藏南洛扎地区侏罗纪—早白垩世层序地层与地层格架——兼论基本层序变化规律调查在区调工作中的运用

Stratigraphic Framework of Jurassic Period and Early Cretaceous in Luozha, South Tibet: including the function of essential sequence law of the regional geological survey

根据米级旋回垂向上的变化规律,新特提斯洋北缘北喜马拉雅被动大陆边缘的沉积层序自侏罗纪—早白垩世共可划分二级层序3个,三级层序18个。早、中侏罗世低位体系域不发育,由海进体系域与高位体系域两部分组成。晚侏罗世出现大型深切河谷。海平面下降幅度最大。早白垩世发育陆架边缘体系域。在此基础上建立了测区侏罗纪—早白垩世地层格架。讨论了当前1∶25万、1∶5万区调填图过程中岩石地层单位内基本层序调查应从静态的代表性基本层序描述转变为动态的基本层序变化规律的调查,阐明了基本层序变化规律与层序地层的关系。

According to the law of Milankovitch Cycles in the perpendicularity, the depositional sequences which lay on the verge of the Neo-Tethys Ocean, north Himalaya continent can be divided into three sequences with type-Ⅱ and eighteen sequences with type-Ⅲ from Jurassic Period to Early Cretaceous. Lowstand System Tracts of Early and Metaphse Jurassic Period was undergrown, of which Transgressive Systems Tract and Highstand Systems Tract made up. And then Late Jurassic Period, it shaped huge incised valley, sea level had sunk deeply, Early Jurassic Period changed into Shelf Systems Tract. Therefore, it is established that the stratigraphic framework of Jurassic Period and Early Cretaceous. Based on the 1 ： 250,000 and the 1 ： 50,000 regional geological survey mapping, the essential sequences of Lithostratigraphic unit will change the static description into the dynamic law survey of basal sequences, which elucidates the relationship of essential sequence law and sequence stratum.