岩盐成因与发育模式——以柴达木盆地英西地区古近系下干柴沟组为例

发布时间：2018-07-28 15:56

【摘要】：柴达木盆地英西地区古近系下干柴沟组为寒冷干旱的咸化湖盆沉积,发育多期岩盐(成层石盐),其成因和发育模式是当前待解决的热点问题。岩心资料揭示完整的成盐单期旋回为"蒸发沉积序列",探井岩性序列组合特征表明湖盆经历了半咸化、咸化和盐湖3个演化阶段。通过包裹体岩相学、均一温度测试及成分研究与含盐层系硫、碳、氧同位素分析明确提出岩盐为低温水下浓缩结晶成因。岩盐形成于蒸发作用强烈的陆相闭塞环境,物质来源为陆源地表水携带而来。咸化阶段中后期与广盐湖阶段发育2种成盐模式,每种模式可再分为初始咸化期、咸化期及成盐期3个演化阶段。连井对比分析表明存在5个岩盐集中发育期,盐湖经历了初始、鼎盛与萎缩3个演化过程。盐湖中心岩盐厚度最大,平面分布具局限性,受古地形控制形成多个次级盐洼中心。垂向上多期岩盐的发育缘于陆相湖盆季节性的湖平面频繁升降。
[Abstract]:The Lower Ganchaigou formation of Paleogene in Yingxi area, Qaidam Basin, is a cold and arid saline lake basin deposit, which develops multi-stage rock salt (stratified rock salt). Its genesis and development model are hot issues to be solved at present. The core data reveal that the complete halogenation cycle is an "evaporative sedimentary sequence", and the lithologic sequence assemblage of the exploration well indicates that the lake basin has undergone three stages of evolution: brackification, salinization and salt lake. By means of petrography, homogenization temperature measurement, composition study and isotopic analysis of sulfur, carbon and oxygen containing salt series, it is clear that rock salt is the origin of concentrated crystallization under water at low temperature. The rock salt is formed in the strong evaporation environment, and the material comes from the surface water. Two salt-forming models were developed in the middle and late stages of salting stage and in the wide salt lake stage. Each model can be divided into three stages: the initial salinization stage, the salinization stage and the salt-forming stage. The correlation analysis of Lian well shows that there are five periods of concentrated development of rock salt, and the salt lake has experienced three evolution processes: initial, peak and atrophy. The salt in the center of salt lake is the most thick, the plane distribution is limited, and many secondary salt sag centers are formed under the control of paleotopography. The development of vertical multistage rock salt is due to the frequent rise and fall of the lake level in the continental lacustrine basin.
【作者单位】：中国石油杭州地质研究院;中国石油青海油田公司勘探开发研究院;
【基金】：中国石油天然气集团公司重大科技专项(2011E-0301-02)资助
【分类号】：P588.247

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