摘要
鄂尔多斯盆地西缘呼鲁斯太剖面上石炭统包括靖远组、羊虎沟组和太原组,发育有堡岛、堡岛—台地和潮控三角洲三种沉积体系,自下而上可以划分出16 个海进- 海退层序旋回,每个层序旋回的时限为1 .1 ~3 .3 Ma ,平均1 .9 Ma ,相当于四级相对海平面变化旋回,属高频层序旋回。每个层序由海侵体系域和早期高位体系域、晚期高位体系域组成,偶发育有强制海退体系域。晚石炭世早期海侵来自祁连海,太原晚期,祁连海与华北连通。研究区古海平面变化表现为先慢速后快速海侵和快速海退,少数为正常海退,并由此建立了古海岸平原的层序地层模式。
The tectonic setting of the study area was aulacogen in Mesoproterzoic to Early Paleozoic, and impactogen in Late Paleozoic.The lithostrtiagaphic units contain Jingyuan Formation,Yanghugou Formation and Taiyuan Formation during Late Carboniferous in Hulusitai section of Ordos basin.Based on the study of high reselution sequence cycle and depositional systems,sixteen T R high reslution sequence cycles occur from Namurian C stage to Stephanian stage in Late Carboniferous strata.There developped barrier lagoon systems (Jingyuan Fm.and Yanghugou Fm.),barrier lagoon with carbonate platform composite systems (Jingyuan Fm.and Yanghugou Fm.)and tidal delta systems(Taiyan Fm.).They average about 1.9 Ma and range from 1.1~3.3 Ma in length,reflecting forth order relative sea level change cycles,and belong to High resolution Sequence Cycles.Each T R sequence is composed of transgressive system tract,early highstand system tract,later highstand system tract,with a few record of forced regression system tract.In general,lowstand ersional sequence bondary and transgressive surface are merged,with no or few record of the lowstand system tract.Transsion came from Qilian Sea during early middle stage of Late Carboniferous.Qilian Sea and Huabei Sea were merged in Late Taiyuan stage.But they are not coincident with forth order sea level fluctuation.It is charcterizied of forth order sea kevel change by the slow rising firstly and then dast rising with interenvening period of fall,and then fast falling with a few forced regression.The third order sea level change reflects that transgression began in Namurian C stage and reached maxium transgrssion in Wesphalian stage and occoured regression in the end of Carboniferous.So,the relative sea level change from the record of the stratigraphy sequences are the composite sea level change with small order cycles superimposed with high order cycles subsidence and sediment influx.Finally,sequence stratigarphic model of paleocoastal plain environment has been proposed.
出处
《沉积学报》
CAS
CSCD
北大核心
1999年第3期397-402,共6页
Acta Sedimentologica Sinica
关键词
鄂尔多斯盆地
晚石炭世
沉积体系
高频层序旋回
Orodos basin Late Carbonferous depositional system high resolustion sequence cycle Hulusitai section