投稿时间：2025-09-25
修订日期：2026-03-12
网络发布日期：2026-04-22
中文摘要:北淮阳成矿带东段广泛出露新元古代花岗质岩石，其岩性主要为正长花岗质片麻岩，并伴生有少量正长花岗岩，且与区内铅锌矿化关系密切。因此，对该套岩石进行系统的成因机制研究，对于深入理解北淮阳成矿带的构造演化及其成矿作用过程，具有重要的科学意义。文章以北淮阳毛坦厂地区新元古代花岗质岩体作为研究对象，综合开展了锆石U-Pb年代学、地球化学等方面的工作。锆石U-Pb定年结果显示，正长花岗质片麻岩的成岩年龄为（803.2±1.3）Ma、正长花岗岩的形成年龄为（803.9±1.4）Ma，两者在误差范围内几乎一致，共同限定了其形成时代为新元古代中期（约804 Ma）。岩石地球化学分析表明，两类岩石均具富硅（w(SiO2)=65.85%~75.74%）、低镁（w(MgO)=0.05%~0.93%，Mg#=21~47）等特征。稀土元素配分模式呈现显著右倾型，轻稀土元素富集（(La/Yb)N=33.1~50.57），重稀土元素相对亏损，且普遍发育强烈的负Eu异常（δEu=0.19~0.33）；微量元素蛛网图中显示明显富集La、Nd、Ce、Zr、Sm、Th、U、Hf等不相容元素，相对亏损Sr、Ti、Nb等元素。综合分析认为，2种岩石均具有A型花岗岩特征，形成于晋宁期桐柏-大别造山后的伸展环境，是地壳物质部分熔融的产物。同时结合岩体含矿特征，也为北淮阳地区铅锌矿找矿提供了新的方向。
Abstract:Neoproterozoic felsic intrusions are widely exposed in the eastern segment of the Beihuaiyang Metalorgenic Belt, dominated by syenogranitic gneiss with subordinate syn- to post-tectonic syenogranite intrusions. These plutons host spatially and temporally associated with Pb-Zn mineralization, rendering their petrogenesis pivotal for constraining the tectonic evolution and metallogenic framework of the belt. This study focuses on the Neoproterozoic granitoids from the Maotanchang area, integrating zircon U-Pb geochronology, whole-rock major- and trace-element geochemistry. LA-ICP-MS zircon U-Pb dating yields concordant weighted mean 206Pb/238U ages of (803.2±1.3)Ma for the syenogranitic gneiss and (803.9±1.4)Ma for the syenogranite, indicating coeval emplacement during the Mid-Neoproterozoic (~804 Ma). Geochemically, both rock types are silica-rich (w(SiO2)=65.85%~75.74%), and markedly Mg-poor (w(MgO)=0.05%~0.93%; Mg#=21~47). Chondrite-normalized REE patterns display strong light-REE enrichment ((La/Yb)N=33.1~50.57), steep heavy-REE depletion, and pronounced negative Eu anomalies (δEu=0.19~0.33). Trace element spider diagrams exhibit marked enrichment in Rb, Th, U, K, Pb, Zr, Hf, Ce, Nd, and La, coupled with systematic depletions in Sr, Ba, Ti, Nb, Ta, and P. Petrogenetic discrimination classifies both units as A-type granites. Their geochemical signatures point to partial melting of potassium-rich, felsic lower-to-middle crust. This melting event occurred during regional lithospheric extension following the culmination of the Jinningian Tongbai-Dabie orogeny. Given the tight spatiotemporal association between these A-type intrusions and Pb-Zn mineralization, this work provides new guidance for future Pb-Zn deposit exploration targeting in the eastern Beihuaiyang Belt.
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基金项目:本文得到深地国家科技重大专项项目（编号：2025ZD1007401）、新一轮找矿突破战略行动科技支撑项目（编号：ZKKJ202525）、中国地质调查局项目（编号：DD20240202702、DD202402027）和国家自然科学基金（批准号：42402095）联合资助
引用文本：
武彬,张雪辉,王冲,丰效坤,韦星,张翔,龚赞,方舒彬,孙建东.2026.北淮阳成矿带东段新元古代花岗岩体成因及其找矿指示[J].矿床地质,45(2):457~474WU Bin,ZHANG XueHui,WANG Chong,FENG XiaoKun,WEI Xing,ZHANG Xiang,GONG Zan,FANG ShuBin,SUN JianDong.2026.Genesis and implication for mineral exploration of Neoproterozoic granite plutons in eastern section of Beihuaiyang metallogenic belt[J].Mineral Deposits45(2):457~474
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