【作者】 林方成；

【导师】 郑明华；

【作者基本信息】 成都理工大学 ， 矿物学 岩石学 矿床学， 2005， 博士

【摘要】 近年来，地方采矿业和国土资源地质大调查的实施，在扬子地台西缘四川乌斯河至金口河的大渡河谷沿岸在上震旦统一下寒武统灯影组白云岩中发现了黑区一雪区、宝水溪、莲花岩等一批整合层状铅锌矿床、矿点或矿化点，绵延长达数十千米的矿化带。带内层状矿体的延伸可达数千米。作者首次对该类层状铅锌矿床进行了较为深入的成矿作用研究，首次提出该类央于白云岩中与黑色富有机质硅岩建造密切共生的层状矿床，属于典型的海底热水沉积成因，即SEDEX型矿床；而与世界上其他SEDEX型矿床在容矿岩石组合、产出构造环境等相对比具有独特性，因而将其命名为SEDEX型大渡河谷式（Dadu River Valley Style）矿床，简称“DRVS式矿床”。作者在DRVS式矿床中识别出典型的震积岩组合及震积构造，这可能是首次发现的与金属矿床有成因联系的震积岩，具有重要的科学意义。作者阐明了强烈的海底地震可能是诱发深部含矿流体发生大规模运移和喷流成矿的动力学机制。通过分子有机地球化学的研究，在矿床中发现丰富的热演化程度高的烃类、沥青、干酪根等有机质，其来源于元古代海相菌藻类低等生物，表明其在矿源层的形成、矿质迁移、矿石沉淀中发挥重要的作用。首次提出矿床的产出受灯影期汉源—峨眉NEE向同沉积凹陷以及发育于凹陷轴部的同生断裂带的控制；同期发育的还有宁南—会理NE东向凹陷，该凹陷是最有希望找到DRVS式矿床的区域。指出喷流成矿在水／岩界面以上在80～86℃条件下形成大规模的层状矿体；在水岩界面以下在140～285℃条件下在同生断裂带内形成脉状、浸染状矿体。矿石以充填-交代、胶体化学沉积、化学沉积、碎屑流沉积等4种方式沉淀。矿石中的硫质来自海水硫酸盐的还原，而Zn、Pb、Fe、SiO₂、Ba、有机质等主要来自中元古界峨边群等基底变质岩系，来源深度可能在5～7km或更深。首次提出，扬子地台西缘存在中元古代VMS型、前寒武纪—寒武纪界限附近SEDEX型、燕山期—喜山期MVT型三个重要的铅锌成矿期，SEDEX型是仅次于MVT型具有重要找矿前景的矿床类型。更多还原

【Abstract】 A number of conformable stratiform Pb-Zn deposits and occurrences have been discovered in recent years along the Dadu River valley on western margin of the Yangtze Craton. The sulfide-bearing blackish siliceous rocks are interbedded in top of dolomite of Upper Sinian — Lower Cambrian Dengying Formation. Based on detail field and microscope observation and ore geochemical analyses, the author put forwards that these deposits are genetically SEDEX-type. In consideration of particular aspects of the deposits such as the combination of dolomite-blackish siliceous rocks-sulfide-dolomite in profile and the ore having formed in stable tectonic setting in early stage of the Yangtze Craton, the author names these deposits as Dadu River Valley Style deposits of SEDEX-type （abbreviated as DRVS deposits）. Typical seismites sequence and seismic structures are recognized within the Pb-Zn orebeds, which might be the first case has ever been reported that seismites occur within Pb-Zn deposits. The author suggests that the hydrothermal exhalative metallogeny have been induced by severe submarine earthquakes in early Cambrian. Highly matured organic matters, e.g., hydrocarbon, bitumen, kerogen, and etc., have been identified in the ore. The organic matters are supposed to have evaluated from Proterozoic marine alga and bacteria, and have take significant roles in metals’ accumulation in ore source bed, metal migration in ore-bearing fluid and deoxidization of SO₄^2- in seawater to S^2- to cause ore precipitation. Through the analysis of ore-forming lithofacies-paleogeographical conditions, the author points out that the DRVS deposits are controlled by both NEE-extending Hanyuan-Emei synsedimentary depression and contemporaneous fault system located at the axis of the depression during Upper Sinian—Lower Cambrian Dengying Period. The development of these synsedimentary depression and fault were affected by Proterozoic basement structures. There was another synsedimentary depression, the NE-extending Ningnan— Huili depression, existed at the same period, where might be the most hopeful region to discover the DRVS deposits. During the mineralization process of the DRVS deposits, two mineralization subsystems existed, one above the rock/ water boundary, which formed the conformable stratiform ores at temperature of 80⁸6℃; the other below the rock/ water boundary, which formed vein ores at temperature of 140-285 ℃. The ores更多还原