前中生代海南岛与华夏、扬子陆块的关系——来自海南岛下二叠统峨查组碎屑锆石年龄的信息

    The relationship between Hainan Island and Yangtze and Cathaysia Block: Evidence from the U-Pb age of detrital zircons of the Lower Permian Echa Formation in Hainan Island

    • 摘要: 海南地块的亲缘性质归属一直存在分歧。选择海南东方市江边乡白查村峨查组进行碎屑锆石LA-ICP-MS U-Pb测年, 获得年龄为635~1814Ma, 具4个年龄峰值, 分别为1700Ma、1580Ma、1073Ma和680Ma, 记录了哥伦比亚(1700Ma和1580Ma)、罗迪尼亚(1073Ma)和泛非(680Ma)三大地质事件。1700 Ma、1580Ma和1073Ma三个峰值可与南极洲、越南SongHien、华夏造山带和扬子陆块东南缘同期的碎屑锆石U-Pb年龄峰值对比, 说明海南地块在中元古代与南极洲、越南、华夏和扬子陆块东南缘共同经历了哥伦比亚和格林威尔(罗迪尼亚)造山事件。1700Ma和1580Ma的峰值虽然在扬子陆块东南缘有弱的显示, 但在扬子陆块内部基本没有该年龄峰值的报道, 680Ma峰值在扬子陆块未出现, 说明中—新元古代海南地块与扬子陆块之间相距较远, 而与华夏、越南和南极洲较近。

       

      Abstract: The relationship of Hainan Island with Yangtze and Cathaysia Block has been of considerable controversy. This paper presents a study of geochronology of detrital zircon from the Echa Formation, Baicha Village, Dongfang City, Hainan Island. The results show 4 major age peaks, i.e., ~1700Ma, ~1580Ma, 1073Ma and 680Ma, recording the events of Columbia (1700Ma and 1580 Ma), Rodinia (1073Ma) and Pan-African (680Ma). The presence of ~1700Ma, ~1580Ma and 1073Ma age peaks is similar to that of Antarctica, Song Hien in Vietnam, Cathaysia orogenic belt and southeast margin of Yangtze Block, revealing that they all experienced the Columbia and Grenville (Rodinia) orogenic activities. The ~1700Ma and ~1580Ma age peaks only appear on the southeast margin of Yangtze Block, but have not been reported inside the Yangtze Block. The 680 Ma age peak appears in the Hainan Island but not in the Yangtze Block, indicating that the Hainan Island was separated or far away from the Yangtze Block, but was adjacent to Cathaysia Block, Vietnam and Antarctica during the Meso-to Neoproterzoic period.

       

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