.5Ga crust, demonstrating for the first time that Archean crust or sediments with abundant Archean zircons exists in the SES. In spite of ∼300 million years of Neoproterozoic igneous activity, we see no evidence of systematic compositional evolution in SES igneous rocks from early low-K suites to late high-K suites. Ediacaran deformation and magmatism of the SES reflects Late Tonian and Cryogenian formation of mostly juvenile crust that was subsequently deformed and chemically modified as a result of collision between large fragments of East and West Gondwana. Terminal collision began at ∼630Ma and caused crustal thickening, melting, uplift, erosion, orogenic collapse, and tectonic escape over a broad region of the East African Orogen, including up to ∼25km of erosion of SES crust. Plate convergence was likely continuous from ∼630Ma, forming major N-S structures. Deformation stopped at ∼550Ma and was followed by exhumation between ∼ 530 and 500Ma. [Copyright &y& Elsevier]