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| 1 | New SHRIMP U-Pb age from the Wuqiangxi Formation of Banxi Group:Implications for rifting and stratigraphic erosion associated with the early Cryogenian (Sturtian) glaciation in South China显示文摘In South China, the Wuqiangxi Formation of the Banxi Group and its equivalents underlie the early Cryogenian (Sturtian) glacial deposits but their thickness varies from <200 m to >2000 m. In the Guzhang section of western Hunan, the Wuqiangxi Formation is only 152 m thick, and an ash bed 58 m below the glacial diamictite yielded a SHRIMP U-Pb age of 809.3±8.4 Ma. In contrast, 90 km south of the Guzhang section towards the basin in Zhijiang area where the Wuqiangxi Formation is ~2200 m thick, an age of 725±10 Ma has been reported from the top of this unit, 300 m below the glacial diamictite. These ages provide new evidence for the regional stratigraphic correlation across the Nanhua basin, and suggest unusually large (>2 km) stratigraphic erosion potentially associated with the Sturtian glaciation in South China. The magnitude of erosion may imply significant uplifting and tectonotopography at the onset of the Sturtian glaciation. | ZHANG ShiHong JIANG GanQing DONG Jin HAN YiGui WU HuaiChun | 2008 | Science China Earth Sciences2008，51，11： | 33 |
| 2 | Single grain Rb-Sr dating of euhedral and cataclastic pyrite from the Qiyugou gold deposit in western Henan, central China显示文摘The Rb-Sr isotopic dating of pyrite mineral from ore deposits can directly provide mineralization age. However, many geological factors may affect the Rb-Sr isotopic system,which baffles application of this method. Employing ultra-low procedural blank Rb-Sr method,we have dated pyrites separated from the No. 4 breccia pipe of the Qiyugou gold deposit,western Henan Province. Single grains of euhedral pyrite crystal with few microcracks yield an isochron age of 126 ± 11 Ma, which represents time of the main mineralization stage of the deposit. Pyrite grains of cataclastic type show nevertheless scattered Rb-Sr isotopic composition and no reasonable isochron can be defined. Crystal morphology and mineral inclusion studies reveal that Rb and Sr of pyrite mineral probably are preserved mainly in biotite, K-feldspar, and sericite mineral inclusions. The dating results likely suggest that cataclastic pyrite is not suitable for the Rb-Sr dating due to modification of the Rb-Sr isotopic system by later hydrothermal activity of fluid. | HAN YiGui LI XiangHui ZHANG ShiHong ZHANG YuanHou CHEN FuKun | 2007 | Chinese Science Bulletin2007，52，13： | 27 |
| 3 | Ages and Hf isotopes of detrital zircons from the Permian strata in the engbatu area(Inner Mongolia) and tectonic implications显示文摘The Central Asian Orogenic Belt(CAOB) was built up through protracted accretion and collision of a variety of terranes/micro-continents during Neoproterozoice Mesozoic time. To understand potential links among Paleozoic subduction and accretionary processes that were operative during the development of the southeastern CAOB, we conducted a combined U-Pb and Hf-isotope analysis of detrital zircons from previously defined Devonian, Carboniferous and Early Permian strata in the Bengbatu area,Inner Mongolia. Detrital zircons from(meta-) sandstones in these strata commonly yield major Paleozoic age populations at ca. 300-261 Ma, 351-300 Ma and 517-419 Ma, and also give several Precambrian ages that range from 2687 Ma to 544 Ma. The youngest ages redefine the deposition of all these strata to be in the Middle Permian(Wordiane Capitanian) or later, much younger than previously considered.These ages, coupled with regional magmatic records, support an interpretation of most surrounding areas as possible detritus sources, including the Mongolian arcs to the north, the Northern Accretionary Orogen to the south, and the intervening Erenhote Hegenshan Ophiolite Belt. Zircons with magmatic ages of ca. 500-350 Ma and ca. 300-261 Ma display a large range of εHf(t) values(-13.97 to +15.31),whereas ca. 350-300 Ma zircons are dominated by positive εHf(t) values(+0.14 to +16.00). These results support the occurrence of two significant shifts of the zircon εHf(t) values, which has tectonic implications for the understanding of the Carboniferouse Permian evolution of the southeastern CAOB. A marked shift from mixed to positive zircon εHf(t) values at 350 -330 Ma likely manifests the incipient opening of the Hegenshan Ocean, due to the slab rollback of the subducting Paleo-Asian Oceanic lithosphere. Another shift from positive to mixed zircon εHf(t) values at ca. 300 Ma likely corresponds to a tectonic switch from syn-orogenic subduction-related to post-orogenic extensional setting, genetically related to the tectonic collapse of a formerly overthickened crust. | Bing Xu Guochun Zhao Jianhua Li Dongxing Liu Bo Wang Yigui Han Paul R. Eizenhofer Xiaoran Zhang Wenzhu Hou Qian Liu | 2019 | Geoscience Frontiers2019，10，1： | 2 |
| 4 | SHRIMP U–Pb ages of K-bentonite beds in the Xiamaling Formation: Implications for revised subdivision of the Meso- to Neoproterozoic history of the North China Craton显示文摘 | Wenbo Su Shihong Zhang Warren D. Huff Huaikun Li Frank R. Ettensohn Xiaoyu Chen Hongmei Yang Yigui Han Biao Song M. Santosh | 2008 | Gondwana Research2008，，3： | 1 |
| 5 | New ^40Ar-^39Ar age constraints on the deformation along the Machaoying fault zone:Implications for Early Cambrian tectonism in the North China Craton显示文摘 | Han Yigui Zhang Shihong Franco Pirajno | 2009 | Gondwana Research2009，16，： | 1 |
| 6 | Detrital zircon constraints on late Paleozoic tectonism of the Bogda region(NW China)in the southern Central Asian Orogenic Belt显示文摘The Chinese North Tianshan(CNTS)in the southern part of the Central Asian Orogenic Belt(CAOB)has undergone multistage accretion-collision processes during Paleozoic time,which remain controversial.This study addresses this issue by tracing the provenance of Late Paleozoic sedimentary successions from the Bogda Mountain in the eastern CNTS through U-Pb dating and Lu-Hf isotopic analyses of detrital zircons.New detrital zircon U-Pb ages(N=519)from seven samples range from 261±4 Ma to 2827±32 Ma.The most prominent age peak is at 313 Ma and subordinate ages vary from 441 Ma to 601 Ma,with some Precambrian detrital zircon ages(~7%)lasting from 694 Ma to 1024 Ma.The youngest age components in each sample yielded weighted mean ages ranging from 272±9 Ma to 288±5 Ma,representing the maximum depositional ages.These and literature data indicate that some previously-assumed'Carboniferous'strata in the Bogda area were deposited in the Early Permian,including the Qijiaojing,Julideneng,Shaleisaierke,Yangbulake,Shamaershayi,Liushugou,Qijiagou,and Aoertu formations.The low maturity of the sandstones,zircon morphology and provenance analyses indicate a proximal sedimentation probably sourced from the East Junggar Arc and the Harlik-Dananhu Arc in the CNTS.The minor Precambrian detrital zircons are interpreted as recycled materials from the older strata in the Harlik-Dananhu Arc.Zircon EHf(t)values have increased since^408 Ma,probably reflecting a tectonic transition from regional compression to extension.This event might correspond to the opening of the Bogda intraarc/back arc rift basin,possibly resulting from a slab rollback during the northward subduction of the North Tianshan Ocean.A decrease of zirconεHf(t)values at^300 Ma was likely caused by the cessation of oceanic subduction and subsequent collision,which implies that the North Tianshan Ocean closed at the end of the Late Carboniferous. | Qian Wang Guochun Zhao Yigui Han Jinlong Yao | 2020 | Geoscience Frontiers2020，11，5： | 1 |
| 7 | Early Cambrian high pressure/low temperature metamorphism in the southeastern Tarim craton in response to circum-Gondwana cold subduction显示文摘The circum-Gondwana subduction initiated by the early Cambrian has been suggested to reflect the establishment of the modern plate tectonics.The metamorphic rocks with low thermobaric(T/P)ratios indicative of cold subduction in the present tectonic regime have not been well investigated.To better understand the circum-Gondwana subduction and to test its possible link with the emergence of the modern plate tectonics,this study focused on blueschist-facies metamorphic rocks in the Altyn Tagh of the southeastern Tarim craton.Mineral assemblage and chemistry,phase equilibrium modelling,and quartz-in-garnet Raman elastic geobarometry reveal that the zoisite blueschist and glaucophane(Gln)-bearing quartz schist in northern Altyn Tagh were metamorphosed to lawsonite to epidote blueschistfacies at 520–545℃ and 16–19 kbar.It reflects high-pressure(HP)/low temperature(LT)metamorphism with low T/P ratios of<300℃/GPa and thermal gradients of<10℃/km.These blueschist-facies metamorphic rocks underwent rapid decompression starting at P-T conditions of<495℃ and<9.6 kbar during exhumation.Ar-Ar geochronology records paragonite Ar-Ar plateau ages of 520–506 Ma for the zoisite blueschist samples and phengite Ar-Ar plateau ages of 522–516 Ma for the Gln-bearing quartz schist samples,suggesting that the peak HP/LT metamorphism occurred prior to ca.522 Ma.Based on new results and available data from the major Gondwana blocks,cold subduction was suggested to profoundly operate along circum-Gondwana in the early Cambrian after the amalgamation of Gondwana.The extensive circum-Gondwana subduction represents the earliest global cold subduction in Earth’s history associated with the establishment of the modern plate tectonics,as directly recorded by the studied early Cambrian blueschist-facies metamorphic rocks and a dramatic drop in the mean T/P of metamorphism since the early Paleozoic. | Qian Liu Toshiaki Tsunogae Guochun Zhao Sam Uthup Kazuki Takahashi Jinlong Yao Yu Wu Yigui Han Kei Ikehata | 2023 | Geoscience Frontiers2023，14，4： | 0 |
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