| 浙西北湖安地区花岗岩剥露程度及其对萤石矿找矿的启示——来自于磷灰石裂变径迹的证据 |
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| 引用本文：闫巧娟,张文高,陈正乐,王晓虎,徐正华,刘勋,丁志磊,王波.2021.浙西北湖安地区花岗岩剥露程度及其对萤石矿找矿的启示——来自于磷灰石裂变径迹的证据[J].地球学报,42(5):651-662. |
| DOI：10.3975/cagsb.2021.051401 |
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| 基金项目:中国地质科学院基本科研业务费项目(编号: DZLXJK201904);中国地质调查局地质调查项目(编号: DD20190161);国家重点研发计划项目(编号: 2018YFC0604005);国家自然科学基金项目(编号: 41902214);浙江省地质勘查局产业结构调整专项资金科研项目(编号: [浙地勘]2020-3) |
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| 中文摘要:浙西北湖(州)—安(吉)地区近年来新发现一系列的大中型萤石矿, 显示出该地区良好的萤石矿成矿潜力。随着勘查工作的持续推进, 地表找矿难度的增加, 对浙西北萤石矿深部找矿潜力的研究逐渐被大家所重视。本文选择浙西北湖安地区典型萤石矿区出露的花岗岩体, 通过磷灰石裂变径迹技术, 获得花岗岩体的裂变径迹年龄, 分析花岗岩经历的热演化历史, 通过温度-时间热史模拟反演, 探讨湖安地区不同区域的剥蚀程度, 推测研究区深部的找矿潜力。研究结果显示, 样品的裂变径迹年龄集中在(29±2) ~ (53±3) Ma之间, 且年龄有自西向东逐渐变新的趋势。温度-时间反演模拟显示, 湖安地区自晚白垩世以来一直处于隆升-剥蚀的状态, 局部地区在新生代经历过快速的抬升和伸展作用, 平均剥蚀速率为0.062 mm/a, 剥蚀量在2 km以上。利用温度-时间模式曲线, 计算了不同区域的典型萤石矿区的剥蚀程度, 结果显示研究区西侧平均剥蚀量为2.89 km, 中间平均剥蚀量为3.69 km, 研究区东侧平均剥蚀量为4.08 km。结合地表地形地貌特征, 以及萤石矿成矿年龄与矿区花岗岩年龄之间的年龄间隔, 认为研究区现今出露地表的花岗岩可能并非萤石矿的成矿地质体, 现今萤石矿的成矿地质体可能还在深部。根据研究区西侧剥蚀量低于东侧, 推断西侧萤石矿深部可能具有更好的成矿潜力。这一结论可以为湖安地区萤石矿下一步勘探工作提供依据。 |
| 中文关键词:裂变径迹 剥蚀厚度 萤石矿 矿体保存 浙西北 |
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| Granite Denudation Degree and Its Implications for Fluorite Prospecting in Hu’an Area, Northwest Zhejiang Province:Evidence from Apatite Fission Track Thermochronology |
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| Abstract:In recent years, a series of fluorite deposits have been discovered in the Hu’an volcanic basin,northwest Zhejiang Province, which shows a good metallogenic potential of fluorite deposits in this area. With the development of exploration and increasing difficulty of surface prospecting, more and more attention has been paid to the study of deep potential of fluorite deposits in Hu’an area. In this paper, the authors selected the granite rock in typical fluorite mining areas in Hu’an area to investigate the denudation degree in different places and predict the deep prospecting potential through apatite fission track technology and temperature-time thermal history simulation inversion study. The results show that the fission track age of the samples is concentrated in the range of (29±2) ~ (53±3) Ma, and the age becomes gradually younger from west to east. The temperature-time inversion simulation shows that the Hu’an area has been in a state of constant uplift and denudation since the Late Cretaceous, and Cenozoic uplift and extension existed in some areas，with an average denudation rate of 0.062 mm/a and the denudation amount more than 4km. Using the temperature time model, the authors calculated the denudation degree of typical fluorite mining areas in different places. The results show that the average denudation amount in the west, middle and east of this area is 2.89 km, 3.69 km and 4.08 km, respectively. Combined with the characteristics of surface topography and geomorphology and the age interval between fluorite mineralization age and granite age in the mining area, the authors hold that the granite outcropped in the study area may not be the ore-forming geological body of fluorite deposit, and the ore-forming geological body of fluorite deposit may still be deep. In addition, the denudation amount in the west of this area is lower than that in the east. Therefore, it is considered that the fluorite deposit in the west of the area may have better metallogenic potential. This conclusion can provide a basis for further exploration of fluorite in Hu’an area. |
| keywords:fission track thermochronology thickness of denudation fluorite deposit conservation of deposit northwest Zhejiang Province |
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