Early Permian A-type Granites in the Zhangdaqi Area, Inner Mongolia, China and Their Tectonic Implications

论文摘要

There is a controversy regarding the amalgamation of Xing’an and Songnen Blocks along the Hegenshan-Heihe Suture（HHS） in the eastern Central Asian Orogenic Belt（CAOB）. To solve this problem, we performed detailed study on the granites from the Zhangdaqi area, adjacent to the north of the HHS in the northern part of the Great Xing’an Range, NE China. Geochemically, the granites in the study area are metaluminous-weak peraluminous and high-K calc-alkaline series. Trace elements of the granites show that LREEs are relatively enriched, while HREEs are relatively deficient and obvious REE fractionation. The granites are characterized by obvious negative Eu anomalies, meanwhile, they are relatively enriched in Rb, K, Th and depleted in Ba, Nb, Sr, P, Ti. All the geochemical features suggest that the granites in the Zhangdaqi area are aluminum A-type granites. The zircon LA-ICP-MS U-Pb ages of these granites are 294–298 Ma, indicating that they formed in the Early Permian. These granites also have positive εHf（t） values（8.4–14.2） and a relatively young two-stage model age between 449 Ma and 977 Ma, implying that the magma was derived from the re-melting of the Early Paleozoic-Neoproterozoic juvenile crust. Combined with geochemical characteristics（Nb/Ta ratios of 9.0–22.2, and Zr/Hf ratios of 52.3–152.0）, we believe that the magmatic source area is a mixture of partial melting of the lower crust and depleted mantle. A-type granites and bimodal volcanic rocks along the Hegenshan-Heihe Suture formed during the Late Carboniferous-Early Permian, indicating that the HHS between Xing’an and Songnen Blocks closed in the late EarlyCarboniferous. Subsequently, the Zhangdaqi area was in a post-orogenic extensional environment from Late Carboniferous to Early Permian and resulted in the formation of the A-type granites.

论文目录

• 1 Introduction
• 2 Geological Setting
• 3 Samples Collection and Analytical Methods
•   3.1 Samples collection
•   3.2 Analytical methods
• 4 Results
•   4.1 Geochemistry
•   4.2 Zircon LA-ICP-MS U-Pb dating
•   4.3 Zircon Lu-Hf Isotopic
• 5 Discussions
•   5.1 Formation age of the granites
•   5.2 Petrogenesis and source properties
•   5.3 Tectonic setting
•   5.4 Geological implication
• 6 Conclusions

文章来源

类型: 期刊论文

作者: ZHANG Li,LIU Yongjiang,SHAO Jun,LI Weimin,LIANG Chenyue,CHANG Ruihong,YANG Hongzhi,FENG Zhiqiang,ZHANG Chao,XU Jia,SHI Yi,YANG Fan,HE Pengfei

来源: Acta Geologica Sinica(English Edition) 2019年05期

年度: 2019

分类: 基础科学

专业: 地质学

单位: College of Earth Sciences, Jilin University,Shenyang Institute of Geology and Mineral Resources,China Geological Survey,Key Lab of Submarine Geoscience and Prospecting Techniques, MOE, Institute for Advanced Ocean Study, College of Marine Geosciences, Ocean University of China,Laboratory for Marine Mineral Resources, Qingdao National Laboratory for Marine Science and Technology,College of Mining Engineering, Taiyuan University of Technology

基金: supported by China Geological Survey Project (Grant NO. DD20160047-02,DD20190042-03),National Key Research and Development Program (Grant NO. 2017YFC0601300-01,2017YFC0601401,2017YFC 0601305-02),Qingdao Leading innovation talents project (19–3–2–19–zhc)

分类号: P588.121

页码: 1300-1316

总页数: 17

文件大小: 1400K

下载量: 10