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Earthquake events in Neoproterozoic and Early Paleozoic and its relationship with supercontinental rodinia.in North China

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Chinese Science Bulletin 2000年第10期45卷 931-935页

作者： Xiufu Qiao Linzhi Gao Chinese Acad Geol Sci Inst Geol Beijing 100037 Peoples R China

Carbonate liquefied veins in limestone and liquefied mud veins in mudstone are the result by earthquake, which is liquefied in sediments and a strong earthquake event remains clearly records in strata. 24 strata units with earthquake events (molar tooth), which are subdivided into 11 seismic periods, have been distinguished from Mid-Proterozoic to Early Paleozoic strata in the Sino-Korean platform. The distributions of them represent paleo-seismic tectonic zones in different periods, which is tallied with convergent continental block before Proterozoic supercontinental rodinia.and the evidence of the breakup or splitting developed in the inner Sino-Korean Platform in 700 Ma.

关键词： seismites carbonate liquefied veins paleo-Tanlu zone rodinia.

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Nature of the Precambrian metamorphic blocks in the eastern segment of Central Tianshan:Constraint from geochronology and Nd isotopic geochemistry

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Science China Earth Sciences 2004年第12期47卷 1085-1094页

作者： LIU Shuwen,GUO Zhaojie,ZHANG Zhicheng,LI Qiugen & ZHENG Haifei The Key Laboratory of Orogenic Belts and Crustal Evolution,Ministry of Education,China School of Earth and Space Sciences,Peking University,Beijing 100871,China The Key Laboratory of Orogenic Belts and Crustal Evolution Ministry of Education China School of Earth and Space Sciences Peking University Beijing China

Granitoid gneisses are widespread in Precambrian metamorphic blocks of eastern segment of the Central Tianshan Tectonic Zone, and they have intrusive contact relationships with their metamorphic sedimentary country rocks of Proterozoic Xingxingxia and Kawabulag groups. Zircon U-Pb ages from a granodioritic gneiss (IW11-1) and a parametamorphic schist (W05-9) are determined at the Weiya area. Euhedral prismatic zircons from the granodioritic gneiss (IW11-1) provide U-Pb isotopic discordia intercept ages of 1218±17 Ma and 426±26 Ma, respectively, and euhedral prismatic zircons from the parametamorphic schist (W05-9) display U-Pb isotopic discordia intercept ages of 1216±74 Ma and 290±15 Ma, respectively. A whole-rock Sm-Nd isotopic isochron is determined in augen granitoid gneiss samples at the Gang- gou-Kumishi area and we obtain the isochron age of 1142±120 Ma, and its ε Nd (t) = -4.3. These geochronological data suggest that these Precambrian metamorphic basement blocks within eastern segment of the Central Tianshan Tectonic Zone can be produced during 1140—1220 Ma, and occur a nearly homochronous metamorphism. Integrated to these geochronological data, Nd depleted mantle model ages (T DM ) and epsilon Nd(t) values of these granitoid gneiss samples indicate that they can derive from mixing in various scales both magmas from mantle and crust sources at a late Mesoproterozoic active continental margin tectonic environment. Similarity in geochronology, Sm-Nd isotopic geochemistry between Weiya-Xingxingxia, Pargangtag and Ganggou-Kumishi areas suggests that they could be a bigger uniform metamorphic basement block, which could be formed by the assembly of the supercontinent rodinia.and be separated by late geological processes.

关键词： Central Tianshan Tectonic Zone, Precambrian metamorphic blocks, granitoid gneisses, isotopic chronolo-gy, active continental margin, supercontinent rodinia.

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Discovery of a Sheeted Dike Complex in the Northern Yangtze Craton and Its Implications for Craton Evolution

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Journal of Earth Science 2012年第5期23卷 676-695页

作者：邓浩 Timothy M Kusky 王璐彭松柏蒋幸福王军鹏王淞杰 Faculty of Earth Sciences China University of Geosciences State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences Three Gorges Research Center for Geo-hazard Ministry of EducationChina University of Geosciences

The Miaowan （庙湾） ophiolite is a highly dismembered ophiolitic complex cropping out near the northern margin of the Yangtze craton. The rocks of this complex consist of, from bottom to top, harzburgite tectonite locally containing podiform chromite, dunite, layered and isotropic gabbro, a sheeted dike complex （SDC）, meta-pillow lavas with chert pods and layers, and tectonically intercalated marble. The SDC is a very important and significant part of the Miaowan ophiolitic sequence, and grades downward into gabbro and ultramafic rocks, and upward into meta-pillow lavas. Some dikes preserve one-way chilled margins, typical of extensional ophiolitic settings, whereas most preserve dou-ble chilled margins, in cases where the chilling direction can be determined. The SDC is mainly com-posed of meta-diabase （dolerite）, meta-plagiogranite, and small amounts of meta-gabbro and ultramafic rocks. LA-ICP-MS zircon dating yields an upper intercept age of 1 026±79 Ma for one meta-plagiogranite, 1 043±23 Ma for a second meta-plagiogranite and I 096±32 Ma for one meta-gabbro at the bottom of the SDC, suggesting formation of the SDC at circa 1 026-1 096 Ma, consistent with the recently determined formation age of the Miaowan ophiolite. Sparse geochemical data on the meta-diabase indicate that the protolith was a sub-alkaline, low-potassium tholeiite similar to mid-ocean ridge basalt （MORB）. The chondrite-normalized rare earth element （REE） patterns of the meta-diabase are generally flat （（La/Yb）N=0.56-0.94）, with a slight depletion in LREE, but no obvious Eu anomalies. Given that the meta-plagiogranites show evidence of formation in a suprasubduction zone environment, we suggest that the basalts were originally island arc tholeiites, perhaps formed in an extensional forearc setting. The geochemistry of the meta-diabase and plagiogranite from the sheeted dikes, together with regional relationships, all agree with the previous interpretations that the Miaowan ophiolite formed in a sup

关键词： ophiolite sheeted dike complex Yangtze craton rodinia.

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