Bozetti, G, Kneller, B, Cronin, BT et al. (3 more authors) (2023) Lateral and temporal variations of a multi-phase coarse-grained submarine slope channel system, Upper Cretaceous Cerro Toro Formation, southern Chile. Journal of Sedimentary Research, 93 (3). pp. 161-186. ISSN 1527-1404
Abstract
Understanding variations in the sedimentary processes and resulting stratigraphic architecture in submarine channel systems is essential for characterizing sediment bypass and sedimentary facies distribution on submarine slopes. In the Santonian to Campanian Cerro Toro Formation, southern Chile, a coarse-grained slope system, informally known as the Lago Sofia Member, developed in a structurally controlled environment, with complex and poorly established relationships with the surrounding mud-rich heterolithic deposits.
A detailed architectural analysis of the most continuous and best-exposed channel system in the Lago Sofia Member, the Paine C channel system, provides insights on lateral facies transitions from channel axis to margin, stacked in a multi-phase sequence of events marked by abrupt changes in facies, facies associations, and architecture.
The Paine C channel system is incised into siltstones and claystones interbedded with thin-bedded very fine sandstones, interpreted to be either channel-related overbank or unrelated background deposits. The coarse-grained deposits are divided into a lower conglomeratic unit and an upper sand-rich unit. The lower conglomeratic unit can be further subdivided into three phases: 1) highly depositional and/or aggradational, dominated by thick and laterally continuous beds of clast- to matrix-supported conglomerate, herein named transitional event deposits; 2) an intermediate phase, including deposits similar to those dominant in phase 1 but also containing abundant clast-supported conglomerates and lenticular sandstones; and 3) a bypass-dominated phase, which records an architectural change into a highly amalgamated ca. 45-m-thick package composed purely of lenticular clast-supported conglomerates with local lenticular sandstones. Between the conglomeratic phases, a meter-scale package composed of interbedded thin- to medium-bedded sandstone and mudstone deposits is interpreted to drape the entire channel, indicating periods of weaker gravity flows running down the channel, with no evidence of bedload transport.
The upper sand-rich unit is divided into lower amalgamated and upper non-amalgamated phases, and represents a rapid architectural change interpreted to record an overall waning of the system. The sandstone unit laps out onto a mass-transport complex which is interpreted to have been triggered initially at the same time as major architectural change from conglomerates to sandstones.
While mindful of the fact that each system is a complete analogue only for itself, we propose a new depositional model for coarse-grained submarine channel systems, in which particular characteristics can provide significant insights into architectural heterogeneity and facies transitions in channelized systems, allowing substantial improvement in subsurface facies prediction for fluid reservoirs.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2023, SEPM (Society for Sedimentary Geology). This is an author produced version of an article published in Journal of Sedimentary Research (JSR). Uploaded in accordance with the publisher's self-archiving policy. |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Institute for Applied Geosciences (IAG) (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 02 May 2023 15:06 |
Last Modified: | 25 Jun 2023 23:20 |
Status: | Published |
Publisher: | SEPM Society for Sedimentary Geology |
Identification Number: | 10.2110/jsr.2022.020 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:198754 |