新疆北东部三塘湖地区二叠纪地幔热液喷流沉积及其形成机理

Research and exploration on the sedimentary characteristics, sedimentary regularities and biological activities of mantle-originated hydrothermal exhalative deposition in modern and geological history are important frontiers of geoscience.This project takes permian laminated mantle-originated hydrothermal exhalative deposits in Yuejingou section in Santanghu area as the research object.This research is based on the comparisons and studies on the stratigraphic compositions and sedimentary characteristics of field outcrops and drilling cores. Microscopy and electron microscopy observations combined with electron probe and X-ray diffraction analysis are adopted to do detailed research on mineralogy and petrology.We analyse the assemblage sequences and forming conditions of main mineral (dolomite，ankerite, analcime,sanidine, orthoclase, albite, high magnesiun calcite, quartz,etc) and thermophilic autotroph.Besides,the petrological characteristics and deposition mechanism of main litho (dolostone, analcime- dolostone, analcimite, algal dolostone, analcime- siliceous stone)are finely discused.Various of methods are taken by using major and trace element analysis as well as istope test analysis ,such as C,O,Sr,Rb,Pb,S,Si,Re,Os,He,to determinte types of litho,geochemistry of mineral and isotope and sedimentary environment,study the properties and origins of hydrotherm and exhaltive activitiy regularities and explore the forming mechanism and sedimentary regularities in intracontinental rift basin in geological history.

现代和地质历史时期中的地幔热液喷流沉积特征、沉积规律及其与生物活动的研究与探索是当代地球科学研究的重大前缘领域之一。本项目拟以新疆三塘湖地区二叠系芦草沟组纹层状热液喷流岩为研究对象，在野外露头和钻井岩心的地层组成、沉积特征对比研究基础上，采用显微、超显微观察，结合电子探针、X光衍射等方法进行矿物学和岩石学精细研究，分析主要矿物(白云石、铁白云石、方沸石、透长石、正长石、钠长石、高镁方解石、石英等)及嗜热自养生物的成生、组合序列及形成条件；探讨主要岩石(白云岩、方沸石白云岩、方沸石岩、藻云岩、方沸石硅质岩等)的岩石学特征及沉淀机理。采用常量、微量元素分析及碳、氧、锶、钕、铅、硫、硅、铼、锇、氦等同位素测试分析,确定不同岩类岩石、矿物的地球化学、同位素地球化学特征及沉积环境，分析热液性质、来源及幕式喷流活动规律，探讨地质历史时期陆内裂谷盆地地幔热液喷流岩的形成机理及沉积规律。

现代和地质历史时期中的地幔热液喷流沉积特征、形成机理及其与生物、油气关系的研究与探索是当代地球科学研究的重大前缘领域之一。本项目采用显微、超显微观察，宏观和微观研究相结合等方法对新疆三塘湖盆地58口钻井的二叠纪芦草沟组及其跃进沟地表剖面进行持续性综合研究，在以下几方面取得创新性成果与认识：1.通过对矿物学和岩石学的精细研究，提出一类新型（三塘湖型）的富含超基性-中酸性岩浆碎屑的纹层状地幔热液喷流沉积岩（简称喷积岩），按照形成方式分为喷爆岩、喷流岩、喷溢岩、喷混岩、喷裂岩以及嗜热嗜毒生物岩；2.提出喷流岩中的白云岩是一类原生白云岩，并初步探讨了其岩石学特征及形成机理，为地质学界争议较大的原生白云岩的存在提供证据和鉴别特征；3.初步分析了“黑烟型”不透明矿物的类型及分布；4.探索了岩浆作用与地幔热液喷流沉积的关系、沉积特征与分布规律，分析其反映的构造－沉积地质意义；5.对富地幔岩浆-热液流体环境中油气的形成特点及机理进行了初步探讨；6.对地幔热液喷流沉积岩的热液性质及热液来源进行了综合分析，探讨其形成的构造-动力学背景和沉积环境，建立地质历史时期陆内深大裂谷型湖泊环境中地幔热液喷流沉积岩系的典型范例。