| 西昆仑普鲁新生代火山岩的矿物化学特征及其对岩浆演化过程的约束 |
| |
| 引用本文： | 张招崇,肖序常,王军,王永,LUO Zhao-hua.西昆仑普鲁新生代火山岩的矿物化学特征及其对岩浆演化过程的约束[J].矿物学报,2005,25(3):237-248. |
| |
| 作者姓名： | 张招崇 肖序常 王军 王永 LUO Zhao-hua |
| |
| 作者单位： | 1. 中国地质科学院,地质研究所,北京,100037;中国地质大学(北京)北京,100083
2. 中国地质科学院,地质研究所,北京,100037 |
| |
| 基金项目： | 地质调查项目（DKD2001001）;国土资源部科技项目（2001010204）;国土资源部科技司重点项目（20001010201）;致谢：在岩相学观察过程中得到鲍佩声研究员的指导,在此表示衷心的感谢! |
| |
| 摘 要： | 对西昆仑普鲁新生代火山岩的矿物学进行了系统的研究。结果表明：该地区火山岩主要由橄榄石、单斜辉石和斜长石组成，并有少量的斜方辉石、黑云母、角闪石、碱性长石和铁钛氧化物。其矿物学特征指示了岩浆的性质有点类似于碱性岩浆，但与典型的碱性玄武岩又有明显的区别，属于橄榄安粗岩系列。利用橄榄石-熔体平衡原理估算了进入高位岩浆房中的熔体的MgO含量约为6．2％，Mg^#为0．57，说明其不是地幔熔融形成的原始岩浆，而是经历了深部岩浆房的分离结晶过程。由单斜辉石估算的高位岩浆房的深度约7～9km。岩浆在高位岩浆房中发生了较长时间的强烈分离结晶作用，分离结晶相主要为橄榄石、单斜辉石和斜长石以及少量的斜方辉石、黑云母、角闪石、碱性长石和铁钛氧化物。不同时期形成的铁钛氧化物指示了分离结晶过程由相对高温高氧逸度向相对低温低氧逸度演化。与此相对照的是岩浆在深部岩浆房中可能只发生了橄榄石和辉石等铁镁矿物的分离结晶作用，且分异作用时间较短。深部岩浆房可能存在于岩石圈地幔或壳幔过渡带中，岩浆由深部岩浆房上升到高位岩浆房中的过程是近绝热的，从浅部岩浆房到地表是快速上升的过程。
|
| 关 键 词： | 矿物学 分离结晶 岩浆房 新生代火山岩 西昆仑 |
| 文章编号： | 1000-4734（2005）03-0237-12 |
| 收稿时间： | 2004-08-10 |
| 修稿时间： | 2004年8月10日 |
MINERAL CHEMISTRY OF THE PULU CENOZOIC VOLCANIC ROCKS IN THE WEST KUNLUN MOUNTAINS AND ITS CONSTRAINTS ON THE MAGMATIC PROCESSES |
| |
| ZHANG Zhao-chong,XIAO Xu-chang,WANG Jun,WANG Yong,LUO Zhao-hua.MINERAL CHEMISTRY OF THE PULU CENOZOIC VOLCANIC ROCKS IN THE WEST KUNLUN MOUNTAINS AND ITS CONSTRAINTS ON THE MAGMATIC PROCESSES[J].Acta Mineralogica Sinica,2005,25(3):237-248. |
| |
| Authors: | ZHANG Zhao-chong XIAO Xu-chang WANG Jun WANG Yong LUO Zhao-hua |
| |
| Abstract: | Systematic studies on the mineralogy of the Pulu Cenozoic volcanic rocks in the west Kunlun mountains show that the rocks consist chiefly of olivine, clinopyroxene and plagioclase with minor orthopyroxene, biotite, hornblende, alkalifeldspar and Fe-Ti oxide. Their mineralogical characteristics have a little similarity to those of alkaline magmas, but have features distinguished with those of the latter, belonging to shoshonites. Based on olivine-melt equilibrium, the MgO contents of the parental melt in the high-level magma chamber are estimated to be 6.2wt% with Mg^# value of 0.57, suggesting that it was not primary magma generated by direct melting of mantle, but has undergone fractional crystalliTation within the deep magma chamber. The depth of the high-level magma chamber, in which strong and long fractional crystallization processes with fractional assemblage of olivine, clinopyroxene and plagioclase with minor orthopymxene, biotite, hornblende, alkali-feldspar and Fe-Ti oxide occurred, is estimated to be about 7-9 km on the light of the composition of clinopyroxene. Fe-Ti oxides formed at different stages indicated that the temperature and oxygen fugacity decreased with the evolution of magmas. In contrast, magmas might have undergone fractional crystallization of olivine and pyroxene within the deep-leval magma chamber at a relatively short period of time. We proposed that the deep-level magma chamber may occur in the lithospheric mantle or crest-mantle transition zone, and that it may be an adiabatic process magmas ascended from the deep-level magma chamber to the high-level magma chamber, and a rapid ascending process from the latter to the surface. |
| |
| Keywords: | mineralogy fractional crystallization magma chamber Cenozoic volcanic rocks West Kunlun Mountains |
| 本文献已被 CNKI 维普 万方数据 等数据库收录！ |
|
