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The timing of tectonic transition from the Paleo-Asian oceanic regime to the Paleo-Pacific regime in the easternmost Central Asian Orogenic Belt remains controversial. To constrain the event, we present new zircon U-Pb ages, Hf isotopic compositions, and whole-rock major- and trace-element data for early Mesozoic igneous rocks from eastern Jilin Province, NE China. These new ages, together with existing age data, indicate that early Mesozoic magmatism in the Kaiyuan–Yanji area can be subdivided into four stages: Early Triassic (ca 250 Ma), Early–Middle Triassic (249–235 Ma), Late Triassic (229–208 Ma) and latest Triassic to Early Jurassic (207–175 Ma). The Early Triassic igneous rocks constitute a bimodal igneous rock association that formed in an extensional environment caused by break-off of the subducting slab during final closure of the Paleo-Asian Ocean. The Early–Middle Triassic magmatism is dominated by adakitic granitoids whose primary magmas were derived from partial melting of thickened mafic lower crust, suggesting that the North China Craton and Songliao–Xilinhot Block were still undergoing collisional orogenesis at 249–235 Ma. The Late Triassic igneous rocks comprise a typical bimodal association of rocks in an E–W-trending belt, formed in a post-orogenic extensional environment related to final closure of the Paleo-Asian Ocean. The latest Triassic to Early Jurassic igneous rocks have calc-alkaline characteristics, were emplaced as a NE–SW-trending belt parallel to the eastern margin of Eurasia, and formed in an active continental margin setting associated with initial subduction of the Paleo-Pacific Plate. We conclude that the tectonic transition between the Paleo-Asian and the Paleo-Pacific regimes took place during the latest Triassic.

The E–W trending Yanshan belt, an intraplate fold-thrust belt located in the northern North China Craton, has experienced several episodes of Mesozoic deformation, which resulted in the widely distributed magmatism and mountain-basin tectonics that completely re-shaped the topography of the eastern North China Craton. The eastern part of the famous Chinese Great Wall was built on the high range of the southeastern Yanshan mountain belt juxta-posed to the plain, which directly relates to the Bohai Bay basin. Our study focuses on which tectonic processes created such mountain-basin couple in Mid-Late Mesozoic times. The U-Pb LA-ICP-MS dating of zircons yield ages of 114 to 201 Ma for various granites and 115 to 116 Ma for volcanic rocks from Yixian and Jiufotang Fms. The detrital zircons from the Lower Cretaceous sandstones yield four age groups of 2587 to 2460 Ma, 2222 to 1828 Ma, 297 to 190 Ma and 187 to 100 Ma, which are all sourced from the Qinglong and surrounding areas and indicating that the Qinglong area started to uplift after the Middle Jurassic. The Qinglong area underwent multiple deformation by NE–SW compression in the Middle-Late Jurassic times, WNW–ESE compression in the Late Jurassic to Early Cretaceous, ENE–WSW extension in the Early Cretaceous and NNW–SSE compression in the Late Cretaceous during the final stage of the Yanshanian orogeny. Meanwhile, widely distributed granite intrusions and emplacement of the Upper Jurassic-Lower Cretaceous volcanic rocks indicate a large amount of magma input into the area. The Qinglong area with the Great Wall along its southern margin close to adjacent plain to the south was uplifted to form the Qinglong highland and surrounding related basins by combination of the following three processes: the multiple tectonic Late Jurassic and Late Cretaceous shortening processes related to Yanshanian orogeny, Early Cretaceous regional extension triggered by slab-retreat of the Paleo-Pacific ocean and inflation of large amount magma at depth during Jurassic and Early Cretaceous.

The stress state and its dynamic background of East Asia, especially that during the late Mesozoic, remain controversial. We analyze the structural evolution of the Bohai Bay Basin (BBB) and it relationship with the regional tectonic history of East Asia. In particular, we focus on the central BBB NW-trending faults that have received little attention due to their inconspicuous structural features. Here we show that the erratic inversion of these NW-trending faults records episodic crustal deformation that is crucial for better understanding the regional tectonism. We find that these faults experienced alternating phases of shortening, stretching and shearing deformation. They initiated as reverse faults during the Late Triassic and reversed to normal faults during the Early Cretaceous. The pre-existing faults determined the development of NW-trending basins, which are synchronous with the peak destruction period of the North China Craton (NCC). The Late Cretaceous marks a stage of regional shortening without magmatism, which we propose to reflect a previously unrecognized period of flat-slab subduction of the Izanagi Plate. During the Early Paleogene (65–40 Ma), the reactivation of the NW-trending faults, likely due to the rollback of the oceanic slab, caused intensive rifting of the basin. During the Late Paleogene (40–23 Ma), they transformed to transtensional faulting due to the north-south oblique stretching from the parallel dextral strike-slip bounding faults. From Neogene, the basin entering its post-rift stage was characterized by the conjugate NE- and NW-trending strike-slip fault systems, likely in response to E-W regional compression.

The provenance of Middle Jurassic-Cretaceous sedimentary rocks deposited in the southern Peruvian Arequipa Basin has been investigated based on the measurement of 41 Sr-Sm-Nd isotopic compositions of sedimentary rocks, 993 U-Pb zircons ages, and 202 Lu-Hf zircon isotope data. The Middle Jurassic units are dominated by Brazilian/Pampean and Grenville/Sunsas and have juvenile to evolved Hf isotopic compositions of Permian zircons. These are consistent with an Eastern Cordillera (EC) provenance. In contrast, the Late Jurassic Labra Formation presents the first appearance of Triassic-Jurassic zircons and an increase in Famatinian zircons thus suggesting a mixed provenance from the EC and/or Altiplano and the Coastal Cordillera (CC). The Gramadal Formation shows older U-Pb zircon ages, which reflect a major contribution from Precambrian sources either from the Amazon craton or the EC thus implying a change in provenance. Another change in provenance is documented for the Hualhuani Formation with sources located both in the CC and EC. Finally, the Santonian Chilcane Formation is characterized by a large contribution of Cretaceous to Famatinian zircons indicating that it was mainly sourced from the CC. Our provenance dataset associated with the depositional setting of the Middle Jurassic to Early Cretaceous formations and the cumulative curves of zircon age distribution, indicate that the Arequipa Basin was not a back-arc setting but rather a rift-like setting. Contrary to the older formations, the Chilcane Formation is dominated by contributions from the CC in a retroarc foreland basin setting. This statement further implies that the Andean basin located eastward of the volcanic arc had evolved directly from a rift to a retroarc foreland basin and implies that the control of Andean subduction on these basins might be much younger than previously thought.

Strike-slip faults, proven to be closely linked to hydrocarbon migration and accumulation, are widespread in the Tarim Basin Craton. Deformation patterns in the eastern part of the Central Uplift Belt of the Tarim Basin are analyzed in detail to understand the deformation model and genetic mechanism of strike-slip faults, how their patterns impact reservoir formation and influence oil and gas potential. Regional tectonic events are taken into consideration to identify the primary factors that controlled the development of strike-slip faults in the region. The Tazhong Uplift in the eastern part of Central Uplift Belt is believed to be a complex anticlinal uplift formed by compression-and-torsion acting on the Cambrian – Middle Ordovician platform during the middle–late Caledonian period. Multi-stage development of this north-trending fault–fold belt and the NE-trending strike-slip faults make it structurally complex. The NE-trending Paleozoic strike-slip faults were formed jointly by the differential thrusting of the Tazhong Uplift along Fault No. I and the NE-trending shear sliding of the basal fault blocks during the middle–late Caledonian – early Hercynian. Based on the distribution of effective source rocks, the tectonic setting during the period critical to hydrocarbon accumulation, and the distribution of conductive faults, the northern slope of the Tazhong Uplift— especially its west-central part where the NE-trending faults are developed is not only located close to the northern hydrocarbon source rock area but also possesses conditions suitable for the development of carbonate reservoirs. In addition, the NE-trending faults provide passage for initial development of the reservoir and the subsequent migration of oil and gas from the Aman area to the uplifted zone, making the Tazhong Uplift an extremely favorable area for oil and gas accumulation with substantial potential for exploration.

The occurrence of pre-existing crust in orogenic belts has important implications for constraining and testing models of orogenic processes and for making paleogeographic reconstructions. Asynchronous magmatic–metamorphic rocks provide an opportunity to reconstruct the positions and constituent blocks of certain Precambrian fragments. Here we report Neoarchean to Neoproterozoic crustal rocks preserved in the North Wulan Terrane (NWT), northwestern China. Our new zircon geochronological data reveal the ca. 2.57 Ga magmatic and 2.0–1.72 Ga metamorphic events in the NWT, implying its involvement in the formation of Columbia supercontinent. Meanwhile, the NWT also recorded the 1.5–1.3, 1.1, 0.9–0.8 and 0.51–0.48 Ga magmatic-metamorphic activities, corresponding to the involvement of regional Precambrian fragments in cyclic supercontinent-related processes from Columbia to Greater Gondwana. Most of the ca. 2.57 and 0.9–0.8 Ga granites are characterized by enriched zircon eHf(t) values of –5.7 to +0.9 and –5.2 to +7.1. Moreover, some of these granites show fractionated characteristics, with high silica contents (80.3–82.3 wt% and 73.9–75.2 wt%), indicating that these rocks were derived mainly from remelting of 3.6–2.7 Ga mature crustal materials and 1.6–2.0 Ga crustal materials without or with minor contribution of juvenile materials, respectively. On the basis of these new results, regional stratigraphy, and previously determined geochemical data and tectonic signatures, it is concluded that the Quanji Massif and the Central Qilian, Hualong and North Wulan terranes probably formed a coherent Qilian–Quanji block as the southeastern extension of the Tarim Craton initiated from the Neoarchean. We propose that from the Neoarchean to early Paleoproterozoic, the primal Qilian–Quanji block was formed by long-term arc-related magma emplacement and reworking of ancient mature crustal materials in southeastern Tarim Craton. Subsequently, the juvenile Tarim–Qilian–Quanji continent was involved in tectonic cycles during its involvement in the supercontinents of Columbia and Rodinia.

Long-lived subduction and accretion of the Paleo-Asian Ocean (PAO) led to the formation of the Central Asian Orogenic Belt (CAOB). The central part of the southern CAOB is crucial to understand the tectonic evolution of the entire CAOB. However, the Paleozoic evolution and the final closure of the central PAO are controversial, and the nature of the Early Paleozoic basins is confusing. The relatively complete Paleozoic strata are well-preserved in Zhusileng area in the central part of the southern CAOB and provide an ideal object to constrain the Paleozoic tectonic setting of the PAO. In this study, detrital zircon U-Pb dating and sedimentological and paleocurrents analyses are conducted on the Cambrian-Devonian strata and Lower Permian strata. Most detrital zircons from the Cambrian-Devonian strata have Precambrian ages, while the detrital zircons from the Lower Permian strata are mainly of Paleozoic age. The North China Craton, Alxa Block and Tarim Craton are not the provenances of the Cambrian-Devonian strata. The central part of the southern CAOB was located in a passive continental margin setting during the Cambrian to Ordovician and received the detritus from the Beishan Orogenic Belt. During the Silurian to Middle Devonian, a nearly east-west-trending foreland basin that resulted from the collision between the Zhusileng-Hangwula terrane and southern Mongolian microcontinent developed. From the Late Devonian to Early Permian, bidirectional subduction of the PAO occurred between the Alxa Block and Zhusileng-Hangwula terrane, resulting in numerous arc-related magmatic rocks. Detritus in the Lower Permian strata was mainly from the Paleozoic magmatic rocks and Cambrian-Devonian strata in Zhusileng and surrounding areas. The Late Paleozoic shortening deformation and the switch of the tectonic setting from subduction/collision to post-collision occurred in the central part of the southern CAOB imply that the central PAO closed between the Early and Late Permian.

Made available in DSpace on 2022-04-28T19:47:55Z (GMT). No. of bitstreams: 0 Previous issue date: 2022-01-01 The Alto Guaporé gold province, southwestern Amazon craton, contains gold deposits that have been mined since the beginning of the 18th century and these deposits, together, have modern-day, pre-mining gold resources of at least 1.8 Moz. The ore is associated with quartz vein systems along the southeastern part of the Aguapei belt, a ~35-km-wide and ~500-km-long, NNW-trending shear zone formed due to reactivation of a terrane-bounding suture. The Aguapei belt evolved by ca. 1150 to 1100 Ma rifting and deposition of siliciclastic sediments in an aulacogen basin, followed by deformation and low-grade metamorphism of the sedimentary sequences during 1100 to 900 Ma terrane collision along the craton margin. The deformation was characterized by a compressional regime until ca. 950 Ma and transition to a transpressional setting during the final 50 m.y. The gold deposits are hosted in a variety of structures that are second-order to the main Aguapei shear zone. The Ernesto and Pau-a-Pique deposits are located ~40 km apart and at jogs along the Aguapei belt. They are marginal to pre-ore igneous rocks, with Ernesto hosted in the basal part of the metasedimentary Fortuna Formation that overlies tonalite and Pau-a-Pique at the contact between metasedimentary rocks and diorite. Three deformational phases comprise the compressional (D1 to D2) to transpressional (D3) tectonic events. In the Pau-a-Pique deposit and the deeper level of the Ernesto deposit, the ore-bearing veins are bedding parallel and follow D2 strike-slip and reverse fault zones, respectively. However, the veins formed during D3 reactivation of the older structures by an array of oblique accommodation faults. In contrast, ores at shallower levels of Ernesto, both in discordant and bedding-parallel veins, are hosted within a ~20-m-thick rigid metaconglomerate with associated dilation due to the structural complexity as sedimentary rocks of the Aguapei Group were folded around the dome-shaped roof of the pre-ore tonalite. The ores in both deposits, as well as in many other deposits of the province, are characterized by disseminated and vein-hosted pyrite. Gold occurs mainly as inclusions in the pyrite, with other hydrothermal phases comprising muscovite, Fe-Ti oxides, and minor apatite, chalcopyrite, and galena. Fluid inclusion data, coupled with stable isotope geochemistry and geothermometry, indicate that gold precipitated from a low-salinity, CO2-rich fluid at ~300°C and ~2.5 kbar. The source for the fluid and gold was the interbedded pelites during devolatilization of the Aguapei Group sequence. The aqueous-carbonic fluid inclusions and the narrow range of d18O values of quartz (12 ± 1‰) from many auriferous veins from the central part of the province represent a regional ore-forming fluid. The broad range of δD for hydrous minerals (-116 to -55‰) reflects influx of small amounts of meteoric water into the steeply dipping shear zones during postgold exhumation. The 40Ar/39Ar geochronology from hydrothermal muscovite indicates a widespread hydrothermal event along the belt between 928 and 920 Ma. Collectively, the geological, geochronological, and geochemical data suggest that metamorphic fluids migrated laterally into and then upward along the Aguapei belt and deposited gold in lower-order structures where strain gradients existed between lithounits. The province has many characteristics of large orogenic gold provinces worldwide and represents a highly prospective and underexplored target region for early Neoproterozoic gold, a time period that generally is not well endowed in gold ores. Faculdade de Ciência e Tecnologia Univ. Federal de Goiás, R. Mucuri S/N, GO Instituto de Geociências e Ciências Exatas Univ. Estadual Paulista, R. 24A 1515, SP State Key Laboratory of Geological Processes and Mineral Resources School of Earth Sciences and Resources China University of Geosciences U.S. Geological Survey Departamento de Geologia e Recursos Naturais Instituto de Geociências Universidade de Campinas, SP Yamana Desenvolvimento Mineral, R. Ministro Orozimbo Nonato 272/19o andar, MG Instituto de Geociências e Ciências Exatas Univ. Estadual Paulista, R. 24A 1515, SP

The metasomatized sub-continental lithospheric mantle (SCLM) is increasingly proposed to play a key control in the formation of giant gold (Au) deposits. However, the extent of Au enrichment in metasomatized SCLM and the Au contents of its derivative partial melts remain poorly constrained. Lamprophyres are derived from low-degree melting of metasomatic and fusible components in the SCLM, and could provide fundamental information about the metasomatized source and metal release compared to mantle peridotites and/or pyroxenites. The giant Jiaodong Au province (> 5000 tons, ∼ 120 Ma) in the eastern part of the North China Craton (NCC) is an ideal locality to assess the Au endowment of metasomatized SCLM which may serve as the source of Au, as indicated by the presence of mantle-dominated volatiles in auriferous fluids associated with the deposits. Based on detailed petrological studies, we analyzed Au, S, Cu and platinum-group element (PGE) contents of the SCLM-derived lamprophyres that are temporally (130–121 Ma) and spatially associated with the Jiaodong lode Au deposits. The lamprophyre dykes were emplaced in the deep crust and did not experience significant degassing and sulfide segregation, and the sulfide saturation occurred at a late stage during magma cooling, as demonstrated by sulfide petrography, S contents, Cu/S and Cu/Pd ratios of the lamprophyres. The relatively oxidized (ΔFMQ +1 – +2), hydrous (2–4 wt.% H2O) lamprophyres display variable and generally low Au contents (0.04–3.59 ng/g, mainly 1–3 ng/g, n = 31), as well as low PGE and Cu contents. Their high Au/Cu(N) and Au/Pd(N) ratios together with high Ba/Nb indicate a discernible Au addition to their source, resulting from multi-stage mantle metasomatism related to subduction. However, the average Au contents of the metasomatized SCLM before large-scale Au mineralization are heterogeneous and overall in a range of 0.5–1.5 ng/g. The values are higher than that of depleted SCLM (

Oxygen fugacity controls the behavior of multivalent elements and compositions of C-O-H fluids in Earth’s mantle, which further affects the cycling of materials between the deep interior and surfac...

We report systematical zircon U–Pb datings, Hf isotopic data, major and trace element date on the Zhangshiying (ZSY) and the Taishanmiao (TSM) two plutons at the southern margin of the North China Craton (NCC), in order to investigate their petrogenesis and geological evolution. LA-ICP-MS U–Pb zircon of the ZSY and TSM granites dating yield a weighted mean 206Pb/238U age of 122.8 ± 1.5 Ma and 112.1 ± 3.2 Ma. The ZSY quartz syenite enriched in SiO2 (65.59–68.1 wt.%), Al2O3 (15.39–15.64 wt.%), high Sr (468–666 ppm), Sr/Y (35–45), (La/Yb)N (20.1–22.1) ratios, low Y(13.1–16.6 ppm), Yb (1.46–1.77 ppm), depleted in Nb, Ta, P, Ti, Mg, Y and negligible Eu anomalies, which suggesting that the quartz syenite are similar to adakitic rocks. Zircons from this pluton give eHf(t) values from −17.6 to −5.7 with an average of −15.2, and their TDM2 ages (1.29–1.91 Ga) are much younger than the basement rocks of the south margin of the NCC, which indicate that the ZSY quartz syenite were generated by partial melting of thickened lower crust with minor involvement of mantle-derived materials. The TSM pluton has characteristic of A-type granite, such as, high SiO2 (69.7–71.87 wt.%), total alkalis (Na2O + K2O = 8.5 to 9.41 wt.%), HFSE (Zr, Nb, Ga, Y), low CaO (0.27–1.25 wt.%), Ba, Sr and Eu. Their eHf(T) values ranges from −12.4 to −1.6 with an average of −7.6 and TDM2 ranges from 1.10 to 1.63 Ga with an average of 1.38 Ma. We propose that the TSM granites results from partial melting of tonalitic crustal sources with a plagioclase-rich residual at high temperatures and low pressure. Materials input from the mantle also is involved for the higher eHf(t) values than tonalitic crustal at the southern margin of NCC and high temperatures. Our results suggested that the thickened LCC at the south margin of the NCC is still existence before the intrusive of the ZSY adakitic rocks (∼123 Ma). During the intrusive of the TSM granites (∼112 Ma) it turns to extensional environment. This extensional event reflects the background of lithospheric thinning and decratonization of NCC.

Although most economic geology research is concentrated at the deposit or mineral-system scale for a single well-defined deposit group with a consistent metal association, there are both academic and economic advantages in considering the similar geodynamic setting of deposits having contrasting metal compositions that are traditionally considered unrelated. As an example, there are a range of mineral deposit types or systems that are spatially associated with the margins of long-lived, relatively cold, buoyant Precambrian cratons or lithosphere with thick mantle lithosphere roots. These diverse hypogene deposit groups include world-class to giant BIF-derived iron ores, Kiruna-type Fe-P deposits, anorthosite-hosted ilmenite deposits, IOCG deposits, carbonatite-associated REE-P-Nb-(Cu) ores, intrusion-hosted Ni-Cu-PGE sulfide ores, SEDEX (and MVT) Pb-Zn-Cu deposits, Zambian Copperbelt-type Cu-Co, and IOCG deposits, that provide a high proportion of the global metal inventory. Their preservation, some older than 2 Giga-years, is due to the buoyancy of the thick, cold cratonic lithosphere. Deep extensional fault systems develop on these craton margins during rifting, leading to deposition of continental-shelf sedimentary sequences that provide both suitable host rocks for mineralization and metal and sulfur-rich high-salinity fluid sources. The long-lived lithosphere margins with fluctuating stress fields enhance the Pb-Zn-Cu endowment potential of these basins by promoting syn-basinal or later gravity-driven flow of high-salinity brines. Compressional or transpressional reactivation drives syn-orogenic fluid flow to produce the Cu-Co ores of the Zambian Copperbelt, or provide the pre-ore thrust architecture of fluid seals over reactive carbonate sequences for Carlin-type gold ores. The deep faults provided preferred conduits for the emplacement of mafic-ultramafic intrusions, with Ni-Cu-PGE sulfide deposits formed within complexities in the magma plumbing systems. The magmatic–hydrothermal group of carbonatite-related REE-P-Nb-Cu, IOCG deposits, and IRGD systems, and the hydrothermal Carlin-type deposits, all formed under extensional high heat-flow tectonic regimes and derived their ore fluids, with the probable exception of Carlin-type ores, from metal- and volatile-fertilized sub-continental lithosphere below the craton margin. The orogenic gold deposits on craton margins in China were also formed during transpressional geodynamic episodes from ore fluids with a fertilized mantle lithosphere source. A detailed analysis shows that most deposit types are sited within 100 km of the margins of Archean cratons, although sediment-hosted Pb-Zn-Cu deposits, that show no obvious relationships to craton margins, require a buffer of 200 km for thick Paleoproterozoic lithospheric blocks. These features brought out in this paper can potentially aid mineral exploration in terms of initial area selection within the available search space, but precise definition of these buffer zones is difficult due to heterogeneity of constraints on the precise location of craton and thick lithosphere boundaries globally. However, the search space for this diverse group of deposits is limited to between 10 and 35% of the continental crust in different regions, within which geophysical methodologies can further constrain more prospective targets.

The Permo-Triassic adakitic magmatism in the southern Korean Peninsula preserves important tectonomagmatic records along the East Asian continental margin. In this study, we present SHRIMP/LA–MC–ICPMS U-Pb zircon ages and Hf isotope signature with whole-rock geochemical compositions of the Middle Permian to Middle Triassic granitoid gneiss-granitoid suites and the Middle to Late Triassic plutonic rocks in the southeastern Korean Peninsula. The former yields three age groups of ca. 272–263 Ma, ca. 258–251 Ma and ca. 243–240 Ma, respectively. The latter group yields ca. 237–216 Ma ages, indicating a long term magmatism that lasted from the Middle Permian to late Triassic. The granitoid gneiss-granitoid suites have chemical compositions similar to high silica adakitic rocks, showing high SiO2 (59.55–73.97 wt.%), Na2O (3.55–5.30 wt.%), Sr/Y (30–401), and La/YbN (11–173), and low MgO (0.18–1.82 wt.%), Y (2–14 ppm) and YbN (2–7). These rocks are peraluminous with high Ba and Sr, and show relatively high K2O contents and K2O/Na2O ratios (> 0.7), with positive correlation between La/YbN vs. Sr/Y ratios and high initial Sr ratios. These features reflect different contribution of the slab-derived adakite melts that interacted with peridotitic mantle in the metasomatized mantle wedge and the Middle Paleoproterozoic lower crustal basement of the Yeongnam Massif. On the contrary, the Triassic alkaline magmatism in the Yeongnam Massif is alternatively interpreted either by a tectonic switch to the extension-dominated arc system or by a delamination of an overthickened arc. The results from this study offer important evidence for a common subduction-accretion system existed between the North and South China Cratons and microcontinents between them along margins of the East Asian continental blocks, with different plate interaction in different locations generating distinct magmatic suites.

Four Tethyan ocean basins are recognised in Asia, the Proto-Tethys (Late Proterozoic - Silurian), Palaeo-Tethys (Middle Devonian - Late Triassic), Meso-Tethys (Middle Permian - Late Cretaceous) and Ceno-Tethys (late Middle Triassic - Eocene). Multi-disciplinary data, including ages of pelagic sediments, ocean plate stratigraphy, seamounts, ophiolites, blueschists, eclogites in accretionary complexes, volcanic arc and magmatic rocks found along suture zones of the Tethyan oceans are described and used to date the opening and closure of these oceans. The evolution of the Tethyan ocean basins in Asia illustrates that Asia has been a giant convergent zone for more than 500 million years and the Phanerozoic construction and evolution of Asia involved the opening and closure of Tethyan ocean basins and the collision and accretion of Gondwana-derived continental blocks and the Indian Craton. Subduction processes, arc and back-arc basin generation, and continent-continent and arc-continent collisions led to the principal orogenic events, basin development and related mineral and energy resource deposits recorded in Asia. Three major orogenic belts are recognised in Asia, the Central Asian Orogenic Belt, that relates to the evolution of the Palaeo-Asia Ocean, and the Tethyan (Tethysides) Orogenic Belt and the Alpine-Himalayan Orogenic Belt which relate to the evolution of Tethyan ocean basins. The principal Tethyan basin related orogenies in Asia are the Bhimphedian Orogeny (Ordovician-Silurian) that reflects the collision of major Asian continental blocks (“Asian-Hun Superterrane”) with Gondwana, the Indosinian (Cimmerian) Orogeny (Permian-Triassic) resulting from Palaeo-Tethyan subduction processes, collisions of Asian blocks and collision of the Cimmerian continent with Asia, and the Himalayan-Tibetan Orogeny (Cretaceous-Palaeogene) caused by subduction of the Meso- and Ceno-Tethys oceans and the Lhasa-Asia and India-Asia collisions.

Deep, carbonate-rich melts are key constituents of kimberlites and are crucial for understanding the cycle of volatile elements in the mantle. On the Siberian craton, the Udachnaya-East kimberlite hosts extremely well-preserved nodules composed of chlorides + carbonates + sulfates, that do not present any relict sedimentary textures. These salty nodules display textures that are commonly observed in quenched liquids and may thus represent the very last stage liquid of the kimberlite. Alternatively, they could represent assimilated sedimentary material, or even post-magmatic hydrothermal alteration, because kimberlites are known to ascend through the lithosphere while assimilating material from their wall rocks. Here we focus specifically on those chloride-carbonate nodules, which are composed of 70% chloride + 30% alkali-carbonate and sulfate, and used two radiogenic systems (Rb-Sr, Sm-Nd) and the isotopic composition of sulfur, in addition to their major and trace element compositions (n = 3). We then compared the results with the same geochemical data on host kimberlites (n = 4), sedimentary cover (n = 3) and hydrothermal veins (n = 3). Taken together, our results show that the nodules are not the product of a contamination by the Cambrian sedimentary cover. Trace element patterns of the nodules display extreme enrichments in the same elements that are relatively depleted in the host kimberlite but also in kimberlites worldwide (K, Rb, Sr, Pb), suggesting that chloride-carbonate nodules are snapshots of the latest stage liquid present in the kimberlite system. Their isotopic compositions (Rb-Sr, Sm-Nd and δ34S) are consistent with a common magmatic source with their host kimberlite. We propose that chloride-carbonate nodules record a missing compositional endmember, which could explain the trend towards more radiogenic Sr isotope ratios at nearly constant Nd signatures observed in their host kimberlite, as well as in other kimberlites worldwide. This observed trend suggests the presence of a recycled component with high Rb/Sr (such as salts or terrigenous sediments) in the mantle sampled by some kimberlites, either in the lithosphere or the asthenosphere. This study highlights that the role of alkalies and halogens may have been underestimated in the genesis of kimberlites at depths where diamonds are stable, as well as in more evolved magmatic stages. Segregations of chlorides and carbonates occur specifically in sulfate-bearing kimberlites, which may thus sample a mantle domain in which sulfates with δ34S > 0‰ are dominant. The existence of such a reservoir could explain the apparent imbalance observed between the chondritic value (δ34S of 0‰) and the negative S isotopic compositions of mantle sulfides (MORB and peridotites).

The Liaodong gold province includes voluminous gold deposits, which occur in an Archean gneiss complex, Paleoproterozoic metamorphic rocks, and Mesozoic granite. However, the ore-forming age, the g...

We investigate regional variations in the Lg-wave quality factor (Q) in the Indian Shield with a tomographic method using the LSMR (an iterative solver of least squares algorithm) iterative solver. Vertical broadband seismograms of 223 crustal earthquakes recorded by 113 stations deployed on the Indian Shield are processed to extract the Lg amplitude spectra. The relatively large dataset with good ray coverage allows us to image the lateral variation of the crustal attenuation over the region. The tomographic inversion reveals that the Lg Q0 in the Indian Shield varies from 50 to 650, while the frequency-dependent parameter (η) varies between 0.4 and 1.1 with an average value of 0.7. The attenuation image at 1 Hz suggests the heterogeneities in the Indian crust and clearly demarcates the diverse geological regimes that were hitherto not known. Structural features such as rift, suture zones, sedimentary, and active regions are characterized by high attenuation (Q0

Timing of the major Baiyun gold deposit (~ 70 t Au) in the northeastern North China Craton is controversial. A textural and geochronological study of high-grade gold ores identifies three generations of xenotime (Xtm-1, Xtm-2 and Xtm-3), even in single grains. The oldest Xtm-1, in grain cores, is of metamorphic origin, with very high U and U/Th ratios, and hump-shaped, HREE-enriched patterns with maximum normalized values at Yb and large negative Eu anomalies. It is dated at 1856 ± 6 Ma, consistent with its crystallization during regional metamorphism related to cratonization. In contrast, 244 ± 2 Ma Xtm-2 overgrowths are of hydrothermal origin, having low U and U/Th ratios and hump-shaped, MREE-enriched patterns with maximum normalized values at Ho and negligible Eu anomalies. Xtm-2 records a previously unrecognized Middle Triassic hydrothermal episode. Xtm-3, in equilibrium with native gold-hosting pyrite and rutile, is also hydrothermal. The Xtm-3 domains have similar U, U/Th ratios, and MREE-enriched patterns to Xtm-2, but a younger crystallization age of 231 ± 1 Ma. Associated rutile grains that show close textural associations with auriferous pyrite and native gold have an in situ SIMS U–Pb an intercept age of 229 ± 4 Ma, consistent with that of Xtm-3. Collectively, these reliable ages indicate that gold mineralization at Baiyun occurred at ca. 230 Ma, predating the emplacement of granite intrusions by more than 3 million years. Both the Middle Triassic hydrothermal event (~244 Ma) and the Late Triassic gold mineralization event (~230 Ma) lie within the temporal window of collisional tectonics in the host orogen. In combination, the new geochronology and fluid-inclusion and geological data support Bayun’s classification as an orogenic gold deposit.

During the late Palaeozoic Era, a series of related marine strata dominated by multi-layer limestones were deposited in the southern North China Craton. In order to gain new insights into the systematic geochemistry of the carbonate succession of the representative formation (Taiyuan Formation), we examined 59 limestone samples collected from the Huaibei Coal Basin (HCB), with a view towards quantitatively determining the major and trace elements and stable isotope compositions. The data obtained can provide essential evidence for reconstruction of the depositional palaeo-environment and tectonic setting of the Taiyuan Formation. Both X-ray diffraction analyses and palaeoredox proxies (e.g. V/Cr, V/(V + Ni) and authigenic U) indicated that the limestone layers were deposited in an oxic–dysoxic zone, with calcite as the main component. Moreover, palaeomagnetic evidence provided support for the conclusion that these limestones were laid down within an epicontinental sea depositional environment under a warm or hot palaeoclimate during the transition between late Carboniferous and early Permian time. Additionally, evidence obtained from our analyses of trace and rare earth elements revealed that the tectonic setting of the Taiyuan Formation (L1–L5) in the HCB transited from an open ocean to a passive continental margin, thereby indicating that this transformation stemmed from the subduction closure of the northeastern Palaeotethys Ocean. The findings of this study would be of interest to those working on the upper Palaeozoic marine strata in the southern North China Craton.

Osmium isotopes, whole rock and mineral geochemical data from peridotite xenoliths from two Miocene McMurdo Volcanic Group cinder cones in the Transantarctic Mountains (TAM) in Southern Victoria Land, Antarctica, reveal that the underlying mantle preserves evidence for major mid-Proterozoic lithosphere formation despite the crust being dominated by late Neoproterozoic-Ordovician (~0.65–0.47 Ga) rocks. The Hooper Crags xenolith suite is dominated by harzburgites with highly refractory olivine Mg# (up to 92.3) and depleted bulk rock major and platinum group element + Re abundances, with 187Os/188Os ratios indicating depletion in the mid-Proterozoic. Pipecleaner Glacier xenoliths, 18 km distant, are lherzolites with olivine Mg# ( 250 km) East Antarctic Craton lithosphere shielding the immediately adjacent circum-cratonic mantle from being affected by convective asthenosphere-driven erosion. This contrasts with mantle lithosphere accreted distally to the East Antarctic Craton (represented by the now-detached Zealandia continent), which did not attain extreme thickness and has therefore been more susceptible to tectonic reworking and lateral translation.

The late Neoarchean, ~2.53 to 2.51 Ga Dagushan banded iron formation (BIF), is a typical Algoma-type BIF located in the northeast part of the North China craton. Despite having undergone upper greenschist to lower amphibolite facies metamorphism, the Dagushan BIF retains evidence of varied depositional facies, making it an ideal archive to evaluate the paleomarine environment and the paragenesis of the ore minerals. A transition from oxide to silicate to carbonate facies BIF is evident in a northward direction. The mineralogical composition shifts from magnetite and quartz in the south through a magnetite-quartz-cummingtonite/stilpnomelane assemblage in the transition zone to magnetite-siderite in the north. Such a distinct distribution of mineralogical facies correlates well with the depositional environment of the BIF. The carbonate facies BIFs formed in a near-shore, proximal environment, whereas the oxide and silicate facies BIF assemblages formed in deeper waters, distal to the paleoshoreline. The BIF samples display characteristic seawater-like rare earth element + yttrium (REE + Y) profiles with positive La and Y anomalies and heavy REE enrichment relative to the light REEs when normalized to post-Archean Australian shale. Positive Eu anomalies suggest a high-temperature hydrothermal contribution to the BIF. The absence of a negative Ce anomaly in nearly all samples, coupled with positive δ56Fe in magnetite in all mineralogical facies, indicates a dominantly anoxic water column contemporaneous with deposition of the BIF. At ~2.53 Ga in the Anshan area, seawater was mostly anoxic and rich in ferrous iron. Dissolved ferrous iron in upwelling hydrothermal fluids was oxidized and precipitated as Fe(III) oxyhydroxides in the photic zone leading to BIF formation. Proximal to hydrothermal vents, magnetite formed via the reaction of Fe(III) oxyhydroxides and aqueous Fe(II) supplied from the hydrothermal fluids and microbial dissimilatory iron reduction (DIR) coupled to organic carbon oxidation. Proximal to a paleoshoreline, siderite formed through DIR, as evidenced by the depleted δ13C values and the presence of graphite. Silicates, such as stilpnomelane and cummingtonite, are considered to be the metamorphic products of early diagenetic silicates (e.g., nontronite) that formed in the water column from admixtures of Fe(III) oxyhydroxides and amorphous silica.

This paper reports new zircon U–Pb ages, whole-rock geochemistry, and Sr–Nd–Pb–Hf–O isotopic compositions for the Funiushan (FNS) pluton of the southern North China Craton (NCC). These data and statistical analyses of previously reported compositions of late Mesozoic granites from the southern NCC are used to constrain late Mesozoic continental recycling and geodynamic processes. The FNS pluton includes coexisting early Early Cretaceous (140 Ma), late Early Cretaceous (130–116 Ma) and highly evolved granites (HEGs; 126–125 Ma). The early Early Cretaceous granites have high Sr contents (332–566 ppm), high Sr/Y (53–138) and (La/Yb)N (29–52) ratios, and low MgO contents (0.15–0.48 wt%). They have relatively low (87Sr/86Sr)i values (0.7051–0.7054), relatively high eNd(t) values (−4.11 to −3.96) and variable eHf(t) values (−22.9 to −0.53). They are also characterized by high initial 206Pb/204Pb values (17.893–17.975) and relatively low δ18O values (5.34‰–7.48‰) as well as Neoproterozoic (851–734 Ma) inherited zircons, suggesting that they have an adakitic affinity formed by recycling of subducted continental crust of the Yangtze Craton (YC) with input from a mantle component. In contrast, the late Early Cretaceous granites have relatively high (87Sr/86Sr)i values (0.7077–0.7085), low eNd(t) values (−14.2 to −12.0), relatively high initial 206Pb/204Pb values (17.398–17.497), eHf(t) values of −23.7 to −10.7, and δ18O values of 5.76‰–6.55‰. These data, and the Neoproterozoic zircon ages (716–702 Ma), indicate that the primary magmas formed from recycled YC crust with a minor contribution from the NCC basement. The late Early Cretaceous HEGs have relatively high eNd(t) values (−9.33 to −8.70), high initial 206Pb/204Pb values (17.656–17.885), intermediate eHf(t) values (−12.3 to −6.18), and relatively low δ18O values (5.22‰–6.72‰), indicating that they formed from subducted YC and mantle material. Previous work on granites of the southern NCC has established two phases of granite formation. Late Jurassic to early Early Cretaceous I-type granites (160–130 Ma) occur throughout the southern NCC. These are adakitic and formed from thickened lower continental crust (LCC). Late Early Cretaceous A-type granites (130–110 Ma) formed from thinned LCC. The differences between Late Jurassic to early Early Cretaceous granites and late Early Cretaceous granites reflect a transformation in tectonic regime from thickening to thinning, which is attributed to rollback of the subducting Paleo-Pacific Plate.

The Bundelkhand craton hosts Banded Iron Formation (BIF) bodies within the east–west trending Bundelkhand Tectonic Zone (BTZ). The BIFs near Mauranipur, BTZ, are massif and are composed of amphibole, quartz, magnetite, and garnet. P–T pseudosection analysis implies that the protolith of these BIFs were carbonate-bearing sediments that underwent metamorphism at 400–450 °C at 0.1–0.2 GPa to stabilize amphibole and garnet via a series of dehydration and decarbonation reactions forming 10–50 µm sized monazite grains in the process. The U-Th-Pb (n = 74) analyses by the electron probe microanalyzer yield three age clusters. The oldest mean age, 3137 ± 96 Ma, is retrieved from low-ThO2 monazites occurring as discrete grains within amphibole bands and is interpreted as the timing of monazite growth caused by fluid-rock interaction. The second age cluster yields an average age of 2567 ± 48 Ma from high-ThO2 domains that laced the low-ThO2 monazite core. Anhedral monazites occurring as inclusions within garnet yield an average age of 2538 ± 120 Ma. These 2500 Ma dates reflect monazite growth during prograde metamorphism. An age of 2168 ± 83 Ma is retrieved from monazite overgrowths in amphibole bands. The ~ 3200 Ma metamorphic event in the Bundelkhand craton is similar to those reported from the Singhbhum and the Dharwar cratons. The ~ 2500 Ma age, when compared with the available geochronological data, constrains the timing of Neoarchean-Paleoproterozoic tectonism and stabilization. The minor Meso-Paleoproterozoic (2100–1900 Ma) age may be related to extension and dyke emplacement.

Introduction: We considered the general principles of creating complex geophysical models for the lithosphere of the central part of the East European Craton and the role of geothermal models in such models. In order to form a reliable initial estimate for a thermal model of the upper crust, we generalised the data on the content of heat generation elements in the rocks of the Early Cambrian basement. Initial data: We studied the peculiar features of the total content of rare and scattered elements obtained using the method of inductively coupled plasma atomic mass spectrometry in the samples of typical rocks of the studied region. A consolidated database was compiled for the content of heat generation elements (potassium, thorium, uranium) and the total content of silica in typical rocks of the crystalline basement of the craton. Assessment of heat generation of the basement rocks: We calculated the heat generation of the crystalline basement rocks in the area based on the initial data on the concentration of radiogenic elements. To assess the values of heat generation, we used the data on the density of the rocks of the basement of the East European Craton and its individual parts. The obtained results of the assessment of heat generation characterise the upper inhomogeneous part of the basement extending to the lower border of the region’s graviactive layer. Data analysis and discussion: We obtained the value of heat generation of the Early Cambrian basement rocks that varies from 0.1 to 7.54 μW/m3 with the average value of 0.528 μW/m3 . Data analysis showed that there was no correlation between the density of the region’s basement rocks and the calculated values of their heat generation. A stable connection was found between the content of silica (SiO2 ) and the value of the calculated heat generation of the rocks. As for the main groups of the basement rocks, heat generation tends to be related to the composition of the rocks, but there is no connection to the age of the formation of the rocks. Conclusions: We presented the main results of the conducted research and outlined a plan for the formation of an initial estimate for the heat generation of the upper crust in the thermal model of the region’s lithosphere.

The recent paper by Chaves and Porcher published in Gondwana Research (2020, v.87, 224–237) asserts the presence of 2.2 Ga eclogite facies rocks in the Itaguara Sequence, Sao Francisco craton (SFC), Brazil. They present images in which the diagnostic high-pressure minerals either occur on cracks (rutile), or as fragmentary matrix grains with unclear mineral relationships (omphacite and phengite). Here I discuss the sample petrology in order to identify the equilibrium assemblage, and utilise a P-T phase modelling approach, integrating the major mineral compositions, to show that these rocks are not retrogressed eclogites. The modelling presented here indicates that peak conditions were likely in the amphibolite facies, reaching maximum pressures of no more than 8 kbar and peak temperatures of ca. 700 °C (at 5 kbar). This result is consistent with that found by Massonne (2020, JSAMES, v.99, 102495) who suggested that mica schists from Itaguara reached maximum pressures of 13–14 kbar, and possibly lower than 10 kbar at 600 °C (i.e. within the medium to high-pressure amphibolite facies). This work shows that declarations of eclogite facies conditions, particularly from Paleoproterozoic terrains, should be accompanied by carefully evaluated petrography and thermodynamic investigations based on minerals (or mineral replacement textures) that indicate equilibrium relationships.

The southern edge of the Eyre Peninsula, experienced a separation from proto-Antarctica in the Cretaceous and has been projected to extend into Terre Adelie Craton, Antarctica. The Archaean and Palaeoproterozoic rocks of the southern Eyre Peninsula, have been modified by the Kimban Orogeny (~1730–1690 Ma) with the development of the regionally extensive Kalinjala Shear Zone, which has been correlated with the Mertz Shear Zone in Antarctica. In this contribution, new structural observations associated with the granulite facies Kalinjala Shear Zone, together with other shear zones, all showing similar kinematics of dextral top-to-the-north transport will be described. The Kimban Orogeny overprints and reworks a major lithospheric boundary between the Gawler Craton and a sequence of preceding events related to the ~ 1850 Ma Cornian Orogeny. Shear zones were initiated during the early stage of the Kimban Orogeny (KD1) in a dextral simple-shear regime, transitioning into a pure-shear (KD2) dominated regime. With shortenings of > 90% in the Kalinjala Shear Zone localized into regions containing pre-existing Tourneford Metdolerite Dykes emplaced at ~ 1810 Ma into the granites of the Donington Suite (1850–1843 Ma) and a basement of 2000–1859 Ma paragneisses. Geometrical relationships reveal the operation of oblique extrusion during the Kimban Orogeny, where a coaxial component acted sub-horizontal and orthogonal to the trend of the Kalinjala Shear Zone. Regions of low-strain and a ‘pinched-in’ and inverted sequence of Mesoproterozoic metasedimentary cover, the Hutchison Supergroup, are bounded by major km-scale shear zones with steep west-dipping tectonic contacts. Post-Kimban subvertical east–west-trending joints and faults record a rifting event which can be related to a Gondwana breakup. With post-rift Neogene fault activity recording additional tectonic episodes where pre-existing basement structures exert significant control on their orientation and distribution. Palaeogeographical reconstructions between the Eyre Peninsula and the Terre Adelie Craton, based on matching basement geology and structural style, are compared and reconciled with this new information.

It is controversial about the tempo–spatial distribution and tectonic attributes of the Paleoproterozoic orogenic belts in the North China Craton (NCC). The Hongqiyingzi Complex in the northern margin of the NCC, comprising orthogneiss, supracrustal sequence and an ophiolitic melange, was investigated to have experienced multiple tectonic evolution from Paleoproterozoic to Mesozoic. However, the depositional age and metamorphic P–T path of the supracrustal sequence have not been well addressed. Garnet mica schists are investigated on the basis of petrography, mineral chemistry, phase equilibria modelling and zircon and monazite dating, which record an extreme case with four phases of metamorphism. The first-phase is characterized by high pressure (HP) granulite facies with the peak conditions of 10–11 kbar/>780 °C, which occurred at ~1.95 Ga. It is considered to correspond to a collisional orogeny with crust thickening widespread in the Paleoproterozoic orogenic belts of the NCC, followed by an exhumation with heating at ~1.92 Ga. The second-phase is marked by the overprinting of staurolite-bearing assemblages with the peak conditions of 6–7 kbar/610–630 °C, which occurred at ~1.85 Ga. It may correlate a separate orogeny occurred along the northern margin of the NCC, following a ~1.90 Ga oceanic subduction. Phase modelling suggests this overprinting over the first-phase HP granulites is mainly controlled by water infiltration. The third-phase andalusite-type and the fourth-phase greenschist facies metamorphism are confined to local equilibrium domains and their ages have not been well constrained. With a comparison of regional geology, the third-phase metamorphism is inferred to be related with the 320–290 Ma extension in the northern part of the NCC during Late Paleozoic, and the fourth-phase metamorphism is correlated with the 250–230 Ma collision occurred along the Solonker Suture Zone in the Central Asia Orogenic Belt during Early Mesozoic. Moreover, detrital magmatic zircons yield ages of 2.0–2.1 Ga, providing a definite upper limit on the deposition of the Hongqiyingzi supracrustal sequence.

The Shanxi Rift located in the central part of the North China Craton (NCC) as a boundary between the Ordos block and the Huabei basin. The Shanxi graben system is a Cenozoic rift and originated from back-arc spreading related to westward subduction of the western Pacific and far field effects caused by northward subduction of the Indian plate. It has also had strong earthquake activity in China since the Quaternary. To investigate the tectonic evolution and tectonic setting of strong earthquakes in the Shanxi Rift, we apply the receiver function $$H$$ H -$$\kappa$$ κ stacking method to determine the crustal thickness and average Vp/Vs ratio in the area. The results show that the thickness of the crust increases from approximately 30 km in the Huabei basin to approximately 47 km in the Yinshan Mountains with a close correlation between the Moho depth and topography. The Yuncheng, Linfen and Taiyuan grabens have varying degrees of crustal thinning. The crustal average Vp/Vs ratio in the Shanxi Rift has significant heterogeneity; the high Vp/Vs ratio (~ 1.85) are found in the Datong and Yuncheng grabens, and Vp/Vs ratio of the Taiyuan and Linfen grabens is approximately 1.75 which close to the global average value ~ 1.782. Combining the observations in this study with previous research, we suggest that the grabens in the Shanxi Rift experienced extensional deformation from south to north and that the possibility of strong earthquakes in the central part of the Shanxi seismic belt is greater than that on the northern and southern sides.

The Spiti Shale Formation is a widely distributed stratigraphic unit of the passive northern margin of the Indian craton, deposited between the Callovian and earliest Cretaceous. The siliciclastic strata are dominated by dark-grey to black argillaceous silt. As the formation has undergone intense tectonic stress involving folding and faulting, it is very difficult to document a complete section. In the type area, the Spiti Valley, six sections have been measured that document parts of the three informal members of the formation, the Lower, Middle, and Upper members. Despite its uniform appearance, eight facies/biofacies types could be distinguished, ranging from the anoxic shale facies, with ammonites and belemnites as the only faunal elements, to the dysoxic Malayomaorica and Bositra biofacies, and the oxic to anoxic offshore shelf facies, which are characterized by low-diversity macrobenthos associations. Other facies are the condensed glauconitic-phosphoritic mudrock facies and the Fe-oolitic siltstone facies (both characterized by sediment starvation), the aerated argillaceous silt–sandstone facies, and the tide-influenced nearshore shelf facies. The benthic macrofauna represents four bivalve-dominated associations all characterized by a very low to low species diversity. They are the Bositra buchii, the Australobuchia spitiensis, the Palaeonucula cuneiformis‒Pruvostiella hermanni‒Indogrammatodon egertonianus, and the Malayomaorica sp.‒Australobuchia spitiensis‒Retroceramus haasti association. Sediments and macrobenthic associations indicate that the Spiti Shale Formation represents outer to inner shelf environments, which for much of the time were subjected to upwelling and anoxic to dysoxic conditions. Distinct shallowing at the top characterizes the transition to the overlying Lower Cretaceous Giumal Formation.

The eastern part of the North China Craton suffered significant lithospheric thinning since the Mesozoic, and petrogenesis of the Dagushan adakitic diorite porphyries provides an excellent opportunity to investigate the lithospheric thinning mechanism and geodynamic setting. The zircon LA-ICP-MS U–Pb geochronology reveals that the representative Dagushan adakitic porphyry was formed at 120.5 ± 0.5 Ma. The Dagushan diorite porphyries are characterized by the relatively high contents of SiO2 (64.25–65.70 wt%), Al2O3 (15.00–15.38 wt%), Sr (333–491 ppm), low contents of Y (6.50–10.3 ppm), and Yb (0.57–0.85 ppm), and resultant high Sr/Y (47–57) and La/Yb (37–55) ratios, exhibiting geochemical characteristics of typical adakites. Moreover, the relatively high MgO contents (MgO = 2.23–2.29 wt%) and Mg numbers (Mg# = 54–56) of the Dagushan adakitic rocks imply that the pristine adakitic magma interacted with mantle peridotite. However, the zircon Hf isotopic signatures (eHf(t) = − 19.0 to − 28.0; TDM2 = 2378–2944 Ma) suggest an ancient lower crustal source. Therefore, it is proposed that the Dagushan adakitic rock was probably generated by partial melting of delaminated lower crust which was triggered by the Tan-Lu Fault Zone, and the interaction of pristine adakitic magma with mantle peridotite during the ascent finally generated the Dagushan high Mg# adakitic rocks. It is suggested that delamination was an important mechanism for lithospheric thinning of the NCC.

Cratons, defined by their resistance to deformation, are guardians of crustal and lithospheric material over billion-year time scales. Archean and Proterozoic rocks can be found in many places on earth, but not all of them represent cratonic areas. Some of these old terrains, inappropriately termed “cratons” by some, have been parts of mobile belts and have experienced widespread deformations in response to mantle-plume-generated thermal weakening, uplift and consequent extension and/or various plate boundary deformations well into the Phanerozoic. It is a common misconception that cratons consist only of metamorphosed crystalline rocks at their surface, as shown by the indiscriminate designation of them by many as “shields.” Our compilation shows that this conviction is not completely true. Some recent models argue that craton formation results from crustal thickening caused by shortening and subsequent removal of the upper crust by erosion. This process would expose a high-grade metamorphic crust at the surface, but greenschist-grade metamorphic rocks and even unmetamorphosed supracrustal sedimentary rocks are widespread on some cratonic surfaces today, showing that craton formation does not require total removal of the upper crust. Instead, the granulitization of the roots of arcs may have been responsible for weighing down the collided and thickened pieces and keeping their top surfaces usually near sea level. In this study, we review the nature and origin of cratons on four well-studied examples. The Superior Province (the Canadian Shield), the Barberton Mountain (Kaapvaal province, South Africa), and the Yilgarn province (Western Australia) show the diversity of rocks with different origin and metamorphic degree at their surface. These fairly extensive examples are chosen because they are typical. It would have been impractical to review the entire extant cratonic surfaces on earth today. We chose the inappropriately named North China “Craton” to discuss the requirements to be classified as a craton.