爱尔兰克莱尔盆地Ross Sandstone组深水浊积岩露头高分辨率层序地层学

High resolution sequence stratigraphy of the Ross Sandstone deepwater turbidite outcrops in the Clare Basin,Ireland

应用高分辨率层序地层学原理和分析方法,通过对爱尔兰西海岸Ross Sandstone组深水浊积朵叶体露头的详细研究,基于侧向稳定展布的泥岩段、沉积构造与岩相组合、砂岩融合的程度以及沉积物的样式与厚度4个方面,建立了研究区高分辨率层序地层格架,探讨了深水浊积朵叶体的沉积模式及不同层次基准面旋回的控制因素。研究表明,富含有机质与棱菊石化石的远洋泥岩是长期基准面旋回的界面。在长期旋回内,侧向展布数千米至数万米的薄层泥岩夹粉砂岩是中期基准面旋回的界面。每一个中期旋回都由数个相互叠置的向上变厚旋回组成,单个向上变厚旋回通常由底部薄层泥岩夹粉砂岩开始,往上逐渐转变为厚层的无构造砂岩;其厚度通常为0.5~7 m,并可稳定延伸数百米至数千米,反映了朵叶体的持续前积作用。

Using the principles and methods of high-resolution sequence stratigraphy,the Ross Sandstone deepwaterturbidite lobe outcrops in the coast of western Irelandare studiedbased on four factors：laterally extensive mudstones,sedimentary structures and lithofacies associations,degree of sand amalgamation and sedimentary pattern and thickness.The high-resolution sequence stratigraphic framework has been established,the depositional model of deepwaterturbidite lobe is proposed,and the controlling factors for base level cycles at different hierarchies are discussed.The results show that,the organic-rich pelagic mudstone with abundant goniatites represents the transition of two adjacent long-term base level hemi-cycles.Within the long-term base level cycle,each mid-term base level cycle is bounded by the thin mudstones with subordinate siltstones which can extend laterally several kilometers to tens of kilometers.Each mid-term cycle is composed of several thickening-upward cycles which are 0.5-7 m thick and several hundred meters to several kilometers across,suggesting continuous lobe progradation.