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Crustal accretion and reworking processes of micro-continental massifs within orogenic belt:A case study of the Erguna Massif,NE China

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Science China Earth Sciences 2017年第7期60卷 1256-1267页

作者： SUN ChenYang TANG Jie XU WenLiang LI Yu ZHAO Shuo College of Earth Sciences Jilin University Changchun 130061 China

This paper summarizes the geochronological, geochemical and zircon Hf isotopic data for Mesozoic granitoids within the Erguna Massif, NE China, and discusses the spatial-temporal variation of zircon Hf isotopic compositions, with the aim of constraining the accretion and reworking processes of continental crust within the Erguna Massif, and shedding light on the crustal evolution of the eastern segment of the Central Asian orogenic belt. Based on the zircon U-Pb dating results, the Mesozoic granitic magmatisms within the Erguna Massif can be subdivided into five stages: Early-Middle Triassic(249–237 Ma), Late Triassic(229–201 Ma), Early-Middle Jurassic(199–171 Ma), Late Jurassic(155–149 Ma), and Early Cretaceous(145–125 Ma).The Triassic to Early-Middle Jurassic granitoids are mainly I-type granites and minor adakitic rocks, whereas the Late Jurassic to Early Cretaceous granitoids are mainly A-type granites. This change in magmatism is consistent with the southward subduction of the Mongol-Okhotsk oceanic plate and subsequent collision and crustal thickening, followed by post-collision extension. Zircon Hf isotopic data indicate that crustal accretion of the Erguna Massif occurred in the Mesoproterozoic and Neoproterozoic. ZirconεHf(t) values increase gradually over time, whereas two-stage model(TDM2) ages decrease throughout the Mesozoic. The latter result indicates a change in the source of granitic magmas from the melting of ancient crust to more juvenile crust. Zircon εHf(t)values also exhibit spatial variations, with values decreasing northwards, whereas TDM2 ages increase. This pattern suggests that,moving from south to north, there is an increasing component of ancient crustal material within the lower continental crust of the Erguna Massif. Even if at the same latitude, the zircon Hf isotopic compositions are also inconsistent. These results reveal lateral and vertical heterogeneities in the lower continental crust of the Erguna Massif during the Mesozoic, wh

关键词： orogenic belt The Erguna Massif Crustal accretion and reworking Mesozoic Granitoids Hfisotope

Revised Chronostratigraphic Framework of the Metamorphic Strata in the Jiangnan orogenic belt,South China and its Tectonic Implications

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Acta Geologica Sinica(English Edition) 2012年第2期86卷 339-349页

作者： GAO Linzhi DING Xiaozhong ZHANG Chuanheng CHENJun LIU Yaorong ZHANG Hang LIU Xanxue PANG Weihua Institute of Geology Chinese Academy of Geological SciencesBeijing 100037China Hunan Institute of Geological Survey Changsha410002HunanChina China University of Sciences Beijing 100083China Chengdu Institute of Mineral and Resource Chengdu 610081SichanChina

In a re-study of regional geology by the China Geological Survey （CGS）, the key problem is in the stratigraphical division and correlation. According to the new isotopic dating of the Mesoand Neoproterozoic in China, there have been great changes in the strata correlation and tectonic explanation. The authors obtained four zircon sensitive high resolution ion micro-probe （SHRIMP） U- Pb datings from the bentonite of the Lengjiaxi Group （822±10 Ma, 823±12 Ma and 834±11 Ma） and Banxi Group （802.6±7.6 Ma） in north Hunan Province, which is considered to be the middle part of the Jiangnan orogenic belt. On the basis of the zircon dating mentioned above, the end of the Wuling orogen is first limited in the period from 822 Ma to 802 Ma in one continued outcrop （Lucheng section） in Linxiang city, Hunan Province. Combining a series of new zircon U-Pb datings in the Yangtze and Cathaysia blocks, several Neoproterozoic volcanic events and distribution of the metamorphic rocks in the Jiangnan orogenic belt have been distinguished. In the context of the global geodynamics, it is useful to set up a practical and high precision chronological framework and basic and unified late Precambrian section in South China.

关键词： chronostratigraphic tectonic events orogenic belt Meso-and Neoproterozoic South China continent

Major Characteristics of the Lajishan orogenic belt of the South Qilian Mountains and Its Geotectonic Attribute

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Acta Geologica Sinica(English Edition) 2002年第1期76卷 110-117页

作者：杨巍然邓清禄吴秀玲 China University of Geosciences Wuhan 430074Huazhong Tectonomechanical Research Center Wuhan 430074 China University of Geosciences Wuhan 430074

The Lajishan orogenic belt is one of the E-W-trending Caledonian orogenicbelts within the Qinling-Qilian orogenic system. It was formed upon the Jiningian basement byintensive taphrogenesis. Its major characteristics comprise the prominent faulting along the northand south boundaries, the highly complicated petrological and petro-geochemical features of thevolcanic rock series, and the development of a new type of ophiolite suite. In terms of tectonicanalysis and the sequential analysis of tectonic settings of magmatic rocks, it is suggested thatthe Lajishan orogenic belt has undergone a complete 'opening-closing' cycle, which can be furtherdivided into 3 second-order 'opening-closing' cycles. The composite characteristics of the'opening-closing' movement show that Laji Mountain is a typical fault orogenic belt. The faultorogenic belt is one of the most important types of intracontinental orogens. It is of criticaltheoretical and practical significance to summarize the characteristics and the diagnostic criteriaof this kind of orogenic belts, and study the mechanism of their formation and build models of theirevolution.

关键词： south Qilian Mountains Laji Mountain orogenic belt 'opening-and-closing' tectonic analysis tectonic setting geotectonic attribute

Crustal　Texture　and　Rheological　Evolution　of　Tongbai－Dabie　orogenic　belt，China

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Journal of Earth Science 1995年第1期14卷 59-63页

作者： Suo Shutian(Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074)

The crustal texture and rheological evolution of the Tongbai-Dabie orogenic belt are approached from a physical standpoint on the basis of a large body of geological, chronological and geophysical data available in the region. Rheological profiles showing variation of rock Strength with depth in the continental crust are constructed for 1-D crustal structure limited to the Present and Meso-Neoproterozoic structural configurations of the deformed belt, respectively .It is emphasized that the crustal texture and composition have been heterogeneous with the rheological stratification and complicated rheological evolution since the Meso-Neoproterozoic at least. The data appear that the Tongbai - Dabie tectonic belt is a polyphase collisional orogen with evidence for cyclically transition from compressional to extensional regimes and rheological behavior in the levels of the crust.

关键词： orogenic belt Physical condition rheological Stratification fluid crustal layer paleorheological Profile.

Dynamic Settings and Interactions between Basin Subsidence and Orogeny in Zhoukou Depression and Dabie orogenic belt

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Journal of Earth Science 2000年第3期19卷 175-177页

作者： Sun Jiazhen Yang Xianghua Faculty of Earth Resources, China University of Geosciences, Wuhan 430074, China Qiu Ronghua He Mingxi Exploration and Development Institute of Henan Oilfield, Nanyang 473132, China

This paper presents a study of the geo dynamic setting and the relation between orogenic uplift and basin subsidence in the inland Zhoukou depression and Dabie orogenic belt. Since the Mesozoic the evolution of Zhoukou depression can be divided into three stages: (1) foreland basin, (2) transitional stage, (3) fault depression. Formation and variations of basin were not only related to the orogenesis, but also consistent with the orogenic uplift.

关键词： foreland basin fault depression orogenic belt dynamic setting.

Paleomagnetic study on orogenic belt:An example from Early Cretaceous volcanic rocks,Inner Mongolia,China

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Paleomagnetic study on orogenic belt:An example from Early C...

Seismic tomography beneath the orogenic belts and adjacent basins of northwestern China

中国科学院地质与地球物理研究所2004学术年会

作者： REN Shoumai~(1,2),ZHU Rixiang~1,HUANG Baochun~1,ZHANG Fuqin~1 & WANG Hongqiang~1 1.Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China 2.Strategic Research Center for Oil and Natural Gas,The Ministry of Land and Resources of China,Beijing 100034,China

We report paleomagnetic results for Early Cretaceous lava flows collected from the Suhongtu area of Inner Mongolia,the middle part of the Tianshan-Mongolia Fold belt(TMFB). Rock-magnetic experiments for different lava flows indicate that the main magnetic mineral is pseudo-single-domain(PSD) *** characteristic high-temperature remanence component is isolated by thermal demagnetization temperature steps between 300℃and 585℃, which yields a mean direction of D=23.6°,I=56.0°withα=2.3°.We interpret this high-temperature remanence component as primary magnetization based mainly upon the petrographic analysis,which shows that the shape of magnetite crystal is relatively rounded square or polygon without internal reflection and deuterogenous phenomenon,The corresponding pole of the high-temperature remanence component is at 71.1°N,200.5°E with A=2.7°. This Early Cretaceous pole is in good agreement with those for Siberia,North China,and Inner Mongolia,suggesting that these continental blocks had already sutured together in the Early Cretaceous,which would further provide constraints on better understanding of the formation and evolution of the TMFB.

关键词： orogenic belt paleomagnetism Suhongtu of Inner Mongolia Eurasia

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Science China Earth Sciences 2001年第5期44卷 468-480页

作者：胥颐刘福田刘建华孙若昧 Institute of Geophysics Chinese Academy of Sciences Beijing China

Three-dimensional velocity images of the crust and upper mantlebeneath orogenic belts and adjacent basins of the northwestern continent of China are reconstructed by seismic tomography, based on arrival data of P wave recorded in seismic networks in Xinjiang, Qinghai, Gansu of China and Kyrgyzstan. The velocity images of upper crust demonstrate the tectonic framework on the ground surface. High velocities are observed beneath orogenic belts, and low velocities are observed in the basins and depressions that are obviously related to unconsolidated sediments. The velocity image in mid-crust maintains the above features, and in addition low velocities appear in some earthquake regions and a low velocity boundary separates the western Tianshan Mts. from eastern Tianshan Mts. The orogenic belts and the northern Tibetan plateau have a Moho depth over 50 km, whereas the depths of the Moho in basins and depressions are smaller than 50 km. The velocity images of upper mantle clearly reveal the colliding relationship and location of deep boundaries of the continental blocks in northwestern China, indicating a weakness of the upper mantle structure of orogenic belts. The top depth of upper mantle asthenosphere varies from place to place. It seems shallower under the northern Tibetan plateau, Altay and Qilian Mts., and deeper under the Tarim and Tianshan regions. Hot mantle probably rose to the bottom of some orogenic belts along tectonic boundaries when continental blocks collided to each other. Therefore their dynamic features are closely correlated to the formation and evolution of orogenic belts in northwestern China.

关键词： seismic tomography orogenic belt northwestern China.

Flysch Trace Fossils from the Hercynian and Indosinianorogenic belts of North western China andTheir Palaeoenvironmental Significance

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Acta Geologica Sinica(English Edition) 1999年第4期73卷 384-394,495-499页

作者： Gong Yiming Faculty of Earth Science China University of Geosciences Wuhan Hubei Province 430074

Twenty-three ichnotaxa have been found in the Silurian and Carboniferous turbidites of the Tianshan orogenic belt and the Triassic turbidites of the East Kunlun-West Qinling orogenic belt of northwestern China. They are Acanthorhaphe isp., ?Arthrophycus isp., Aulichnites parkerensis, Chondrites isp., C. intricatus, C. targionii, Cochlichnus anguineus, coprolite, Dendrotichnium haentzscheli, Helminthopsis isp., Helminthopsis abeli, H. hieroglyphica, H. cf. irregularis, Imbrichnus isp., Kunlunichnus qinghaiensis, Laevicyclus rotaeformis, Lophoctenium tianshanensis, Megagrapton isp., Micatuba verso?, Muensteria isp., Neonereites, Palaeophycus, and Zoophycos caudagalli, two of which, namely, Kunlunichnus qinghaiensis and Lophoctenium tianshanensis, are new ichnospecies. The described trace fossils can be grouped into five ichno-assemblages: the Aulichnites-Imbrichnus ichno-assemblage representing turbidity current deposits of a restricted anoxic deep-sea basin, the Lophoctenium ichno-assemblage showing the deep-sea or ocean environments relevant to a plate subduction, the Zoophycos-Helminthopsis ichnoassemblage representing the upper-middle turbidity fan deposits of a pelagic and hemipelagic environment, the Megagrapton-Chondrites ichno-assemblage representing the middle-lower turbidity fan deposits of an oceanic archipelago and the Kunlunichnus ichno-assemblage indicating bathyal turbidity current deposits.

关键词： flysch trace fossils Silurian Carboniferous Triassic Tianshan Mountains Kunlun Mountains orogenic belt northwestern China

Au(Cu)Ore-Fluid Dynamics in Bordering orogenicbelt of Simao-Nanping Basin, Yunnan Province

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Journal of China University of Geosciences 2002年第1期13卷 53-57,72页

作者： CaoZhimin XuZemin 等 College of Marine Geoscience Ocean University of QingdaoQingdao266003 College of EarthScience Chengdu University of TechnologyChengdu610059

The paleohydrogeologic condition and the tectonic stress field during the mineralization epoch of the Au (Cu) ore fluid in the bordering orogenic belt of Simao-Nanping basin reveal that the complicated paleohydrodynamic condition during the Devonian-Carboniferous period in the northern Ailao-shan was favorable for the pre-enrichment of the mineral elements, and that the migration and the distribution of the groundwater were controlled by the tectonic stress field and driven by temperature and hydraulic gradients during the Yanshan-Himalayan movement epoch. Therefore, the determination of the low-pressure zone of the maximum principal stress is effective for the location of the Au deposits (ore spots).

关键词： Au (Cu) deposits ore-fluid orogenic belt border of Simao-Nanping basin Yunnan Province.