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引用本文:康丛轩,杨献忠,蔡逸涛,黄先觉,孔广林,李朝维. 华北克拉通南缘蚌埠隆起古元古代侵入体地质地球化学特征[J]. 中国地质, 2019, 46(6): 1481-1495.
KANG Congxuan,YANG Xianzhong,CAI Yitao,HUANG Xianjue,KONG Guanglin,LI Chaowei. Geological and geochemical characteristics of the Paleoproterozoic intrusions in Bengbu uplift,southeast North China Craton[J]. Geology in China, 2019, 46(6): 1481-1495(in Chinese with English abstract).
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华北克拉通南缘蚌埠隆起古元古代侵入体地质地球化学特征
康丛轩1,2, 杨献忠1, 蔡逸涛1, 黄先觉3, 孔广林3, 李朝维3
1.中国地质调查局南京地质调查中心, 江苏 南京 21006;2.河海大学地球科学与工程学院, 江苏 南京 211100;3.安徽省地质矿产勘查局 312地质队, 安徽 蚌埠 233040
摘要:
华北陆块是世界上最古老、最大的克拉通地块之一。蚌埠隆起作为华北陆块的组成部分,其初始陆壳的形成时限为中太古代晚期,随着扬子陆块与华北陆块碰撞、拼接,经历了较为复杂的演化过程。为了深入探讨蚌埠隆起带古元古代岩浆活动,更新补充年代学及岩石地球化学分析数据,本次通过对区内古元古代侵入体的野外观察、年代学和岩石地球化学研究,在庄子里岩体和磨盘山岩体中分别获得锆石U-Pb年龄为(2089±44)Ma、(2133±27)Ma。地球化学研究显示两岩体明显富钠贫钾,总体铝碱比偏高,钙碱比偏低,属准铝—铝过饱和类型;轻稀土相对富集,具明显的铕负异常,铈异常不明显或无异常;K、Nb、Sr、P和Ti有较明显的亏损,Rb、Th、U、Nd、Zr和Sm相对富集,成因类型具备造山后A型花岗岩特征。εNdt)值介于-3.87~+3.20,暗示侵入体可能来源于同一源区,Nd两阶段模式年龄(2.37~2.84 Ga)与华北克拉通主体形成于太古宙,并以2.40~2.50 Ga为主体相一致。εHft)值介于-9.77~+9.59,且差别较大,说明其具物质起源的复杂性,古老的两阶段Hf模式年龄(2.27~2.96 Ga)说明其物质起源主要为新太古宙,与蚌埠隆起拉张背景时间上具有一致性。构造环境判别属板内花岗岩范畴,表现为非造山构造环境,暗示其伸展构造背景。
关键词:  华北克拉通  蚌埠隆起带  古元古代侵入体  地球化学  年代学  安徽省  地质调查工程
DOI:10.12029/gc20190615
分类号:P581
基金项目:安徽省公益性地质调查基金项目(2014-K-5)资助。
Geological and geochemical characteristics of the Paleoproterozoic intrusions in Bengbu uplift,southeast North China Craton
KANG Congxuan1,2, YANG Xianzhong1, CAI Yitao1, HUANG Xianjue3, KONG Guanglin3, LI Chaowei3
1.Nanjing Center of Geological Survey, CGS, Nanjing 210016, Jiangsu, China;2.School of Earth Sciences and Engineering, Hohai University, Nanjing 210016, Jiangsu, China;3.No. 312 Geological Party, Bureau of Geology and Mineral Resources Exploration of Anhui Province, Bengbu 233040, Anhui, China
Abstract:
North China landmass is the oldest landmass and one of the largest craton massifs in the world. Bengbu uplift is a part of the North China landmass, and its initial formation of continental crust is late Archean in the time limit. With the collisions and stitching of the Yangtze platform and North China continental block, the Bengbu uplift experienced complex evolution processes. In order to further explore the Paleoproterozoic magmatic activity in the Bengbu uplift, the authors updated the data of geochronologic and geochemical analysis. Based on field observation, geochronology and geochemistry of Paleoproterozoic intrusions in this area, the authors obtained zircon U-Pb ages of (2089±44)Ma and (2133±27)Ma for Zhuangzili and Muopanshan granites. The geochemical data show that granites have high-Na and low-K significantly, and belong to the quasi-aluminum supersaturated type. They are characterized by relative enrichment of LREE with a strong Eu negative anomaly and insignificant Ce anomaly. The elements of K, Nb, Sr, P and Ti are characterized by measurable depletion, and there exists relative enrichment of Rb, Th, U, Nd, Zr and Sm. Intrusion projection points are distributed in A type granite area in the discrimination diagram of genetic type. Nd twophase age (2.37-2.84 Ga) is consistent with the age of North China Craton formed in Archean, with 2.40-2.50 Ga being the main stage. εHf(t) values vary between -9.77 and +9.59, with obvious differences, suggesting the complexity of the origin of the material, and the old two-phase Hf model age (2.27-2.96 Ga) suggests that the main material was derived during Neoarchean. The tectonic environment belongs to the granite category within the plate and non-orogenic tectonic environment, which implies its extensional tectonic setting.
Key words:  North China Craton  Bengbu uplift  Paleoproterozoic intrusions  geochemistry  chronology  Anhui Province  geological survey engineering