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Neoproterozoic Tectonic Setting of Southeast China:New Constraints from SHRIMP U-Pb Zircon Ages and Petrographic Studies on the Mamianshan Group

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Acta Geologica Sinica(English Edition) 2010年第2期84卷 333-344页

作者： WU Ganguo yu xinqi DI Yongjun ZHANG Da State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences Beijing 100083 China Key Laboratory of Lithosphere Tectonics and Lithoprobing Technology of Ministry of Education China University of Geosciences Beijing 100083 China

Precambrian tectonic history of Zhejiaug, Fujian, and Jiangxi provinces of south China is important for understanding the tectonic evolution of South China but its magmatic activity, petrogenesis, stratigraphic sequence of the Mamianshan Group is still strongly controversial. Here we present new sensitive high resolution ion micro-probe （SHRIMP） U-Pb zircon geochronological data for the Mamianshan Group and petrographical data to constrain the tectonic framework of the regions. Our results showed that the SHRIMP U-Pb zircon age of green schists of the Dongyan Formation is 796.5±9.3 Ma, the Daling Formation is 756.2±7.2 Ma, and mica-quartz schist of the Longbeixi Formation is 825.5±9.8 Ma. These data indicate that the Mamianshan Group was formed not in the Mesoproterozoic, but in the Neoproterozoic and its stratigraphic sequences should be composed of Longbeixi, Dongyan, and Daling Formations from the bottom to the top. Rocks from this Group, from Zhejiang, Fujian and Jiangxi provinces, constituted the upper basement of the Cathaysia Block that overlay the lower basement of the Mayuan Group. Detailed petrographic studies demonstrate that the amphibole schists of the Dongyan Formation in the Mamianshan Group were formed within an intra-arc rift setting rather than a continental rift as previously suggested. Rather, this island-arc type formation was developed by collision and/or subduction between various blocks resulting from the breakup of the supercontinent Rodinia at c.850-750 Ma. The Zhuzhou conglomerate, distributed near Dikou Town, Jian＇ou City, Fujian Province and previously considered as evidence of the Mesoproterozoic Dikou movement, is shown here not to be the basal conglomerate above the angular unconformity between the upper and lower basements. Our conclusions have important implications for understanding the Precambrian tectonics of South China.

关键词： Intra-arc amphibole schist Dongyan Formation Zhuzhou conglomerate Southeast China

Triassic Nappe in the Central Part of the Southern Central Asian Orogenic Belt(Ejinaq,NW China):Evidence from Structural Analysis and Geothermochronology

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Acta Geologica Sinica(English Edition) 2023年第1期97卷 13-34页

作者： SU He CHEN Xuanhua yu xinqi SHAO Zhaogang yu Wei ZHANG Yiping WANG Yongchao School of Earth Sciences and Resources China University of GeosciencesBeijing 100083China SinoProbe Center Chinese Academy of Geological Sciences and China Geological SurveyBeijing 100037China School of Resources and Environmental Engineering Hefei University of TechnologyHefei 230009China

The thrust nappe played an important role in the Mesozoic tectonic evolution of the middle part of the Central Asian Orogenic Belt(CAOB).However,the timing,structural style and kinematic processes of the thrust nappe remain controversial,particularly the detail of the thrust nappe in the Guaizihu region(110 km east of Ejinaq).In this study,we investigate new field mapping,seismic sections,geochronology and low-temperature thermochronometric dating to provide constraints on the history of this thrust nappe in the Chaheilingashun area(northwestern Guaizihu region).The field mapping,seismic sections and structural analysis reveal that the autochthonous system had developed a series of strong fold structures in the upper Permian *** allochthonous system mainly contains Devonian monzogranite(U-Pb age,ranges from 386.7 to 389.0 Ma)and Meso–Neoproterozoic schists(the maximum depositional age,~880 Ma),which were thrust upon the upper Permian strata during Middle to Late *** on similar rocks,geochronological dating and the Yagan thrust,we suggest that the postulated root zone of this allochthon might have originated from the Huhetaoergai area(40–60 km northwest of the study area).The geochronological results reveal that the lower age limit of this thrust nappe is constrained by the Lower–Middle Triassic syntectonic sediments(tuffaceous sandstone,~247 Ma),which is the sedimentary response of the fold structure.,The timing of the termination of this thrust nappe is defined by the cooling age(^(40)Ar/^(39)Ar data,217–211 Ma)of the Devonian monzogranite and Meso–Neoproterozoic ***,we consider this thrust event in the study area to potentially have occurred in the period from 247 Ma to 211 Ma,which may represent the tectonic response to the closure of the Paleo-Asian Ocean.

关键词： fold thrust nappe Triassic Zhusileng–Hangwula southern CAOB

New Ar-Ar Isotopic Ages of the Southern Tianshan Mountains, Kyrgyzstan and their Geological Implications

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Acta Geologica Sinica(English Edition) 2018年第4期92卷 1662-1663页

作者： XIAO Weifeng WANG Zongxiu CHEN Zhengle HAN Shuqin yu xinqi Institute of Geomechanics Chinese Academy of Geological Sciences Beijing 100081 China School of Earth Sciences and Resources China University of Geosciences Beijing 100083 China

Objective The Late Paleozoic Southern Tianshan Ocean is usually considered to be the last-closed ocean in the Tianshan Orogeny. However, there is still no consensus if this is indeed the case. Blueschist, eclogite and ophiolite are present in the Atbashi Range, Kyrgyzstan, which are believed to be the relics of the Southern Tianshan Ocean. New data obtained through Ar-Ar isotopic analysis in this research provide reliable chronological restrictions for this problem.

关键词： Kyrgyzstan and their Geological Implications New Ar-Ar Isotopic Ages of the Southern Tianshan Mountains

The Early Jurassic magmatism in northern Guangdong Province, southeastern China: Constraints from SHRIMP zircon U-Pb dating of Xialan complex

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Science China Earth Sciences 2009年第4期52卷 471-483页

作者： yu xinqi DI YongJun WU GanGuo ZHANG Da ZHENG Yong DAI YanPei State Key Laboratory of Geological Processes and Mineral Resources China University of GeosciencesBeijing 100083China Key Laboratory of Lithosphere Tectonics and Lithoprobing Technology of Ministry of Education China University of GeosciencesBeijing 100083China

This paper reports SHRIMP zircon U-Pb ages of 196±2 Ma for granite, and 195±1 Ma for gabbro from the Xialan complex in the Meizhou area, northern Guangdong Province. These results shed new light on the calm stage of magmatic activity in southeastern China during 200-180 Ma, and revealed that the back-arc extension induced by the subduction of the western Pacific plate may have begun at 195 Ma at least. Field observation on the fresh outcrops allows us to recognize some features formed by magma mixing. A part of the gabbro has a fine-grained rim of 20-30 cm at the margin, and thins gradually to-ward the granite; numerous dark fine-grained to microcrystalline dioritic enclaves developed in the granite. These enclaves vary in shape and size, dark minerals concentrated at the margin of enclaves, and the contact between enclaves and host rock is either obvious or obscure, or gradational. In addi-tion, needle-shaped apatites are included in the enclaves. The REE patterns of gabbros, as well as the trace element patterns, are generally consistent with those of granitic rocks. The above characters further suggest that in the Early Jurassic the injection of basic magma had melted deep continental crust and produced acidic magma, and the Xialan complex was produced by the mixing of them.

关键词： Xialan complex SHRIMP zircon U-Pb ages magma mixing the Early Jurassic Meizhou northern Guangdong Province

Mesozoic Thrust-Nappe and Extensional Structure Frameworks in the East Segment of Southeast Yangtze Block, Southeast China

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Journal of Earth Science 2020年第4期31卷 772-794页

作者： xinqi yu Ziwei Chen Jun Hu Yan Zeng Xiu Liu yu He Zishen Wang Linghui Meng School of Earth Sciences and Resources China University of GeosciencesBeijing 100083China Chongqing Institute of Geology&Mineral Resources Chongqing 400042China

Multi-stage Mesozoic thrust-nappe and extensional structures are distributed in the east segment of the Southeast Yangtze Block situated in the junction region of Zhejiang-Jiangxi-Anhui provinces. The features and genetic mechanism of the deformations were analyzed after a detailed field observation of their distribution, geometry, and kinematics. In addition, the time sequences of the thrust and extensional structures were determined by combining the results of the comparative analysis with the chronological evidence of strata and magmatic rocks cut by a fault or formed after a fault according to field facts. This study identified three stages of the nappe structures and at least two stages of the extensional structures during the Mesozoic. The geotectonic setting of the nappe and extensional structures was considered to be related to the different geodynamics in the study area including the Early Mesozoic geological event, i.e., N-S compression, forming Lantian fault, etc.;the Late Mesozoic flat-slab subduction, forming Xiaoxi thrust fault and tectonic window;and the roll-back of the paleoPacific Plate, forming extensional structures like basin marginal fault;the last compression, forming Wucheng-Shenxian fault. These findings provide additional evidence for remodeling the tectonic and geodynamic evolution of Southeast China.

关键词： Mesozoic nappe structure extensional structure time sequence east segment of the Southeast Yangtze Block

Deformation Stages and Ar-Ar Age Data of the Wan-Zhe-Gan Tectonic Zone,Southeast China,and Their Tectonic Significance

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Acta Geologica Sinica(English Edition) 2011年第6期85卷 1373-1389页

作者： yu xinqi WANG De＇en JIANG Dazhi JIANG Laili ZHOU Xiang LI Chunlin State Key Laboratory of Geoprocesses and Mineral Resources China University of Geosciences Beijing 100083 China No. 332 Geological Team of Anhui Bureau of Geology and Mineral Resources Huangshan Anhui 245000 China Department of Earth Sciences University of Western Ontario London Ontario Canada N6A 5B7 Anhui Institute of Geological Survey Hefei Anhui 230001 China

The major tectonic zone that passes through the border regions of the Anhui, Zhejiang, and Jiangxi Provinces in southeast China has been commonly referred to as the Wan-Zhe-Gan fault zone. Geologically, this zone consists of several regional fault belts of various ages and orientations. We have categorized the faults into four age groups based on field investigations. The Neoproterozoic faults are northeast striking. They start from the northeast Jiangxi Province and extend northeastward to Fuchuan in Anhui Province, the same location of the northeast Jiangxi-Fuchuan ophiolite belt. The faults probably acted during the Neoproterozoic as a boundary fault zone of a plate or a block suture with melange along the faults. The nearly east-west- or east-northeast-striking faults are of Silurian ages （40Ar/39Ar age 429 Ma）. This group includes the Qimen-Shexian fault and the Jiangwang-Jiekou ductile shear belt. They represent a major tectonic boundary in the basement because the two sides of the fault have clear dissimilarities. The third group of faults is north-northeast striking, having formed since the early-middle Triassic with 40Ar/39Ar ages of 230-254 Ma. They form a fault belt starting from Yiyang in northern Jiangxi and connect with the Wucheng as well as the Ningguo-Jixi faults. This fault belt is a key fault-magmatic belt controlling the formation of Jurassic-Cretaceous red basins, ore distribution, magmatic activity, and mineralization. When it reactivated during the late Cretaceous, the belt behaved as a series of reverse faults from southeast to northwest and composed the fourth fault group. Therefore, classifying the Wan-Zhe-Gan fault zone into four fault groups will help in the analysis of the tectonic evolution of the eastern segment of the Jiangnan orogen since the Neoproterozoic era.

关键词： The Wan-Zhe-Gan fault zone changes of orientations different evolution stages 40Ar/39Ar geochronology the border region of Zhejiang Jiangxi and Anhui Provinces

Rectifying the Neoproterozoic Stratigraphic Framework of Eastern Jiangnan Orogen, Southeast China

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Acta Geologica Sinica(English Edition) 2020年第6期94卷 1822-1848页

作者： yu xinqi LIU Junlai CHEN Ziwei HU Jun ZENG Yan LIU Xiu LIU Mengyan HE yu MENG Linghui WANG Zishen School of Earth Sciences and Resources China University of GeosciencesBeijing 100083China Chongqing Institute of Geology&Mineral Resources Chongqing 400042China

Studies on the metamorphic and related magmatic rocks within the Jiangnan Orogen,southern China,are important to understand the formation and evolution of this Neoproterozoic orogen because they can provide evidence for revealing the tectonic evolution of the South China *** on from earlier attempts at stratigraphic correlation and creating a framework for the low-grade metamorphosed basement,new first-hand information on the composition and deformation of the East Jiangnan Orogen basement indicates that the sedimentary rocks in the north are composed of the sequential Shangxi Group(Gp)and the overlying Likou Gp,with a clear regional unconformity in *** Likou Gp includes the Zhentou Formation(Fm.)and the Dengjia Fm.,with the previously named Puling *** basalt interbeds within the Dengjia *** Xucun granodiorite pluton of^830 Ma intrudes the Shangxi Gp,thereby resulting in a 100 mwide hornfels zone within the wall rocks,indicating that the formation of the group occurred earlier than that of the *** contrast,the southern metamorphic rocks of the Xikou Gp and the overlying Jingtan *** flaky,disordered,and strongly *** Jingtan *** roughly equivalent to the Heshangzhen Gp and includes the Zhoujiacun conglomerates in the lower part and a rhyolite in the upper part with interbedded *** assessment of Neoproterozoic stratigraphic sequences and magmatic rocks in the east of the Jiangnan Orogen differs from and rectifies previous studies,emphasizing that explanation of analytical results,particularly geochronology,should be consistent with facts gathered in the field.

关键词： tectonics stratigraphy geochronology unconformity zircon U-Pb Puling basalt Yangtze-Cathasia blocks Nanhua System(Ediacaran)

Exhumation history of the Huangshan granite pluton,southern Anhui Province:New insights from fission-track analysis

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Science China Earth Sciences 2011年第4期54卷 528-539页

作者： ZHENG Yong yu xinqi yuAN WanMing WANG De'En JIANG GongBing ZHU DeLai WANG Cheng JIA YingYing State Key Laboratory of Geological Processes and Mineral Resources China University ofGeosciences Beijing 100083 China Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China 332 Geological Team of Anhui Bureau of Geology and Mineral Resources Huangshan 245000 China World Heritage offices Huangshan Management Council Huangshan 245800 China

The dating of the uplift onset of the Huangshan pluton in the southern part of Anhui Province associated with the collision between paleo-Pacific Block and the Eurasian Block is a fundamental issue to better understand the uplift mechanisms and the regional tectonic evolution. Х^2 values of seven zircon fission track （ZFF） samples collected from the south part of the Huangshan pluton were all 〈5%. Based on the grain ages of four typical ZFr samples, three thermal overprints ranging in 113-123, 72-95 and 49-66 Ma were distinguished respectively using the binomial peak-fitting method in accordance with the tectonic thermal events after south China shifted into circum-Pacific tectonic region. Apatite fission track （AFT） study of the Huangshan pluton shows ages lie between 15±3 and 56±6 Ma with all Х^2 values 〉5%, and all are significantly younger than their host rock formation ages, indicating that the samples have experienced post-formation thermal history. Based on the AFT resuits and topography characteristics in the Huangshan pluton, three zones with different denudation intensities caused by the differential uplift of the fault blocks were recognized in this paper, indicating that denudation was driven by the increase in elevation significantly. Modeling of the AFT data shows that the earlier cooling phase took place in the early Cenozoic and involved 3.3, 3.8 and 6.0℃/Ma of cooling rates equivalent to the exhumation rates of 90, 104 and 167 m/Ma in different fault blocks. The last phase of cooling took place from -10 Ma with average cooling rate of -5.6℃/Ma, equivalent to average denudation rates of -156 m/Ma. The fission track results imply that the regional compression field plays an important role for the differential exhumation between individual fault blocks of the Huangshan pluton.

关键词： Huangshan pluton thermal overprints apatite fission track cooling fault block

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皖南兰田残留向斜不是构造窗

地质论评 2000年第4期46卷 337-346页

作者：余心起安徽省地质矿产局332地质队黄山市245000

兰田地区翔实的1∶5万区调填图工作,收集了丰富的前震旦系实测地层剖面资料、震旦系休宁组底界角度不整合资料及后期构造变动的证据,证实了皖南属晋宁期造山带,并存在元古宙地层的完整层序,而震旦系—寒武系则为原地沉积在前震旦系基底... 详细信息

兰田地区翔实的1∶5万区调填图工作,收集了丰富的前震旦系实测地层剖面资料、震旦系休宁组底界角度不整合资料及后期构造变动的证据,证实了皖南属晋宁期造山带,并存在元古宙地层的完整层序,而震旦系—寒武系则为原地沉积在前震旦系基底之上的盖层。加里东期区域伸展体制条件下兰田地区产生滑覆断层体系,震旦系—寒武系盖层残留在前震旦系基底之上形成向斜构造。中生代的构造作用对兰田地区构造轮廓产生了不可忽视的改造,但未造成翻天覆地的造山作用,不存在“兰田构造窗”。

关键词：残留向斜构造构造窗元古宙休宁兰田