摘要
伊盟隆起东胜地区在古生代和中生代早期,地温梯度低,烃源岩热演化程度低,中生代晚期地温梯度增高,地温梯度可达每百米3.3℃。伊盟隆起东胜地区在中生代晚期发生的构造热事件,以及后期的持续抬升是热流体运动活跃时期,并使该区石炭-二叠系、三叠系及侏罗系的煤化作用主要发生在中侏罗—早白垩世,早白垩世是古生代煤系地层的主要生气期,从早白垩世至今为煤成气的主要运移与破坏时期,也是东胜砂岩铀矿主要的成矿时期。通过镜质体反射率、磷灰石裂变径迹等资料对区内构造演化及生烃史的分析,由于伊盟隆起东胜地区石炭-二叠系及侏罗系煤系地层尚处于低成熟或未熟演化阶段,促使铀矿富集的还原剂-油气只能来自伊盟隆起以南成熟度较高地区的石炭-二叠系煤系地层。
Geothermal gradient was low in Paleozoic and Early Mesozoic in Dongsheng area, Yimeng uplift, resulting in a low level of thermal evolution of source rocks, and it increased up to 3.3℃/100m in Late Mesozoic. The Late Mesozoic tectonic thermal events and the later continuous uplifting in Dongsheng area would have resulted in the active movement of thermal fluid. As a result, the coalification of Permo-Carboniferous, Triassic and Jurassic in the study area mainly occurred during Middle Jurassic to Early Cretaceous. Gas was mainly generated from the Paleozoic coal measure strata in Early Cretaceous, and the humic gas have mainly migrated and dissipated since Early Cretaceous, which is also the main mineralization period of the sandstone uranium impregnations in the area. Based on analyses of tectonic evolution and hydrocarbon generation history in the study area by using vitrinite reflectance and apatite fission track data, the hydrocarbons acting as the reducing agents for enrichment of uranium can only be sourced from the Permo-Carboniferous coal measure strata in the area with relatively high maturity to the south of Yimeng uplift, because the Permo-Carboniferous and Jurassic coal measure strata in the study area are still in immature to low mature evolutionary stages.
出处
《石油与天然气地质》
EI
CAS
CSCD
北大核心
2006年第2期187-193,共7页
Oil & Gas Geology
基金
国家重点基础研究发展规划(973)项目(2003CB214605)
中国煤成气成藏机制及经济开采基础研究项目(2002CB211704)
长江学者和创新团队发展计划资助项目(IRT0559)
关键词
磷灰石裂变径迹
古地温
热演化史
金属铀矿
成葳期次
伊盟隆起
鄂尔多斯盆地
apatite fission track
palaeogeotherm
thermal evolution history
uranium ore
reservoiring stage
Yimeng uplift
Ordos basin