中国北方宁南盆地古近纪晚期咸化湖盆演化及其区域地质意义

发布时间：2018-03-12 18:01

本文选题：咸化湖盆　切入点：蒸发岩　出处：《地质学报》2017年04期 　论文类型：期刊论文

【摘要】：本文以宁南盆地北部的贺家口子清水营组剖面为研究目标,对古近纪晚期清水营组的岩性特征、石膏主元素地球化学特征和泥岩有机地球化学特征进行研究,结果表明:清水营组岩性以灰绿-紫红色泥岩、石膏及二者互层为主,可划分为8个二级沉积旋回和3个一级沉积旋回。石膏中CaO含量反映了咸化湖盆中石膏的化学沉积作用,Al_2O_3等为陆源碎屑来源,清水营组下段为盐湖深水环境沉积的纯净石膏;中段石膏沉积的水体较浅。清水营组下段地层泥岩TOC和生烃潜量(S_1+S_2)较高,说明在咸化湖盆演化早期气候较湿润、水体较深;而泥岩降解潜力相对小,反映有机质以高等植物来源为主,陆源输入较多。在此研究基础上,认为宁南盆地清水营组沉积包括:蒸发岩的沉积和碎屑岩的沉积;咸化湖盆演化尚未达到钾盐等盐岩沉淀的高浓缩阶段。咸化湖盆演化主要经历了早期封闭深水盐湖发育阶段、中期封闭浅水盐湖鼎盛阶段和晚期开阔浅水盐湖消亡阶段。宁南盆地古近纪晚期咸化湖盆演化与盆地的持续构造沉降和各次级沉积坳陷最终连为统一的湖泊这一重大区域沉积事件有明显的响应关系。
[Abstract]:In this paper, hejiakouzi water Ningnan basin northern camp group section as the research object, the lithology characteristics of late Paleogene Qingshuiying formation, gypsum research, major element geochemistry and organic geochemistry of mudstone shows Qingshuiying formation lithology in the grey green purple red mudstone, gypsum and two mutually the main layer, can be divided into 8 sedimentary cycles and two grade 3 level. The content of CaO in gypsum sedimentary cycle reflects the chemical deposition of gypsum saline lake in Al_2O_3, such as terrigenous sources, Qingshuiying group pure gypsum as Saline Lake deposited under deep water environment; water is the middle of gypsum deposits shallow. Qingshuiying formation mudstone group under paragraph TOC and potential hydrocarbon generation amount (S_1+S_2) in high saline lacustrine basin evolution of early climate is more humid, the water is deep; and the mudstone degradation potential is relatively small, reflecting the organic matter to the sources of higher plants mainly terrigenous Input more. On the basis of this research, that the Qingshuiying formation sedimentary Ningnan basin include sedimentary evaporite deposits and clastic rocks; saline lacustrine basin evolution has not yet reached the stage of high concentration potassium salt rock sedimentation. Saline lacustrine basin evolution mainly experienced the early development stage of Saline Lake closed deep water, shallow Saline Lake closed mid stage and late open shallow Saline Lake extinction stage. Late continuous tectonic Ningnan basin Paleogene saline lacustrine basin evolution and basin subsidence and the secondary sedimentary depression finally unified lakes this major regional sedimentary events have obvious response.

【作者单位】：长安大学地球科学与资源学院;中国地质科学院地质力学研究所;
【基金】：国家自然基金项目(编号:41173055) 中央高校基本科研业务费专项资金(编号:310827172101)联合资助的成果
【分类号】：P534.61

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