| 辽东岫岩晚侏罗世荒地岩体的地球化学、年代学与Hf同位素及构造意义 |
| |
| 引用本文： | 薛吉祥,刘正宏,刘杰勋,董晓杰,冯帆,连光辉.辽东岫岩晚侏罗世荒地岩体的地球化学、年代学与Hf同位素及构造意义[J].地球科学,2020,45(6):2030-2043. |
| |
| 作者姓名： | 薛吉祥 刘正宏 刘杰勋 董晓杰 冯帆 连光辉 |
| |
| 作者单位： | 吉林大学地球科学学院, 吉林长春, 130061 |
| |
| 基金项目： | 国家自然科学基金项目41272223国家自然科学基金项目41340024中国地质调查局项目12120113098500 |
| |
| 摘 要： | 辽东半岛中生代晚侏罗世岩浆活动较少，研究程度较低.通过对辽宁岫岩县荒地花岗岩岩体进行锆石U-Pb测年、岩石地球化学和锆石Lu-Hf同位素分析来进一步了解辽东半岛晚侏罗世的构造动力学背景，荒地花岗岩的岩浆锆石U-Pb加权平均年龄为161.1±3.6 Ma（MSWD=1.4），表明荒地岩体的形成时代为晚侏罗世，为燕山期岩浆活动的产物.该岩体含白云母等富铝矿物，地球化学数据也显示，该岩体为过铝质高钾钙碱性系列，富集K、Rb、Cs、Ba等大离子亲石元素，亏损Nb、Ti、P等高场强元素，具轻稀土元素富集，重稀土元素亏损的特征，Eu为中等负异常（δEu=0.33~0.80）.该花岗岩A/CNK平均值为1.10，CIPW标准矿物中出现刚玉分子（>1%）.由此认为该岩体为经历了高程度的结晶分异作用的S型花岗岩.荒地花岗岩CaO/Na2O比值小于0.3，εHf（t）小于0（-36.968~-23.298），表明该岩石由地壳的泥质岩熔融形成.两阶段Hf模式年龄TDMC=2 680~3 568 Ma，表明该岩体源岩的组成物质从地幔储库中脱离的时间为新太古代至古太古代，同时与辽东半岛侏罗纪其他花岗岩进行了比较.综上所述，该岩体形成于古太平洋板块向欧亚大陆俯冲后俯冲角度变大、向更深处俯冲的背景之下.
|
| 关 键 词： | 荒地岩体 华北克拉通 锆石U-Pb年龄 Hf同位素 S型花岗岩 地球化学 |
| 收稿时间： | 2019-11-02 |
Geochemistry,Geochronology, Hf Isotope and Tectonic Significance of Late Jurassic Huangdi Pluton in Xiuyan,Liaodong Peninsula |
| |
| Abstract: | Late Jurassic magmatic activity in the Liaodong Peninsula was less and the research degree was lower. In this paper, zircon U-Pb dating, geochemistry and zircon Lu-Hf isotope analysis were carried out to further understand the tectonic dynamics of the Liaodong Peninsula in the Late Jurassic. The U-Pb weighted mean age of magmatic zircons in the Huangdi granite is 161.1±3.6 Ma (MSWD=1.4), indicating that the formation of the Huangdi granite is the Late Jurassic, which is the product of the Yanshanian magmatism. The pluton contains muscovite and other aluminum-rich minerals geochemical data show that the pluton is the peraluminum calcium alkaline series, enriched with LILE such as K, Rb, Cs, and Ba, and depleted HFSE such as Nb, Ti, and P. With the characteristics of light rare earth element enrichment and heavy rare earth element loss, Eu is a moderate negative anomaly (δEu=0.33-0.80).The average A/CNK value of the granite is 1.10, and the corundum molecule (>1%) appears in the CIPW standard mineral. It is considered that the pluton is an S-type granite that has undergone a high degree of crystallization differentiation. The CaO/Na2O ratio of the Huangdi granite is less than 0.3, and the εHf(t) is less than 0 (-36.968 to -23.298), indicating that the rock is formed by the mudstone of the earth's crust. The single-stage Hf mode age is TDM=1 728-2 311 Ma, the two-stage Hf mode age is TDMC = 2 680-3 568 Ma. It is shown that the time when the constituent materials of the source rock of the pluton were separated from the mantle reservoir was Neo-Archean to Ancient Archean.In summary, the pluton is formed in the background of the ancient Pacific plate subduction to the Eurasian continent and the subduction angle becomes larger and submerged deeper. |
| |
| Keywords: | |
| 本文献已被 CNKI 等数据库收录！ |
| 点击此处可从《地球科学》浏览原始摘要信息 |
|
点击此处可从《地球科学》下载全文 |
|
