Research On The Relationship Between Phase Sandstone Type Uranium Southern Margin Of The Basin In The Western Part Of The Ili Xishanyao Deposition

This thesis is conducted by sedimentology, sedimentary petrography,Lithofaciespalaeogeography and sandstone type uranium geology，based on a large number of corescharacteristic decription,according to logging,outcrop,core,and sedimentary geochemistry,to setup sedimentary facies indicators,to divide sedimentary microfacies and to study on therelatioship bettwen sedimentary microfacies and sandstone type uranium mineralizationof Xishanyao Formation in middle and western part of the southern margin,Yili basin.It is determined that, the texture of maturity and composition of sedimentary in study area islow, sedimentary source is as close, provenance is active continental margin; DetritalLA-ICP-MS zircon ages arebasically similar to that of outcropping magmatic rock of onChabuchar mountain located in southern edge of the study area. Generally paleocurrent directionof flow was from the south to the north in study area. So the main source of sediments isChabuchar mountain in study area. Environment of water was variable weak oxidation andweak reduction。Probability Cumulative Grain Size Curves analysis of sedimentary rock in study area indicatemainly two-stage type，three-stage type and Small part of them is of four-stage type. The C-Mdiagram reveals that, sandbody of Xishanyao Formation at the southern margin of Yili basin wasdeposited as drag flow， the upper member were deposited as rolling transport population，andthe lower member were deposited as rolling transport and saltation transport population, soXishanyao Formation is classified as typical river-deltaic environment sediments. In general,in Xishanyao Formation,the grain size in upper member is coarse than that in lower member.The upper member is similar to sand bodis of braided river stream sand bodies, and the lowermember is similar to sand bodis of braided meandering stream. By calculating the sedimentaryenvironment discriminant function，it is discovered that sedimentary environments of XishanyaoFormation in the study area are as to stream (delta)，while all samples for grain size analysis fallinto a range of stream sand inσi-Sk discretization analysis diagram and Mz-σidiscretization analysis diagram.The grain is coarse, the sorting is bad, and grow up with enticular bedding, curled bedding,has thick sand and sand in the ratio of distributionthe lower member of Xishanyao Formation, isa set of braided stream delta front deposition. There are four main sedimentary pile body in the southern margin of Yili basin，they are Honghaigou sedimentary pile body,Sudongbulakesedimentary pile body, Wukurqi sedimentary pile body，Mengqiguer sedimentary pile body,main sedimentary microfacies developed in this stratum are distributary channel, branch river,overbank deposit, debouch bar, sheet sand, distal bar..The grain is fine,and grow up with climbing bedding,dualistic structure is obvious, lowermember of Xishanyao Formation this paper first time to propose that was deposited asmeandering stream delta plain, which is developed with a series of crevasse splays, and thispaper described the causes and sedimentary model of crevasse splay. The main sedimentarymicrofacies in the upper member of Xishanyao Formation are distributary channel, crevassesplay, point bar,floodplain (interdistributary bay deposit), flood lake, flood swampsmicrofacies. the author identifed four meandering stream,they are Honghaigou-Kujieertaidistributary channel,Sudongbulake-Wukurqi distributary channel, Wukurqi distributarychannel, Mengqiguer distributary channel, these meandering rivers are all with varying degreesof developmental crevasse splay deposit.In Xishanyao Formation，study results showed that, in the lower member of XishanyaoFormation,uranium mineralization is mainly developed in distributary channel of braided streamdelta and a small part of that developed in branch river. This paper first time to propose that, inthe upper member of Xishanyao Formation, uranium mineralization is mainly developed in thecrevasse splay of meandering stream delta plain, meandering stream is slao a importantmicrofacy for mineralization and a small part of uranium mineralization is developed in branchriver which formed in front of the crevasse splay.Finally, the author comprehensive analysis of sedimentary microfacies and interlayeroxidation zone, Langka area delineated as prospects for the upper and lower sections, drilling ofNo.50155delineated as metallogenic prospects for the upper section，line165to the north westof Sudongbulake area delineated as prospects for the lower section.