地学前缘 ›› 2023, Vol. 30 ›› Issue (3): 386-398.DOI: 10.13745/j.esf.sf.2022.12.57

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内蒙古白乃庙铜金矿区侵入岩锆石和磷灰石裂变径迹年代学及其地质意义

吕钊1(), 许展2, 庞建章3, 王继春2, 王建平1,*(), 袁硕浦1   

  1. 1.中国地质大学(北京) 地球科学与资源学院, 北京 100083
    2.内蒙古自治区地质调查院, 内蒙古 呼和浩特 010020
    3.中国地震局 地质研究所, 北京 100029
  • 收稿日期:2021-06-22 修回日期:2021-09-19 出版日期:2023-05-25 发布日期:2023-04-27
  • 通讯作者: 王建平(1972—),男,教授,主要从事矿床学的教学与科研工作。E-mail: jpwang@cugb.edu.cn
  • 作者简介:吕 钊(1996—),男,硕士,矿物学、岩石学、矿床学专业。E-mail: lvzhao01@qq.com
  • 基金资助:
    内蒙古自治区地质勘查基金管理中心综合研究项目“中部满都拉-白乃庙一带铜金多金属矿成矿规律与找矿预测”(2018-01-YS01)

Zircon and apatite fission track chronology of intrusive rocks in the Bainaimiao Cu-Au deposit, Inner Mongolia

LÜ Zhao1(), XU Zhan2, PANG Jianzhang3, WANG Jichun2, WANG Jianping1,*(), YUAN Shuopu1   

  1. 1. School of Earth Sciences and Resources, China University of Geosciences (Beijing), Beijing 100083, China
    2. Geological Survey Institute of Inner Mongolia, Hohhot 010020, China
    3. Institute of Geology, China Earthquake Administration, Beijing 100029, China
  • Received:2021-06-22 Revised:2021-09-19 Online:2023-05-25 Published:2023-04-27

摘要:

斑岩铜矿形成后常常遭受后期抬升剥蚀和破坏改造,内蒙古白乃庙铜金矿床是中国北方造山带中少有的几个早古生代斑岩铜矿床之一,其变化保存过程研究具有理论和找矿双重意义。锆石裂变径迹和磷灰石裂变径迹热年代学研究表明,自150 Ma以来白乃庙铜金矿区总体剥蚀量为3.11~3.25 km。矿区内岩体隆升冷却呈快速—缓慢—快速阶梯状3个阶段:150~<90 Ma快速剥露阶段,构造应力以挤压作用为主,平均剥蚀速率0.045 7 mm/a;90~<20 Ma稳定剥蚀阶段,矿区构造应力由挤压转变为伸展,平均剥蚀速率0.003 3 mm/a;20 Ma至今快速剥露阶段,矿区构造应力为挤压作用,平均剥蚀速率0.038 8 mm/a。加里东期到燕山期,矿区受古亚洲洋俯冲、碰撞以及陆内造山活动的影响,白乃庙铜金矿成矿后处于挤压和伸展交替的环境,为白乃庙铜金矿的变化保存提供了有利的地质条件。

关键词: 白乃庙铜金矿, 构造-热历史, 裂变径迹年龄, 矿床变化保存

Abstract:

Porphyry copper deposits often experience late-stage uplifting, denudation, destruction and transformation after deposition. The Bainaimiao Cu-Au deposit in Inner Mongolia is one of the few Early-Paleozoic porphyry copper deposits in the orogenic belt of northern China, therefore, it is of both theoretical and practical (in mineral prospecting) significance to study the mineral alteration/preservation processes. According to thermochronological analysis of zircon fission tracks and apatite fission tracks, the total denudation of the Cu-Au mining area since 150 Ma is between 3.11-3.25 km, and the late-stage uplifting and cooling of intrusive rocks in the study area can be characterized by a three-stage process. During the rapid exhumation stage between 150-90 Ma, the tectonic stress is mainly compressional, and the average denudation rate is 0.0457 mm/a; in the stable denudation stage from 90 to 20 Ma, extensional stress dominates, and the average denudation rate is 0.0033 mm/a; and during the rapid exhumation stage from 20 Ma to present, compressional stress again dominates, and the average denudation rate is 0.0388 mm/a. Thus, from the Caledonian to Yanshanian, affected by subduction and collision of the ancient Asian Ocean and intracontinental orogenic activities, the mining area is under tectonic stresses alternating between compressional and extensional, which provides favorable geological conditions for mineral alteration/preservation in the Bainaimiao Cu-Au deposit.

Key words: Bainaimiao Cu-Au deposit, structural-thermal history, fission track age, mineral alteration/preservation

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