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本文将参加年度优秀论文评选,如果您觉得这篇文章很好,请投下您宝贵的一票,谢谢! 支持(2)   不支持(0)

柴达木盆地北缘西段嗷唠山辉长闪长岩锆石SHRIMP U-Pb定年及岩石地球化学特征
投稿时间:2015-06-01  修订日期:2016-03-06  点此下载全文
引用本文:邵鹏程,陈世悦,孙娇鹏,马帅,刘金,汪峰.2018.柴达木盆地北缘西段嗷唠山辉长闪长岩锆石SHRIMP U-Pb定年及岩石地球化学特征[J].地质学报,92(9):1888-1903
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作者单位E-mail
邵鹏程 中国石油大学(华东)地球科学与技术学院,山东青岛,266500 shaopengcheng98@163.com 
陈世悦 中国石油大学(华东)地球科学与技术学院,山东青岛,266500 sunjiaopeng@163.com 
孙娇鹏 中国石油大学(华东)地球科学与技术学院,山东青岛,266500  
马帅 中国石油大学(华东)地球科学与技术学院,山东青岛,266500  
刘金 中国石油大学(华东)地球科学与技术学院,山东青岛,266500  
汪峰 中国石油大学(华东)地球科学与技术学院,山东青岛,266500  
中文摘要:本文对柴达木盆地北缘西段嗷唠山辉长闪长岩进行了系统的年代学和地球化学研究,分析其成因,并对晚古生代柴北缘构造属性特征给予补充。研究表明,嗷唠山辉长闪长岩具低SiO2、K2O值,富钠、富铝、高Mg#等特征。测试样品富集大离子亲石元素Rb、Ba、K等,亏损高场强元素Ta、Nb、Ti、P等,∑LREE/∑HREE和(La/Yb)N值均较低,具有较微弱的负Eu异常至正Eu异常。稀土元素配分曲线显示,相对同期中酸性岩浆岩而言,曲线更为平坦,轻重稀土分异程度较低。通过锆石的SHRIMP U-Pb定年,获得了辉长闪长岩样品加权平均年龄为370.4±3.4 Ma,对应于古生代晚泥盆世岩浆活动。主、微量元素地球化学特征分析表明,岩石具有岛弧或活动大陆边缘岩浆岩的属性,可能起源于受地壳物质混染,并受俯冲流体交代的岩石圈地幔区。总结前人对柴北缘新元古代—古生代洋壳俯冲、陆陆碰撞的构造背景分析,并结合本次地球化学构造环境判别,认为嗷唠山辉长闪长岩形成于造山期后岩石圈拆沉所导致的拉张、伸展、减薄的构造环境,标志着柴北缘地区加里东期造山作用的结束。
中文关键词:柴北缘  辉长闪长岩  中基性  晚泥盆世  岩石圈拆沉
 
SHRIMP Zircon U-Pb Dating and Petro-Geochemistry of Aolaoshan Gabbro-Diorite in the Western North Margin of Qaidam Basin
NameInstitution
SHAO PengchengChina University of Petroleum, School of Geosciences, Qingdao, Shandong, 266500
CHEN ShiyueChina University of Petroleum, School of Geosciences, Qingdao, Shandong, 266500
SUN JiaopengChina University of Petroleum, School of Geosciences, Qingdao, Shandong, 266500
MA ShuaiChina University of Petroleum, School of Geosciences, Qingdao, Shandong, 266500
LIU JinChina University of Petroleum, School of Geosciences, Qingdao, Shandong, 266500
WANG FengChina University of Petroleum, School of Geosciences, Qingdao, Shandong, 266500
Abstract:Systemic chronology and petro-geochemistry analysis of Aolaoshan gabbro-diorite was conducted to analyze its genesis, which makes up understanding of tectonic attributes of the northern Qaidam in Late Paleozoic time. Our study shows that the Aolaoshan gabbro diorite is characterized by high SiO2 and K2O contents, low Na and Al contents, and high Mg#. The primitive mantle normalized spider diagram shows that the rock is enriched in large ion lithophile elements (Rb, Ba, K) and depleted in high field strength elements (Ta, Nb, Ti and P). The chondrite normalized REE distribution pattern shows a relatively flat, low differentiation curve of LREE and HREE, with low ∑LREE/∑HREE and (La/Yb)N ratios and weak negative to positive Eu anomalies, compared with that of contemporary intermediate-felsic intrusive rocks. SHRIMP U-Pb zircon dating yields an average weighted age of 370.4±3.4 Ma for the gabbro-diorite samples from the Aolaoshan area, which corresponds to Lae Paleozoic magmatic activity. The major and trace element geochemistry analysis illustrates that the rock is of attributes of magmatic rocks formed in island arc or active continental margin, suggesting that it probably originated from lithosphere mantle contaminated by crust material and metasomatized by fluid in subduction belt. Based on the previous studies on the Neoproterozoic Late Paleozoic oceanic crust subduction and collision between continents tectonic setting, and combined with geochemical tectonic environment discrimination in this study, it can be concluded that the Aolaoshan gabbro-diorite formed in a lithosphere thinning and crustal extension environment resulted from post-orogenic lithosphere delamination, which marks the end of Caledonian orogenesis in the northern margin of Qaidam region.
keywords:northern margin of Qaidam basin  gabbro-diorite  intermediate-felsic  Late Devonian  lithosphere delamination
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