The “underfilled trinity model” of foreland basins revisited: reality or myth?

作     者：Xiu-Mian Hu Eduardo Garzanti Juan Li Marcelle Bou Dagher-Fadel Giovanni Coletti An-Lin Ma Wen-Dong Liang Wei-Wei Xue 

作者机构：State Key Laboratory of Mineral Deposits ResearchInstitute of Continental GeodynamicsSchool of Earth Sciences and EngineeringNanjing University Department of Earth and Environmental SciencesUniversit a di Milano-Bicocca Department of Earth SciencesUniversity College London 

出 版 物：《Journal of Palaeogeography》 (古地理学报(英文版))

年 卷 期：2024年第04期

页      面：675-705页

核心收录：

学科分类：070904[理学-构造地质学] 0709[理学-地质学] 07[理学] 

基　　金：financially supported by National Natural Science Foundation of China projects (91755209  41525007) 

摘      要：The “underfilled trinity model of foreland-basin stratigraphy was proposed based on the observation that the initial sedimentary stages along the western and northern front of the western and central Alps were represented by shallow-water carbonates(Calcaires a Nummulites) overlain by hemipelagic marls(Marnes Bleues) and capped by siliciclastic turbidites(Gr es d Annot). Subsequently, this model has been widely accepted and applied in foreland basins worldwide. We here re-investigated the Eocene-Oligocene sedimentary succession of the Western Alps to check its validity. Major geological features of this region include: i) the existence of a Cretaceous-Eocene unconformity spanning more than 25 Myr in the studied sections; ii) a virtually synchronous age of the Calcaires a Nummulites, Marnes Bleues, and Gr es d Annot formations across the Western Alps; iii) a long-term deepening-upward trend, from inner to outer ramp,documented by the Calcaires a Nummulites, followed by the pelagic Marnes Bleues and by the Gr es d Annot turbidites; iv) the provenance of the Gr es d Annot Formation from the Maures-Est erel Massif and/or CorsicaSardinia block in the south, rather than from the Alpine orogen in the east. By integrating field observations,sedimentological, biostratigraphic, and provenance analyses, we found the Eocene “underfilled forelandmodel too simplistic and inadequate to explain the basin evolution in the western Alpine region. Based on the alternative scenario proposed herein, the Annot and Barr^eme basins formed in the late Eocene(40-35 Ma) in an extensional/transtensional setting during a period of major change in tectonic stress fields across western Europe on the upper plate of the Apennine subduction.