scholarly journals The role of mass-transport complexes (MTCs) in the initiation and evolution of submarine canyons

2021 ◽  
Author(s):  
Nan Wu ◽  
Harya Nugraha ◽  
Fa Zhong ◽  
Michael Steventon
Keyword(s):  
Mass Transport ◽  
Continental Shelf ◽  
Failure Mechanism ◽  
Fluvial Systems ◽  
Offshore Area ◽  
Seismic Reflection Data ◽  
Reflection Data ◽  
Gravity Flows ◽  
Flow Convergence ◽  
Gravity Driven

The offshore area of the Otway Basin, located within the SE continental margin of Australia, is dominated by a multibranched canyon system where submarine mass-transport complexes (MTCs) are widely distributed. We integrate high-resolution multi-beam bathymetric and seismic reflection data to investigate the importance of regionally distributed MTCs in dictating the evolution of canyon systems. We interpret three regionally distributed MTCs that fail retrogressively and affect almost 70% of the study area. Within the MTCs, we observed seven canyons that initiated from the continental shelf edge and extended to the abyssal plain. Although these canyons share common regional tectonics and oceanography, the scales, morphology, and distribution are distinctly different. This is devoted to the presence of failure-related scarps (i.e. headwall and sidewall scarps) that control the initiation and formation of the canyons. The retrogressive failure mechanisms of MTCs have created a series of the headwall and lateral scarps on the continental shelf and slope regions. In the continental shelf, where terrestrial input (i.e. fluvial systems) is absent, the origin of the canyons is related to the local failure events and the contour current activities occurring near the pre-existing, massive headwall scarps (c. 120 m high, 3km long). The occurrence of these local failures has provided the necessary sediment input for subsequent gravity-driven, downslope sediment flows. In the continental slope region, the widespread scarps can capture gravity flows initiated from the continental shelf, developing an area of flow convergence, which greatly widens and deepens the canyon system. The gradual diversion and convergence through MTCs related scarps have facilitated the canyon confluence process, which has fundamentally changed the canyoning process. Thus, we conclude that the retrogressive failure mechanism of MTCs has a direct contribution to the initiation, distribution, and evolution of the canyons, especially in areas where fluvial input is missing. Moreover, the retrogressive failure mechanism is responsible for the canyon deepening and confluence process, which can greatly facilitate the delivery of sediment into deep oceans.

scholarly journals Structural constraints on the subduction of mass-transport deposits in convergent margins

2019 ◽  
Vol 500 (1) ◽  
pp. 115-128 ◽  
Author(s):  
Jacob Geersen ◽  
Andrea Festa ◽  
Francesca Remitti
Keyword(s):  
Mass Transport ◽  
Plate Boundary ◽  
Structural Constraints ◽  
Convergent Margins ◽  
Sediment Thickness ◽  
Long Runout ◽  
Seismic Reflection Data ◽  
Reflection Data ◽  
Landslide Volume ◽  
Mass Transport Deposits

AbstractThe subduction of large and heterogeneous mass-transport deposits (MTDs) is discussed to modify the structure and physical state of the plate boundary and therewith exert an influence on seismicity in convergent margins. Understanding which subduction-zone architectures and structural boundary conditions favour the subduction of MTDs, primarily deposited in oceanic trenches, is therefore highly significant. We use bathymetric and seismic reflection data from modern convergent margins to show that a large landslide volume and long runout, in concert with thin trench sediments, increase the chances for an MTD to become subducted. In regions where the plate boundary develops within the upper plate or at its base (non-accretionary margins), and in little-sedimented trenches (sediment thickness <2 km), an MTD has the highest potential to become subducted, particularly when characterized by a long runout. On the contrary, in the case of a heavily sedimented trench (sediment thickness >4 km) and short runout, an MTD will only be subducted if the thickness of subducting sediments is higher than the thickness of sediments under the MTD. The results allow identification of convergent margins where MTDs are preferentially subducted and thus potentially alter plate-boundary seismicity.

scholarly journals How do tectonics influence the initiation and evolution of submarine canyons A case study from the Otway Basin, SE Australia

2021 ◽  
Author(s):  
Nan Wu ◽  
Harya Nugraha ◽  
Michael Steventon ◽  
Fa Zhong
Keyword(s):  
Late Miocene ◽  
Submarine Canyon ◽  
Turbidity Currents ◽  
Submarine Canyons ◽  
Seismic Reflection Data ◽  
Reflection Data ◽  
Depositional Processes ◽  
Seabed Topography ◽  
Gravity Driven ◽  
Unconformity Surface

The architecture of canyon-fills can provide a valuable record of the link between tectonics, sedimentation, and depositional processes in submarine settings. We integrate 3D and 2D seismic reflection data to investigate the dominant tectonics and sedimentary processes involved in the formation of two deeply buried (c. 500 m below seafloor), and large (c. 3-6 km wide, >35 km long) Late Miocene submarine canyons. We found the plate tectonic-scale events (i.e. continental breakup and shortening) have a first-order influence on the submarine canyon initiation and evolution. Initially, the Late Cretaceous (c. 65 Ma) separation of Australia and Antarctica resulted in extensional fault systems, which then formed stair-shaped paleo-seabed. This inherited seabed topography allowed gravity-driven processes (i.e. turbidity currents and mass-transport complexes) to occur. Subsequently, the Late Miocene (c. 5 Ma) collision of Australia and Eurasia, and the resulting uplift and exhumation, have resulted in a prominent unconformity surface that coincides with the base of the canyons. We suggest that the Late Miocene intensive tectonics and associated seismicity have resulted in instability in the upper slope that consequently gave rise to emplacement of MTCs, initiating the canyons formation. Therefore, we indicate that regional tectonics play a key role in the initiation and development of submarine canyons.

EVOLUTION AND MORPHOLOGY OF RAFTED BLOCKS IN AN ANCIENT DEEPWATER MASS TRANSPORT COMPLEX (EXMOUTH PLATEAU, OFFSHORE NW AUSTRALIA)

2020 ◽  
pp. 1-67 ◽  
Author(s):  
Ovie Emmanuel Eruteya ◽  
Yakufu Niyazi ◽  
Kamaldeen Olakunle Omosanya ◽  
Daniel Ierodiaconou ◽  
Andrea Moscariello
Keyword(s):  
Mass Transport ◽  
Deep Water ◽  
High Amplitude ◽  
3D Seismic ◽  
Complex Flow ◽  
Seismic Reflection Data ◽  
Exmouth Plateau ◽  
Reflection Data ◽  
Transport Complex ◽  
Nw Australia

Submarine mass wasting plays a fundamental role in transporting substantial volumes of sediments basinward including gigantic slide blocks. However, the understanding of processes involved in block generation and their associated deformation until flow arrest remains limited, especially in data-starved deep-water settings. Here a 2D and 3D seismic reflection data from the Exmouth Plateau, offshore NW Australia is used to investigate the architecture of large blocks preserved within an ancient mass transport complex (MTC) and their interaction with the basal shear surface (BSS). The evolution of the investigated MTC (MTC-BDF) is related to instability along the flanks of an underlying bifurcative Miocene canyon. MTC-BDF spans ∼75 km by ∼35 km containing at least 32 well-imaged blocks (within the 3D seismic coverage) encapsulated in a well-deformed debrite background. These carbonate blocks interpreted as rafted blocks have lengths ranging from 0.48 km to 3.40 km with thicknesses reaching up to 165 m. Interestingly, the blocks are more abundant in a region characterized by moderate-high amplitude debrites. Erosional morphologies encompassing a unique groove and other circular to irregular-shaped depressions mapped along the BSS provide evidence for the erosive nature of the flow. The origin of the groove is related transported blocks gouging the BSS. Importantly, intra block deformations recorded within these blocks as fault and fold systems suggest a complex flow regime within MTC-BDF, with the deformations arising either during block translation or also possibly upon the arrest of the failed mass in interaction with bathymetric elements. Our findings suggest inherent deformations within these blocks may serve as high-permeability conduits with implications for deep-water drilling operations within this segment of the Exmouth Plateau and elsewhere in other hydrocarbon-rich deep-water settings.

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