欢迎访问《高校地质学报》官方网站,今天是
分享到:

高校地质学报 ›› 2024, Vol. 30 ›› Issue (05): 559-576.DOI: 10.16108/j.issn1006-7493.2024040

• • 上一篇    下一篇

北武夷上水桥萤石矿区黑云母石英二长岩成因:来自年代学及地球化学的制约

曾祥辉1,3,孟德磊1,3,曾闰灵1,2,3,蒋起保1,3,欧阳永棚1,2,3*   

  1. 1. 江西省地质局第十地质大队,鹰潭 335001;
    2. 关键矿产资源勘查与开发江西省重点实验室,南昌 330009;
    3. 鹰潭市紧缺及优势矿产勘查与研究重点实验室,鹰潭 335001
  • 出版日期:2024-10-20 发布日期:2024-10-20

Petrogenesis of the Biotite Quartz Monzonite from Shangshuiqiao Fluorite Deposit, North Wuyi Area: Constraints from Geochronology and Geochemistry

ZENG Xianghui1,3,MENG Delei1,3,ZENG Runling1,2,3,JIANG Qibao1,3,OUYANG Yongpeng1,2,3*   

  1. 1. The tenth Geological Brigade of Jiangxi Geological Bureau, Yingtan 335001, China;
    2. Jiangxi Province Key Laboratory of Exploration and Development of Critical Mineral Resources, Nanchang 330009, China;
    3. Yingtan Key Laboratory of Exploration and Research of Scarce and Advantage Minerals, Yingtan 335001, China
  • Online:2024-10-20 Published:2024-10-20

摘要: 上水桥萤石矿是北武夷地区近些年来新探明的一处极具开采前景的中型萤石矿床,目前开展的研究工作极为薄弱。该项工作以矿区赋矿岩体黑云母石英二长岩为研究对象,对其展开系统的岩相学、锆石U-Pb年代学和全岩地球化学分析。锆石U-Pb定年结果表明,上水桥黑云母石英二长岩成岩年龄为235~236 Ma,为印支期岩浆活动的产物。全岩地球化学分析结果显示,该岩体具有富碱、贫磷钛的特征,具有较高的σ值(2.59~3.61)和偏低的A/CNK值(0.96~1.16),属钾玄质、准铝质—弱过铝质岩石;微量及稀土元素方面,岩石相对富集大离子亲石元素(Rb、Th、U、K)和LREE,亏损Ba、Sr、Nb、Ta、P、Ti、HREE等元素,同时整体具有较高的稀土含量(ΣREE=356×10-6~448×10-6)和弱负铕异常(Eu/Eu*=0.61~0.76)。此外,岩石整体具有较高的Zr+Nb+Ce+Y含量(381×10-6~546×10-6)和Ga/Al比值(104×Ga/Al=2.60~3.07),以及较低的b/Sr(0.31~0.82)、Rb/Ba(0.11~0.18)和TFeO/MgO比值(2.02~2.22),属后造山型(PA型)铝质A型花岗岩。综合地球化学投图判别结果及区域岩浆活动、沉积作用等特征,文章认为上水桥矿区黑云母石英二长岩可能为多板块汇聚模式下陆内造山作用末期后造山伸展的构造背景下的产物,成矿阶段岩石中黑云母的水解及斜长石的绢云母化作用可能为萤石成矿提供F和Ca来源。

关键词: 北武夷, 上水桥萤石矿, 印支期, 铝质A型花岗岩, 岩石成因

Abstract: Shangshuiqiao fluorite ore is a newly discovered medium fluorite deposit with great exploitation prospect in northern Wuyi area in recent years. However, little research has been carried out on this deposit. In this paper, petrographic, zircon U-Pb chronological and whole-rock geochemical analyses have been carried out on the biotite quartz monzonite from the the Shangshuiqiao fluorite deposit. The zircon LA-ICP-MS U-Pb ages show that the biotite quartz monzonite was formed at  235~236 Ma, which is the product of Indosinian magmatism. According to the geochemical analyses, the biotite quartz monzonite samples are characterized by high alkali (Na2O+K2O), Mg and Fe contents and low P and Ti contents. They have high σ values (2.59 and 3.61) and low A/CNK ratios (0.96 to 1.16), belonging to the typical high-K series with metaluminous to weakly peraluminous. In terms of trace and rare earth elements, the biotite quartz monzonite is enriched in Rb, Th, U, K and light rare earth elements (LREEs), but depleted in Ba, Sr, Nd, Ta, P, Ti and heavy rare earth elements (HREEs), as well as high rare earth elements (ΣREE varying from 356×10-6 to 448×10-6) and weak negative Eu anomalies (Eu/Eu* between 0.61 and 0.76). Besides, the biotite quartz monzonite displays high Zr+Nb+Ce+Y content (varying from 381×10-6 to 546×10-6) and Ga/Al ratio (104×Ga/Al between 2.60 and 3.07), with lower Rb/Sr (0.31 to 0.82), Rb/Ba (0.11 to 0.18) and TFeO/MgO ratios (2.02 to 2.22), belong to post-orogenic (PA type) aluminous A-type granites. In addition, based on the results of geochemical mapping and characteristics of regional magmatism and sedimentation, we suggest that the biotite quartz monzonite from Shangshuiqiao fluorite deposit may be formed in the postorogenic extensional tectonic environment at the end of intracontinental orogeny under the background of multi-plate convergence. During the mineralization stage, the biotite hydrolysis and sericitization of plagioclase in biotite quartz monzonite may provide F and Ca sources for fluorite mineralization.

Key words: north Wuyi area, Shangshuiqiao fluorite deposit, Indosinian, aluminous A-type granite, petrogenesis

中图分类号: