摘要:
在沉积学、生物地层学研究之基础上,结合沉积地球化学资料,对龙门山马角坝地区石炭系进行了露头层序地层学研究。首次识别出9个三级层序和若干个四至五级高频层序。在三级层序中,岩关组2个、大塘组3个、威宁组2个、马平组2个,它们均可作区域性对比。其中,四个层序分别与冈瓦纳大陆晚古生代五次冰川事件中四次间冰期一冰期旋回相对应,表明其成因与冰川型全球海平面变化有关。显然,研究区石炭纪层序主要受控于全球海平面升降旋回,具有全球对比意义。
Abstract:
Based on key boundaries,systems tracts and stacking patterns,in conjunction with regional geological and biostratigraphic data,the Carboniferous carbonate strata in the Majiaoba district,Sichuan are grouped,for the first time,into nine third-order sequences:two in the Yanguan Formation,three in the Datang Formation,two in the Weining Formation and two in the Maping Formation,all of which,in turn,may be subdivided into a number of the fourth- or fifth-order high-frequency sequences or parasequences.The time intervals of individual third-order sequence range between 2 and 11.5 Ma.And the differences of these sequences are attributed to the variations in periods of relative sea-level rises or falls,amplitudes of tectonic subsidence,rates of carbonate production and modes of sediments supply in the study area.
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