地质科技通报2025，Vol.44Issue(4)：217-232,16.DOI:10.19509/j.cnki.dzkq.tb20240678
早志留世华南扬子地区大陆风化作用与上升洋流演化及其对龙马溪组黑色页岩有机质富集的指示
Evolution of continental weathering and upwelling in Early Silurian and the implications for the organic matter accumulations in the black shales of Longmaxi Formation in the Upper Yangtze Block of South China
摘要
Abstract
The deposition mechanism of organic-rich shales in the Lower Silurian Longmaxi Formation is still under debate.[Objective]In order to reconstruct the climatic and oceanic environments during the Early Silurian,and reveal the influence of continental weathering and upwelling on the organic matter accumulation,[Methods]this study presents the geochemical compositions of the Lower Silurian succession in the BD 1 Well of the Upper Yangtze Platform.[Results]The results show that despite persistently restricted watermass conditions,the Longmaxi period experienced a transition from weak chemical weathering intensity in the early period to intense chemical weathering in the late period.During the early stage of Longmaxi Formation deposition,coinciding with the termination of the Hirnantian glaciation,global climatic warming and associated deglaciation induced a significant increase in fluvial runoff.This amplified runoff intensified continental weathering and erosion rates,concurrently elevating primary productivity.The deposition of organic-rich black shale within the Longmaxi Formation exhibits distinct spatiotemporal heterogeneity.Temporally,the evolution of continental weathering was modulated by pronounced climatic fluctuations.Only episodes of intense weathering facilitated the enrichment of organic matter within the Lower Longmaxi Formation.Spatially,across the Yangtze Sea paleoshelf,organic matter and biogenic silica enrichment was primarily driven by strong upwelling dynamics specific to the outer shelf setting,contrasting with the inner shelf regions.[Conclusion]This study reveals the mechanisms of organic matter enrichment in the study area during the Early Silurian.It summarizes the diverse spatial development patterns of organic-rich shale in the Longmaxi Formation of the Yangtze Block of South China,providing new perspectives for understanding organic matter enrichment mechanisms within the Longmaxi Formation.关键词
大陆风化作用/上升洋流/龙马溪组/有机质/黑色页岩/扬子地区Key words
continental weathering/upwelling/Longmaxi Formation/organic matter/black shale/Yangtze Block分类
天文与地球科学引用本文复制引用
冉倍,杨向荣,齐爽怡,史嘉欣,杨增辉,严德天..早志留世华南扬子地区大陆风化作用与上升洋流演化及其对龙马溪组黑色页岩有机质富集的指示[J].地质科技通报,2025,44(4):217-232,16.基金项目
国家自然科学基金项目(42402123) （42402123）
大学生创新创业训练计划项目(Yz2024027) （Yz2024027）
