东北石油大学学报2025，Vol.49Issue(6)：57-69,84,14.DOI:10.3969/j.issn.2095-4107.2025.06.005
基于米氏旋回的海相碳酸盐岩低级序不整合面识别
Low-order unconformity recognition of marine carbonate rocks based on Milankovitch cycles:an example of fifth member of the Majiagou Formation in the Ordos Basin
摘要
Abstract
The spatial distribution of low-order unconformities in sedimentary carbonate rocks exerts a profound influence on the development of karst reservoirs.The identification and characterization pose formidable challenges that traditional geological methods are ill-equipped to address.Confronted with the inherent limitations of conventional approaches,including exorbitant costs,poor spatial continuity,and insufficient quantification,for identifying low-order unconformities in carbonate formations,this study selects the fifth member of the Majiagou Formation in the Ordos Basin as a model system.An in-novative,highly efficient quantitative identification method is proposed,which is firmly rooted in the Milankovitch cycle theory.This study integrates multiple analytical techniques,including spectral analy-sis,the Pearson correlation coefficient method,the null hypothesis model,and the dynamic"exposure time-dissolution amount"model.By correlating gamma-ray logging curves with the 405 ka long eccen-tricity cycle,we quantitatively characterize key geological parameters,such as the sedimentation rate(ranging from 2.5 to 3.0 cm/ka)of the target formation,the geological age of low-order unconformities(spanning from 468.6 to 460.1 Ma),and the dissolution intensity.The results of this research reveal the presence of four distinct phases of low-order unconformities,with a cumulative sedimentation hiatus of 0.3 million years and a maximum stratigraphic loss of 9 meters.A statistically significant negative cor-relation is observed between the dissolution intensity and the relative sea-level rise rate.During periods of slow sea-level rise(0.7 m/Ma over 1.4 million years),karst caves with diameters ranging from 0.2 to 0.4 mm are formed.In contrast,rapid sea-level rise events(1.2 m/Ma over 0.9 million years)lead to the development of only micro-pores with diameters of 0.05 to 0.10 mm.This study represents a signif-icant advancement by for the first time elucidating the"lag response"mechanism driven by the coupling of climate change and sea-level fluctuations.It challenges and revises the long-standing assumption of"long-term exposure during regressive unconformities"in traditional sequence stratigraphy models.The proposed method provides essential quantitative technical support for predicting karst reservoirs in re-gions characterized by high-frequency sea-level fluctuations.The findings of this study have far-reaching implications for both the practical exploration of deep subsurface reservoirs and the theoretical under-standing of sedimentary processes in the Ordos Basin and other similar cratonic basins.关键词
低级序不整合面/海相碳酸盐岩/米氏旋回/台地/岩溶储层/频谱分析/沉积速率/海平面变化/马家沟组/克拉通盆地/鄂尔多斯盆地Key words
low-order unconformity/marine carbonate rocks/Milankovitch cycles/platform/karst res-ervoir/spectral analysis/sedimentation rate/sea level/Majiagou Formation/Craton Basin/Ordos Basin分类
天文与地球科学引用本文复制引用
张斌弛,铁木尔巴特,张月,邵世国,王守志,王林,文慧俭,梅曦,李润民..基于米氏旋回的海相碳酸盐岩低级序不整合面识别[J].东北石油大学学报,2025,49(6):57-69,84,14.基金项目
黑龙江省自然科学基金联合引导项目(LH2024D010) （LH2024D010）
