Acoustic facies and depositional processes in the upper submarine canyon Swatch of No Ground (Bay of Bengal)

2003 ◽  
Vol 50 (5) ◽  
pp. 979-1001 ◽  
Author(s):  
B Kottke ◽  
T Schwenk ◽  
M Breitzke ◽  
M Wiedicke ◽  
H.R Kudrass ◽  
...  
Keyword(s):  
Bay Of Bengal ◽  
Submarine Canyon ◽  
Depositional Processes ◽  
Acoustic Facies

COOL-WATER CARBONATE FACIES PATTERNS AND DIAGENESIS-THE KEY TO THE GIPPSLAND BASIN 'VELOCITY PROBLEM'

1998 ◽  
Vol 38 (1) ◽  
pp. 137 ◽  
Author(s):  
D.A. Feary ◽  
T.S. Loutit
Keyword(s):  
Submarine Canyon ◽  
Velocity Variation ◽  
Carbonate Facies ◽  
Seismic Attribute ◽  
Seismic Reflection Data ◽  
Cool Water ◽  
Depositional Processes ◽  
Attribute Analysis ◽  
Gippsland Basin ◽  
Water Carbonate

Throughout much of the exploration history of the offshore Gippsland Basin it has been difficult to achieve acceptable accuracy or precision for time-depth conversions beneath the stratigraphically and sonically complex Seaspray Group, overlying exploration targets within the hydrocarbon-rich Latrobe Group. A regional seismic stratigraphic and seismic attribute analysis of the Oligocene-Recent Seaspray Group has been carried out as the first step towards resolving this long-standing Gippsland Basin 'velocity problem'.High-resolution 2D seismic reflection data and downhole logs were used to determine the depositional history and sequence characteristics of the Seaspray Group. This analysis was based on the premise that velocity variation must be related to, or controlled by, the nature and distribution of the dominantly cool-water carbonate facies of the Seaspray Group, and that solution of the velocity problem must be based on understanding the particular depositional and geochemical characteristics of cool-water carbonates.Detailed seismic stratigraphic analysis of the G92A dataset shows that the 16 unconformity-bounded seismic sequences within the Seaspray Group form four mega-sequences, each separated by major erosional (channel-cutting) events, with sequences reflecting variable sediment inputs from northeasterly and southwesterly sources. Seaspray Group characteristics result from interaction of complex depositional and post-depositional processes, including river incision, submarine canyon erosion, slumping, subaerial exposure, karstification, and subsurface diagenesis and erosion. Seismic attribute analysis records the variability of diagenesis and shows that diagenetic effects are predominantly concentrated along sequence boundaries, sometimes to significant depths below the sequence boundary.Results to date indicate that application of a velocity model based on this new interpretation will enable improved precision of depth estimates to the top Latrobe Group unconformity to less than five per cent.

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.

Morphology, architecture, and evolutionary processes of the Zhongjian Canyon between two carbonate platforms, South China Sea

2018 ◽  
Vol 6 (4) ◽  
pp. SO1-SO15 ◽  
Author(s):  
Yintao Lu ◽  
Wei Li ◽  
Shiguo Wu ◽  
Bryan T. Cronin ◽  
Fuliang Lyu ◽  
...  
Keyword(s):  
Seismic Data ◽  
Large Scale ◽  
Middle Miocene ◽  
Sedimentary Environment ◽  
Submarine Canyon ◽  
High Amplitude ◽  
Seismic Facies ◽  
Coarse Grained ◽  
Carbonate Platforms ◽  
Depositional Processes

Two isolated Neogene carbonate platforms (Xisha and Guangle carbonate platforms) have developed in the rifted uplifts since the Early Miocene. A large-scale submarine canyon system, the Zhongjian Canyon (ZJC), has developed in the tectonic depression between the two platforms since the Middle Miocene. High-resolution bathymetry data and 2D and 3D seismic data reveal the existence of the ZJC on the present seafloor, as well as in Neogene intervals. It exhibits typical characteristics of deepwater canyons that cut the surrounding rocks and indicate strong erosional features. The ZJC resulted from northwest–southeast strike-slip fault activities during synrift and postrift stages, and it periodically grew during the development of carbonate platforms since the Middle Miocene. We identified four cycles of parallel to subparallel high amplitude and dim reflectors in seismic data, which we interpreted as alternating canyon fill, based on the interpretation of seismic facies. Thus, the sedimentary evolution of the ZJC can be divided into four typical stages, which were in the Middle Miocene, Late Miocene, Early Pliocene, and Pleistocene. Considering the tectonic background of the carbonate platforms, as well as the on-going igneous activities, the sediment filling the canyon could be derived from a mixture of carbonate clasts, igneous clasts, mud, and silt. The laminar high-amplitude reflectors and dim-reflector package represented a fining-upward sedimentary cycle. The coarse-grained sediment in canyon fillings could be turbidites, carbonate debrites, and even igneous clasts. In contrast, the fine-grained sediment is likely to be dominated by pelagic to hemipelagic mud, and silt. This case study describes a deepwater canyon under a carbonate-dominated sedimentary environment and has significant implications for improving our knowledge of periplatform slope depositional processes. Furthermore, the insight gained into periplatform slope depositional processes can be applied globally.

Quartz arenites of the Cambro-Ordovician Kamouraska Formation, Quebec Appalachians, Canada: I. Deep-water depositional processes in a continental-slope environment

2011 ◽  
Vol 48 (8) ◽  
pp. 1209-1231 ◽  
Author(s):  
Pierre Malhame ◽  
Reinhard Hesse
Keyword(s):  
Continental Slope ◽  
Deep Water ◽  
Submarine Canyon ◽  
Turbidity Currents ◽  
Lawrence Estuary ◽  
Depositional Processes ◽  
Iapetus Ocean ◽  
Quartz Arenite ◽  
Exposed Part ◽  
Polymictic Conglomerate

The Kamouraska Formation is an uppermost Cambrian – lowermost Ordovician quartz-arenite-dominated unit of controversial origin deposited on the southeastern slope of Laurentia bordering the Iapetus Ocean. It is exposed in the Quebec Appalachians on the south shore of the St. Lawrence Estuary. The formation consists of basal polymictic conglomerate and overlying massive sheet-like quartz arenite. The conglomerate beds are reversely and reversely to normally graded. The quartz arenite beds are generally massive, although they may show coarse-tail grading. Beds containing full or partial Bouma sequences are rare. Paleoflow directions from ripple-cross lamination, ripple marks on bed surfaces, and sole marks point towards southeast, south, and southwest. The clastic sediments of the Kamouraska were transported into the deep sea by sediment gravity flows that evolved from hyperconcentrated to concentrated density flows, and then to turbidity currents. The depositional environment is interpreted to have been a southwest-trending meandering submarine canyon. The exposed part of the canyon deposits is slightly oblique to the strike of slope. If correct, our interpretation establishes the preservation of continental-slope deposits in more distal deep-water siliciclastic sedimentary rocks of the Taconian orogen in Quebec, which traditionally have been interpreted as submarine-fan and (or) basin-plain deposits. The orientation of a canyon near parallel-to strike of the slope may have been controlled by syn-depositional growth faults. The coarsest hyperconcentrated flows, which deposited the conglomerate, were restricted to the deepest parts of the canyon during its early stages of development, whereas the concentrated density flows that deposited the massive quartz-arenite beds covered a wider area.

scholarly journals Submarine mass failures as tsunami sources: their climate control

2010 ◽  
Vol 368 (1919) ◽  
pp. 2417-2434 ◽  
Author(s):  
D. R. Tappin
Keyword(s):  
Submarine Canyon ◽  
Coarse Grained ◽  
Sediment Type ◽  
Potential Hazard ◽  
Convergent Margins ◽  
Climate Control ◽  
River Deltas ◽  
Storm Waves ◽  
Depositional Processes ◽  
Climate Controls

Recent research on submarine mass failures (SMFs) shows that they are a source of hazardous tsunamis, with the tsunami magnitude mainly dependent on water depth of failure, SMF volume and failure mechanism, cohesive slump or fragmental landslide. A major control on the mechanism of SMFs is the sediment type, together with its post-depositional alteration. The type of sediment, fine- or coarse-grained, its rate of deposition together with post-depositional processes may all be influenced by climate. Post-depositional processes, termed sediment ‘preconditioning’, are known to promote instability and failure. Climate may also control the triggering of SMFs, for example through earthquake loading or cyclic loading from storm waves or tides. Instantaneous triggering by other mechanisms such as fluid overpressuring and hydrate instability is controversial, but is here considered unlikely. However, these mechanisms are known to promote sediment instability. SMFs occur in numerous environments, including the open continental shelf, submarine canyon/fan systems, fjords, active river deltas and convergent margins. In all these environments there is a latitudinal variation in the scale of SMFs. The database is limited, but the greatest climate influence appears to be in high latitudes where glacial/interglacial cyclicity has considerable control on sedimentation, preconditioning and triggering. Consideration of the different types of SMFs in the context of their climate controls provides additional insight into their potential hazard in sourcing tsunamis. For example, in the Atlantic, where SMFs are common, the tsunami hazard under the present-day climate may not be as great as their common occurrence suggests.

A correlation of CL emissions from Penrith sandstone with elemental distributions obtained by simultaneous SEM-CL and EDS analysis

1995 ◽  
Vol 53 ◽  
pp. 392-393
Author(s):  
Paul J. Wright
Keyword(s):  
Optical Microscope ◽  
Electron Gun ◽  
High Electron ◽  
Collection System ◽  
Electron Hole ◽  
Depositional Processes ◽  
Eds Analysis ◽  
Distribution Mapping ◽  
Backscattered Electron ◽  
Electron Imaging

Most industrial and academic geologists are familiar with the beautiful red and orange cathodoluminescence colours produced by carbonate minerals in an optical microscope with a cold cathode electron gun attached. The cement stratigraphies interpreted from colour photographs have been widely used to determine the post depositional processes which have modified sedimentary rock textures.However to study quartzose materials high electron densities and kV's are necessary to stimulate sufficient emission. A scanning electron microscope with an optical collection system and monochromator provides an adequate tool and gives the advantage of providing secondary and backscattered electron imaging as well as elemental analysis and distribution mapping via standard EDS/WDS facilities.It has been known that the incorporation of many elements modify the characteristics of the CL emissions from geological materials. They do this by taking up positions between the valence and conduction band thus providing sites to assist in the recombination of electron hole pairs.

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