哀牢山成矿带壳幔相互作用与金成矿关系探讨——以元阳大坪金矿床为例  

Relationship between crust-mantle reaction and gold mineralization in Ailaoshan metallogenic belt:A case study of Daping gold deposit in Yuanyang

作　　者：袁士松[1,2] 葛良胜[2] 路彦明[2] 郭晓东[1,2] 王美娟[2] 王治华[1,2] 邹依林[1,2] 

机构地区：[1]中国地质大学地球科学与资源学院,北京100083 [2]中国人民武装警察部队黄金地质研究所,河北廊坊065000

出　　处：《矿床地质》2010年第2期253-264,共12页Mineral Deposits

基　　金：国家"十一.五"科技支撑项目(编号:2006BAB01B10);国家重点基础研究发展计划(编号:2009CB42100)的联合资助

摘　　要：哀牢山成矿带位于云南省中南部,带内相续发现了墨江金厂、镇沅老王寨和元阳大坪等一批大型-超大型金多金属矿床。滇西南地区的莫霍面等深度特征、大陆地温梯度和大地热流高异常特征以及地球深层次结构特征,一致表明哀牢山地区在新生代处于强烈的壳幔相互作用时期。以大坪超大型金矿床同位素组成为例开展了示踪学研究,结果表明,成矿物质及成矿流体均以上地幔或下地壳来源为主,成矿过程中有少量地壳浅部的大气饱和水、岩浆水或它们的混合流体的加入。区域地球物理场特征及同位素示踪学研究一致表明,在哀牢山成矿带内矿床形成过程中,伴随有强烈的深部岩浆活动,壳幔相互作用对该地区矿床的形成有重要贡献。The Ailaoshan metallogenic belt is located in the middle-south part of Yunnan Province, where there are several large-superlarge gold-polymetallic deposits such as Jinchang in Mojiang, Laowangzhai in Zhenyuan and Daping in Yuanyang. Regional geophysical characteristics show that the NW-striking Ailaoshan metallogenic belt has a complicated crust-mantle structure. The Moho discontinu-ity isobath features reveal that the crust in the northeast is thicker than that in the southwest and represents a mantle-slope on the whole. Regional studies of the seismic wave velocity of the lower crust and the upper mantle indicate that there exists a large-area low-velocity anomalous belt in southwest Yunnan Province, which perhaps has relationship with the thermal dynamical effect caused by partial melt of the lower crust materials resulting from the uplift of the upper mantle materials in the crust-mantle boundary. Such a phenomenon also implies that there once occurred a strong crust-mantle reaction in the Ailaoshan metallogenic belt. The high anomalous features of the continental geothermal gradient and the terrestrial heat flow demonstrate that the metallogenic belt has characteristics of high-temperature and low-pressure mantle slope, which might be attributed to the heat flow uplift caused by intense crust-mantle reaction at depth. Detailed isotope studies of the Daping superlarge gold-polymetallic deposit shows that the main source of the ore-forming fluid was deep crust-mantle mixed fluid rather than gas-saturation water, magmatic water or their mixed water in the upper crust. The coherence between regional geophysical and isotope characteristics shows that the ore-forming progress was accompanied by the strong deep magmatic activity in the Ailaoshan metallogenic belt, and that the crust-mantle reaction made an important contribution to the mineralization in Ailaoshan area.

关 键 词：地质学 壳幔相互作用 哀牢山成矿带 超大型矿床 大坪金矿 云南 

分 类 号：P618.51[天文地球—矿床学]