Evolving fill-and-spill patterns across linked early post-rift depocentres control lobe characteristics: Los Molles Formation, Argentina
Author(s)
Type
Journal Article
Abstract
Inherited rift topography controls the sediment routing, timing of sand supply, and sedimentary linkage of early post-rift depocentres. Exhumed examples of early post-rift turbidite systems are rare and previous studies have examined the evolution of individual depocentres; in contrast, the detailed evolution of early post-rift turbidite systems across multiple depocentres has never been documented. Current fill-and-spill models do not detail the stratigraphic architecture and evolution of sedimentological characteristics of multiple intraslope fans developed across topography, including bed type distributions. Here, the evolution of three intraslope fans that developed across two early post-rift depocentres is documented along an 18 km long transect in the southern Neuquén Basin, Argentina. The relative chronology of sand supply in depocentres is constrained with new U–Pb ages, and sediment source areas with provenance analysis. The early post-rift intraslope fans record progradation of the system and progressive sedimentary linkage of post-rift depocentres, transverse to local syn-rift structures, with sediment routing subparallel to the cratonic basin margin. The large-scale stratigraphic architecture of intraslope fans indicates an evolution as a fill-and-spill system, with initial confinement through flow stripping and overspill to spillover with erosion and bypass across a transverse topographic high separating the depocentres. Changes in early post-rift intraslope fan characteristics, including thickness, sandstone content, lobe complex stacking patterns, stratal termination patterns and bed type distribution, record changing confinement through time within a depocentre, and spatially across depocentres. The strong spatial and vertical stratigraphic variability of transitional flow deposits and hybrid event beds reflects enhanced erosion, sediment bypass and flow transformation across transverse relief between the two depocentres during the spillover phase. These findings advance current understanding of early post-rift turbidite systems and refine fill-and-spill models, which will help the prediction of spatial and vertical changes in rock quality and connectivity in subsurface hydrocarbon reservoirs and CO2 storage sites.
Date Issued
2024-08
Date Acceptance
2024-02-24
Citation
Sedimentology, 2024, 71 (5), pp.1385-1704
ISSN
0037-0746
Publisher
Wiley
Start Page
1385
End Page
1704
Journal / Book Title
Sedimentology
Volume
71
Issue
5
Copyright Statement
© 2024 The Authors. Sedimentology published by John Wiley & Sons Ltd on behalf of International Association of Sedimentologists.
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
License URL
Identifier
https://onlinelibrary.wiley.com/doi/10.1111/sed.13190
Subjects
Back-arc
BASIN-FLOOR FANS
DEPOSITIONAL EVOLUTION
early post-rift
fill-and-spill
Geology
hybrid event beds
HYBRID EVENT BEDS
intraslope lobe
NEUQUEN BASIN
NORTHERN FOSSA MAGNA
Physical Sciences
rift basin
RIFT-BASIN
Science & Technology
SEQUENCE STRATIGRAPHY
STRATIGRAPHIC ARCHITECTURE
SUBMARINE SLOPE
TURBIDITE-SYSTEM
Publication Status
Published
Date Publish Online
2024-06-19