赣北晚二叠世的层序地层及高频沉积旋回研究

A STUDY ON STRATIGRAPHIC SUCCESSION AND HIGH－FREQUENCY SEDIMENTARY CYCLES OF THE LATE PERMIAN STRATA IN NORTHERN JIANGXI

本文依据露头剖面及钻孔资料，在对其沉积物进行详细的微相及沉积环境研究的基础上，将赣北上二叠统划分为4个三级层序，并详细地论述了各三级层序的特征。丰城长兴组的吴家坪初期近源缓坡、早期具深切谷的近源缓坡边缘、中期台盆相间的断裂边缘、长兴期具滩礁内陆地镶边陆架等4个发展阶段，表明这种复杂多变的五级高频沉积旋回形成的根源是地壳运动造成沉积背景的不同，与秦岭-大别洋向北俯冲削减的快慢悉悉相关。根据更小级别的间断加积沉积旋回的研究，它们的时限与地球运动轨道的岁差和短偏心率旋回大体吻合。从而，认为控制间断加积沉积旋回的主导机制是地球轨道周期性变化导致的气候周期性变化。

：Based on an intensive study of the microfacies and sedimentary environment of the sediments from surface exposures and boreholes, the author has divided the Upper Permian of northern Jiangxi into four 3rd－order successions, of which the characteristics have also been dealt with in some detail． These complicated and varied 5th－order high frequency sedimentary cycles have gone through 4 development stages including the Wujiaping initial stage of proximal gentle slope demonstrated in the Fengcheng Changxing Formation, the Wujiaping early stage of proximal gentle slope Margin with deep valley，the Wujiaping middle stage of alternating platform and basin controlled by marginal faults, and the Changxing stage of continental shelf with bank reef inland margin． Their formation is intimately related with the contrast in sedimentary settings resulted from crustal movement, and also with the speed of the underthrusting and consuming of the Qinling－Dabie Ocean Plate northwards． Based on a study of the interrupted aggradational sedimentary cycles of the even lower order, their time limit coincides roughly with the precession of the Earth＇s orbit and the short eccentricity cycle, therefore the author believes that the main mechanism responsible for the interrupted aggradational sedimentary cycles is the cyclic variation in climate resulted from the cyclic variation of the Earth＇s orbit．