MESOZOIC-CENOZOIC MAGMATISM IN SOUTHERN SOUTH CHINA SEA AND ITS SURROUNDING AREAS AND ITS IMPLICATIONS TO TECTONICS
MESOZOIC-CENOZOIC MAGMATISM IN SOUTHERN SOUTH CHINA SEA AND ITS SURROUNDING AREAS AND ITS IMPLICATIONS TO TECTONICS
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发表时间：
2005
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通讯作者：
Liu Hai-ling;C. Key
中科院分区：
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作者：
Liu Hai-ling;C. Key
对南海南部南沙海域及邻区中新生代岩浆活动的时空分布、地球化学特征、构造环境等进行了总结。燕山期（侏罗纪至白垩纪）以西部和南部中酸性岩浆活动为主要特征，代表东南亚中生代岩浆带在孙达兰的延伸。同时，南沙群岛和加里曼丹之间南部的基性-超基性岩是原始南海洋壳的代表，在其向南俯冲过程中被并入混杂岩。早喜马拉雅期（古新世至始新世）岩浆活动相对平静.喜马拉雅晚期第一纪（渐新世晚期至中新世中期）岩浆活动再次活跃，但仅限于砂拉越至卡加延一带，西部以英安岩、花岗闪长岩、安山岩、闪长岩为主，东部以玄武安山岩为主。强度和规模可能太小，导致形成的火山弧有关的原始南海俯冲。晚喜马拉雅期第二期（晚中新世-第四纪）岩浆活动达到高潮，大部分地区发生了大规模的中基性火山喷发，特别是中南半岛南部和北方加里曼丹岛。这可能表明该地区存在上涌地幔热团。
The spatial-temporal distribution, geochemistry, tectonic environment of Mesozoic-Cenozoic magmatism in the region of Nansha sea area in southern South China Sea and its adjacent areas are summarized. The Yan- shanian period (from Jurassic to Cretaceous) was characterized mainly by intermediate-acid magmatic activities in the west and south, representing the extension of the SE Asian Mesozoic magmatic belt in Sundaland. Meanwhile, basic-ultrabasic rocks in the south between Nansha Islands and Kalimantan are representative of the oceanic crust of the proto-South China Sea that was incorporated into melanges during its southward subduction. The Early Himala- yan period (from Paleocene to Eocene) was relatively quiet in terms of magmatic activity. Then during the first epoch of the Late Himalayan period (from Late Oligocene to Middle Miocene), magmatism was active again but was restricted to a zone extending from Sarawak to Cagayan, and is represented mainly by dacite, granodiorite, andesite, diorite in the west and by basaltic andesite in the east. The intensity and scale were probably too small to lead to formation of a volcanic arc related to the subduction of the proto-South China Sea. During the second epoch of the Late Himalayan period (from Late Miocene to Quaternary) the magmatic activity reached its climax, as large-scale intermediate-basic volcanic eruption occurred in most parts of the area, especially in southern Indochina Peninsula and northern Kalimantan Island. This is perhaps indicative of an upwelling mantle hot-blob in the area.