doi:10.16186/j.cnki.1673-9787.2020090066

Received:2020/09/15

Revised:2020/10/26

Published:2022/03/15

Milankovitch cycle and sedimentary response of the  fine-grained sedimentary rocks in Dongying depression

DONG Xinjun1, FENG Zhendong1, NINGShuyuan 1, ZHANG Pengfei2, CHENTao 2, ZHANG Lin1, GAO Di1, WU Wei1

1.College of resources and environment, Henan Polytechnic University, Jiaozuo 454000 , Henan, China;2.Exploration and Development Research Institute, ShengH Oilfield Branch of Sinopec, Dongying  257000 , Shandong, China

Abstract: : Milankovitch cycle is an important theory and method that is usually utilized to study the cyclicity of fine-grained sediment.In this paper,deep-lake fine-grained rocks of the   in the Dongying depression were studied by means of wavelet change and spectrum analysis of natural gamma logging data.Milankovitch cycle division was carried out on the deep-water fine-grained rocks in the cores of well LY1,the results were compared with the corresponding petrogeochemical and mineral indices,and the sedimentary responses controlled by the Milankovitch cycles were analyzed.The results showed that 2.5 fourth-order,10 fifth-order,and 28 sixth-order cycles could be identified in the   section.The fine-grained rocks in the Dongying depression had obvious evolutionary stages in paleoclimate,paleowater depth,paleosalinity,paleoredox,and sediment supply,which could be divided into two stages.Long eccentricity period was divided into a warm-wet semi-cycle and a dry-cold semi-cycle.During the former,there were more surface runoff,more abundant terrigenous debris supply,and higher organic matter content.The lithologic assemblages corresponding to the warm-wet semi-cycle were mainly characterized by layered and laminated structures.During the latter,there were little surface runoff,smaller amount of terrigenous debris supply,and lower organic matter content.The lithologic assemblages corresponding to the dry-cold semi-cycle were mainly characterized by blocky and layered structures.As a result,there was a good correlation between the sedimentary environment and the astronomical cycle,and the long eccentricity period might have played an important role in the evolution of the lacustrine fine grains deposition.

Key words:Milankovitch cycle;fine-grained rock;sedimentary environment; ;Dongying depression

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