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西藏林周县扎雪地区林子宗群帕那组火山岩的地球化学特征及其地质意义
引用本文:黄映聪,杨德明,郑常青,和钟铧,戴琳娜,李建国,张耀宇.西藏林周县扎雪地区林子宗群帕那组火山岩的地球化学特征及其地质意义[J].吉林大学学报(地球科学版),2005,35(5):576-580.
作者姓名:黄映聪  杨德明  郑常青  和钟铧  戴琳娜  李建国  张耀宇
作者单位:吉林大学,地球科学学院,吉林,长春,130061
基金项目:地质调查局区域地质调查项目
摘    要:分布于西藏林周县扎雪地区的林子宗群帕那组火山岩,主要由流纹质-粗安质熔岩和火山碎屑岩组成.岩石总体上反映出高Al高K的特点,Al2O3的质量分数平均为14.55%,K2O Na2O的质量分数平均为8.78%,K2O质量分数平均为5.77%,K2O/Na2O比值平均为2.07,显示了高钾钙碱性-钾玄质火山岩的特征.稀土配分曲线呈轻稀土富集的右倾形式,并具有中等-强烈的负Eu异常.微量元素Rb、Th强烈富集,Ta、Ba、U相对富集,而Y、Yb、Sr等相对亏损.岩石地球化学特征显示了陆壳重熔的特点.研究表明,扎雪地区帕那组火山岩是40 Ma左右陆壳加厚并部分熔融形成的,是印度板块和欧亚板块后碰撞作用的产物.

关 键 词:岩石地球化学  部分熔融  后碰撞作用  西藏  西藏林周  扎雪  地区  林子宗群  火山岩  岩石地球化学特征  地质意义  Area  Group  Volcanic  Rocks  Pana  Geochemical  Characteristics  Geological  Implication  后碰撞作用  欧亚板块  熔融  陆壳加厚  研究  陆壳重熔  亏损
文章编号:1671-5888(2005)05-0576-05
收稿时间:2004-10-22
修稿时间:2004年10月22日

The Geochemical Characteristics of the Pana Volcanic Rocks of the Linzizong Group in the Zhaxue Area, Linzhou County, Tibet and Its Geological Implication
HUANG Ying-cong,YANG De-ming,ZHENG Chang-qing,HE Zhong-hua,DAI Lin-na,LI Jian-guo,ZHANG Yao-yu.The Geochemical Characteristics of the Pana Volcanic Rocks of the Linzizong Group in the Zhaxue Area, Linzhou County, Tibet and Its Geological Implication[J].Journal of Jilin Unviersity:Earth Science Edition,2005,35(5):576-580.
Authors:HUANG Ying-cong  YANG De-ming  ZHENG Chang-qing  HE Zhong-hua  DAI Lin-na  LI Jian-guo  ZHANG Yao-yu
Institution:College of Earth Sciences, Jilin University, Changchun 130061, China
Abstract:The Pana volcanic rocks of the Linzizong Group in Zhaxue area,Linzhou County,Tibet are mainly composed of rhyolitic-trachy lavas and volcanoclastic rocks.Its geochemical characteristics(14.55% of Al_2O_3 8.78% of K_(2)O+Na_(2)O,5.77% of K_(2)O,K_(2)O/Na_(2)O=2.07) suggest that the Pana Formation volcanic rocks belong to high-Al,high-K calc-alkaline-shoshonite series.LREE in the volcanic rocks were slightly enriched with moderate to strong Eu anomalies.In the volcanic rocks,Rb and Th were intensively enriched,Ta,Ba and U moderately enriched while Y,Yb and Sr relatively depleted.The lithogeochemical study suggests that the Pana Formation volcanic rocks were formed about 40 Ma by anatexis of the thickened continental crust in the post-collision process between Indo plate and Eurasia plate.
Keywords:lithogeochemistry  partial melting  post-collision  Tibet
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