The Identification of Early Paleozoic O-Type Adakitic Rocks in Zhengxiangbaiqi Area, Inner Mongolia and Its Significance
详细信息
- 责任者：Qin Ya (Guangxi Scientific Experiment Center of Mining Metallury and Environment ; Guilin University of Technology ; Guilin 541004 ; China) ; Liang Yihong
- 刊名：Earth Science Frontiers
- 出版年：2013
- 卷期：20(5
- 关键词：埃达克岩 ; adakite ; 内蒙古 ; Inner Mongolia
- 页码：p.106-114
- 图表：11 illus., 3 tables, 25 refs.
- 分类号：0801
- issnNo：ISSN1005-2321
- isbnNo：CN11-3370/P
摘要
The Xinmin pluton is mainly composed of adamellite in Zhengxiangbaiqi area,Inner Mongolia.The LA-ICP-MS zircon U-Pb ages of two adamellite samples are 457±11 Ma and 423.1±9.9 Ma respectively.Two age samples both have the age of more than 1000 Ma,suggesting that this area have ancient crystallization basement or micro-massif.Geochemical studies indicate that the Xinmin pluton is rich in SiO2(73.52%-74.68%),Al2O3(14.31%-15.26%),Na2O(Na2O contents vary from 3.82% to 5.25% and the ratios of Na2O/K2O are between 1.26and 2.5)and Sr((435.4-719.7)×10-6),but low in MgO(0.29%-0.39%),Y((3.46-4.81)×10-6)and Yb((0.38-0.48)×10-6),with high Sr/Y ratios ranging from 103.54to 177.09.The Xinmin granitoid has low REE contents(∑REE:(20.98-40.79)×10-6,with strong fractionations between LREE and HREE((La/Yb)N:8.32-16.90)and Eu positive anomalies(δEu:1.18-2.2).The spider diagram of primitive mantle normalized trace elements show the enrichment in LILE such as Ba,K,Sr,and Rb,and the depletion in HFSE such as Th,U,Nb,Ta,P,and Ti.All of the above features show that Xinmin plutons have the characteristics of O-type adakites.Combined with regional geological background,the Xinmin granitoid reflects the subduction event of the Paleo-Asian Ocean to the North China Plate.
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