Influence of water and sediment supply on the stratigraphic record of alluvial fans and deltas: Process controls on stratigraphic completeness

Abstract

[1] Stratigraphy contains the most complete record of information necessary to quantitatively reconstruct paleolandscape dynamics, but this record contains significant gaps over a range of time and space scales. These gaps result from stasis on geomorphic surfaces and erosional events that remove previously deposited sediment. Building on earlier statistical studies, we examine stratigraphic completeness in three laboratory experiments where the topography of aggrading deltas was monitored at high temporal and spatial scales. The three experiments cover unique combinations in the absolute magnitudes of sediment and water discharge in addition to generation of accommodation space through base-level rise. This analysis centers on three time scales: (1) the time at which a record is discretized (t), (2) the time necessary to build a deposit with mean thickness equivalent to the maximum roughness on a surface (T c ), and (3) the time necessary for channelized flow to migrate over all locations in a basin (T ch ). These time scales incorporate information pertaining to the time-variant topography of actively changing surfaces, kinematics by which the surfaces are changing, and net deposition rate. We find that stratigraphic completeness increases as a function of t/T c but decreases as a function of T c /T ch over the parameter space covered in the experiments. Our results suggest that environmental signals disconnected from a sediment routing system are best preserved in systems with low T c values. Nondimensionalizing t by T c , however, shows that preservation of information characterizing system morphodynamics is best preserved in stratigraphy constructed by systems with low water to sediment flux ratios.Citation: Straub, K. M., and C. R. Esposito (2013), Influence of water and sediment supply on the stratigraphic record of alluvial fans and deltas: Process controls on stratigraphic completeness,

High-Frequency Sequences in the Quaternary of Pelotas Basin (coastal plain): a record of degradational stacking as a function of longer-term base-level fall

“…These factors influence and are recorded in even higher frequency scales, as lagoon level changes (Lagoa dos Patos -300 yr), increased vegetation in dune fields (60 yr) and shoreline erosion (22 yr) (Table 3 -High III from the studies of Toldo Jr. et al 1999, 2004, 2005; Barboza et al 2006;Martinho et al 2008Martinho et al , 2009Martinho et al , 2010Dillenburg et al 2017 in press). As already observed in experimental studies, the signal of autogenic processes may be preserved in the stratigraphic record (Paola et al 2009;Jerolmack & Paola 2010;Straub & Esposito 2013;Kim et al 2014).…”

Experimental alluvial fans: Advances in understanding of fan dynamics and processes

“…Research in the Delta basin at Tulane University's (Louisiana, USA) Sediment Dynamics Laboratory investigated the completeness of stratigraphic record preservation on experimental alluvial fans and deltas (Straub and Esposito, 2013;Straub and Wang, 2013;Fig. 3).…”

“…Subject to gradual base-level rise, the experiments demonstrated that environmental signals disconnected from a sediment routing system are best preserved in systems with low surface roughness. Two time scales were proposed by Straub and Esposito (2013) to explain the stratigraphic completeness: the amount of time necessary to generate a deposit to explore topography changes, and the rate of net deposition characterised by the mobility of the channel on the delta tops. They also suggested that stratigraphic completeness in deltaic settings is controlled by the balance of aggradation and lateral channel migrations, with rapid aggradation relative to lateral channel migration leading to high stratigraphic completeness, whereas rapid lateral migration of deep channels relative to system aggradation results in frequent deposit reworking (Straub and Esposito, 2013, p. 12).…”

“…This has implications for the interpretation of environmental change from alluvial fan sequences, and a better understanding of the frequency and magnitude of allogenic events that are preserved needs to be developed in controlled experimental conditions and then applied to field areas. Initial experiments have attempted to quantify the magnitude of autogenic dynamics related to allogenic processes on fan deltas (Straub and Esposito, 2013;Straub and Wang, 2013), but wider experiments need to be undertaken to better constrain the shredding potential in a range of environmental settings to guide researchers in the field of the magnitude of external forcing that may have been preserved intact in any given environment. Secondly, although a clear autogenic signal has been found on experimental alluvial fans, how to differentiate between this signal and allogenic-driven change in the flow regime on alluvial fans in the field remains unclear.…”

Late Miocene fluvial distributary system in the northern Danube Basin (Pannonian Basin System): depositional processes, stratigraphic architecture and controlling factors of the Piešťany Member (Volkovce Formation)

“…FDS typ i cally con sist of a range of sed i men tary en vi ron ments the char ac ter of which strongly de pends on cli mate and tec tonic set ting. The mor phology of FDS re sults from pre-ex ist ing to pog ra phy and in ter play be tween ac com mo da tion rate and sed i ment sup ply (e.g., MacCarthy, 1990;Blair and McPherson, 1994;Harvey et al, 2005;Hickson et al, 2005;Pope and Wilkinson, 2005;Nichols and Fisher, 2007;Blair and McPherson, 2009;Straub and Esposito, 2013;Straub and Wang, 2013). An anal y sis of evo lution of such a depositional sys tem needs a de tailed ap proach with con sid er ation of vari able in put data.…”