On the Age of the Ophiolitic Complexes in Northeastern Jiangxi:A Micropaleontological Analysis

The age assignment of cherts from ophiolitic/metamorphic complexes in northeastern Jiangxi is widely regarded as one of the crucial issues in the tectonic interpretation of South China. The ophiolitic and metamorphic complexes in northeastern Jiangxi have been traditionally regarded as part of the Proterozoic "Banxi (=Penhsi) Group" of the Jiangnan Uplift. However, recent reports of Late Paleozoic radiolarians from the rock complexes have caused some researchers to question the traditional interpretation of the tectonic and paleogeographic framework in the region; but other workers are suspicious about these findings. In order to test the validity of the putative radiolarians, we, an interdisciplinary study group including micropaleontologists, tectonic specialists and regional geologists, conducted field investigations and multiple re-samplings of the localities where the reported fossils were collected. Our comprehensive study shows that the chert of the ophiolitic complex and the associated low-grade metamorphic slate yield Mesoproterozoic and Neoproterozoic acritarchs, confirming the traditional view of their age assignment (Proterozoic); on the other hand, no recognizable radiolarian fossils have been discovered therein, thus raising questions about the recently published result of Paleozoic radiolarian findings. Probable causes for the putative radiolarian findings are thus discussed herein. Geochemical characteristics indicate that the chert sedimentation most probably occurred under a continental margin setting.

作 者： YANG Qun Wang Yujing Yin Leiming SHU LiangShu LOU Fasheng WANG Bo   作者單位： YANG Qun,Wang Yujing,Yin Leiming(Nanjing Institute of Geology and Palaeontology,Chinese Academy of Sciences,Nanjing,Jiangsu 210008)

SHU LiangShu,WANG Bo(Department of Earth Sciences,Nanjing University,Nanjing,Jiangsu 210093)

LOU Fasheng(Geological Survey of Jiangxi Province,Nanchang,Jiangxi 330201) 

刊 名： 地質(zhì)學(xué)報（英文版）  SCI 英文刊名： ACTA GEOLOGICA SINICA  年，卷(期)： 2005 79(3)  分類號： P5  關(guān)鍵詞： radiolarians   chert   Banxi Group   northeastern Jiangxi  

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