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Intensification of the East Asian Monsoon in Southern China at about300-400 kaBP Inferred from Eolian Deposits in the middle-lower Reaches of the yangtze river

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Acta Geologica Sinica(English Edition) 2017年第3期91卷 1095-1108页

作者： QI Lin QIAO Yansong LI Yuehui WANG Yan PENG Shasha HE Zexin YANG Shuaibin HAN Chao ZHANG Xujiao School of Earth Sciences and Resources China University of Geosciences Institute of Geomechanics Chinese Academy of Geological Sciences Key Laboratory of Neotectonic Movement & Geohazard

In the East Asian monsoon region, eolian deposits widely distributed in the middle-lower reaches of the Yantgze river are among the best materials available for studies on Quaternary climate change in the subtropical zone of Southern China. Typical eolian deposits in this region include upper Xiashu Loess （XL） and underlying Vermiculated Red Soil （VRS） layers. In this paper, chronological and paleoclimatic studies are conducted on an eolian deposit sequence near Jiujiang （J J） city in northern Jiangxi province. A magnetostratigraphic study, combined with optically stimulated luminescence （OSL） dating, is conducted on the JJ section and provides further evidence that eolian deposits in the middle-lower reaches of the yangtze river have been formed since the late Early Pleistocene, and that the boundary age between the XL and VRS layers is about 300-400 kaBP. In grain-size records of the JJ section, the median grain-size and content of the 〉30μn size fraction increase sharply after 300-400 kaBP, representing an East Asian winter monsoon intensification event. Further pollen analysis reveals differing pollen assemblages before and after 300-400 kaBP： there is an evident increase in plants adapted to grow in a warm humid environment after 300-400 kaBP, implying an increase in precipitation caused by intensification of the East Asian summer monsoon. Global ice volume and uplift of the Tibet Plateau （TP） are regarded as crucial factors influencing variations of the East Asian monsoon on a long-term scale. The deep-sea JlSO record, which reflects variations in global ice volume, shows no obvious change after 300-400 kaBP. Moreover, the influence of global ice volume changes on the East Asian summer and winter monsoons is inverse; the global ice volume increase （decrease） implies a strengthened （weakened） winter monsoon and weakened （strengthened） summer monsoon. We therefore interpret the coupled intensifications of the East Asian summer and winter monsoons at about 300-40

关键词： middle-lower yangtze river eolian deposit magnetostratigraphy grain-size pollen EastAsian monsoon

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Large-scale Migration of Fluids toward Foreland Basins during Collisional Orogeny: Evidence from Triassic Anhydrock Sequences and Regional Alteration in the middle-lower yangtze Area

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Acta Geologica Sinica(English Edition) 2004年第1期78卷 203-220页

作者： HOUZengqian YANGZhusen LIYinqing ZENGPusheng MENGYifeng InstituteofMineralResources ChineseAcademyofGeologicalSciencesBeijing100037

The middle-lower yangtze area underwent a series of complex tectonic evolution, such as Hercynian extensional rifting, Indosinian foreland basining, and Yanshanian transpression-transtension, resulting in a large distinctive Cu-Fe-Au metallogenic belt. In the tectonic evolution, large-scale migration and convergence of fluids toward foreland basins induced during the collisional orogeny of the yangtze and North China continental blocks were of vital importance for the formation of the metallogenic belt. Through geological surveys of the middle-lower yangtze area, three lines of evidence of large-scale fluid migration are proposed: (1) The extensive dolomitic and silicic alteration penetrating Cambrian-Triassic strata generally occurs in a region sandwiched between the metallogenic belt along the yangtze river and the Dabie orogenic belt, and in the alteration domain alternately strong and weak alteration zones extend in a NW direction and are controlled by the fault system of the Dabie orogenic belt; it might record the locus of the activities of long-distance migrating fluids. (2) The textures and structures of very thick middle-lower Triassic anhydrock sequences in restricted basins along the river reveal the important contribution of the convergence of regional hot brine in restricted basins and the chemical deposition or their formation. (3) Early-middle Triassic syndepositional iron carbonate sequences and Fe-Cu-Pb-Zn massive sulfide deposits alternate with anhydrock sequences or are separated from the latter, but all of them occur in the same stratigraphic horizon and are intimately associated with each other, being the product of syndeposition of high-salinity hot brine. According to the geological surveys, combined with previous data, the authors propose a conceptual model of fluid migration-convergence and mineralization during the Dabie collisional orogeny.

关键词： large-scale migration of fluids collisional orogeny anhydrock sequence regional alteration middle-lower yangtze river

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3-D isotropic and anisotropic tomography of P-wave travel times from the Anhui airgun experiment in the yangtze river

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Earthquake Science 2021年第1期34卷 36-46页

作者： Xihui Shao Ying Liu Xiaofeng Tian Huajian Yao Bin Liu Laboratory of Seismology and Physics of Earth's Interior School of Earth and Space SciencesUniversity of Science and Technology of ChinaHefei 230026China Geophysical Exploration Center China Earthquake AdministrationZhengzhou 450003China Mengcheng National Geophysical Observatory University of Science and Technology of ChinaMengcheng 233500China CAS Center for Excellence in Comparative Planetology University of Science and Technology of ChinaHefei 230026China

The middle-lower yangtze river is a typical transition region between the nearly NW-oriented Tethys and NE-trending Pacific tectonic *** of different periods and directions overlap strongly during these *** NE-trending yangtze river compound structural belt and NW-trending Tongling-Hangzhou structural belt both control the magmatic activities and distributions of the metallogenic belts in the ***,we obtain 3-D high-resolution isotropic and azimuthally anisotropic velocity structures at depths of 1–10 km using the first arrivals from airgun *** velocity maps correspond well with the tectonic structures,with high-velocity anomalies distributed in ore-concentrated districts and low-velocity anomalies distributed along the yangtze *** fast directions are generally consistent with the fault strike,indicating that the azimuthal anisotropy is mainly dominated by the fault and fracture trends in the upper *** complicated fast directions near the Luzong and Tongling ore deposits reveal complex deformations in the upper crust,which are mainly caused by the intersection of the yangtze river compound and Tongling-Hangzhou structural *** magma intrusion beneath the two ore deposits(Luzong and Tongling)are connected at depths of 5–10 km.

关键词： middle-lower yangtze river 3-D high-resolution velocity structure azimuthal anisotropy crustal deformation

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