铜陵凤凰山岩体SHRIMP锆石U-Pb年龄与构造变形及其对岩体侵位动力学背景的制约

张达; 吴淦国; 狄永军; 臧文拴; 邵拥军; 余心起; 张祥信; 汪群峰

铜陵凤凰山岩体SHRIMP锆石U-Pb年龄与构造变形及其对岩体侵位动力学背景的制约

张达^{1, 2,},
吴淦国^{1, 2},
狄永军¹,
臧文拴¹,
邵拥军³,
余心起¹,
张祥信¹,
汪群峰¹

1.
中国地质大学地质过程与矿产资源国家重点实验室, 北京 100083
2.
中国地质大学岩石圈构造、深部过程及探测技术教育部重点实验室, 北京 100083
3.
中南大学地学与环境工程学院, 湖南长沙 410083

基金项目:

国家自然科学基金重点项目 40434011

国家重点基础研究发展规划项目 1999CB043206

国家自然科学基金项目 40372050

详细信息

作者简介:
张达(1967-)，男，副教授，主要从事区域构造、区域成矿规律研究.E-mail：zhda@263.net

中图分类号: P597; P541
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出版历程
- 收稿日期: 2006-02-11
- 刊出日期: 2006-11-25

Emplacement Dynamics of Fenghuangshan Pluton (Tongling, Anhui Province): Constraints from U-Pb SHRIMP Dating of Zircons and Structural Deformation

1.
State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, China
2.
Key Laboratory of Lithospheric Tectonics and Lithoprobing Technology of Ministry of Education, China University of Geosciences, Beijing 100083, China
3.
School of Geosciences and Environmental Engineering, Central South University, Changsha 410083, China

摘要

摘要: 地球动力环境对岩浆来源和侵位机制具有重要的控制作用.铜陵矿集区中生代中酸性侵入岩和大规模成矿作用有密切关系.凤凰山岩体为凤凰山矿田的主要组成部分, 主要岩石类型为花岗闪长岩、石英二长闪长岩.根据精确锆石SHRIMP测年结果, 凤凰山岩体²⁰⁶Pb/²³⁸U年龄为(144.2±2.3) Ma, 是晚侏罗世形成的一个典型岩体, 和铜陵矿集区主要成矿岩体的形成时代一致.接触带构造变形特征显示岩体侵位受控于区域左旋剪切应力场作用.内部构造变形特征表明凤凰山岩体在深部主要为左旋螺旋式强力上升, 浅部为气球膨胀式主动侵位.岩体形成时代及构造变形特征表现出晚侏罗世铜陵矿集区和成矿有关的侵入岩系列的形成可能和古太平洋板块的向北斜向俯冲所导致的左旋剪切应力场有关.
- 铜陵 /
- 凤凰山岩体 /
- 锆石SHRIMPU-Pb年龄 /
- 构造变形 /
- 地球动力学
Abstract: Geodynamic settings play an important role in controlling generation, ascent and final emplacement of magma. Mesozoic intermediate-acid intrusive rocks are closely related with large scale mineralization in the Tongling metallogenic cluster area. The Fenghuangshan pluton, which consists of granodiorite and quartz monzodiorite, is the main part of the Fenghuangshan ore field. Zircon SHRIMP ²⁰⁶Pb/²³⁸U dating shows that the Fenghuangshan pluton formed at (144.2±2.3) Ma, belonging to the Late Jurassic era, which is in accordance with most of metallogenic plutons of the Tongling metallogenic cluster area. The contact deformation shows that the Fenghuangshan pluton was controlled by a regional sinistral shear stress field. The internal deformation indicates that the pluton experienced sinistral spiral ascent and final ballooning emplacement. The age and structural deformation imply that the Late Jurassic pluton related to mineralization may correlate with sinistral shear stress field induced by the northward oblique subduction of the paleo-Pacific plate.
- Tongling /
- Fenghuangshan pluton /
- SHRIMP U-Pb dating of zircons /
- structural deformation /
- geodynamics.

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图 1 铜陵凤凰山岩体地质构造

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图 2 凤凰山岩体锆石形态特征及SHRIMP测试结果

Fig. 2. Characteristics of zircon shape and SHRIMP testing data

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图 3 铜陵凤凰山岩体锆石一致性曲线图

Fig. 3. Zircon U-Pb SHRIMP dating concordia diagram of Fenghuangshan pluton

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图 4 凤凰山岩体接触带及内部构造

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图 5 铜陵凤凰山岩体接触带构造变形样式(相应位置见图 4)

Fig. 5. Contact structural deformation in the Fenghuangshan pluton

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图 6 铜陵凤凰山岩体线理及面理构造分布

a.实测面理及磁面理图; b.实测包体、线理及磁线理图

Fig. 6. Distribution of lineation and foliation in Fenghuangshan pluton

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图 7 铜陵凤凰山岩体内部构造变形样式(相应位置见图 4)

Fig. 7. Inner structural deformation in the Fenghuangshan pluton

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图 8 凤凰山岩体侵位动力学模式

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表 1 铜陵凤凰山岩体花岗岩类锆石SHRIMPⅡ分析结果

Table 1. Granite zircon SHRIMPⅡ analysis results of Fenghuangshan pluton in Tongling area

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