摘要
本文对鄂尔多斯盆地东缘晋西挠褶带临县紫金山杂岩体进行了锆石LA-ICPMSU-Pb年代学及地球化学研究。锆石LA-ICPMSU-Pb测得紫金山碱性杂岩的结晶年龄为138.3±1.1Ma（MSWD=2.3,9个样品点）;地球化学研究表明该套火成岩富碱（K2O＋Na2O=8.60%～15.62%）,强烈富集大离子亲石元素和LREE、具有Eu正异常,亏损Nb、Ta、Ti等高场强元素,高Nb/Ta比值（16.85～18.19）,表明岩石起源于交代富集地幔的部分熔融。结合区域地质背景,文章提出紫金山碱性杂岩可能是早白垩世华北克拉通大规模伸展背景下由交代富集地幔部分熔融作用的产物,该期岩石圈深部的强烈岩浆—热活动是鄂尔多斯盆地燕山晚期构造热事件发生的主要原因。
The Zijinshan alkaline igneous complex cropped out in the eastern margin of the Ordos basin. In this paper, we report its zircon LA-ICP MS U-Pb dating and its geochemical characteristics. Zircon LA-ICP MS U-Pb dating yields an age of 138.3±1.1Ma. The geochemical analysis reveals that the alkaline complex shows high K2O＋Na2O（8.60%～15.62%）, enrichment in LREE and LILE （e.g. Rb, Sr, Ba, Th, La, etc.）, depletion in HFSE （e.g. Nb, Ta and Ti, etc.）, high Nb/Ta and LREE/HREE ratios, and, no significant Eu anomalies. Therefore, we propose that the Zijinshan alkaline complex most likely originates from partial melting of an enriched metasomatic mantle during Yanshanian period,which has been considered to be an important contribution to the Ordos geothermal anomalies.
出处
《地质论评》
CAS
CSCD
北大核心
2007年第5期656-663,共8页
Geological Review
基金
国家重点基础研究发展计划973项目(编号2003CB2146000)
西北大学地质学系国家基础科学人才培养基地创新基金资助项目(批准号XDCX04-14)的成果。
