Deglacial changes in the strength of deep southern component water and sediment supply at the Argentine continental margin

2017 ◽  
Vol 32 (8) ◽  
pp. 796-812 ◽  
Author(s):  
Grit Warratz ◽  
Rüdiger Henrich ◽  
Ines Voigt ◽  
Cristiano M. Chiessi ◽  
Gerhard Kuhn ◽  
...  
Keyword(s):  
Continental Margin ◽  
Sediment Supply ◽  
Water And Sediment

How submarine channels (re)shape continental margins

2020 ◽  
Vol 90 (11) ◽  
pp. 1581-1600
Author(s):  
Luke A. Pettinga ◽  
Zane R. Jobe
Keyword(s):  
Continental Margin ◽  
Evolution Model ◽  
Sediment Supply ◽  
Tectonic Deformation ◽  
Continental Margins ◽  
Sedimentary Processes ◽  
Submarine Channels ◽  
Active Tectonic ◽  
Tectonic Settings ◽  
Longitudinal Profiles

ABSTRACT Submarine landscapes, like their terrestrial counterparts, are sculpted by autogenic sedimentary processes toward morphologies at equilibrium with their allogenic controls. While submarine channels and nearby, inter-channel continental-margin areas share boundary conditions (e.g., terrestrial sediment supply, tectonic deformation), there are significant differences between the style, recurrence, and magnitude of their respective autogenic sedimentary processes. We predict that these process-based differences affect the rates of geomorphic change and equilibrium (i.e., graded) morphologies of submarine-channel and continental-margin longitudinal profiles. To gain insight into this proposed relationship, we document, classify (using machine learning), and analyze longitudinal profiles from 50 siliciclastic continental margins and associated submarine channels which represent a range of sediment-supply regimes and tectonic settings. These profiles tend to evolve toward smooth, lower-gradient longitudinal profiles, and we created a “smoothness” metric as a proxy for the relative maturity of these profiles toward the idealized equilibrium profile. Generally, higher smoothness values occur in systems with larger sediment supply, and the smoothness of channels typically exceeds that of the associated continental margin. We propose that the high rates of erosion, bypass, and deposition via sediment gravity flows act to smooth and mature channel profiles more rapidly than the surrounding continental margin, which is dominated by less-energetic diffusive sedimentary processes. Additionally, tectonic deformation will act to reduce the smoothness of these longitudinal profiles. Importantly, the relationship between total sediment supply and the difference between smoothness values of associated continental margins and submarine channels (the “smoothness Δ”) follows separate trends in passive and active tectonic settings, which we attribute to the variability in relative rates of smoothness development between channelized and inter-channel environments in the presence or absence of tectonic deformation. We propose two endmember pathways by which continental margins and submarine channels coevolve towards their respective equilibrium profiles with increased sediment supply: 1) Coupled Evolution Model (common in passive tectonic settings), in which the smoothness Δ increases only slightly before remaining static, and 2) Decoupled Evolution Model (common in active tectonic settings), in which the smoothness Δ increases more rapidly and to a greater final value. Our analysis indicates that the interaction of the allogenic factors of sediment supply and tectonic deformation with the autogenic sedimentary processes characteristic of channelized and inter-channel areas of the continental margin may account for much of the variability between coevolution pathways and depositional architectures.

The high-supply, current-dominated continental margin of southeastern South America during the late Quaternary

2014 ◽  
Vol 81 (2) ◽  
pp. 339-354 ◽  
Author(s):  
Hendrik Lantzsch ◽  
Till J.J. Hanebuth ◽  
Cristiano M. Chiessi ◽  
Tilmann Schwenk ◽  
Roberto A. Violante
Keyword(s):  
South America ◽  
Continental Margin ◽  
Late Quaternary ◽  
Current System ◽  
Contrast Material ◽  
Sedimentary Facies ◽  
Current Strength ◽  
Sediment Supply ◽  
Secondary Importance ◽  
La Plata

AbstractThe continental margin off the La Plata Estuary (SE South America) is characterized by high fluvial sediment supply and strong ocean currents. High-resolution sediment-acoustic data combined with sedimentary facies analysis, AMS-14C ages, and neodymium isotopic data allowed us to reconstruct late Quaternary sedimentary dynamics in relation to the two major sediment sources, the La Plata Estuary and the Argentine margin. Sediments from these two provinces show completely different dispersal patterns. We show that the northward-trending La Plata paleo-valley was the sole transit path for the huge volumes of fluvial material during lower sea levels. In contrast, material from the Argentine margin sector was transported northwards by the strong current system. Despite the large sediment volumes supplied by both sources, wide parts of the shelf were characterized by either persistent non-deposition or local short-term depocenter formation. The location and formation history of these depocenters were primarily controlled by the interplay of sea level with current strength and local morphology. The high sediment supply was of secondary importance to the stratigraphic construction, though locally resulting in high sedimentation rates. Thus, the shelf system off the La Plata Estuary can be considered as a hydrodynamic-controlled end-member.

scholarly journals Water and sediment supply affect basin-filling sedimentation patterns

Eos ◽  
2013 ◽  
Vol 94 (32) ◽  
pp. 288-288
Author(s):  
Ernie Balcerak
Keyword(s):  
Sediment Supply ◽  
Water And Sediment
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