期刊
MARINE AND PETROLEUM GEOLOGY
卷 121, 期 -, 页码 -出版社
ELSEVIER SCI LTD
DOI: 10.1016/j.marpetgeo.2020.104623
关键词
Gamma-ray spikes; Organic-rich source rock; Compositional variations; Uranium precipitation
Prominent high-value gamma-ray spikes in the maximum flooding surfaces of the Middle Oxfordian-Kimmeridgian succession (Alge Member) display stratigraphic and regional variations in the southwestern Barents Sea. These variations suggest heterogeneities in the composition of the Alge Member, thus, challenging the common perception that this interval is a homogenous succession of organic-rich black shale. This study explores the overall variation in; clay mineral composition, source rock quality, minerals and macerals, core logs and seismic facies of the Alge Member. Gamma-log fluctuations were found to be independent of these variations. Uranium precipitates on sea bottom sediments when conditions change from oxic to anoxic. Fluctuations in sea level may result in such changes and, hence, guide gamma-ray responses. Sea level fluctuations also lead to a changing distance to the shoreline, which again influences sediment types, grain sizes, and source rock quality. Thus, indirectly sea level appears to be the common denominator, which sometimes matches source rock richness with spikes on gamma logs. Presence and absence of gamma-ray spikes are, hence, an additional tool to reveal the redox conditions in the SW Barents Sea, which has implications for the understanding of the paleogeography (or paleobathymetry) during deposition.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据