古地理学报2024，Vol.26Issue(4)：962-971,10.DOI:10.7605/gdlxb.2024.04.086
鄂尔多斯盆地西北缘奥陶系克里摩里组等深流沉积
Contour current deposits in the Ordovician Kelimoli Formation,northwestern margin of Ordos Basin
摘要
Abstract
Contour current deposits are a common type of deep-water deposits.However,limited work has been done on identification and formative mechanisms of contour current deposits in the rock re-cord.Here,a new type of contour current deposits(lenticular contour current deposits)is documented in the Ordovician Kelimoli Formation of the study area in the Ordos Basin.The results show that There are four types of lithofacies and lithofacies associations in the study area,including lenticular micrite(lithofa-cies 1),mainly lenticular silt-sized silt-crystalline limestone(lithofacies 2),micrite and sparry calcar-enite or calcirudite(lithofacies 3),and bedded calcirudite(lithofacies 4).It is found that lenticular mi-crite,silt-sized silt-crystalline limestone,and calcarenite or calcirudite are present as fine-grained through coarse-grained to fine-grained facies sequences.These deposits are characterized by relatively thin bed thickness,wavy surface,lenticular geometry,and association with muddy lamina,stripe,and spot,which are attributed to the persistent effect of contour current.Silt-sized silt-crystalline limestones are usu-ally mottled.Bedded calcirudites with imbricate structures and the inverse Chinese character of"small"are likely to be storm deposits.In addition,carbon and oxygen isotopes indicate that relative sea level and paleotemperature show two rising to falling cycles and a continously-rising half cycle.It is also found that the contour current in the study area are low energy thermohaline circulation and that the strength of the contour current is positively correlated with eustatic sea level and salinity change.Finally,the energy of the contour current increases gradually upsection with occassional transient extremes,which might be also effected by storms in the Kelimoli stage.关键词
等深流/等深流沉积/克里摩里组/奥陶系/鄂尔多斯盆地Key words
contour current/contour current deposit/Kelimoli Formation/Ordovician/Ordos Basin分类
天文与地球科学引用本文复制引用
李华,何幼斌,姚凤南,何一鸣,姜纯伟,张显坤,吴吉泽,徐艳霞,梁建设..鄂尔多斯盆地西北缘奥陶系克里摩里组等深流沉积[J].古地理学报,2024,26(4):962-971,10.基金项目
国家自然科学基金项目(编号:42272113,42272115)资助.[Financially supported by the National Natural Science Foundation of China(Nos.42272113,42272115)] （编号:42272113,42272115）
