中国东部中生代晚期岩浆核杂岩隆起-拆离带构造成矿特征与金-多金属矿田勘查
Tectonic metallogenic characteristics of Late Mesozoic magmatic core complex uplift-detachment zone in eastern China and prospecting for gold-polymetallic ore fields
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摘要: 中国东部中生代晚期发育伸展构造, 诱发强烈的岩浆活动, 出现大规模成矿事件。本文将伸展构造核部出露中生代晚期岩浆杂岩、边部出露拆离断层作为主要标志, 将多期岩浆侵入形成的变质核杂岩和伸展穹窿均归入中生代晚期岩浆核杂岩隆起-拆离带构造范畴。前者主要形成深源金-多金属矿床, 后者主要形成浅源有色金属矿床。前者主要产于古老变质岩区, 后者主要产于古生代沉积-火山岩区。岩浆上侵的诱因, 主要与晚中生代太平洋板块的俯冲-折返机制有关。结合地球物理资料, 探讨了岩浆核杂岩的深部控制因素。基于"岩浆核杂岩隆起-拆离带"岩浆期后热液成矿模式, 总结了岩浆热液型贵金属、有色金属矿床的分布规律、成矿条件和找矿标志, 提出了中尺度"矿田找矿"的新方向, 在辽南、皖北地区预测了有利的隐伏远景区。Abstract: Extensional structures developed in the Late Mesozoic in eastern China, which induced intense magmatic activity and large-scale metallogenic events.This paper will extend structure of the Late Mesozoic magmatic core complex and edge exposed detachment fault as the main logo, the multiphase magmatic intrusion formed metamorphic core complex and extensional dome are classified as the structural category of Late Mesozoic magmatic core complex uplift-detachment belts.The former mainly forms deep-sourced gold-polymetallic deposits, while the latter mainly forms shallow-sources non-ferrous metal deposits.The former is mainly distributed in the area of ancient metamorphic rocks, while the latter mainly occurred in the area of Paleozoic sedimentary-volcanic rocks.The inducement of magmatic uptrusion is mainly related to the subduction-reentry mechanism of the Pacific plate in Late Mesozoic.Combining with geophysical data, the deep controlling factors of magmatic core complex are discussed.Based on the post-magmatic hydrothermal metallogenic model of magmatic core complex uplift-detachment zone, the distribution, metallogenic conditions and prospecting criteria of magmatic hydrothermal deposits of precious and non-ferrous metals are summarized.A new direction of mesoscale ore field prospecting is proposed, and favorable concealed prospect areas are predicted in southern Liaonan and northern Anhui.