Detrital Serpentinite from the Guajira Peninsula, Colombia
Detrital Serpentinite from the Guajira Peninsula, Colombia
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产自哥伦比亚瓜希拉半岛的碎屑蛇纹岩
DOI：
10.1130/mem130-p55
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发表时间：
1971
期刊：
影响因子：
--
通讯作者：
J. Lockwood
中科院分区：
文献类型：
--
作者：
J. Lockwood
瓜希拉半岛Cerros de Parashi地区中生代千层岩和变质泥质岩序列中，出现了被块状蛇纹岩完全包围的小透镜状碎屑蛇纹岩。这些透镜体厚达30米，由分选差的角砾岩组成，这些角砾岩不规则地向上渐变成层状蛇纹岩砂岩和页岩。砂岩层理发育，河道构造和交错层理也很常见。对蛇纹岩砂岩和页岩的两次化学分析表明，它们是正常的蛇纹岩成分。岩石中原始的碎屑蛇纹石矿物为蜥蜴石和温石棉，但在上绿片岩相变质期部分被反长花岗岩所取代。碎屑蛇纹岩是由大型海底混浊流或泥石流形成的，周围的大块蛇纹岩被认为是重力滑动形成的。
Small lenses of detrital serpentinite, completely surrounded by massive serpentinite, occur within a sequence of Mesozoic phyllites and metasiltstones in the Cerros de Parashi area, Guajira Peninsula. These lenses, which are as much as 30 m thick, consist of poorly sorted breccias that grade irregularly upward into bedded serpentinite sandstone and shale. Graded bedding is well developed in the sandstones, and channel structures and cross-bedding are also common. Two chemical analyses of serpentinite sandstone and shale show them to be of normal serpentinite composition. The original detrital serpentine minerals in these rocks were lizardite and chrysotile, but they have been partially replaced by antigorite during a period of upper greenschist facies metamorphism. The detrital serpentinites were formed by large submarine turbidity currents or mudflows, and the massive serpentinites surrounding them are believed to have been emplaced by gravity sliding.