Controls on gravel termination in seven distributary channels of the Selenga River Delta, Baikal Rift basin, Russia

Tian Y. Dong, Jeffrey A. Nittrouer, Elena Il'icheva, Maksim Pavlov, Brandon McElroy, Matthew J. Czapiga, Hongbo Ma, Gary Parker

Research output: Contribution to journalArticle

Abstract

The Selenga River Delta, Lake Baikal, Russia, is ~600 km2 in size and contains multiple distributary channels that receive varying amounts of water and sediment discharge. The delta is positioned along the deep-water (~1600 m) margin of Lake Baikal, a half-graben-styled rift basin, qualifying it as a modern analogue of a shelf-edge delta system. This study provides a detailed field survey of channel bed sediment composition, channel geometry, and water discharge. The data and analyses presented here indicate that the Selenga Delta exhibits downstream sediment fining over tens of kilometers, ranging from predominantly gravel (coarse pebble) and sand near its apex to silt and sand at the delta-lake interface. We developed an analytical framework to evaluate the downstream elimination of gravel within the multiple distributary channels. The findings include the following. (1) The Selenga River Delta consists of at least eight orders of distributary channels. (2) With increasing channel order downstream, channel cross-sectional area, width-depth ratio, water discharge, boundary shear stress, and sediment flux systematically decrease. (3) The downstream elimination of gravel in distributary channels is caused by declining boundary shear stress as a result of water discharge partitioning among the bifurcating channels. (4) Over longer time scales, gravel is contained on the delta topset due to frequent and discrete seismic events that produce subsidence and accommodation, so that coarse sediment cannot be transported to the axis of the Baikal Rift basin. The distribution of sediment grain size in deltaic channels, as related to hydrodynamics and sediment transport, plays a critical role in influencing stratigraphy, because the sustained tectonism leads to high preservation potential of the delta topset sedimentary deposits. Therefore, the Selenga River Delta provides an opportunity to explore the interactions between modern deltaic sedimentation processes and tectonics that affect the production of basin stratigraphy.

Original languageEnglish (US)
Pages (from-to)1297-1312
Number of pages16
JournalBulletin of the Geological Society of America
Volume128
Issue number7
DOIs
StatePublished - Jan 1 2016

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gravel
basin
river
sediment
shear stress
lake
stratigraphy
deltaic sedimentation
water
sand
analytical framework
shelf break
pebble
graben
field survey
sediment transport
silt
subsidence
partitioning
grain size

ASJC Scopus subject areas

  • Geology

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Controls on gravel termination in seven distributary channels of the Selenga River Delta, Baikal Rift basin, Russia. / Dong, Tian Y.; Nittrouer, Jeffrey A.; Il'icheva, Elena; Pavlov, Maksim; McElroy, Brandon; Czapiga, Matthew J.; Ma, Hongbo; Parker, Gary.

In: Bulletin of the Geological Society of America, Vol. 128, No. 7, 01.01.2016, p. 1297-1312.

Research output: Contribution to journalArticle

Dong, Tian Y. ; Nittrouer, Jeffrey A. ; Il'icheva, Elena ; Pavlov, Maksim ; McElroy, Brandon ; Czapiga, Matthew J. ; Ma, Hongbo ; Parker, Gary. / Controls on gravel termination in seven distributary channels of the Selenga River Delta, Baikal Rift basin, Russia. In: Bulletin of the Geological Society of America. 2016 ; Vol. 128, No. 7. pp. 1297-1312.
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