老挝巴根钾盐矿区下盐段钾石盐层的成因

光卤石沉积改造后的次生钾石盐表现低溴高铷的特征, 对认识由光卤石淋滤去除氯化镁形成钾石盐的钾盐矿床具有指示意义。以矿区ZK0707钻孔的下盐层(含矿段)为研究对象,对其主量元素和微量地球化学进行分析研究。光卤石中微量元素Br、Rb、K含量及Br×1000/Cl系数的变化指示成盐卤水经过了阶段性的浓缩和淡化过程。下层盐由下至上依次为石盐岩-光卤石岩-钾石盐岩-石盐岩,与卤水蒸发浓缩的顺序相反；钾石盐岩直接沉积在光卤石层之上,且钾石盐表现低Br高Rb特征。推测巴根钾盐矿床沉积成矿模式,光卤石沉积后,通过下部盐背斜塑性流动,抬升,发生了沉积改造,光卤石在陆相水淋虑作用下生成钾石盐。因此,陆相水(裂隙水)的输入在成矿卤水演化和沉积改造过程中扮演了重要角色。

Cause of Potassium Salt Layer in Lower Salt Section of Bagan Potassium Salt Mining Area in Laos

Secondary sylviteafter the conversion of carnallite sediments showsthe characteristics of low bromine and high rubidium. It has important implications for the understanding of the sylvitedeposits formed by carnallite leaching and removing magnesium chloride to form sylvite. Taking the lower salt layer (ore-bearing section) drilled in ZK0707 mine as the research object, the main elements and trace geochemical analysis of the lower salt were studied. The changes in contents of trace elements Br, Rb, K and coefficient ofBr×1000/Clin carnallite indicate that the salt brine has undergone a stage of concentration and desalination. Thesequence ofthe lower salt from bottom to top is salt rock-carnallitite-sylvinite rock-salt rock, which is reverse to the evaporation and concentration of brine.The sylvinite rock is directly deposited on the carnallite layerand it shows the character oflow Br high Rb. The sedimentary metallogenic model of the Bagan sylvite deposit was confirmed. After the carnallite was deposited, the sedimentary alteration occurred through the plastic flowingand uplifting of the lower salt anticline, and the carnallite generated sylvite under the action of continental water leaching. So it plays an important role that the input of terrestrial water (fissure water) in the evolution and sedimentation ofthe ore-forming brine.