Quantifying sediment supply to continental margins: Application to the Paleogene Wilcox Group, Gulf of Mexico

AAPG Bulletin ◽  
2018 ◽  
Vol 102 (09) ◽  
pp. 1685-1702 ◽  
Author(s):  
Jinyu Zhang ◽  
Jacob Covault ◽  
Michael Pyrcz ◽  
Glenn Sharman ◽  
Cristian Carvajal ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Sediment Supply ◽  
Continental Margins

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.

Continental Margins of the Gulf of Mexico

1974 ◽  
pp. 683-693 ◽  
Author(s):  
John W. Antoine ◽  
Ray G. Martin ◽  
T. G. Pyle ◽  
William R. Bryant
Keyword(s):  
Gulf Of Mexico ◽  
Continental Margins

Recurrence of turbidity currents on glaciated continental margins: A conceptual model from eastern Canada

2020 ◽  
Vol 90 (10) ◽  
pp. 1305-1321
Author(s):  
Alexandre Normandeau ◽  
D. Calvin Campbell
Keyword(s):  
Conceptual Model ◽  
Sea Level ◽  
Deep Water ◽  
Turbidity Current ◽  
Sediment Supply ◽  
Turbidity Currents ◽  
Continental Margins ◽  
Submarine Canyons ◽  
Eastern Canada ◽  
Current Activity

ABSTRACT Turbidity currents in submarine canyons transport large volumes of sediment and carbon to the deep sea and are known to present a major risk to submarine infrastructure. Understanding the origin, the triggers, the recurrence, and the timing of these events is important for predicting future events and mitigating their impact. Depending on the morphological and latitudinal setting of submarine canyons, different external controls will govern the recurrence of turbidity currents. Here, we assess the recurrence of turbidity currents in shelf-incising submarine canyons off eastern Canada in order to examine the effects of external forcings such as glacier retreat and sea level on the deep-water sedimentary record. We used multibeam bathymetry, sub-bottom profiles, and the analysis of turbidites in sediment cores to infer the triggers of turbidity currents over time and propose a conceptual model for the activity of turbidity currents during glacial retreat. The chronostratigraphy of turbidites shows that turbidity current activity in the glaciated The Gully submarine canyon (eastern Canada) was highest between 24 ka cal BP (LGM) and 17 ka cal BP, with > 100 turbidites per 1,000 yr, when the ice sheet was directly delivering sediment to submarine canyons. As the ice margin retreated, the dominant sediment supply switched to glaciofluvial and then to longshore drift, while RSL remained low. The recurrence of turbidity currents nonetheless decreased drastically to < 10 per 1000 yr during that time, pre-dating the rise in RSL. This timing suggests that the reduction of turbidity-current activity is closely linked to retreating glaciers rather than to sea-level rise, which occurred later. Following the retreat of the ice sheet, sea level rose progressively to drown the shallow banks on the continental shelf, and turbidity currents ceased being active after 13 ka cal BP. In the late Holocene, landslide and concomitant turbidity-current recurrence increased to 1 per 1,000 yrs, with at least four new events recorded in deep water. This study shows that glacial sediment supply and sea level controlled the type of sediment supply to the continental slope, which in turn controlled the triggers of turbidity currents over time and the flushing of sediment to the deep water. By comparing with other glaciated margins, we propose a conceptual model explaining the recurrence of turbidity currents, taking into account RSL change and the position of the ice margin relative to the shelf edge. This conceptual model can help predict turbidity-current activity and offshore geohazards on other ancient and modern glaciated continental margins.

Crustal and lithospheric architecture of the Gulf of Mexico and its continental margins from ambient noise Rayleigh wave tomography

2021 ◽  
Author(s):  
Luan C. Nguyen ◽  
Alan Levander ◽  
Fenglin Niu ◽  
Guoliang Li
Keyword(s):  
Gulf Of Mexico ◽  
Rayleigh Wave ◽  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Ambient Noise ◽  
Vertical Component ◽  
Continental Margins ◽  
Continental Lithosphere ◽  
Short Period

<p>The Gulf of Mexico formed as a result of continental breakup between the North and SouthAmerican plates and a short period of seafloor spreading in the Late Jurassic-Early Cretaceous. This small ocean basin offers an opportunity to further our understanding of continental rifting processes and the geologic evolution of continental margins during and after rifting. However, previous knowledge of lithospheric structure has been limited to crustal investigations. We constructed a 3D shear-wave velocity model for the Gulf of Mexico region using cross-correlations of the ambient noise field and measurement of vertical component Rayleigh wave phase velocities in the period band 15 to 95 s. We employed continuous data recorded by more than 500 stations in seismic networks in the US, Mexico and Cuba. Our model shows distinct variation in lithospheric structures that reliably identify and constrain the properties of extended continental and oceanic domains. We estimate the depth of the lithosphere-asthenosphere boundary to be in the range of 85-100 km with the thinnest lithosphere under the oceanic region. A low velocity zone is observed below the lithosphere centered at ~150 km depth with a minimum shear-wave velocity of ~4.45 km/s. Lithospheric mantle underlying the offshore Texas Gulf Coast between oceanic lithosphere and unextended continental lithosphere is characterized by reduced shear-wave velocity. This might indicate that extension resulted in permanent deformation of the continental lithosphere. The differential thinning between the crystalline crust and mantle lithosphere suggests that the extended continental lithosphere has cooled and thickened by approximately 30 km since breakup.</p>

Assessment of coastal dune vulnerability to natural and anthropogenic disturbances along the Gulf of Mexico

2006 ◽  
Vol 33 (2) ◽  
pp. 109-117 ◽  
Author(s):  
M. LUISA MARTÍNEZ ◽  
JUAN B. GALLEGO-FERNÁNDEZ ◽  
JOSÉ G. GARCÍA-FRANCO ◽  
CORAL MOCTEZUMA ◽  
CLAUDIA D. JIMÉNEZ
Keyword(s):  
Gulf Of Mexico ◽  
Human Activities ◽  
Conservation Status ◽  
Management Strategies ◽  
Coastal Zone Management ◽  
Vulnerability Index ◽  
Sediment Supply ◽  
Dynamic State ◽  
Zone Management ◽  
Natural Dynamics

Human population density is globally three times higher along the coasts than inland, and thus environmental impacts of human activities are greater in magnitude on coastal ecosystems such as beaches and dunes. Vulnerability assessment (the loss of capacity to return to the original dynamic state after system displacement) is thus necessary to evaluate the conservation status and determine the most relevant disturbance events. Twenty-six sites along 902 km of Gulf of Mexico coastline, varying in conservation status and sedimentary dynamics, were sampled. At each site a vulnerability index (VI) was calculated based on variables that described geomorphological condition, marine influence, aeolian influence, vegetation condition and human effects. Vulnerability was very variable along the coast and only 19% of the sampled locations (mostly in the central Gulf of Mexico) displayed low vulnerability. Cluster analyses of the values assigned to the checklists for each location grouped the studied sites into three, according to their VI values. Low vulnerability locations had abundant sediment supply and low human impact. Locations with medium to high VI were mostly affected by their natural geomorphological and marine features and had medium to intense human activities. Management strategies should consider the observed variability in vulnerability, the natural dynamics of these systems and the role of human activities and interests, in order to achieve adequate policies and establish well-informed priorities for integrated coastal zone management.

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