博格达陆内碰撞造山带挤压-拉张构造转折期的侵入活动  

Intrusive activities during compression-extension tectonic conversion in the Bogda intracontinental orogen.

作　　者：顾连兴[1] 胡受奚[1] 于春水[1] 赵明[1] 吴昌志[1] 李宏宇[1] 

机构地区：[1]南京大学地球科学系,南京大学成矿作用国家重点实验室,南京210093

出　　处：《岩石学报》2001年第2期187-198,共12页Acta Petrologica Sinica

基　　金：国家 30 5项目 ( 96 -915 -0 5 -0 3-0 1)成果 ;南京大学现代分析中心测试基金;南京大学成矿作用国家重点实验室课题资助

摘　　要：博格达造山带位于准噶尔与吐鲁番 -哈密前寒武纪地块之间 ,是一个早 -中石炭世的陆内裂谷带 ,该裂谷带于中 -晚石炭世闭合。岩相学、岩石化学、稀土元素、微量元素和同位素研究表明 ,该造山带侵入岩以辉绿岩岩床、岩株和岩墙为主 ,仅有少数中 -酸性岩岩株。这些侵入岩的橄榄拉斑玄武质原始岩浆可能来自轻度亏损的地幔源区 ,并在地壳深部形成过分层岩浆房。辉绿岩和中 -酸性岩分别是分层岩浆房的上部和下部层位岩浆先后上侵和演化产物。野外地质关系及上大河沿中 -酸性侵入体的 2 98.4± 0 .76 Ma Rb- Sr等时线年龄 ,不但表明博格达地区晚于海西期的侵入活动并不重要 ,还表明该造山带侵入岩的定位紧随博格达裂谷的陆内碰撞 ,并代表了地球动力学环境由挤压变为拉张这个重大转折时期。The Bogda orogen is situated between the Jungar and the Turfan Hami Precambrian blocks, and was an early to middle Carboniferous intracontinental rift, which was closed during the middle to late Carboniferous times. Studies involving petrography, petrochemistry, rare earth elements, trace elements and isotopes indicate that the intrusive bodies of the orogen are dominated by diabasic sills, stocks and dykes with few intermediate to acidic stocks. The olivine tholeiitic primary magma for these intrusives might have been derived from slightly depleted mantle sources, and have formed a stratified magma chamber deep in the crust. The diabases and intermediate acidic rocks are proposed to represent magmas from the upper and the lower portions of the stratified chamber, which ascent successively and evolved, respectively. Field relations and the Rb Sr isochron age of 298.4±0.76 Ma of the Shangdaheyan intermediate acidic intrusion suggest not only that post Hercynian intrusive activities are not remarkable in the Bogda region, but also that the emplacement of the present intrusives followed closely the intracontinental collision of the Bogda rift and may represent the important conversion from compression to extension in earth dynamics.

关 键 词：花岗岩 辉绿岩 侵入岩 大陆裂谷 造山带 侵入活动 

分 类 号：P542.2[天文地球—构造地质学] P588.121[天文地球—地质学]