大兴安岭中南段印支期成矿事件及其地球动力学背景

As one of the sixteen major metallogenic belts in China, the Da Hinggan Mountains have been the hot spots among domestic and foreign geologists for many years. Most researchers thought that the metallogenesis in Da Hinggan Mountains was related to the Yanshannian magmatism. Some ore deposits in this region, however, were actually formed during Indosinian according to the recent study. Therefore, under what tectonic setting did the Indosinian metallogenic event in Da Hinggan Mountains take place? How many ore deposits are the products of this metallogenic event? How were these Indosinian ore deposits formed? And whether were these ore deposits reworked by Yanshanian tectono-magmatic activity? To answer these questions, the Cu, Sn, Ag, Pb, Zn and Mo deposits occurring in the south-central part of Da Hinggan Mountains are selected to study in detail in this proposal. Based on the former researchers' and applicant's work, the first thing is to idenfy the Indosinian metallogenic event through the geochronogical study. Then, the Indosinian granites and related ore deposits will be studied to recognize the main mineralization types, lasting time, and the geodynamic setting, in order to discuss the relationship between Indosinian tectono-magmatic activity and metallogenesis. This will finally deepen the understanding of the metallogeny in Da Hinggan Mountains, enrich the researches on superimposed metallogenesis in complex orogenic belt, and provide reliable theory for the mineral exploration and potential assessment in the region.

作为我国16个重要成矿带之一，大兴安岭地区一直是国内外地学界的研究热点。长期以来，有关大兴安岭地区的金属成矿作用，多被认为与燕山期岩浆活动有关。然而，近年来的年代学研究陆续发现确有一些矿床形成于印支期，那么印支期成矿地质事件到底是在一个什么样的地质背景下形成的？都有哪些矿床与印支期成矿事件有关？这些矿床是如何形成的？是否受到了燕山期构造-岩浆活动改造？针对这些科学问题，本项目拟选择大兴安岭中南段地区铜锡银铅锌钼多金属矿床，在前人和申请者以往工作基础上，以成岩成矿年代学为研究重点，首先确认印支期成矿事件，其次对与印支期成矿有关的花岗岩类及相关矿床开展深入研究，查清印支期成矿事件主要矿化类型、持续时间、产生的地球动力学背景，探讨大兴安岭中南段地区印支期构造岩浆活动与成矿之间的耦合关系，深化对本区成矿规律的认识，丰富复杂造山带叠加成矿的研究内容，并为区域找矿勘查和资源潜力评价提供可靠的理论依据。

作为我国16个重要成矿带之一，大兴安岭地区一直是国内外地学界的研究热点。长期以来，有关大兴安岭地区的金属成矿作用，多被认为与燕山期岩浆活动有关。然而，近年来的年代学研究陆续发现确有一些矿床形成于印支期，那么印支期成矿地质事件到底是在一个什么样的地质背景下形成的？都有哪些矿床与印支期成矿事件有关？这些矿床是如何形成的？是否受到了燕山期构造-岩浆活动改造？针对这些科学问题，本项目拟选择大兴安岭中南段地区铜锡银铅锌钼多金属矿床，在前人和申请者以往工作基础上，以成岩成矿年代学为研究重点，首先确认了印支期成矿事件，其次对与印支期成矿有关的花岗岩类及相关矿床开展了深入研究，查清了大兴安岭中南段地区印支期成矿事件主要矿化类型、持续时间和产生的地球动力学背景，探讨大兴安岭中南段地区印支期构造岩浆活动与成矿之间的耦合关系，深化对本区成矿规律的认识，尤其是在强烈的燕山期成矿事件中去鉴别出印支期成矿事件，丰富复杂造山带环境下的叠加成矿的研究内容，并为区域找矿勘查和资源潜力评价提供可靠的理论依据。根据本次研究，大兴安岭中南段地区印支期成矿事件的主要矿化类型是矽卡岩型铅锌矿床和斑岩型钼矿床，印支期矿化持续的时间大约是从：245Ma~235Ma，其地球动力学背景应该是处于同碰撞向碰撞后伸展转换阶段。在白音诺尔铅锌矿床，根据地质穿插关系、矿化类型的不同、成矿物质来源示踪已经地质年代学研究，发现了两期矿化事件，早期印支期的矽卡岩型铅锌矿化叠加了晚期燕山期的热液脉型铅锌矿化，该项研究为本区叠加成矿作用研究提供了一个范例。总之，本基金项目的研究已经顺利完成了既定的研究目标。