西藏塔惹增地区上石炭统—下二叠统拉嘎组火山岩夹层的发现及其地质意义
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摘要
冈底斯带广泛分布晚古生代火山岩地层。岩石学、地球化学特征表明,冈底斯带的构造属性在晚古生代已经发生转变。在冈底斯带中西部塔惹增地区晚石炭世—早二叠世拉嘎组中发现了火山岩夹层。根据岩石地球化学特征分析,该火山岩属岛弧环境,标志着晚古生代冈底斯发生首次造弧作用,该时期冈底斯中西部已经由被动大陆边缘向主动大陆边缘转化。
Late Paleozoic volcanic strata are widely distributed in the Gangdise belt. Petrological and geochemical characteristics show that remarkable change of the Gangdise belt had already taken place in late Paleozoic. The authors found volcanics intercalation in Late Carboniferous-Early Permian Laka Formation within Tarezeng area along central and western segment of the Gangdise belt. Petrological and geochemical characteristics show that it belonged to an island arc environment and marked the first arc-producing action of the Gangdise belt that took place in Late Paleozoic. During that period, central and western segment of the Gangdise belt had already experienced the conversion from the passive continental margin to active continental margin.
Late Paleozoic volcanic strata are widely distributed in the Gangdise belt. Petrological and geochemical characteristics show that remarkable change of the Gangdise belt had already taken place in late Paleozoic. The authors found volcanics intercalation in Late Carboniferous-Early Permian Laka Formation within Tarezeng area along central and western segment of the Gangdise belt. Petrological and geochemical characteristics show that it belonged to an island arc environment and marked the first arc-producing action of the Gangdise belt that took place in Late Paleozoic. During that period, central and western segment of the Gangdise belt had already experienced the conversion from the passive continental margin to active continental margin.
引文
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2 吉林大学地质调查研究院.1∶25万申扎县区域地质调查报告.2003.
[2]西藏自治区地质矿产局.西藏自治区区域地质志[M].北京:地质出版社,1982.
[3]西藏自治区地质矿产局.西藏自治区岩石地层[M].武汉:中国地质大学出版社,1997.
[4]李才,吴彦旺,王明,等.青藏高原泛非—早古生代造山事件研究重大进展[J].地质通报,2010,29(12):1733-1736.
[5]马德胜,熊兴国,蒋开源,等.西藏改则地区班公湖-怒江结合带内上三叠统的发现及其地质意义[J].地质通报,2011,30(11):1701-1705.
[6]耿全如,王立全,潘桂棠,等.西藏冈底斯带石炭纪陆缘裂陷作用:火山岩和地层学证据[J].地质学报,2007,81(9):1259-1276.
[7]王立全,潘桂棠,朱第成,等.西藏冈底斯带石炭纪—二叠纪岛弧造山作用:火山岩和地球化学证据[J].地质通报,2008,27(9):1509-1534.
1 吉林省地质调查院.1∶25万多巴区域地质调查报告.2003.
2 吉林大学地质调查研究院.1∶25万申扎县区域地质调查报告.2003.