余梦明, 闫义, 黄奇瑜, 刘海泉, 张新昌, 兰青, 陈文煌, 钱坤. 菲律宾蛇绿岩及其大地构造意义[J]. 海洋地质与第四纪地质, 2015, 35(6): 53-71. DOI: 10.16562/j.cnki.0256-1492.2015.06.006
引用本文: 余梦明, 闫义, 黄奇瑜, 刘海泉, 张新昌, 兰青, 陈文煌, 钱坤. 菲律宾蛇绿岩及其大地构造意义[J]. 海洋地质与第四纪地质, 2015, 35(6): 53-71. DOI: 10.16562/j.cnki.0256-1492.2015.06.006
YU Mengming, YAN Yi, HUANG Chiyue, LIU Haiquan, ZHANG Xinchang, LAN Qing, CHEN Wenhuang, QIAN Kun. PHILIPPINE OPHIOLITES AND THEIR TECTONIC SIGNIFICANCE[J]. Marine Geology & Quaternary Geology, 2015, 35(6): 53-71. DOI: 10.16562/j.cnki.0256-1492.2015.06.006
Citation: YU Mengming, YAN Yi, HUANG Chiyue, LIU Haiquan, ZHANG Xinchang, LAN Qing, CHEN Wenhuang, QIAN Kun. PHILIPPINE OPHIOLITES AND THEIR TECTONIC SIGNIFICANCE[J]. Marine Geology & Quaternary Geology, 2015, 35(6): 53-71. DOI: 10.16562/j.cnki.0256-1492.2015.06.006

菲律宾蛇绿岩及其大地构造意义

PHILIPPINE OPHIOLITES AND THEIR TECTONIC SIGNIFICANCE

  • 摘要: 菲律宾出露有20余套规模各异的俯冲带上板块(SSZ)型蛇绿岩,它们的时代以晚中生代为主,仅少数为新生代。大多数菲律宾蛇绿岩出露相对完整,包括由二辉橄榄岩、方辉橄榄岩、纯橄岩等组成的变质地幔岩,和堆晶辉石岩、辉长辉绿岩等深成岩,以及枕状玄武岩、熔岩等喷出岩,甚至燧石岩等上覆沉积物,部分发育席状岩墙群和与蛇绿岩相关的构造混杂岩及变质基底。其中喷出岩在地球化学特征上整体表现出类似MORB和IAT的REE配分模式,具LILE富集和HFSE (如Nb、Ta相对La、Th)弱到中等程度亏损的特征。通过对菲律宾蛇绿岩的形成年代、岩石组合、地球化学特征及构造环境的分析,并与东南亚地区其他同时代蛇绿岩和周缘边缘海进行对比,将菲律宾蛇绿岩分为两部分。(1)菲律宾活动带蛇绿岩,该蛇绿岩带自西向东出露晚中生代弧前、新生代弧前扩张盆地和晚中生代岛弧、弧后盆地的残留,推测晚中生代蛇绿岩来自中特提斯洋向古太平洋板块俯冲所形成的沟-弧-盆体系,是菲律宾新生代岛弧岩浆活动的基底,而夹于晚中生代蛇绿岩之间的始新世蛇绿岩来自老的岛弧基底之上由于新特提斯洋俯冲形成的弧前扩张盆地。(2)菲律宾陆块蛇绿岩,其中巴拉望微陆块晚中生代蛇绿岩来源于古南海,而构造叠置于它们之上的新生代蛇绿岩则来源于古南海俯冲对应形成的边缘海,如苏禄海和南海;三宝颜微陆块或可能是古南海的南部被动大陆边缘,其蛇绿岩可能是古南海的残片,抑或三宝颜微陆块可能是婆罗洲南部东爪哇-西苏拉威西地体的延续,故该蛇绿岩又可能是新特提斯洋的残片。

     

    Abstract: Ophiolites are the fragments of subducted oceanic plates.There are more than 20 SSZ-types of ophiolites or ophiolitic complexes in the Philippine archipelago.Most of them are late Mesozoic in age,excluding some Eocene parts,such as the Coto Ophiolite in the Zambales,the Angat Ophiolite in the Southern Sierra Madre,the Central Cordillera basement,and Palawan ophiolites,and also except the Oligocene Amnay Ophiolite in the Mindoro Island.Philippine ophiolites show typical ophiolitic sequence,starting from serpentinized mantle rocks in the lower part,through layered to massive ultramafic and mafic cumulated gabbros and dike-sill complexes to volcanic rocks on the top.The serpentinized mantle rocks include residual lherzolites,harzburgites,websterites,lenses of dunite,whiles the volcanic succession consists of pillow basalts and massive lavas covered by deep-sea cherts.The volcanic rocks are characterized by a relative flat REE pattern of MORB-like,enriched in LILE and middle to weak depleted HFSE(such as Nb and Ta depleted relative to La and Th).
    Based on their formation ages,emplacement mechanisms,geochemical characteristics and tectonic settings, the Philippine ophiolites could be subdivided into two distinct belts:the Philippine Mobile Belt Ophiolites and the Philippine micro-Continent Ophiolites.
    We suppose that there should be a huge incipient arc and backarc basin,named the Philippine Incipient Arc and the Proto-Philippine Sea respectively,for the Philippine Mobile Belt Ophiolites.The former is comprised of late Mesozoic IA type ophiolites of the Philippine Mobile Belt and the Amami Plateau in the West Philippine Sea Basin.But the later represent by late Mesozoic MORB-like ophiolites of the Philippine Mobile Belt.And the both are formed by the subduction of the Meso-Tethys to the Proto-Pacific in Mesozoic. However,the Philippine Incipient Arc sequently split into 3 slices by opening of the West Philippine Sea Basin and Central Valley Basin in Eocene due to subduction of the Pacific and the Neo-Tethys.
    The Philippine micro-Continent Ophiolites consist of the ophiolites of the Palawan micro-Continent and the Zamboanga Peninsula.The late Mesozoic ophiolites of the Palawan micro-Continent and the Darvel Bay Ophiolite of the NE Borneo share a same origin,all source from the Proto-South China Sea.The Eocene-Oligocene ophiolites of the Palawan micro-Continent,however,should be sourced from the Proto-South China Sea subduction-related Cenozoic marginal sea basins such as the Sulu Sea and the South China Sea.Since lacking valuable data to make more restrictions,the late Mesozoic Zamboanga Peninsula ophioliteis are probably fragments of the Proto-South China Sea,or as like as the Meratus Ophiolite in SW Borneo and the Balantak Ophiolite in east Sulawesi island,which are formed by subduction of the Neo-Tethys Ocean beneath the Borneo.

     

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