摘要
近年来,鄂尔多斯盆地陇东地区铝土岩天然气勘探获重大突破,但对盆地东部本溪组铝土岩研究较少,亟需加强基础地质研究。通过岩心观察、铸体薄片等技术手段,结合主微量及稀土元素测试开展地球化学分析,研究含铝岩系的古盐度、古氧化还原环境、古气候及物源特征。结果表明:①晚石炭世本溪期历经多期海侵海退,沉积环境由海相咸水环境向陆相淡水环境过渡,并在湖田段沉积末期转变为海相咸水环境,期间氧化还原环境交替出现;②含铝岩系受化学风化作用影响显著,本溪早期受晚古生代冰期影响,温度下降,之后因全球变暖事件,气温升高;③含铝岩系底部铝土质铁矿物源自下伏马家沟组碳酸盐岩,中上部铝土岩及泥岩源于硅酸盐岩及岩浆岩等,物质来源多样。
In recent years,a great breakthrough has been made in the natural gas exploration of bauxite deposits in the Longdong area of the Ordos Basin,but there is little research on bauxite deposits of the Benxi Formation in the east of the basin.It is urgent to strengthen basic geological research.Through core observation,thin section,and other experimental methods,combined with major elements,trace elements,and rare earth elements,geochemical analysis was carried out to study the paleosalinity,paleo-redox conditions,paleoclimate,and provenance characteristics of bauxite deposits.The results show that:(1)The Benxi period of the Late Carboniferous experienced multiple transgressions and regressions.The sedimentary environment changed from a marine saline water environment to a continental freshwater environment,and then changed to a marine saline water environment at the end of the Hutian period,with alternate redox conditions.(2)Bauxite deposits are significantly affected by chemical weathering.In the early stage of the Benxi period,due to the influence of the Late Paleozoic Ice Age,the temperature dropped,and then the temperature rose due to the global warming event.(3)Iron minerals in the bottom of bauxite deposits come from the underlying carbonate rocks of Majiagou Formation,and the material of bauxite and mudstone in the middle and upper parts comes from silicate rocks and magmatic rocks,with various material sources.
作者
潘博
赵伟波
刘蝶
刘燕
王怀厂
余瑜
PAN Bo;ZHAO Weibo;LIU Die;LIU Yan;WANG Huaichang;YU Yu(Research Institute of Exploration and Development,PetroChina Changqing Oilfield Company,Xi’an 710018,China;National Engineering Laboratory for Exploration and Development of Low Permeability Oil and Gas Fields,Xi’an 710018,China;State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Chengdu University of Technology,Chengdu 610059,China)
出处
《天然气地球科学》
CAS
CSCD
北大核心
2023年第6期1072-1089,共18页
Natural Gas Geoscience
基金
中国石油长庆油田分公司勘探事业部技术研发项目“神木—米脂地区古生界含铝岩系分布规律研究”(编号:2022-40)资助.
