The Role of Mass Wasting In the Progressive Development Of Submarine Channels (Espírito Santo Basin, Se Brazil)

Abstract

ABSTRACT:A Pliocene-Quaternary submarine channel system, influenced by a localized mass wasting, is investigated in this work using high-resolution 3D seismic data from offshore Espírito Santo Basin, SE Brazil. Three abandoned channels, a channel belt and an mass-transport deposit (MTD) are recognized in the channel system within a confluence region confined by salt diapirs. In this confluence region, the cross-sectional area (CSA) of the channel system can be up to 1.2 km 2 , i.e., 4 to 10 times larger than CSA in other parts of the channel system. Such significant changes in the architecture and morphology of the channel system resulted from the interaction between mass-wasting processes and turbidity flows. We postulate that a basal erosional scar was created by mass-wasting processes and was filled with an MTD. This basal scar was then used as a preferential pathway for turbidity flows, which were captured by its headwall and lateral margins. The interpreted data shows that the captured turbidity flows greatly widened the basal scar, but caused only small modifications in scar height. Part of the MTD within the basal scar was removed downslope by turbidity flows, and was replaced by channel-fill deposits. This paper shows a flow-capture process occurred in a confluence region on continental slope. Basal scars can capture turbidity flows and facilitate flow channelization, which is a key process for submarine-channel initiation. The replacement of MTD by channel-fill deposits has profound implications for reservoir volumes and net-to-gross ratios in channel systems and partly depends on the turbidity-flows properties, such as their erosive ability and frequency. The more erosive and frequent flows are captured by the basal scar, the larger is the accommodation space created for succeeding sand-prone turbidites.

Submarine sediment routing over a blocky mass‐transport deposit in the Espírito Santo Basin, SE Brazil

“…All follow a similar trend line, but have increasing width:height ratios from the blocks, to depocentres, to channels. (b) Width:height plots comparing stratigraphic elements observed in this study and previous publications (Babonneau et al., ; Clark & Pickering, ; Deptuck et al., ; Di Celma et al., ; Gamboa & Alves, ,b; Gong et al., ; Hampton et al., ; Masson et al., ; McHargue et al., ; Omosanya & Alves, ; Qin et al., ). The measurements from this study are black…”

“…These results are compared with width and height measurements from different stratigraphic elements in the literature. These include MTD blocks (Gamboa & Alves, ; McHargue et al., ; Moscardelli & Wood, ; Omosanya & Alves, ), different elements from within a channel system (Babonneau, Savoye, Cremer, & Klein, ; Clark & Pickering, ; Deptuck, Sylvester, Pirmez, & O'Byrne, ; Di Celma, Brunt, Hodgson, Flint, & Kavanagh, ; Gamboa & Alves, ; Gong et al., ; Qin, Alves, Constantine, & Gamboa, ), landslides, debris flows and MTDs (Gamboa & Alves, ; Hampton et al., ; Masson et al., ) and plunge pools (Lee, Talling, Ernst, & Hogg, ). All these data are compiled on a graph (Figure b).…”

“…EAGE | 823 literature. These include MTD blocks(Gamboa & Alves, 2015a;McHargue et al, 2011;Moscardelli & Wood, 2008;Omosanya & Alves, 2014), different elements from within a channel system(Babonneau, Savoye, Cremer, & Klein, 2002;Clark & Pickering, 1996;Deptuck, Sylvester, Pirmez, & O'Byrne, 2007;Di Celma, Brunt, Hodgson, Flint, & Kavanagh, 2011;Gamboa & Alves, 2015a;Gong et al, 2016;Qin, Alves, Constantine, & Gamboa, 2017), landslides, debris flows and MTDs…”

Exhumed lateral margins and increasing flow confinement of a submarine landslide complex

“…The quasi‐instantaneous modification of the seascape by these events leads to the rerouting, capture and ponding of subsequent flows (e.g. Alves & Cartwright, ; Ortiz‐Karpf et al ., ; Kneller et al ., ; Fallgatter et al ., ; Qin et al ., ). Therefore, understanding of the formation and infill of major submarine landslides is required to assess their geohazard potential and the stratigraphic evolution of continental margins.…”

Submarine channel network evolution above an extensive mass-transport complex: A 3D seismic case study from the Niger delta continental slope

“…In some extreme cases, they can even control the submarine channel avulsion or confluence; for example, Ortiz-Karpf et al (2015) introduced the role of masstransport complexes in triggering the occurrence of channel avulsion and controlling the evolution of subsequent avulsion channels/lobes in Magdalena Fan, offshore Colombia. Qin et al (2017), on the other hand, investigated the effect of mass-transport deposits in terms of capturing unconfined flows to merge distinct channels offshore Espirito Santo Basin, SE…”