高校地质学报2025，Vol.31Issue(2)：200-212,13.DOI:10.16108/j.issn1006-7493.2024007
柴北缘中侏罗世晚期气候逐渐干热化与湖相有机质富集机制
Lacustrine Organic Matter Accumulation During Gradually Arid Palaeoclimate in the Late of Middle Jurassic,Northern Qaidam Basin
摘要
Abstract
In order to clarify the accumulation mechanism of organic matter in shale under the gradually arid palaeoclimate in the Late of Middle Jurassic for Northern Qaidam Basin,this paper systematically analyzed the palaeoclimate characteristics and its relation with the supply and preservation of organic matter by means of organic geochemistry,inorganic geochemistry and mineral composition analysis of shale samples for Seven Member of Dameigou Formation from some wells in Yuqia area.Compared with the lower gray-black shale,the upper gray-brown shale is characterized by higher organic matter content and sapropelic organic matter type.The higher contents of carbonate minerals and Sr/Cu,and the lower palaeoclimate index C value,with wide range,indicate gradually arid palaeoclimate with high frequency fluctuation.Apparent difference of C value for gray-brown shale in lateral direction reflects that the palaeoclimate at the same period is also stable.Lower Al and Ti contents indicate weak input of terrigenous detrital matter.Higher P/Ti and Ba/Al indicate higher palaeoproductivity.Lower Pr/Ph and higher pyrite content indicate more reducing water conditions.Higher Sr/Ba and mostly high gammacerane index reflect water salinization of the lake and water stratification in most areas.Based on the above proxies,it can be concluded that a certain degree of arid palaeoclimate is favorable to the decrease of terrigenous matter input,the increase of palaeoproductivity,the enhancement of water reducibility and salinity,and the stratification of most areas,which can facilitate sapropelic organic matter accumulation.关键词
气候逐渐干热化/高频波动/纵横向特征/大煤沟组七段/地球化学特征/矿物组成/有机质富集Key words
gradually arid palaeoclimate/high frequency fluctuation/vertical and lateral attributes/Seven Member of Dameigou Formation/geochemistry characteristics/mineral composition/organic matter accumulation分类
地质学引用本文复制引用
郭望,陈刚,李玉宏,张云鹏,李永红,党洪量..柴北缘中侏罗世晚期气候逐渐干热化与湖相有机质富集机制[J].高校地质学报,2025,31(2):200-212,13.基金项目
国家重大科技专项(2016ZX05034001-006) （2016ZX05034001-006）
国家自然科学基金项目(41602162) （41602162）
中国地质调查局项目(DD20240049)联合资助 （DD20240049）
