Lateral accretion in a deep-marine channel complex

implications for channellized flow processes in turbidity currents

Mason Dykstra, Ben Kneller

Research output: Contribution to journalArticle

55 Citations (Scopus)

Abstract

Some deep-marine channels show striking similarities to fluvial channels, despite major differences in the properties of the flows that they conduct. Some field observations from deep-marine channel deposits within a Late Cretaceous palaeo-canyon in the Rosario Formation of Baja California, Mexico, that bear on these comparisons have been reported. These channel deposits contain erosively based lateral accretion sets. These sets are generally a few metres thick and resemble fluvial point bar deposits. Sediment movement and deposition within these accretion deposits was induced by turbidity currents several to many times thicker than the depth of the channel, moving at several metres per second. The inclined sets define laterally migrating and sinuous channels locally at a high angle to the confining canyon. The instantaneous channel widths varied from 6 to 39 m, the depths from 2 center dot 5 to 4 m and the sinuosities from 1 center dot 3 to 3 center dot 1. Palaeocurrent data, taken mostly from clast imbrication in conglomerates, indicates current modes along the channel thalweg, but with other directions representing either secondary flow (oriented primarily up the point bar) or over-passing canyon-confined flow. It is suggested that, at times, the lower part of the turbidity currents flowing down the channels behaved similarly to within-bank fluvial currents, with a cross-channel component of flow towards the cut bank, and return flow at the bed sweeping up the point bar. At other times, this secondary circulation may be absent or reversed, which may be related to changes in flow thickness, coupling with the overriding flow and possible flow separation.

Original languageEnglish
Pages (from-to)1411-1432
Number of pages22
JournalSedimentology
Volume56
Issue number5
Early online date5 Jan 2009
DOIs
Publication statusPublished - Aug 2009

Keywords

  • Deep-marine
  • helical flow
  • lateral-accretion
  • meandering
  • point bar
  • sinuous
  • cretaceous rosario formation
  • large ocean basins
  • submarine-fan
  • sea fan
  • sinuous channel
  • Baja California
  • process Model
  • evolution
  • architecture

Cite this

Lateral accretion in a deep-marine channel complex : implications for channellized flow processes in turbidity currents. / Dykstra, Mason; Kneller, Ben.

In: Sedimentology, Vol. 56, No. 5, 08.2009, p. 1411-1432.

Research output: Contribution to journalArticle

@article{c1f9c14601f14cc2a21d1481119d78e2,
title = "Lateral accretion in a deep-marine channel complex: implications for channellized flow processes in turbidity currents",
abstract = "Some deep-marine channels show striking similarities to fluvial channels, despite major differences in the properties of the flows that they conduct. Some field observations from deep-marine channel deposits within a Late Cretaceous palaeo-canyon in the Rosario Formation of Baja California, Mexico, that bear on these comparisons have been reported. These channel deposits contain erosively based lateral accretion sets. These sets are generally a few metres thick and resemble fluvial point bar deposits. Sediment movement and deposition within these accretion deposits was induced by turbidity currents several to many times thicker than the depth of the channel, moving at several metres per second. The inclined sets define laterally migrating and sinuous channels locally at a high angle to the confining canyon. The instantaneous channel widths varied from 6 to 39 m, the depths from 2 center dot 5 to 4 m and the sinuosities from 1 center dot 3 to 3 center dot 1. Palaeocurrent data, taken mostly from clast imbrication in conglomerates, indicates current modes along the channel thalweg, but with other directions representing either secondary flow (oriented primarily up the point bar) or over-passing canyon-confined flow. It is suggested that, at times, the lower part of the turbidity currents flowing down the channels behaved similarly to within-bank fluvial currents, with a cross-channel component of flow towards the cut bank, and return flow at the bed sweeping up the point bar. At other times, this secondary circulation may be absent or reversed, which may be related to changes in flow thickness, coupling with the overriding flow and possible flow separation.",
keywords = "Deep-marine, helical flow, lateral-accretion, meandering, point bar, sinuous, cretaceous rosario formation, large ocean basins, submarine-fan, sea fan, sinuous channel, Baja California, process Model, evolution, architecture",
author = "Mason Dykstra and Ben Kneller",
year = "2009",
month = "8",
doi = "10.1111/j.1365-3091.2008.01040.x",
language = "English",
volume = "56",
pages = "1411--1432",
journal = "Sedimentology",
issn = "0037-0746",
publisher = "Wiley-Blackwell",
number = "5",

}

TY - JOUR

T1 - Lateral accretion in a deep-marine channel complex

T2 - implications for channellized flow processes in turbidity currents

AU - Dykstra, Mason

AU - Kneller, Ben

PY - 2009/8

Y1 - 2009/8

N2 - Some deep-marine channels show striking similarities to fluvial channels, despite major differences in the properties of the flows that they conduct. Some field observations from deep-marine channel deposits within a Late Cretaceous palaeo-canyon in the Rosario Formation of Baja California, Mexico, that bear on these comparisons have been reported. These channel deposits contain erosively based lateral accretion sets. These sets are generally a few metres thick and resemble fluvial point bar deposits. Sediment movement and deposition within these accretion deposits was induced by turbidity currents several to many times thicker than the depth of the channel, moving at several metres per second. The inclined sets define laterally migrating and sinuous channels locally at a high angle to the confining canyon. The instantaneous channel widths varied from 6 to 39 m, the depths from 2 center dot 5 to 4 m and the sinuosities from 1 center dot 3 to 3 center dot 1. Palaeocurrent data, taken mostly from clast imbrication in conglomerates, indicates current modes along the channel thalweg, but with other directions representing either secondary flow (oriented primarily up the point bar) or over-passing canyon-confined flow. It is suggested that, at times, the lower part of the turbidity currents flowing down the channels behaved similarly to within-bank fluvial currents, with a cross-channel component of flow towards the cut bank, and return flow at the bed sweeping up the point bar. At other times, this secondary circulation may be absent or reversed, which may be related to changes in flow thickness, coupling with the overriding flow and possible flow separation.

AB - Some deep-marine channels show striking similarities to fluvial channels, despite major differences in the properties of the flows that they conduct. Some field observations from deep-marine channel deposits within a Late Cretaceous palaeo-canyon in the Rosario Formation of Baja California, Mexico, that bear on these comparisons have been reported. These channel deposits contain erosively based lateral accretion sets. These sets are generally a few metres thick and resemble fluvial point bar deposits. Sediment movement and deposition within these accretion deposits was induced by turbidity currents several to many times thicker than the depth of the channel, moving at several metres per second. The inclined sets define laterally migrating and sinuous channels locally at a high angle to the confining canyon. The instantaneous channel widths varied from 6 to 39 m, the depths from 2 center dot 5 to 4 m and the sinuosities from 1 center dot 3 to 3 center dot 1. Palaeocurrent data, taken mostly from clast imbrication in conglomerates, indicates current modes along the channel thalweg, but with other directions representing either secondary flow (oriented primarily up the point bar) or over-passing canyon-confined flow. It is suggested that, at times, the lower part of the turbidity currents flowing down the channels behaved similarly to within-bank fluvial currents, with a cross-channel component of flow towards the cut bank, and return flow at the bed sweeping up the point bar. At other times, this secondary circulation may be absent or reversed, which may be related to changes in flow thickness, coupling with the overriding flow and possible flow separation.

KW - Deep-marine

KW - helical flow

KW - lateral-accretion

KW - meandering

KW - point bar

KW - sinuous

KW - cretaceous rosario formation

KW - large ocean basins

KW - submarine-fan

KW - sea fan

KW - sinuous channel

KW - Baja California

KW - process Model

KW - evolution

KW - architecture

U2 - 10.1111/j.1365-3091.2008.01040.x

DO - 10.1111/j.1365-3091.2008.01040.x

M3 - Article

VL - 56

SP - 1411

EP - 1432

JO - Sedimentology

JF - Sedimentology

SN - 0037-0746

IS - 5

ER -