东昆仑山脉晚志留世-早侏罗世花岗类岩石中锆石微量元素地球化学特征及地质意义
发布时间：2019-03-17 10:43
【摘要】：为了更深入的认识东昆仑山脉岩浆作用和构造演化历史,本文采用激光剥蚀电感耦合等离子质谱仪(LA-ICP-MS)方法对东昆仑山脉中部和东部不同时代的花岗类岩石中锆石进行了系统的微量元素分析。东昆仑山脉晚志留世二长花岗岩和晚二叠世、晚三叠世、早侏罗世花岗岩中绝大多数锆石Th/U0.5,锆石的球粒陨石标准化REE配分曲线均为HREE相对于MREE和LREE富集,并且具有Ce正异常和Eu负异常,为典型的岩浆锆石。晚志留世二长花岗岩和晚二叠世、晚三叠世花岗岩锆石具有低的Ce正异常,高的Eu负异常;早侏罗世花岗岩锆石则具有高的Ce正异常,高Nb、Ta含量,低Eu负异常;晚二叠世花岗岩锆石还具有高∑REE、Y、Th、U含量;而晚三叠世花岗岩锆石则在所有样品中具有最高的Hf含量,是演化程度高的岩浆产物。除此之外,晚志留世、晚二叠世、晚三叠世和早侏罗世样品中部分锆石呈现LREE富集,说明它们在岩浆晚期可能遭受LREE富集热液的改造。根据锆石Ti温度计,计算出所有样品的结晶温度小于800℃,说明它们很有可能形成于富集流体的俯冲带环境。结合前人研究资料和所分析锆石的U-Pb年龄数据,对东昆仑山脉中古-中生代多期的构造-岩浆事件提供了新的约束:(1)晚志留世二长花岗岩的形成可能与一个小型洋盆的俯冲作用有关,其岩浆源区是地壳浅部的沉积基底;(2)晚二叠世花岗岩可能是在古特提斯洋向北俯冲过程中由于幔源岩浆使浅层地壳发生熔融形成;(3)晚三叠世-早侏罗世花岗岩在羌塘和昆仑-柴达木同碰撞过程形成。
[Abstract]:In order to better understand the magmatic and tectonic evolution history of the Eastern Kunlun Mountains, In this paper, laser denudation inductively coupled plasma mass spectrometer (LA-ICP-MS) is used to analyze the trace elements of zircon in granitic rocks of central and eastern Kunlun Mountains. In the late Silurian monzonitic granite and late Permian, late Triassic and early Jurassic granites in the East Kunlun Mountains, the majority of zircon Th/U0.5, zircon normalized REE partition curves are enriched in HREE relative to MREE and LREE. Ce positive anomaly and negative Eu anomaly are typical magmatic zircon. The zircon of late Silurian monzonitic granite and late Permian, late Triassic granite had low Ce positive anomaly and high Eu negative anomaly, while early Jurassic granite zircon had high Ce positive anomaly, high Nb,Ta content and low Eu negative anomaly. The zircon of late Permian granite also has a high 鈭，
本文编号：2442218
[Abstract]:In order to better understand the magmatic and tectonic evolution history of the Eastern Kunlun Mountains, In this paper, laser denudation inductively coupled plasma mass spectrometer (LA-ICP-MS) is used to analyze the trace elements of zircon in granitic rocks of central and eastern Kunlun Mountains. In the late Silurian monzonitic granite and late Permian, late Triassic and early Jurassic granites in the East Kunlun Mountains, the majority of zircon Th/U0.5, zircon normalized REE partition curves are enriched in HREE relative to MREE and LREE. Ce positive anomaly and negative Eu anomaly are typical magmatic zircon. The zircon of late Silurian monzonitic granite and late Permian, late Triassic granite had low Ce positive anomaly and high Eu negative anomaly, while early Jurassic granite zircon had high Ce positive anomaly, high Nb,Ta content and low Eu negative anomaly. The zircon of late Permian granite also has a high 鈭，
本文编号：2442218
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