四川盆地东北部黄金口背斜三叠系富K、Li和B卤水成因和演化  

Genetic evolution of Triassic K-Li-B rich brines in Huangjinkou anticline,northeast Sichuan basin

作　　者：牛新生[1] 张永生[1] 苏奎[1] 邢恩袁[1] 左璠璠 桂宝玲[1] 商雯君 NIU Xinsheng;ZHANG Yongsheng;SU Kui;XING Enyuan;ZUO Fanfan;GUI Baoling;SHANG Wenjun(Ministry of Natural Resources Key Laboratory of Saline Lake Resources and Environments Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China)

机构地区：[1]中国地质科学院矿产资源研究所,自然资源部盐湖资源与环境重点实验室,北京100037

出　　处：《地质学报》2024年第10期2847-2859,共13页Acta Geologica Sinica

基　　金：国家自然科学基金项目(编号41402076,91962219);中国地质科学院矿产资源研究所基本科研业务费项目(编号KK2210,K1413);中国地质调查项目(编号DD20230296,DD20221913)联合资助的成果。

摘　　要：四川盆地东北部地区三叠系嘉陵江组四、五段—雷口坡组一段赋存丰富的卤水资源,卤水中富集K、Li、B等元素,具有潜在的开发利用价值。长期以来,一般认为川东北三叠系中卤水因溶解地层中的钾盐矿物而富集K物质,但这一认识并没有得到确证,此外,对卤水中Li和B的成因和演化鲜有报道。本文以川东北三叠系深层卤水为研究对象,以地球化学和稳定同位素分析为主要方法,运用聚类分析对比采自13口钻井卤水的地球化学数据。与海水相比,区内深层卤水中的K^(+)、Ca^(2+)、Li和B明显富集,而Mg^(2+)和SO_(4)^(2-)则相对亏损。卤水的^(87)Sr/^(86)Sr和δ^(34)S值均与卤水储层的^(87)Sr/^(86)Sr和δ^(34)S值相一致,进一步说明深层卤水为海水原地蒸发浓缩形成。Q型聚类分析表明,北2井和川宣地1井的卤水化学组分相似,川25井、ZK601井、恒成1井、恒成3井的卤水化学组分相近,证明川25井和ZK601卤水中K的富集是由于卤水溶解了地层中的钾盐矿物(杂卤石)。白云岩化导致了卤水中Ca^(2+)明显富集,而Mg^(2+)明显亏损,地层中赋存的硫磺和H_(2)S证明了大量硫酸被还原,使得SO_(4)^(2-)出现明显亏损。还原作用不仅导致卤水和石膏δ^(34)S的升高,而且引起了区域内石膏和卤水的δ^(34)S高于同时期海水的δ^(34)S值。嘉陵江组沉积晚期,三江地区流纹质火山岩浆喷发产生了大量携带含Li和B元素的气体和热液载体,进而被搬运至蒸发盐盆中。火山热液和气体中的Li、B具有相对较低的δ^(7)Li值和δ^(11)B值,在提升卤水中Li和B含量的同时,也降低了卤水δ^(7)Li值和δ^(11)B值,使得其低于正常海水的δ^(7)Li值和δ^(11)B值。The 4th and 5th members of the Jialingjiang Formation and the 1st Member of the Leikoupo Formation in the northeast Sichuan basin host abundant brine resources rich in K,Li,B,and other elements,presenting significant potential for development and utilization.While it has long been assumed that the enrichment of K in Triassic brines in northeast Sichuan is due to the dissolution of potassium salt minerals in the strata,this hypothesis lacks definitive confirmation.In addition,research on the origin and evolution of Li and B in these brines remains limited.In this paper,the deep brine of Triassic in northeast Sichuan Province is taken as the research object.Compared to seawater,these brines exhibit significant enrichment in K^(+),Ca^(2+),Li+,and B,while Mg^(2+)and SO_(4)^(2-)are relatively depleted.The^(87)Sr/^(86)Sr andδ^(34)S values of the brine are consistent with those of the brine reservoir,suggesting in-situ formation through seawater evaporation and concentration.The Q-type cluster analysis shows that the chemical components of Bei 2 and CXD1 are similar,and the chemical components of C25,ZK601,HC1,and HC3 are similar.It is inferred that the enrichment of K in the brines of C25 and ZK601 is caused by the brine dissolving potassium salt minerals(polyhalite)in the formation.Dolomitization processes lead to the enrichment of Ca^(2+)and depletion of Mg^(2+)in the brine.The occurrence of sulfur and H_(2)S in the formation proves that a large amount of sulfuric acid is reduced,resulting in an obvious loss of SO_(4)^(2-).The reduction not only elevates theδ^(34)S values of the brine and gypsum but also causes theδ^(34)S values of both gypsum and brine in the region to exceed those of contemporaneous seawater.During the late Jialingjiang Formation period,the eruption of rhyolitic magma in the Sanjiang area generated significant quantities of gases and hydrothermal liquids rich in Li and B,which were subsequently transported to evaporite basins.Theδ^(7)Li andδ^(11)B values of Li and B in volcanic hydrothermal fl

关 键 词：川东北 黄金口背斜 深层卤水 钾 锂 硼 

分 类 号：P619.211[天文地球—矿床学]