四川盆地广安构造三叠系深藏杂卤石地质特征及找钾启示  

Geological characteristics and implications for potassium prospecting of Triassic deep polyhalite,Guang'an structure,Sichuan Basin

作　　者：赵世民 刘治成 张律 杨籼 曾成杰 雷琴 ZHAO Shimin;LIU Zhicheng;ZHANG Lü;YANG Xian;ZENG Chengjie;LEI Qin(113 Geological Team of Sichuan Bureau of Geology and Mineral Resources,Luzhou 646000,China;Sichuan Insitute of Land Science and Technology(Sichuan Satellite Application Technology Center),Chengdu 610045,China)

机构地区：[1]四川省地质矿产勘查开发局一一三地质队,四川泸州646000 [2]四川省国土科学技术研究院(四川省卫星应用技术中心),四川成都610045

出　　处：《沉积与特提斯地质》2023年第1期117-129,共13页Sedimentary Geology and Tethyan Geology

基　　金：四川省政府性投资地质勘查项目“四川省广安市广安区大安钾盐(杂卤石)远景评价”。

摘　　要：广安构造作为四川盆地重要的隐伏含钾构造之一,下—中三叠统雷口坡组—嘉陵江组杂卤石广泛发育。前人对杂卤石的找钾启示研究较少,杂卤石是否是易溶性钾盐的找矿标志尚无定论。本文通过野外调查、老井复查,结合广安构造ZK1井测录井、岩心样品测试等资料开展杂卤石地质条件及找钾启示研究,以期为广安地区下一步钾盐勘探开发提供参考。ZK1井钻遇杂卤石矿(化)层6层,单层厚度最大为7.03 m,累计厚度可达11.21 m。杂卤石主要呈块状、浸染状与硬石膏共生,少量条带状、簇状、星点状。镜下可见杂卤石呈板状、纤维状、它形粒状、放射状、团块状等。含钾剖面序列为“硬石膏—杂卤石—硬石膏”,KCl最高品位22.9%,平均品位14.57%,石盐层不发育。研究认为ZK1井杂卤石以后生交代成因为主,少量原生成因。在靠近盐湖中心区域,硬石膏层相对较薄的凹陷地段,很可能是易溶性钾盐的找矿突破点。The Guang'an Anticline is one of the important hidden potassium bearing structures in Sichuan Basin.Polyhalites occurs widespread in the Leikoupo and Jialingjiang Formations of lower-middle Triassic.There are few previous studies on implications of potassium prospecting of polyhalite,and whether polyhalite is a prospecting indicator of soluble sylvite is still a debated topic.In this work,based on field investigation and previous well review,combined with the data of logging and core testing of ZK1 well in Guang'an structure,the geological conditions and implications of potassium prospecting of polyhalite are studied,in order to provide reference for the next sylvite exploration and development in Guang'an area.Six mineralized polyhalite layers are intersected by ZK1,with a maximum thickness of 7.03 m and a total thickness of 11.21 m.Polyhalite is mainly massive,disseminated with a small amount of banded,clustered and star shaped,and the paragenous mineral is anhydrite.Under the microscope,the polyhalite occurs as plate,fibrous,anhedral granular,radial and crumby,etc.The potassium bearing sequence is interbedding of anhydrite and polyhalite with the highest grade of KCl 22.9%(average grade 14.57%),and the halite layer is not developed.The results suggest that the polyhalite in ZK1 is mainly derived of epigenetic metasomatism with little primary origin.In the areas close to the central facies of the salt lake,the depression with relatively thin anhydrite layer is key target of soluble sylvite.

关 键 词：杂卤石 钾盐 三叠系 广安构造 四川盆地 

分 类 号：P619.211[天文地球—矿床学]