CAJ | 학술논문

以地质背景和岩石组构分析为基础,系统研究了酒泉盆地青西凹陷下沟组湖相热水沉积岩中的流体包裹体特征.结果表明,热水沉积岩中的原生流体包裹体以气液二相包裹体为主、单一液相和单一气相包裹体较少、偶见含子矿物三相包裹体.成矿流体属NaCl-H_2O型热液体系,温度为90～200℃,盐度为8%～22%NaCl,密度为0.99～1.2 g/cm~3,成矿压力为15～180 MPa.结合锶同位素等地球化学资料分析,认为成矿流体属于深循环的下渗湖水与岩浆水共同构成的中低温、中高盐度和中偏高密度混合热卤水.提出以不同产状的重晶石、铁白云石和萤石为代表的热水沉积岩的成矿热流体系统,自主喷流通道、分支喷流通道经喷流口至附近及远端的盆地热卤水沉积区存在温度、盐度、密度和压力等物理化学参数逐渐降低的分带性变化规律.在热流体特征分析基础上,对研究区早白垩世湖底热流体成矿机制和成因模式进行了探讨.
이지질배경화암석조구분석위기출,계통연구료주천분지청서요함하구조호상열수침적암중적류체포과체특정.결과표명,열수침적암중적원생류체포과체이기액이상포과체위주、단일액상화단일기상포과체교소、우견함자광물삼상포과체.성광류체속NaCl-H_2O형열액체계,온도위90～200℃,염도위8%～22%NaCl,밀도위0.99～1.2 g/cm~3,성광압력위15～180 MPa.결합송동위소등지구화학자료분석,인위성광류체속우심순배적하삼호수여암장수공동구성적중저온、중고염도화중편고밀도혼합열서수.제출이불동산상적중정석、철백운석화형석위대표적열수침적암적성광열류체계통,자주분류통도、분지분류통도경분류구지부근급원단적분지열서수침적구존재온도、염도、밀도화압력등물이화학삼수축점강저적분대성변화규률.재열류체특정분석기출상,대연구구조백성세호저열류체성광궤제화성인모식진행료탐토.
Based on the analysis of geologic background and rock textures, fluid inclusions in the lacustrine hydrothermal sedimentary rock from the Xiagou Formation, Lower Cretaceous in the Qingxi sag, Jiuquan basin was studied. The results show that native fluid inclusions in the hydrothermal sedimentary rock are dominated by vapor-liquid types, with minor haploid liquid and haploid vapor inclusions as well as triune inclusions of filial mineral. The mineralizing fluid is NaCl-H_2O hydrothermal brine system. The temperature vary between 90℃ and 200℃, salinities between 8% and 22% NaCl eq., density between 0.99 g/cm~3 and 1.2 g/cm~3 and mineralization pressure between 15 MPa and 180 MPa. Sr isotope geochemical analysis suggests that mineralizing fluid was the mixed hot brine consisting of deep circulation descending lake water and magmatic fluid, which was characterized by low-mid temperature, mid-high salinity and mid-high density. This study indicates that ore-forming hydrothermal fluid system which formed hydrothermal sedimentary rocks such as various barite, ankerite and fluorite shows zonation changes in terms of temperature, salinity, density and pressure, decreasing from the main exhalative-channel-branch exhalative-channel-exhalative mouth-near exhalative mouth-distal basin. Based on the analysis of the characteristics of hot fluid, the mineralization mechanism and genesis model of the Early Cretaceous sublacustrine hot fluid in the area is discussed.