泰国暖颂钾盐矿床粗粒岩盐沉积特征及其成因研究

老挝－泰国呵叻高原钾盐矿床储量大、品位高、易开发，粗粒岩盐在该钾盐矿床中普遍发育，其对水成盐转化、水体掺杂过程、钾盐富集演化等沉积环境具有重要的指示作用，然而，关于其成因至今仍未有详细报道。利用岩石学、显微岩相学和沉积学方法对呵叻高原西南部暖颂县钾盐矿床钻孔岩芯第一沉积旋回粗粒岩盐的成因进行了研究，得到如下结论:(1)粗粒岩盐主要有 3种成因，浅水环境中蒸发浓缩阶段原生生长，浅水环境中干盐湖阶段胶结生长，埋藏环境中孔隙卤水重结晶生长；(2)根据粗粒岩盐的成因、沉积规律和钻孔岩性特征可将马哈萨拉堪组下盐层沉积演化划为 5个沉积阶段:岩盐沉积稳定阶段、岩盐沉积过渡阶段、光卤石沉积初期阶段、光卤石沉积稳定阶段和次生岩盐沉积阶段；(3)研究区钾盐矿床整体的沉积环境为浅水。粗粒岩盐在矿层中的赋存特征、成因以及与其它岩相的组合特征共同表明了钾盐在沉积过程受到了不同程度的淡水稀释和埋藏后的改造作用。

Characteristics and Origin of Coarse Halite in the First Sedimentary Cycleof the Potash Deposit，Non Sung District，Nakhon Ratchasima Province，Thailand

PotashdepositinLaos-ThailandKhoratPlateauischaracterizedbylargereserves，highgrade，and easytoexploitation.Coarsehalitecrystalsarewidelydistributedinthispotashdeposit，whichplaysanimportant role in revealing the sedimentary environment such as water-salt transformation，paleo-hydrodynamic conditions，potash sedimentation，etc.In this paper，the origin and geological significance of coarse halite crystals in the first sedimentary cycle of the potash deposit in Non Sung district，southwest of Khorat Plateau were discussed.The following understandings were obtained:(1)Coarse halite crystals mainlyhave three origins，including primary growth in the concentration stage in shallow water environment，cemented growth in desiccation stage in shallow water environment，and recrystallized growth of pore brine in burial environment；(2)the sedimentary evolution of the first sedimentary cycle in the Mahasarakham Formation inthestudyareacanbedividedintofivedepositionalstagesfrombottomup:stageofhalitestabledeposition， stageofhalite-transit-to-carnallite，earlystageofcarnallitedeposition，stageofcarnallitestable deposition， and stage of secondary halitedeposition；(3)The sedimentary environment of the potash deposit in the study area is shallow water.The occurrence characteristics，and lithofacies of coarse halite crytals in the potash layer indicatethatthe potashdeposithasbeendilutedbyrelativelyfresh water during the deposition process and experienced diagenetic process.