| 鄂尔多斯盆地东缘紫金山侵入岩热演化史与隆升过程分析 |
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| 引用本文： | 陈刚,丁超,徐黎明,章辉若,胡延旭,杨甫,李楠,毛小妮.鄂尔多斯盆地东缘紫金山侵入岩热演化史与隆升过程分析[J].地球物理学报,2012,55(11):3731-3741. |
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| 作者姓名： | 陈刚 丁超 徐黎明 章辉若 胡延旭 杨甫 李楠 毛小妮 |
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| 作者单位： | 1. 西北大学 地质学系,大陆动力学国家重点实验室,西安 710069;2. 中国石油天然气股份有限公司长庆油田分公司,西安 710021 |
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| 基金项目： | 国家重点基础研究，国家自然科学基金，教育部高校博士点专项科研基金，国家留学基金，留学人员择优经费共同资助 |
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| 摘 要： | 运用LA-ICP MS锆石U-Pb定年、角闪石和黑云母40Ar-39Ar定年、锆石和磷灰石裂变径迹(FT)分析等构造热年代学研究方法,探讨分析了鄂尔多斯盆地东缘紫金山侵入岩的热演化历史及其抬升冷却过程.紫金山侵入岩主要由次透辉二长岩和正长岩组成,锆石U-Pb测年给出的岩浆侵位-结晶年龄为136.7 Ma,角闪石和黑云母40Ar-39Ar测年获得的岩浆结晶-固结年龄集中在133.1~130.4 Ma,表明紫金山侵入岩主要形成于早白垩世的136.7~130.4 Ma.侵入岩T-t轨迹与磷灰石FT模拟热史路径综合揭示了鄂尔多斯盆地东缘紫金山侵入岩抬升冷却的三个构造热演化阶段:1) 136~120 Ma侵位岩浆结晶-固结阶段,岩体平均冷却速率高达52 ℃/Ma;2) 120~30 Ma岩体相对缓慢抬升冷却阶段,平均抬升冷却速率为2.5 ℃/Ma;3) 30 Ma以来岩体快速抬升冷却阶段,平均抬升冷却速率3.6 ℃/Ma,尤以近10 Ma以来的快速抬升冷却最为显著,抬升冷却速率接近7 ℃/Ma.结合区域构造动力学环境分析认为,鄂尔多斯盆地东缘的紫金山岩浆活动与华北克拉通早白垩世构造体制转换过程的大规模岩浆活动属于相同时期、统一构造作用的产物,早白垩世末期以来由慢到快的差异抬升过程主要受控于华北克拉通东部(古)太平洋体系与其西南部特提斯体系之间相互联合、彼此消长的构造作用.
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| 关 键 词： | 鄂尔多斯盆地东缘 紫金山侵入岩 构造热年代学 抬升冷却过程 |
| 收稿时间： | 2011-11-06 |
Analysis on the thermal history and uplift process of Zijinshan intrusive complex in the eastern Ordos basin |
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| CHEN Gang
,
DING Chao
,
XU Li-Ming
,
ZHANG Hui-Ruo
,
HU Yan-Xu
,
YANG Fu
,
LI Nan
,
MAO Xiao-Ni.Analysis on the thermal history and uplift process of Zijinshan intrusive complex in the eastern Ordos basin[J].Chinese Journal of Geophysics,2012,55(11):3731-3741. |
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| Authors: | CHEN Gang DING Chao XU Li-Ming ZHANG Hui-Ruo HU Yan-Xu YANG Fu LI Nan MAO Xiao-Ni |
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| Institution: | 1. State Key Laboratory of Continental Dynamics, Department of Geology, Northwest University, Xi'an 710069, China;2. Changqing Oilfield Company, PetroChina Company Limited, CNPC, Xi'an 710021, China |
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| Abstract: | Thermochronological data of in-situ zircon U-Pb, hornblende and biotite 40Ar-39Ar, and zircon and apatite fission track (FT) are presented in this paper for studying the thermal history and uplift-cooling process of Zijinshan intrusive complex at the eastern margin of the Ordos basin in the central North China Craton (NCC). Alkaline intrusive rocks dominate the complex with the diopside monzonite and syenite as the dating samples in this work. Zircon U-Pb dating of the monzonite provides the initial crystallization age of the Early magmatic intrusion at 136.7 Ma, and 40Ar-39Ar dating of hornblendes and biotites indicates the late crystallization to solidification age of the emplaced magma to be mainly in a range of 133.1~130.4 Ma. A conclusion can be therefore drawn that the intrusive complex was mainly formed in 136.7~130.4 Ma of the Early Cretaceous. Based on the comprehensive analysis of the thermochronological T-t curve of the complex and the apatite FT modeling thermal path of the monzonite and altered sandstone, it can be further concluded that the uplift-cooling process of the Zijinshan complex and its intruded area of the eastern Ordos basin has experienced at least three tectono-thermal stages as follows: (1) the crystallization to consolidation stage of the magma emplacement during 136~120 Ma at an extremely high cooling rate of 52 ℃/Ma; (2) the slow uplift-cooling stage during 120~30 Ma at an average uplift-cooling rate of 2.5 ℃/Ma; and (3) the fast uplift-cooling stage initiated at 30~Ma with an average uplift-cooling rate of 3.6 ℃/Ma, accompanied by a more rapid uplift-cooling process since 10 Ma at an average rate of 7 ℃/Ma. Zijinshan magma intrusion in the eastern Ordos basin is an exhibition of the dynamic transformation and its related large-scale magmatism in NCC during Early Cretaceous. Then, the 2-stage differential uplifting processes are dynamically associated with far-field effects produced by synchronous convergences toward the central NCC of the (Paleo-) Pacific plate and Tethys or Indian plate at fluctuating subduction rates during Late Cretaceous to Neogene and Quaternary. |
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| Keywords: | Eastern Ordos basin Zijinshan intrusive complex Tectono-thermochronology Uplift-cooling process |
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