东特提斯域思茅盆地钾盐成矿研究进展  

Research Advances in Potash Forming of the Simao Basin,Eastern Tethyan Realm

作　　者：王立成[1] 刘成林[1] 沈立建[1] 伯英[1] WANG Licheng;LIU Chenglin;SHEN Lijian;BO Ying(MNR Key Laboratory of Metallogeny and Mineral Assessment,Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China)

机构地区：[1]自然资源部成矿作用与资源评价重点实验室中国地质科学院矿产资源研究所,北京100037

出　　处：《地质学报》2018年第8期1707-1723,共17页Acta Geologica Sinica

基　　金：国家自然科学基金项目(编号41572067;41502080);国家重点发展研究计划项目(973计划)(编号2011CB403007)联合资助的成果

摘　　要：思茅盆地位于东特提斯域,其内的勐野井钾盐矿是我国唯一的前第四纪固体钾盐矿,长期以来对此钾盐矿与呵叻巨型钾盐盆地的资源量差异和成因存在着有较大争议。特别是如下几个问题:其钾盐成矿时代是晚白垩世和古新世,还是侏罗纪的争议;其物质来源还存在陆源,海源和多源的不同认识;矿床成因机理模式也悬而未决。本文在前人研究基础上,结合项目组的最新进展,对上述这些问题的进行梳理与评述认为:勐野井组地层为晚白垩世Albian-Cenomanian期,同沉积的原生钾盐也是在此时期富集成矿;钾盐成矿后期特别是约14Ma以来,受到多期次的热液流体作用,形成次生脉状钾盐:钾盐成矿物质可能以中特提斯洋侵入的海水为主,辅以陆源水体和深部流体。总结认为,思茅与呵叻等盆地在晚白垩世都是干旱沙漠环境中彼此隔绝的小湖盆,随着中特提斯洋海水自西向东的入侵,海水由思茅流向了呵叻,形成了统一的思茅-呵叻海,这个模型可以解释有关成钾物源及思茅与呵叻盆地的成钾关系。思茅盆地钾盐矿的形成和后期变化始终受到了构造活动的控制,经历了最初断陷阶段,到沉积后期受印度-欧亚大陆碰撞导致的挤压和走滑运动影响。The Mengyejing potash deposit, which is located in the southern Simao basin of eastern Tethyan realm and approximately 500 km north of the Khorat basin, is only pre-Quaternarya solid potash deposit in China. The Khorat basin contains immense potash deposits occurring mainly in the Maha Sarakham Formation. There has long been dispute about resources amounts and genesis between the Mengyejing potash deposit and the Khorat huge potash basin, especially about the questions below. Controversies still occur over potash-forming ages over the late Cretaceous, Paleocene and even Jurassic; potash material sources from continental, marine and multiple sources; and their ore-formation mechanisms. Through summarizing previous research and the results in this study, we suggest that the Mengyejing Formation stratum is Albian to Cenomanian of the Late Cretaceous in age and the primary potash deposited at the same time. The primary potash was affected by multiple hydrothermal fluids during the post depositional stage, especially since 14 Ma, resulting in the formation of secondary vein-type potash. The ore-forming material of potash deposit might be dominantly sea water due to incursion of the Mid-Tethyan Ocean with minor amount of continental water and deep fluids. It can be concluded that the Simao and Khorat basins were isolated lakes in arid desert environment during the Late Cretaceous and the transgression of Mid- Tethys Ocean from west to east resulted in flowing of seawater into Khorat basin, forming a unified Simao- Khorat Sea. This model can interpret the relation between the sources of the potash deposits and genetic link between of Simao and Khorat basins. The formation and late-stage alteration of the potash deposits in the Simao basin had been controlled mainly by tectonic activities from initial faulted subsidence to compression and strike-slip by the collision of India and Asia at the post-sedimentation stage.

关 键 词：勐野井组 钾盐 晚白垩世 海侵 构造运动 思茅盆地 

分 类 号：P619.211[天文地球—矿床学]