黑龙江省三江盆地鹤岗凹陷下白垩统猴石沟组沉积特征

Sedimentary characteristics of Lower Cretaceous Houshigou Formation in Hegang Depression, Sanjiang Basin, Heilongjiang Province

笔者等通过对鹤岗凹陷北部露头和钻孔资料的综合利用,结合少量的样品分析及薄片鉴定工作,对研究区下白垩统猴石沟组主要岩石学特征、沉积相类型及展布特征进行了综合研究,在此基础上,以砂岩型铀矿成矿理论为指导,对猴石沟组有利成矿砂体的沉积相类型进行了初步讨论。认为①猴石沟组砂体以长石岩屑砂岩和岩屑砂岩为主,主要为陆相淡水沉积环境,具较高的还原容量;②研究区内猴石沟组主要为扇三角洲沉积环境,并划分为辫状河道、漫滩沼泽、水下分流河道、河口坝、席状砂和分流间湾等6种微相;③猴石沟组沉辫状河道砂体可作为寻找潜水氧化带型砂岩型铀矿的重点类型,而水下分流河道砂体是作为寻找层间氧化带型砂岩型铀矿的主攻类型。

Objectives: The sedimentary facies types of the favorable ore-forming sand bodies of the Houshigou Formation are preliminarily discussed under the guidance of the metallogenic theory of sandstone-type uranium deposits,combined with a small amount of sample analysis and thin section identification work,through the comprehensive utilization of outcrop and borehole data in the north of Hegang Depression.Methods: In this paper,the main petrological characteristics,sedimentary facies types and distribution characteristics of the Lower Cretaceous Houshigou Formation in the study area are comprehensively studied.Conclusions: It is shown that:(1)The sand bodies of the Houshigou Formation are mainly feldspathic lithic sandstones and lithic sandstones,which are mainly continental freshwater sedimentary environments with high reduction capacity;(2)The Houshigou Formation in the study area is mainly fan delta sedimentary environment,and is divided into six microfacies: braided channel,floodplain swamp,underwater distributary channel,estuary bar,sheet sand and distributary bay;(3)The submerged braided channel sand body of the Houshigou Formation can be used as a key type for searching for phreatic-oxidized-type sandstoneuranium deposit, while the underwater distributary channel sand body is the main type for searching for interlayer-oxidized-zone-type sandstone uranium deposit.