Reliable chronostratigraphic correlations for Precambrian cratons are critical for understanding associated tectonic processes and the environments in which early life evolved. This study examines implications of recent geochronological advances for the Statherian‒Tonian chronostratigraphic framework of the Greater North China Craton (GNCC), which encompasses the Langrim and Quanji-Central Qilian blocks, in addition to the traditional North China Craton (NCC). New age constraints subdivide the Statherian-Tonian stratigraphic record of the GNCC into three stages: ca. 1.78‒1.35, 1.35‒1.24, and 1.24‒0.80 Ga. Late Statherian deposition initiated in the Xionger Rift Basin and progressed toward an epicontinental carbonate sea covering the GNCC by ca. 1600 Ma. This corresponds with the initial breakup of Columbia that established evolutionary niches for early eukaryotes. An extensive ca. 1.35‒1.0 Ga depositional gap resulted from protracted collision, uplift, and erosion on the GNCC, associated with the Grenville-age, southward-migrating foreland basin in which black shales of the ca. 1.38 Ga Xiamaling Formation and related units were deposited. Between ca. 1240 and 800 Ma, deposition of carbonate-dominated successions indicates the development of an embayment on the Langrim Block (Pyeongnam Basin) that gradually expanded across the entire GNCC, corresponding to the rifting and breakup of Rodinia.

The North China Craton (NCC), confined by a series of late Paleoproterozoic-Neoproterozoic extensional basins, is likely a key piece in welding the supercontinent Columbia. The debate regarding the connection between the northern NCC and either the North Australia Craton or the Siberia Craton is essential for understanding the assemblage and break-up of Columbia. The northern marginal rift system (NMRS) of the NCC is an ideal region in which imprints related to neighboring cratons could be preserved. However, the absence of a well-calibrated chronologic framework obstructs subregional attribution and regional correlation and obscures the tectothermal reconstruction of the Proterozoic NMRS, although the zircon U-Pb ages of the volcanic interbeds and crosscutting dykes were sporadically obtained from the Bayan Obo, Zha'ertai, Huade, Shi'nagan and Langshan groups. This study presents two SHRIMP U-Pb ages constraining the Sailinhudong Group (SG) in Darhan-Muminggan Joint Banner to the early Mesoproterozoic (probably the early Calymmian), including one zircon U-Pb age of ca. 1.58 Ga from a volcanic interbed and the other baddeleyite Pb-Pb age of ca. 1.31 Ga from a crosscutting gabbro-diorite dyke. Zircon Hf isotopic compositions of the ca. 1.58 Ga tuff layer in the volcanic-seismic succession from the lower SG are all depleted, similar to those of the ca. 1.58 Ga tuffite layer overlying the seismic succession in the third member of the Gaoyuzhuang Formation in the Yanliao Rift. In conjunction with previous studies, we propose an external origin for the tuff layers and associating seismic successions. A ca. 1.58 Ga catastrophic eruption is inferred to have transmitted substantial tephra and emanated considerable energy to the northern NCC. The ca. 1.58 Ga catastrophic event is considered an anchoring point for attributing and correlating the Calymmian successions through the northern NCC. According to the latest lithostratigraphic and chronostratigraphic advances, the late Paleoproterozoic-Neoproterozoic successions outcropping in the NMRS are further subdivided into the Statherian (the Zha'ertai Group and lower parts of the Bayan Obo and Huade groups), Calymmian (the Sailinhudong, Shi'nagan and middle parts of the Bayan Obo and Huade groups) and Tonian (the northern Langshan Group).

The geochronological research of the Mesoproterozoic Changcheng Group, North China Craton (NCC), has been concentrated for several decades. Although lots of significant progress have been achieved in recent years, the exact age of some key horizons and the relevant units, including that of the Tuanshanzi Formation, are still somewhat ambiguous. So far, all the previous chronological studies of the Tuanshanzi Formation have been focused on the zircon U-Pb age dating of the intercalated alkalic volcanic rocks in this formation. However, due to the complicated category of the zircons from the eruptive alkalic rocks, to some extent, it resulted in dispute both about the precise depositional age of the Tuanshanzi Formation and that of the underlying Chuanlinggou Formation, especially while the porphyry dikes and the rapakivi-granite apophysis, truncated by the Changcheng Group in the Yanshan Mountains, have been dated successfully since early 2010's. Hence, further work is needed to verify the exact depositional age of the Tuanshanzi Formation. Recently, some interbedded tuffite beds in the lower part of the Tuanshanzi Formation are firstly recognized in the Miyun and the Pinggu districts, Beijing City, in the Yanshan Mountains. High-precision SHRIMP zircon U-Pb dating yields tuffite ages of 1634 +/- 9Ma and 1637 +/- 8Ma, and the depositional age of the Tuanshanzi Formation can be calibrated more precisely. Combining with the previous works, the bottom age of the Tuanshanzi Formation, the same with the top age of the underlying Chuanlinggou Formation, can be constrained more tightly as similar to 1638Ma, and the chronostratigraphic framework of the Changcheng Group in the Yanshan Mountains can be revised, too. This may conform with the characteristic of the rapid depositional setting in this area during the latest Changchengian Period (1650 similar to 1600Ma), which should represent a sort of successions from the constantly extending rift-basin to the passive continental margin along the northern NCC. Further, it can lead a more credible stratigraphic correlation of all the Changchengian successions at the NCC, especially between the Luoyukou Formation at the southern margin of the NCC, and the Tuanshanzi-Dahongyu formations in the Yanshan Mountains. Moreover, it may be inferred that, corresponding to the deposition of the Tuanshanzi-Dahongyu and the Luoyukou formations, around similar to 1638Ma, for the first time, the warm, clean, shallow carbonate sea covered both at the northern and southern margins of the NCC. Simultaneously, probably a narrow but unobstructed carbonate sea passage, roughly north-south, emerged in the central of the NCC. This indicated that, from this time on, the NCC had been not only developed in the more extensional tectonic setting, but also isolated enough with the surrounding newborn seas (juvenile oceans). All these would prevent the input of the terrigenous clasts both from the NCC and the previous converged cratons, i.e. the main body of the Supercontinent Columbia (Nuna), and be suitable for the formation of carbonate rocks. Therefore, it should mark the new stage of the break-up between the NCC and the Columbia, as well as the supercontinent itself.

The driving forcing behind the secular evolution of the Earth system is controversial. Zircon, a common mineral in the continental crust, is a testimony of the growth and evolution of the continental crust and a recorder of Earth system evolution because of the time scale of the UPb isotopic chronology system zircon contains. Here, we compiled the largest known database of 2,042,944 zircon UPb ages derived by sampling the global continental crust. Comprehensive time series analysis techniques enable the identification of periodicities in the zircon production history and the growth and evolution of the continental crust over Earth's history. After the evaluation and exclusion of hot spot data impacts, we systematically obtained long-term cyclicities of zircon production of ca. 800, 360, 220, 160, 69, 57, 44, 30, 20, and 17 Myr, which are objective and statistically robust. These cycles are consistent with periodicities derived from multiple geological processes, i.e., mantle plumes, plate tectonics, orogenic events, large magmatic events, climate change, biological extinctions, and even meteorite impacts. The periodicities of these geological phenomena, including zircon production, indicate the periodicity of Earth system evolution in the past 3 billion years. Furthermore, these terrestrial periodicities also correspond to cyclic astronomical perturbations, such as the precession of the galactic warp, the galactic year, and the movement period of the solar system in the Milky Way, within error. Therefore, we suggest that the growth and evolution of the continental crust, and even Earth system evolution, probably originate from the periodic driving forcing of the Earth's astronomical environment.

在内蒙古乌拉特前旗大佘太镇附近的什那干群"下岩组"中下部,第一次发现了层凝灰岩等火山沉积夹层,并对其中的层凝灰岩(NM-1191)开展了SHRIMP锆石U-Pb年代学研究,精确标定其喷发时间为1614±8 Ma.由此可以确认,什那干群整体上应属于国际古元古代固结纪(Statherian Period,1800～1600 Ma)末期-中元古代盖层纪(Ca-lymmian Period,1600～1400 Ma)初期(相当于中国中元古代长城纪(1800～1600 Ma)末期-蓟县纪(1600～1400 Ma)初期)沉积.这一新的年代地层学归属的确定,显示什那干群与毗邻的渣尔泰山群及白云鄂博群(化德群)的相应层位,应属于"三群并立"、"同时异相"的沉积古地理格局;同时这也表明,该群基本可与华北克拉通北缘-中部的大红峪组-高于庄组对比,并与南缘洛峪口组-龙家园组大体相当.结合相关资料可进一步推知,位于鄂尔多斯西缘贺兰山-千里山一带的黄旗口组-王全口组及阿拉善南缘龙首山地区墩子沟群中下部(即第一、第二岩组),也应与什那干群的层位基本一致.这一广泛存在的对比关系很可能也说明,至少到中元古代盖层纪早期,阿拉善(阴山)地块仍隶属于华北克拉通的范畴,并与鄂尔多斯西缘、燕辽盆地-华北中部带及熊耳裂谷区等,共同拥有一个统一的"泛华北"陆表海.什那干群新的年代学约束及相关地层单元年代学等时框架的建立,为重新认知该阶段华北克拉通北缘沉积-构造古地理及其演化,探讨华北克拉通与哥伦比亚超大陆关系等重要命题,提供了关键的年代地层学约束.

Mid-Neoproterozoic low-delta O-18 metamafic rocks from the Leeuwin Complex, southwestern Australia, are reported for the first time. Sensitive high-resolution ion microprobe (SHRIMP) zircon U-Pb dating of these upper amphibolite- to granulite-facies mafic rocks yields igneous protolith ages of 674-660 Ma. The metamafic rocks are generally classified as subalkaline tholeiitic rocks with an ocean island basalt (OIB) affinity. They have low Mg# values (22-50) and Cr (0.19-105 ppm) and Ni (0.62-115 ppm) contents, with whole-rock epsilon(Nd)(t) values of 1.4 to + 1.5 and zircon epsilon(Hf)(t) values of - 0.3 to + 3.5. Using these data in combination with the incompatible trace element characteristics, it is inferred that the protoliths of the rocks were derived from low-degree partial melting of relatively depleted asthenospheric mantle in a continental rift environment, and the magmas underwent some crustal contamination and fractional crystallization of mafic minerals. Zircon cores from the metamafic rocks yield delta O-18 values of 0.89 to 4.10 parts per thousand, which are lower than normal mantle values (5.3 +/- 0.3 parts per thousand). These cores preserve oscillatory zoning or banding in cathodoluminescence images, and individual samples have concordant ages and preserve a narrow range of delta O-18 values, suggesting that the low-delta O-18 signatures are of primary magmatic origin. It is inferred that these low-delta O-18 metamafic rocks were generated by contamination by low-delta O-18 felsic crustal wall rocks and interaction of the magma with surface water at shallow depths in an extensional regime during the mid-Neoproterozoic.

A U-Pb geochronological and rare earth element (REE) geochemical study of zircon, monazite and garnet was carried out on rocks of Mesoproterozoic and Archean crustal domains in the Rauer Group of East Antarctica. The zircon and monazite U-Pb age spectra define concordia intercepts mainly at ca 1200, 990-910, and 530-500 Ma, suggesting that the Mesoproterozoic crustal domain is a significant part of the Rayner Complex that also underwent early Neoproterozoic and Cambrian high-grade metamorphism. The age data, mineral inclusion assemblages in zircon, and REE features for zircon and garnet indicate that all the granulite facies mineral assemblages in this domain might have formed during early Neoproterozoic metamorphism. Some zircon and monazite grains or domains have experienced complete U-Pb isotopic resetting during Cambrian reworking, which did not result in new zircon and monazite growth. The Archean crustal domain consists mainly of Paleo-Mesoarchean orthogneisses interleaving with Neoproterozoic paragneisses that contain inherited metamorphic zircon domains with ages of ca 1330 and 970 Ma. The mineral assemblages in these gneisses formed during a single Cambrian granulite facies metamorphic event. Garnet-bearing and -free rocks cooled to solidus temperatures at ca 527 and 517 Ma, respectively, whereas the isotopic system of early-crystallized zircon was completely reset during the growth of new zircon. As such, all the zircon domains in the same sample could have the same concordant or weighted mean age. The 511 Ma monazite and 506 Ma zircon overgrowths in a paragneiss have REE contents in equilibrium with garnet, implying that later modification and isotopic resetting of zircon and monazite might have resulted in younger U-Th-Pb ages and, in this case, establishing the age-mineral assemblage relationship based on REE partition coefficients between zircon/monazite and garnet may be invalid. Overall, the available data support the notion that different crustal components of the Rauer Group were juxtaposed in the Cambrian as a consequence of the Gondwana assembly.

High-P(HP) eclogite and associated garnet-omphacite granulite have recently been discovered in the Mulantou area, northeastern Hainan Island, South China. These rocks consist mainly of garnet, omphacite, hornblende, quartz and rutile/ilmenite, with or without zoisite and plagioclase. Textural relationships, mineral compositions and thermobarometric calculations demonstrate that the eclogite and garnet-omphacite granulite share the same three-stage metamorphic evolution, with prograde, peak and retrogradeP-Tconditions of 620-680 degrees C and 8.7-11.1 kbar, 820-860 degrees C and 17.0-18.2 kbar, and 700-730 degrees C and 7.1-8.5 kbar respectively. Sensitive high-resolution ion microprobe U-Pb zircon dating, coupled with the identification of mineral inclusions in zircon, reveals the formation of mafic protoliths before 355 Ma, prograde metamorphism atc. 340-330 Ma, peak to retrograde metamorphism atc. 310-300 Ma, and subsequent pegmatite intrusion at 295 Ma. Trace element geochemistry shows that most of the rocks have a MORB affinity, with initial epsilon(Nd)values of +2.4 to +6.7. As with similar transitional eclogite-HP granulite facies rocks in the thickened root in the European Variscan orogen, the occurrence of relatively highP-Tmetamorphic rocks of oceanic origin in northeastern Hainan Island suggests Carboniferous oceanic subduction leading to collision of the Hainan continental block, or at least part of it, with the South China Block in the eastern Palaeo-Tethyan tectonic domain.

The Meso-Tethys was a late Paleozoic to Mesozoic ocean basin between the Cimmerian continent and Gondwana. Part of its relicts is exposed in the Bangong-Nujiang suture zone, in the north-central Tibetan Plateau, that played a key role in the evolution of the Tibetan plateau before the India-Asia collision. A Penrose-type ophiolitic sequence was newly discovered in the Ren Co area in the middle of the Bangong-Nujiang suture zone, which comprises serpentinized peridotites, layered and isotropic gabbros, sheeted dikes, pillow and massive basalts, and red cherts. Zircon U-Pb dating of gabbros and plagiogranites yielded Pb-206/U-238 ages of 169-147 Ma, constraining the timing of formation of the Ren Co ophiolite. The mafic rocks (i.e., basalt, diabase, and gabbro) in the ophiolite have uniform geochemical compositions, coupled with normal mid-ocean ridge basalt-type trace element patterns. Moreover, the samples have positive whole-rock epsilon(Nd)(t) [+9.2 to +8.3], zircon epsilon(Hf)(t) [+17 to +13], and mantle-like delta O-18(5.8-4.3 parts per thousand) values. These features suggest that the Ren Co ophiolite is typical of midocean ridge-type ophiolite that is identified for the first time in the Bangong-Nujiang suture zone. We argue that the Ren Co ophiolite is the relic of a fast-spreading ridge that occurred in the main oceanic basin of the Bangong-Nujiang segment of Meso-Tethys. Here the Meso-Tethyan orogeny involves a continuous history of oceanic subduction, accretion, and continental assembly from the Early Jurassic to Early Cretaceous.

The zircon U-Pb chronology database provides a good opportunity to obtain important zircon growth peak periods in the Earth's history so as to study the origin and evolution of the crust. It should be noted that research preference affects the objectivity of zircon sampling, leading to hot data in the database and age statistics. To evaluate the influence of hot data on statistical results, the W and Y indexes are introduced. Using a Gaussian model of multipeak fitting of zircon U-Pb age frequencies, we identify seven major growth peaks in zircons from the Chinese continental crust, which are 2498.95, 1855.82, 828.88, 444.29, 249.46, 131.96, and 58.21 Ma. Due to differences in the time scales of zircon growth peaks, these peaks can be divided into two categories: first-order zircon growth peaks (I) and second-order zircon growth peaks (II), which represent longer and shorter time scales, perhaps due to different kinds of geological dynamics, respectively. In addition, there are clear correspondences between these ages and various geological events recognized by most scholars, namely, the Wutai orogeny, Lvliang orogeny, Jinning orogeny, Caledonian orogeny, Indosinian orogeny, Yanshanian orogeny, and Himalayan orogeny, respectively.

>The formation, composition and evolution of the oldest continental crust is the logical starting point for discussing the differentiation and development of the crust-mantle system and the tectonic evolution of the Earth. Searching for and identifying the oldest continental crust and investigating the processes and peri-

The amount of zircon U-Pb geochronological data for China has grown rapidly in recent years. Nearly 410,000 items of zircon U-Pb geochronological data, representing more than 7,000 relevant articles in the Elsevier Science Database, have been collected to a database in this research. Statistics on the ages and absolute errors of these collated data, yielded smallest standard errors for (Pb-206/U-238), (Pb-207/U-235), and (Pb-207/Pb-206) ages within respective time intervals of < 1388.96 Ma, 1388.96-3282.52 Ma, and > 3282.52 Ma. The ages and their absolute errors were determined using three main geochronology methods, based on laser ablation inductively coupled mass spectrometer (LA-ICP-MS), sensitive high-resolution ion microprobe (SHRIMP), and secondary ion mass spectrometer (SIMS) measurements. We compared the influence of these different methods on errors for each age interval. In addition, using a Gaussian model of multi-peak fitting of zircon U-Pb age frequencies, we identified seven growth peaks in zircons from the Chinese continental crust, which are 48.60 Ma, 131.49 Ma, 249.91 Ma, 444.27 Ma, 835.95 Ma, 1860.65 Ma, and 2505.54 Ma. It is clear that there are correspondences between these ages and various geological events, namely, the Wutai movement, Lvliang movement, Jinning movement, Caledonian movement, Indo-China movement, Yanshan movement, and Himalayaorogeny movement, respectively. The time and spatial distributions of these zircons correspond to distinct geological events on the Chinese continent, reflecting its crustal evolution.

Crustal deformation can be closely associated with Earth surface process. A combined approach of geological mapping, petrology, geochronology and structural analysis of the Taili Beach, North China, reveals a detailed magmatic and deformation history associated with orogenesis and intensive exhumation. Three groups of rocks developed along the Taili beach, including gneisses, mylonites and massive granites. Gneisses recorded near E-W-trending rootless fold and subvertical gneissosity of lower structural level. Mylonites exposed along ENE-trending ductile shear zone, with porphyritic protomylonite permeated into gneiss of lower-middle structural level. Gneisses formed in Neo-Archean to Paleo-Proterozoic, were modified by similar to 230-220 Ma magmatic and deformation event. This tectonic event is related to the Indosinian orogenesis, leading to the re-melting of the lower crust Archean rocks and intense deformation forming subvertical gneissosity and sinistral mylonites zones within N-S direction compression. The structural analysis indicates that rootless fold Si formed at the depth of similar to 24-20 km, gneissosity formed at similar to 18-15 km, while mylonite foliation S-2 formed at similar to 12-10 km and felsic leptynite formed at similar to 8-7 km. Massive granites intruded into gneisses and mylonites at depth <3 km (not late than 159Ma). The deformation sequence indicates that the Tail crust uplifted nearly 20 km during the similar to 230-220 Ma to similar to 159 Ma. The intensive exhumation in orogenesis may be related to earth surface erosion process.

The zircon U-Pb geochronology method has become an indispensable method for geologic research. This paper collected the zircon U-Pb geochronology data scattered in various publications such as journal articles and Master or Doctoral Dissertations in China since 1980s, and built a sub-database of the Chinese single-grain zircon age database. The sub-database covers 2331 documents published by the end of 2017, with valid data reaching 154,768 entries, which can be used for preliminary analysis of the big data and related earth science research. The analysis of the age-age absolute error relationships in the sub-database shows that the errors of Age ((206)pb/U-238), Age (Pb-207/U-235), and Age (Pb-207/Pb-206) are different in different geological time intervals. Because of their smallest errors and best confidences, Age (Pb-206/U-238) , Age (Pb-207/U-235), and Age (Pb-207/Pb-206) can be selected as the recommended ages for different geological time intervals. Age (Ph-206/U-238), Age (Pb-207/U-235) , and Age (Pb-207/Pb-206) can be selected as the recommended age in the age range of less than 1684. 4Ma, 1684.4 -2855. 2Ma, and greater than 2855. 2Ma, respectively, although Age (Pb-207/U-235) is complicated. The recommended age chosen was applied to the comparison of LA-ICP-MS, SHRIMP and SIMS, and it was found that the three different methods are applicable to different geological ages. The recommended age is applied to draw the age-frequency diagram, then Gaussian multi-peak fitting is used to find that there are six growth peaks in zircons in China of 131.71 Ma, 255. 17 Ma , 442. 42Ma , 811. 56Ma , 1868. 36 Ma and 2505. 31 Ma, and seven peaks in the Cenozoic in smaller scales, i. e. , 16. 99Ma, 27. 64Ma, 35. 26Ma, 43. 44Ma, 48. 27Ma, 52. 74Ma and 62. 07Ma. The location distribution of test points which represent every peak and every peak itself can correspond to geological events in the mainland China.

Impure calcite marbles from the Precambrian metamorphic basement of the Wuhe Complex, southeastern margin of the North China Craton, provide an exceptional opportunity to understand the depositional processes during the Late Archean and the subsequent Palaeoproterozoic metamorphic evolution of one of the oldest cratons in the world. The studied marbles are characterized by the assemblage calcite + clinopyroxene + plagioclase + K-feldspar + quartz + rutile ± biotite ± white mica. Based on petrography and geochemistry, the marbles can be broadly divided into two main types. The first type (type 1) is rich in REE with a negative Eu anomaly, whereas the second type (type 2) is relatively poor in REE with a positive Eu anomaly. Notably, all marbles exhibit remarkably uniform REE patterns with moderate LREE/HREE fractionation, suggesting a close genetic relationship. Cathodoluminescence imaging, trace elements and mineral inclusions reveal that most zircons from two dated samples display distinct core-rim structures. Zircon cores show typical igneous features with oscillatory growth zoning and high Th/U ratios (mostly in the range 0.3–0.7) and give ages of 2.53 − 2.48 Ga, thus dating the maximum age of deposition of the protolith. Zircon rims overgrew during granulite-facies metamorphism, as evidenced by calcite + clinopyroxene + rutile + plagioclase + quartz inclusions, by Ti-in-zircon temperatures in the range 660–743 °C and by the low Th/U (mostly < 0.1) and Lu/Hf (< 0.001) ratios. Zircon rims from two dated samples yield ages of 1839 ± 7 Ma and 1848 ± 23 Ma, respectively, suggesting a Palaeoproterozoic age for the granulite-facies metamorphic event. These ages are consistent with those found in other Precambrian basement rocks and lower-crustal xenoliths in the region, and are critical for the understanding of the tectonic history of the Wuhe Complex. Positive Eu anomalies and high Sr and Ba contents in type 2 marbles are ascribed to syn-depositional felsic hydrothermal activity which occurred at 2.53 − 2.48 Ga. Our results, together with other published data and the inferred tectonic setting, suggest that the marbles' protolith is an impure limestone, rich in detrital silicates of igneous origin, deposited in a back-arc basin within an active continental margin during the late Archean and affected by synchronous high-T hydrothermalism at the southeastern margin of the North China Craton.

The northern Prince Charles Mountains (PCM) in East Antarctica represent the largest continuously exposed section of the Rayner Complex and may provide important insights into the tectonic evolution of the Rayner orogen. We present new U-Pb and Hf isotopic data for zircons from felsic orthogneisses, mafic granulites, paragneisses and charnockites and additional Nd isotopic data for the former two rock types from the Beaver Lake area in the northern PCM. Zircons from the felsic orthogneisses document protolith ages of ca. 1170-1070 Ma, with Hf and Nd model ages of 1.99-1.74 Ga, suggesting the generation of the felsic magmas by partial melting of crustal rocks that were extracted from the mantle during the Paleoproterozoic. Detrital zircons from one paragneiss sample yield a major age population at ca. 1480-1140 Ma and three subordinate populations at ca. 2130-1850, 1780-1620 and 1010-860 Ma, whereas those from another paragneiss sample produce a major age population at ca. 1180-830 Ma and a subordinate age population at ca. 1370-1230 Ma. Discounting the effects of zircon recrystallization during post -depositional metamorphism, we infer that the sedimentary precursors to the aforementioned paragneiss samples were deposited after ca. 1200 and 1020 Ma, respectively, in intra- or back arc basins of the Rayner continental arc. Charnockites were either emplaced at ca. 980 Ma or episodically at ca. 1050 and ca. 950 Ma, with Hf model ages of 1.97-1.90 Ga. They were derived from partial melting of a Paleoproterozoic source region similar to the surrounding felsic orthogneisses at deeper levels. Zircon overgrowth domains from all of the studied rock types indicate that high-grade metamorphism took place at ca. 945-915 Ma. Only one paragneiss sample from the Else Platform preserves evidence of Cambrian metamorphic reworking. Based on published data from the Rayner Complex and the Eastern Ghats Belt of India, we speculate that long-lived convergent processes between the Indian craton and East Antarctica lasted from ca. 1500 to 900 Ma. Therefore, the Rayner Complex may represent the exposed orogenic root of a large Meso-Neoproterozoic accretionary orogen. (C) 2017 Elsevier B.V. All rights reserved.

Mount Brown is a unique inland outcrop between Prydz Bay and Denman Glacier that provides useful insights into the tectonic evolution of the Indian Ocean sector of Antarctica. The bedrock in this area is dominated by felsic orthogneisses with subordinate amounts of mafic granulites, anatectic paragneisses and pegmatite veins. Sensitive high-resolution ion microprobe (SHRIMP) U-Pb zircon dating reveals the emplacement of mafic granulite and felsic orthogneiss protoliths at ca. 1490-1400 Ma, sedimentation of paragneiss precursors after ca. 1250 Ma, and subsequent high-grade metamorphism accompanied by partial melting at ca. 920-900 Ma. The trace element geochemistry of these early Mesoproterozoic mafic-felsic igneous rocks indicates that they formed in a continental arc setting. Nd isotopic compositions for these rocks yield initial epsilon(Nd) values ranging from +2.8 to -6.6 and Nd depleted mantle model ages clustering between 2.4 and 1.7 Ga, implying a significant crustal formation in the Paleoproterozoic. Petrographic textures, mineral compositions, and pressure-temperature (P-T) pseudosection calculations for mafic granulite and paragneiss in the system NC(K)FMASHTO [Na2O-CaO(-K2O)-FeO-MgO-Al2O3-SiO2-H2O-TiO2-Fe2O3] system suggest that early Neoproterozoic metamorphism reached peak P-T conditions of 830-870 degrees C and 7-8 kbar, followed by near-isobaric cooling to 760-830 degrees C and 7-8.5 kbar. The age spectra and characteristics of geological events at Mount Brown are similar to those in the Rayner Complex, thereby supporting an eastward continuation of the Rayner orogen to Wilhelm II Land. Combined with existing data, we infer that a protracted tectonic evolution between the Indian craton and East Antarctica (possibly the Ruker craton) might have occurred for a period of ca. 600 Myr from long-lived oceanic subduction-accretion at ca. 1500-1000 Ma to final collision at ca. 1000-900 Ma. (C) 2016 Elsevier B.V. All rights reserved.

The Early Permian Tarim large igneous province (Tarim LIP) consists mainly of basaltic lavas, mafic–ultramafic intrusions including dikes and, syenite bodies in the Tarim Basin, NW China. A major unit of the Tarim LIP, the Wajilitag intrusive complex, consists of olivine pyroxenite, clinopyroxenite and gabbro units (from bottom to top), diorite and syenite rocks occurred in the upper part of the complex and alkali mafic dikes intrude the clinopyroxenite phase. Here we report the zircon U–Pb age and Hf isotopes, geochemical characteristics and Sr–Nd–Pb isotopic data of the alkali mafic dikes, and diorite, aegirine–nepheline syenite and syenite porphyry units in the Wajilitag intrusive complex. Zircons from the diorite and alkali mafic rocks yield concordant crystallization ages of 275.2±1.2Ma and 281.4±1.7Ma, respectively. The diorite and syenitic rocks in Wajilitag area have a narrow range of SiO2 contents (51.9–57.3wt.%), and are enriched in total alkalis (Na2O+K2O=8.3–14.3wt.%), among which the aegirine–nepheline syenite and syenite porphyry have the geochemical affinity of A-type granites. The alkali mafic rocks and syenitic rocks have high Al2O3 (19.4–21.1wt.%), Zr, Hf, Ba contents, total rare earth element abundances and LREE/HREE ratios and low Mg# value, K, P and Ti contents. Diorites have lower Al2O3 contents, total REE abundances and LREE/HREE ratios and higher Mg# values than the alkali mafic rocks and syenitic rocks. The diorites and syenitic rocks have low initial 87Sr/86Sr ratios (0.7034–0.7046), and high εNd(t) values (0.1–4.1) and zircon εHf(t) values (−0.9–4.4). All the diorites and syenitic rocks show the 206Pb/204Pb ratios ranging of 18.0–19.5, 207Pb/204Pb of 15.4–15.6 and 208Pb/204Pb of 38.0–39.9. Sr–Nd isotopic ratios indicate a FOZO-like mantle source for the diorite and syenitic rocks, similar to that of the mafic–ultramafic rocks in the Wajilitag complex. In contrast, zircon Hf isotopes of basalt and syenite elsewhere in the Tarim LIP indicate a FOZO-like component may also contribute to Tarim LIP magmatism. Geochemical and Sr–Nd–Pb–Hf isotopic features reflect that diorites and syenitic rocks are probably derived from a FOZO-like mantle source, consistent with a plume mantle origin and then underwent crystal fractionation process.

The Tarim continental flood basalts (CFBs) provide important clues about the genesis and magmatic evolution of the Early Permian Tarim Large Igneous Province (Tarim LIP) in northwestern China. Here we present results of LA–MC–ICPMS Lu–Hf isotope analysis on Early Permian (ca. 290Ma) zircons extracted from the Tarim CFBs in the Keping area, northwest of the Tarim Basin. Zircons from two sub-groups of Keping basalts (Groups 1a and 1b) have similar Lu–Hf isotopic compositions and exhibit a relatively large range of 176Hf/177Hf ratios between 0.282422 and 0.282568. Their negative εHf(t) values (−6.8–−1.4) are generally lower than the whole-rock εHf(t) values of their host basalts (−2.8–2.1), and are distinct from other known intrusive rocks (−0.3–7.1) in the Tarim LIP and their hosted zircons (4.9–8.8). Systematic studies of Hf isotopic data from Tarim and its adjacent regions reveal that these zircons are probably xenocrysts, sourced from coeval igneous rocks in the South Tianshan Orogen (e.g., the Lower Permian Xiaotikanlike Formation volcanic and pyroclastic rock suite). This, together with the presence of Precambrian zircons in Keping basalts, clearly indicates crustal contamination during their eruptions and provides hints about the potential contaminant sources. Geochemical modeling further suggests that the earlier erupted Group 1b basalts experienced more contamination, predominantly by some high Th–U–Pb rock components, most likely from the South Tianshan Orogen. The later erupted Group 1a basalts in the Keping area have been less contaminated with mainly the Tarim Precambrian rocks. Another group of the Tarim CFBs in the Northern Tarim Uplift (Group 2) appears to have undergone negligible crustal contamination but possesses evidence for variable source compositions. The modeling also indicates that the uncontaminated parental magmas of various Tarim LIP rocks (from the picrites and basalts to ultramafic–mafic and syenitic intrusive rocks) exhibit a wide range of εNd(t) values (ca. −5–5), reflecting source isotopic heterogeneity, which may be a consequence of plume–lithosphere interaction during the generation of the Tarim LIP.