The
Jinshajiang suture zone:tectono-stratigraphic subdivision and revision of age |
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作者单位: | WANG Xiaofeng,JIAN Ping,HE Longqing,WANG Chuanshang(Yichang Institute of Geology and Mineral Resources,Chinese Academy of Geological Sciences,Yichang 443003,China);Ian Metcalfe(Asia Centre,University of New England,Australia)
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摘 要: |
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收稿时间: | 4 May 1999 |
The Jinshajiang suture zone: tectono-stratigraphic subdivision and revision of age |
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Authors: | WANG Xiaofeng Ian Metcalfe JIAN Ping HE Longqing WANG Chuanshang |
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Institution: | 1. Yichang Institute of Geology and Mineral Resources,Chinese Academy of Geological Sciences,Yichang 443003,China 2. Asia Centre,University of New England,Australia |
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Abstract: | Integrated study of rock assemblage, tectonic setting, geochemical feature, fossil contained and isotopic geochronology on
the metamorphic mixed bodies, exposed in the Jinshajiang suture zone, suggests that one informal lithostratigraphic unit,
the Eaqing Complex, and three tectono-stratigraphic units, the Jinshajiang ophiolitic melange, the Gajinxueshan Group and
the Zhongxinrong Group, can be recognized there. It is first pointed out that the redefined Eaqing Complex might represent
the Meso- to Neo-Proterozoic remnant metamorphic basement or mi-crocontinental fragment in the Jinshajiang area. The original
rocks of it should be older than (1627 ±192) Ma based on the geochronological study. The zircon U-Pb age of plagiogranites
within the Jinshajiang ophiolitic assemblage is dated for the first time at (294 ± 3) Ma and (340 ± 3) Ma respectively. The
Jinshajiang ophiolite is approximately equivalent to the Ailaoshan ophiolite in the formation age, covering the interval from
the Late Devonian to the Carboniferous. Dating of U-Pb age from basalt interbeds indicates that the redefined Gajinxueshan
Group and Zhongxinrong Group may be considered Carboniferous to Permian and latest Permian to Middle Triassic in age. In geotectonic
terms the Jinshajiang suture zone is thought to be a back-arc basin in the eastern margin of the Paleo-Tethys. This back-arc
basin started in the Late Devonian, and formed in the Devonian-Carboniferous. The collision event around the Permian/Triassic
boundary to the Middle Triassic led to the closure of the back-arc basin and formation of suture. |
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Keywords: | Jinshajiang suture zone complex ophiolitic melange Paleo-Tethys |
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