Genesis and character of thin-bedded turbidites associated with submarine channels

Larissa A S Hansen* (Corresponding Author), Richard H T Callow, Ian A. Kane, Fabiano Gamberi, Marzia Rovere, Bryan T. Cronin, Benjamin C Kneller

*Corresponding author for this work

Research output: Contribution to journalArticle

33 Citations (Scopus)
23 Downloads (Pure)

Abstract

Submarine channel-related thin-bedded turbidites are deposited in environments such as external levees, internal levees, depositional terraces and at times of channel abandonment. Thin-bedded turbidites are defined as beds that are less than 10 cm thick, but the described environments can at times contain beds up to 100 cm thick which would be classified as medium- or thick-bedded. This paper addresses examples of these environments from the modern seafloor, outcrop and the subsurface to suggest criteria that assist in the differentiation of levees and terraces from an architectural, sedimentological, ichnological and hydrocarbon reservoir perspective. External levees confine channel belts and are elongate sedimentary deposits that are a product of over-spill of turbidity currents from the channel belt they confine. External levees often have predictable vertical, lateral and downstream changes in thickness and sand content but are commonly modified by collapse of the inner external levee into the channel, by collapse on the outer external levee, by sediment waves, and by interaction of external levees with topographic features such as other channels, other external levees, basin margins or previous slump/slide blocks, which can greatly modify the sand distribution within them.

A combination of internal levees, depositional terraces and slide blocks of external levee sediment make up thin-bedded turbidites within channel belts. We differentiate between wedge-shaped internal levees and topographically flat or subdued depositional terraces, whose differing geometries and sand distribution reflect the fact that the flow processes involved in the formation of these deposits are different. The characteristic wedge shape of an internal levee requires sufficient space within the channel belt for the over-spilling current to spread, decelerate and deposit the majority of its silt and sand grade suspended sediment before reaching the bounding topography of the channel belt. In the case of depositional terraces the space available in the channel belt is insufficient for the current to decelerate and deposit the majority of its sediment before reaching the bounding topography of the channel belt, creating confined sheet-like deposits.

External levees, internal levees and depositional terraces have distinct sedimentological characteristics such as sand bed thickness trends and sedimentary structures that can be used to distinguish them. Together with sedimentological characteristics, in some systems these thin-bedded turbidite deposits contain distinctive trace fossil assemblages, where channel proximal deposits such as proximal external levees, internal levees and depositional terraces can have much higher ichnodiversity than sand-rich channel axes and more mud-dominated outer external levees.

The depositional sites for internal levees and depositional terraces within channel belts can be formed by various processes such as entrenchment, point bar accretion, meander bend cut-off, channel margin failure, or changes in the flow parameters. These processes can result in elevated surfaces within the confines of the channel belt that subsequently become prone to the deposition of over-bank deposits.

The development and preservation of levees and terraces is closely related to the evolution of the channel belt as a whole, which is controlled both by allogenic mechanisms (such as sea-level fluctuations, changes in turbidity current size and sediment calibre, and changes in the equilibrium profile of the channel), and by autogenic mechanisms (such as channel avulsion and resulting knick-point migration). Where preserved in the rock record thin-bedded turbidites have been uncommon primary targets for hydrocarbon field development, since most efforts have focused on the channel-fills which have the highest proportion of sand. However, thin-bedded turbidites can contain large amounts of sand, of which individual beds can be very laterally continuous, and hence can make significant secondary reservoir targets.
Original languageEnglish
Pages (from-to)852-879
Number of pages27
JournalMarine and Petroleum Geology
Volume67
Early online date20 Jun 2015
DOIs
Publication statusPublished - Nov 2015

Fingerprint

submarine channel
terrace
sands
deposits
sand
levee
sediments
beds
turbidity current
turbidity
chutes
wedges
margins
topography
hydrocarbons
spilling
sediment
sediment wave

Keywords

  • submarine channels
  • thin-bedded turbidites
  • levees
  • terraces
  • external levees
  • internal levees
  • depositional terraces
  • hydrocarbons
  • reservoir
  • ichnology

Cite this

Hansen, L. A. S., Callow, R. H. T., Kane, I. A., Gamberi, F., Rovere, M., Cronin, B. T., & Kneller, B. C. (2015). Genesis and character of thin-bedded turbidites associated with submarine channels. Marine and Petroleum Geology, 67, 852-879. https://doi.org/10.1016/j.marpetgeo.2015.06.007

Genesis and character of thin-bedded turbidites associated with submarine channels. / Hansen, Larissa A S (Corresponding Author); Callow, Richard H T; Kane, Ian A.; Gamberi, Fabiano; Rovere, Marzia; Cronin, Bryan T.; Kneller, Benjamin C.

In: Marine and Petroleum Geology, Vol. 67, 11.2015, p. 852-879.

Research output: Contribution to journalArticle

Hansen, LAS, Callow, RHT, Kane, IA, Gamberi, F, Rovere, M, Cronin, BT & Kneller, BC 2015, 'Genesis and character of thin-bedded turbidites associated with submarine channels', Marine and Petroleum Geology, vol. 67, pp. 852-879. https://doi.org/10.1016/j.marpetgeo.2015.06.007
Hansen, Larissa A S ; Callow, Richard H T ; Kane, Ian A. ; Gamberi, Fabiano ; Rovere, Marzia ; Cronin, Bryan T. ; Kneller, Benjamin C. / Genesis and character of thin-bedded turbidites associated with submarine channels. In: Marine and Petroleum Geology. 2015 ; Vol. 67. pp. 852-879.
@article{a468e1b45db44e85824e1561e1b58aed,
title = "Genesis and character of thin-bedded turbidites associated with submarine channels",
abstract = "Submarine channel-related thin-bedded turbidites are deposited in environments such as external levees, internal levees, depositional terraces and at times of channel abandonment. Thin-bedded turbidites are defined as beds that are less than 10 cm thick, but the described environments can at times contain beds up to 100 cm thick which would be classified as medium- or thick-bedded. This paper addresses examples of these environments from the modern seafloor, outcrop and the subsurface to suggest criteria that assist in the differentiation of levees and terraces from an architectural, sedimentological, ichnological and hydrocarbon reservoir perspective. External levees confine channel belts and are elongate sedimentary deposits that are a product of over-spill of turbidity currents from the channel belt they confine. External levees often have predictable vertical, lateral and downstream changes in thickness and sand content but are commonly modified by collapse of the inner external levee into the channel, by collapse on the outer external levee, by sediment waves, and by interaction of external levees with topographic features such as other channels, other external levees, basin margins or previous slump/slide blocks, which can greatly modify the sand distribution within them.A combination of internal levees, depositional terraces and slide blocks of external levee sediment make up thin-bedded turbidites within channel belts. We differentiate between wedge-shaped internal levees and topographically flat or subdued depositional terraces, whose differing geometries and sand distribution reflect the fact that the flow processes involved in the formation of these deposits are different. The characteristic wedge shape of an internal levee requires sufficient space within the channel belt for the over-spilling current to spread, decelerate and deposit the majority of its silt and sand grade suspended sediment before reaching the bounding topography of the channel belt. In the case of depositional terraces the space available in the channel belt is insufficient for the current to decelerate and deposit the majority of its sediment before reaching the bounding topography of the channel belt, creating confined sheet-like deposits.External levees, internal levees and depositional terraces have distinct sedimentological characteristics such as sand bed thickness trends and sedimentary structures that can be used to distinguish them. Together with sedimentological characteristics, in some systems these thin-bedded turbidite deposits contain distinctive trace fossil assemblages, where channel proximal deposits such as proximal external levees, internal levees and depositional terraces can have much higher ichnodiversity than sand-rich channel axes and more mud-dominated outer external levees.The depositional sites for internal levees and depositional terraces within channel belts can be formed by various processes such as entrenchment, point bar accretion, meander bend cut-off, channel margin failure, or changes in the flow parameters. These processes can result in elevated surfaces within the confines of the channel belt that subsequently become prone to the deposition of over-bank deposits.The development and preservation of levees and terraces is closely related to the evolution of the channel belt as a whole, which is controlled both by allogenic mechanisms (such as sea-level fluctuations, changes in turbidity current size and sediment calibre, and changes in the equilibrium profile of the channel), and by autogenic mechanisms (such as channel avulsion and resulting knick-point migration). Where preserved in the rock record thin-bedded turbidites have been uncommon primary targets for hydrocarbon field development, since most efforts have focused on the channel-fills which have the highest proportion of sand. However, thin-bedded turbidites can contain large amounts of sand, of which individual beds can be very laterally continuous, and hence can make significant secondary reservoir targets.",
keywords = "submarine channels, thin-bedded turbidites, levees, terraces, external levees, internal levees, depositional terraces, hydrocarbons, reservoir, ichnology",
author = "Hansen, {Larissa A S} and Callow, {Richard H T} and Kane, {Ian A.} and Fabiano Gamberi and Marzia Rovere and Cronin, {Bryan T.} and Kneller, {Benjamin C}",
note = "Acknowledgements We acknowledge the support of the PRACSS Joint Industry Project at University of Aberdeen, funded by BG Group, BP, DONG, RWE Dea, Petrochina, Statoil and Tullow Oil. We also acknowledge the entire crew of the Urania Research vessel which was used to acquire the CHIRP lines, bathymetric data and gravity cores from the Tyrrhenian Sea, Italy. Our colleagues Michal Janocko and Mike Mayall are thanked for the discussions and comments. Our colleagues Pan Li, Amanda Santa Catharina, Guilherme Bozetti and Matheus Silveira Sobiesiak are thanked for their assistance during field work where some of the ideas in this paper were synthesized. Finally we thank one anonymous reviewer and Brian Romans for their invaluable feedback which made some of the ideas introduced in this review much more succinct.",
year = "2015",
month = "11",
doi = "10.1016/j.marpetgeo.2015.06.007",
language = "English",
volume = "67",
pages = "852--879",
journal = "Marine and Petroleum Geology",
issn = "0264-8172",
publisher = "Elsevier",

}

TY - JOUR

T1 - Genesis and character of thin-bedded turbidites associated with submarine channels

AU - Hansen, Larissa A S

AU - Callow, Richard H T

AU - Kane, Ian A.

AU - Gamberi, Fabiano

AU - Rovere, Marzia

AU - Cronin, Bryan T.

AU - Kneller, Benjamin C

N1 - Acknowledgements We acknowledge the support of the PRACSS Joint Industry Project at University of Aberdeen, funded by BG Group, BP, DONG, RWE Dea, Petrochina, Statoil and Tullow Oil. We also acknowledge the entire crew of the Urania Research vessel which was used to acquire the CHIRP lines, bathymetric data and gravity cores from the Tyrrhenian Sea, Italy. Our colleagues Michal Janocko and Mike Mayall are thanked for the discussions and comments. Our colleagues Pan Li, Amanda Santa Catharina, Guilherme Bozetti and Matheus Silveira Sobiesiak are thanked for their assistance during field work where some of the ideas in this paper were synthesized. Finally we thank one anonymous reviewer and Brian Romans for their invaluable feedback which made some of the ideas introduced in this review much more succinct.

PY - 2015/11

Y1 - 2015/11

N2 - Submarine channel-related thin-bedded turbidites are deposited in environments such as external levees, internal levees, depositional terraces and at times of channel abandonment. Thin-bedded turbidites are defined as beds that are less than 10 cm thick, but the described environments can at times contain beds up to 100 cm thick which would be classified as medium- or thick-bedded. This paper addresses examples of these environments from the modern seafloor, outcrop and the subsurface to suggest criteria that assist in the differentiation of levees and terraces from an architectural, sedimentological, ichnological and hydrocarbon reservoir perspective. External levees confine channel belts and are elongate sedimentary deposits that are a product of over-spill of turbidity currents from the channel belt they confine. External levees often have predictable vertical, lateral and downstream changes in thickness and sand content but are commonly modified by collapse of the inner external levee into the channel, by collapse on the outer external levee, by sediment waves, and by interaction of external levees with topographic features such as other channels, other external levees, basin margins or previous slump/slide blocks, which can greatly modify the sand distribution within them.A combination of internal levees, depositional terraces and slide blocks of external levee sediment make up thin-bedded turbidites within channel belts. We differentiate between wedge-shaped internal levees and topographically flat or subdued depositional terraces, whose differing geometries and sand distribution reflect the fact that the flow processes involved in the formation of these deposits are different. The characteristic wedge shape of an internal levee requires sufficient space within the channel belt for the over-spilling current to spread, decelerate and deposit the majority of its silt and sand grade suspended sediment before reaching the bounding topography of the channel belt. In the case of depositional terraces the space available in the channel belt is insufficient for the current to decelerate and deposit the majority of its sediment before reaching the bounding topography of the channel belt, creating confined sheet-like deposits.External levees, internal levees and depositional terraces have distinct sedimentological characteristics such as sand bed thickness trends and sedimentary structures that can be used to distinguish them. Together with sedimentological characteristics, in some systems these thin-bedded turbidite deposits contain distinctive trace fossil assemblages, where channel proximal deposits such as proximal external levees, internal levees and depositional terraces can have much higher ichnodiversity than sand-rich channel axes and more mud-dominated outer external levees.The depositional sites for internal levees and depositional terraces within channel belts can be formed by various processes such as entrenchment, point bar accretion, meander bend cut-off, channel margin failure, or changes in the flow parameters. These processes can result in elevated surfaces within the confines of the channel belt that subsequently become prone to the deposition of over-bank deposits.The development and preservation of levees and terraces is closely related to the evolution of the channel belt as a whole, which is controlled both by allogenic mechanisms (such as sea-level fluctuations, changes in turbidity current size and sediment calibre, and changes in the equilibrium profile of the channel), and by autogenic mechanisms (such as channel avulsion and resulting knick-point migration). Where preserved in the rock record thin-bedded turbidites have been uncommon primary targets for hydrocarbon field development, since most efforts have focused on the channel-fills which have the highest proportion of sand. However, thin-bedded turbidites can contain large amounts of sand, of which individual beds can be very laterally continuous, and hence can make significant secondary reservoir targets.

AB - Submarine channel-related thin-bedded turbidites are deposited in environments such as external levees, internal levees, depositional terraces and at times of channel abandonment. Thin-bedded turbidites are defined as beds that are less than 10 cm thick, but the described environments can at times contain beds up to 100 cm thick which would be classified as medium- or thick-bedded. This paper addresses examples of these environments from the modern seafloor, outcrop and the subsurface to suggest criteria that assist in the differentiation of levees and terraces from an architectural, sedimentological, ichnological and hydrocarbon reservoir perspective. External levees confine channel belts and are elongate sedimentary deposits that are a product of over-spill of turbidity currents from the channel belt they confine. External levees often have predictable vertical, lateral and downstream changes in thickness and sand content but are commonly modified by collapse of the inner external levee into the channel, by collapse on the outer external levee, by sediment waves, and by interaction of external levees with topographic features such as other channels, other external levees, basin margins or previous slump/slide blocks, which can greatly modify the sand distribution within them.A combination of internal levees, depositional terraces and slide blocks of external levee sediment make up thin-bedded turbidites within channel belts. We differentiate between wedge-shaped internal levees and topographically flat or subdued depositional terraces, whose differing geometries and sand distribution reflect the fact that the flow processes involved in the formation of these deposits are different. The characteristic wedge shape of an internal levee requires sufficient space within the channel belt for the over-spilling current to spread, decelerate and deposit the majority of its silt and sand grade suspended sediment before reaching the bounding topography of the channel belt. In the case of depositional terraces the space available in the channel belt is insufficient for the current to decelerate and deposit the majority of its sediment before reaching the bounding topography of the channel belt, creating confined sheet-like deposits.External levees, internal levees and depositional terraces have distinct sedimentological characteristics such as sand bed thickness trends and sedimentary structures that can be used to distinguish them. Together with sedimentological characteristics, in some systems these thin-bedded turbidite deposits contain distinctive trace fossil assemblages, where channel proximal deposits such as proximal external levees, internal levees and depositional terraces can have much higher ichnodiversity than sand-rich channel axes and more mud-dominated outer external levees.The depositional sites for internal levees and depositional terraces within channel belts can be formed by various processes such as entrenchment, point bar accretion, meander bend cut-off, channel margin failure, or changes in the flow parameters. These processes can result in elevated surfaces within the confines of the channel belt that subsequently become prone to the deposition of over-bank deposits.The development and preservation of levees and terraces is closely related to the evolution of the channel belt as a whole, which is controlled both by allogenic mechanisms (such as sea-level fluctuations, changes in turbidity current size and sediment calibre, and changes in the equilibrium profile of the channel), and by autogenic mechanisms (such as channel avulsion and resulting knick-point migration). Where preserved in the rock record thin-bedded turbidites have been uncommon primary targets for hydrocarbon field development, since most efforts have focused on the channel-fills which have the highest proportion of sand. However, thin-bedded turbidites can contain large amounts of sand, of which individual beds can be very laterally continuous, and hence can make significant secondary reservoir targets.

KW - submarine channels

KW - thin-bedded turbidites

KW - levees

KW - terraces

KW - external levees

KW - internal levees

KW - depositional terraces

KW - hydrocarbons

KW - reservoir

KW - ichnology

U2 - 10.1016/j.marpetgeo.2015.06.007

DO - 10.1016/j.marpetgeo.2015.06.007

M3 - Article

VL - 67

SP - 852

EP - 879

JO - Marine and Petroleum Geology

JF - Marine and Petroleum Geology

SN - 0264-8172

ER -