Fluvial sedimentation and its reservoir potential at foreland basin margins: a case study of the Puig-reig anticline (South-eastern Pyrenees)

Sun, X., Alcalde, J., Gomez-Rivas, E., Owen, A. , Griera, A., Martín-Martín, J. D., Cruset, D. and Travé, A. (2021) Fluvial sedimentation and its reservoir potential at foreland basin margins: a case study of the Puig-reig anticline (South-eastern Pyrenees). Sedimentary Geology, 424, 105993. (doi: 10.1016/j.sedgeo.2021.105993)

Abstract

Fluvial fans represent one of the dominant sedimentary systems at the active margins of non-marine foreland basins. The Puig-reig anticline at the north-eastern margin of the Ebro Foreland Basin (SE Pyrenees, Spain) exposes continuous outcrops of Late Eocene-Early Oligocene fluvial deposits, from proximal to medial fluvial fan environments. The proximal deposits, found in the north limb of the anticline, especially in the northwest zone. These deposits are characterised by conglomerates with minor interbedded sandstones, with thick and wide sheet-like geometries with unscoured or variably scoured basal surfaces. These are interpreted to be the deposits of unconfined flash floods and wide-shallow channel streams. The medial deposits, covering the rest of the anticline, consist of interbedded conglomerates, sandstones and claystones. These are interpreted to have been deposited from braided to meandering channel streams and overbank areas. Distal deposits are found towards the south, beyond the anticline, and are characterised by sandstone and clay deposits of terminal lobes and lacustrine deltas. This study assesses the impact of the primary depositional characteristics, diagenesis and deformation of the most heterolithic portion of the system, with implications for increasing our understanding of folded fluvial reservoirs. Diagenetic processes, mainly mechanical compaction and calcite cementation, resulted in overall low intergranular porosity, with limited relatively high porosity developed in sandstone lithofacies in the medial deposits. Deformation associated with thrusting and fold growth resulted in the formation of abundant fractures, with relatively high fracture intensities observed in sandstone lithofacies in the anticline crest. This study shows that post-depositional processes can both improve and diminish the reservoir potential of basin proximal fluvial deposits, through the development of fracture networks and by compaction-cementation. The comparison of the Puig-reig anticline with other similar settings worldwide indicates that foreland basin margin locations may be potential areas for effective reservoirs, even in the case of low intergranular porosity.

• Item Type: Articles
• Additional Information: Funding was provided by the Catalan Council to the Grup Consolidat de Recerca “Geologia Sedimentària” (2017SGR-824) and the DGICYT Spanish Project PGC2018-093903-B-C22. XS acknowledges funding by the China Scholarship Council for a PhD scholarship (201806450043). JA is funded by MICINN (Juan de la Cierva fellowship - IJC2018-036074-I). EGR acknowledges funding provided by the Spanish Ministry of Science, Innovation and Universities (“Ramón y Cajal” fellowship RYC2018-026335-I).
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Owen, Dr Amanda
• Authors: Sun, X., Alcalde, J., Gomez-Rivas, E., Owen, A., Griera, A., Martín-Martín, J. D., Cruset, D., and Travé, A.
• College/School: College of Science and Engineering > School of Geographical and Earth Sciences
• Journal Name: Sedimentary Geology
• Publisher: Elsevier
• ISSN: 0037-0738
• ISSN (Online): 1879-0968
• Published Online: 08 September 2021
• Copyright Holders: Copyright © 2021 The Authors
• First Published: First published in Sedimentary Geology 424: 105993
• Publisher Policy: Reproduced under a Creative Commons License