作　　者： ; ; ; ; ; ;

机构地区： 中国科学院广州地球化学研究所

出　　处： 《矿物岩石地球化学通报》 2003年第3期209-214,共6页

摘　　要： 海南岛西部中元古代花岗质片麻岩和海西 印支期似斑状花岗岩中发现了大量暗色包体。本文对暗色包体进行了详细地研究 ,以确定其性质、来源和所揭示的地质意义。研究表明 ,暗色包体显示强烈剪切变形和糜棱岩化的特征 ,并可区分三期片理 ;包体为异源包体 ,具深源火成岩特征 ,成分与太古代TTG岩系类似 ,为高Al2 O3大陆型英云闪长岩 花岗闪长岩岩石组合 ,产于大陆或大陆边缘俯冲带环境。结合Sr Nd Pb同位素结果 ,认为该暗色包体可能是海南岛存在太古宙最早陆核的标志 ,来源于亏损地幔、但可能含有地壳成分或受地壳强烈混染。海南岛西部类TTG岩系包体的发现 ,有可能为深入研究海南岛乃至华南古老结晶基底及地壳演化提供新的证据。 A great number of Darkcolor enclave s have been discovered in Meso-Proterzoic granitoidites and Hercynian-Indonian por phyric granites in western Hainan province. In this paper, we studied the Darkco lor enclaves in Meso-proterzoic granitoidites in detail in order to make sure t heir characteristics, sources and geological implications. The Darkcolor enclave s in Meso-Proterzoic granitoidites had been mylonited and deformed intensely, s howing three periods of schistosity.Stmdies on the mineralogy, petrology and geo chemistry of the Darkcolor enclaves indicate that their origination is significa ntly different from the host rocks and the sources are igneous rocks from a deep source with similar chemical compositions to TTG rock series,of wchich the rock assemblages are quartz micadiorite-granodiroite with high Al 2O 3 continenta l type that derived from continent or continental margin setting. We also obtain ed the whole rock Sm-Nd isochrone age of 2885.01±83.09Ma from three samples. A ccording to the Sr,Nd and Pb isotope data, we think analogous TTG darkcolor encl aves may symbol the pioneer continental core which might have existed in Archean , and their sources might be from the depleted mantle with the crustal assimilat ion or having crustal composition. The discovery of the Darkcolor enclaves with the characteristics of Archean TTG rock series in Hainan island will provide new evidences for the antiquity crystal basement and crustal evolution in Hainan is land in East China.

关 键 词： 海南岛 类 岩系 暗色包体 地质意义 剪切交形 糜棱岩化 地壳演化 大地构造格局

领　　域： [天文地球] [天文地球] [天文地球] [天文地球]