Climatic versus halokinetic control on sedimentation in a dryland fluvial succession

Abstract

Fluvial systems and their preserved stratigraphic expression as the fill of evolving basins are controlled by multiple factors, which can vary both spatially and temporally, including prevailing climate, sediment provenance, localised changes in the rates of creation and infill of accommodation in response to subsidence, and diversion by surface topographic features.In basins that develop in response to halokinesis, mobilised salt tends to be displaced by sediment loading to create a series of rapidly subsiding mini-basins, each separated by growing salt walls. The style and pattern of fluvial sedimentation governs the rate at which accommodation becomes filled, whereas the rate of growth of basin-bounding salt walls governs whether an emergent surface topography will develop that has the potential to divert and modify fluvial drainage pathways and thereby dictate the resultant fluvial stratigraphic architecture. Discerning the relative roles played by halokinesis and other factors such as climate-driven variations in the rate and style of sediment supply, is far from straightforward.

Morphodynamics of rivers strongly affected by monsoon precipitation: Review of depositional style and forcing factors

“…In some settings, the conglomerates contain caliche clasts, ferruginous concretions, sandstone clasts and wood fragments in addition to mud clasts (e.g., Turner, 1986;Deluca and Eriksson, 1989;Cain and Mountney, 2009;Plink-Björklund et al, 2014a, 2014b. The conglomerates vary from clast to matrix supported, and from disorganized to imbricated or stratified (e.g., North and Taylor, 1996;Plink-Björklund and Birgenheier, 2013;Banham and Mountney, 2014) (Fig. 11).…”

“…few decimeters to multi-meter thick packages (Fig. 11a-c) that are common at the bases of the channels and above internal erosion surfaces (e.g., Deluca and Eriksson, 1989;North and Taylor, 1996;Zaleha, 1997;Hinds et al, 2004;Cain and Mountney, 2009;Plink-Björklund and Birgenheier, 2013;Banham and Mountney, 2014) (Fig. 11).…”

“…of a sand and mud couplet, a few dm to multiple meters thick (e.g., PlinkBjörklund and Birgenheier, 2013). Thickness of the depositional units that do not form lateral accretion sets, but rather occur as downstream or vertically accreted units, varies from a few dm to 5-10 m (e.g., Sneh, 1983;Stear, 1985;Turner, 1986;Nichols and Hirst, 1998;Hinds et al, 2004;Hampton and Horton, 2007;Banham and Mountney, 2014;PlinkBjörklund and Birgenheier, 2013) (Figs. 10, 16-19).…”

“…In some cases convoluted laminations (e.g., Sneh, 1983; or structureless sandstones (Nichols and Hirst, 1998) occur at the top of the depositional units. The tops of the units are quite commonly erosionally truncated (e.g., Banham and Mountney, 2014) (Fig. 10a-b, d).…”

Evolution of fluvial systems in salt-walled mini-basins: A review and new insights

“…In isolated basins, where fluvial activity is limited due to preferential drainage into adjacent basins, active fluvial processes tend to be dominated by: (i) localised reworking and redistribution of sediment from uplifted salt-wall topography; (ii) delivery of sediment 17 via the overspill of drainage pathways from adjacent basins; and (iii) the development of minor drainage pathways within the basin via supply along the basin axis, in some cases in the form of episodic non-confined flow rather than channelised flow (Abdullatif, 1989;Banham and Mountney, 2013b). Non-confined flows that give rise to depositional sediment bodies with thin but laterally extensive sheetlike elements and only minor channel elements are especially common in relatively isolated, sediment-starved basins under semiarid climates (Rahn, 1967;Williams 1970;Benvenuti, 2005;Banham and Mountney, 2013a, b).…”