China
Africa
Explore chapters and articles related to this topic
Ocean Disposal
Published in Stephen M. Testa, Geological Aspects of Hazardous Waste Management, 2020
Abyssal plains are characterized as large, nearly flat areas of the deep ocean floor adjacent to the outer margins of the continental rise. Sedimentary deposits are comprised of varying amounts of pelagic clays, hemipelagic muds, calcareous oozes, and turbidite deposits, depending upon proximity to the continental margin sediment sources (Table 13-5). Stratification is quite variable. Pelagic zones of relatively low permeability occur interstratified with turbidite layers which generally grade from coarse at the base to relatively fine at the top of the sequence. Thus, permeability varies with grain size. Depositional patterns are also complex. Deep-seated faults or other structural elements also exist, reflecting tectonic related activities or differential consolidation.
Introduction
Published in Sukumar Laik, Offshore Petroleum Drilling and Production, 2018
Deep sea bottom/abyssal plain – It is the most extensive area and depths of 3–6 km occur over 76% of the ocean basins. It consists of flat lands although isolated mountain peaks, which occasionally rise high enough to become islands and ridges with valley/trenches along the middle, dot these plains.
Lithospheric evolution, thermo-tectonic history and source-rock maturation in the Gippsland Basin, Victoria, southeastern Australia
Published in Australian Journal of Earth Sciences, 2022
J. Röth, A. Parent, C. Warren, L. S. Hall, D. Palmowski, N. Koronful, S. S. Husein, V. Sachse, R. Littke
After the Albian–Cenomanian inversion (basin phase C1), the Gippsland Basin developed to an internally eastward draining depositional system in which coarse-grained erosional material entered from the uplifted basin margins and lacustrine shales of the Emperor (e.g. Kipper Shale) and Golden Beach subgroups covered the reactivated rift valley—separated by the basin-wide Longtom Unconformity. Upper Santonian marine shales (Anemone Formation) demonstrate a first marine ingression from the east. A broadening retro-gradational coastal plain with associated deltas and barrier systems developed in the west and along the uplifted rift margins (Hill et al., 1998; Norvick et al., 2001; Woollands & Wong, 2001). This short-lived rift sequence (basin phase E3) coincides with the generation of oceanic crust below the abyssal plain beyond the CEFS (Norvick et al., 2001; O’Halloran & Johnstone, 2001).
Illuminating centimeter-level resolution stratum via developed high-frequency sub-bottom profiler mounted on Deep-Sea Warrior deep-submergence vehicle
Published in Marine Georesources & Geotechnology, 2021
Xinghui Cao, Zhiguo Qu, Binjian Shen, Hanyu Zhang
These data appeared during the SY166 dive, as shown in Figure 10. The first layer of sediment was about 2 m thick, which was much thicker than the sediment in other dives. As this dive was on the abyssal plain at a depth of 3313 m, this phenomenon was likely induced by sediment characteristic changes in the abyssal plain topography. Furthermore, few surficial organisms are present in this province. The seabed surficial sediment was very soft, and the acoustic characteristics were different at depths of 1 and 2 km. A layered structure at a depth of approximately 2 m was evident and stable. This is a second layer but not a secondary echo reflection which is confirmed because the distance between the surface layer and sonar reference is not the same as the surface and the second layer, changing throughout the segment, as well as there is a clear third-layer structure under the second layer in some regions. This result at least confirms that deep ocean sediment is less affected by organisms and bubbles, and sound attenuation in the sediment is lower than that in areas with high biological activities.
Scientific ocean drilling in the Australasian region: a review
Published in Australian Journal of Earth Sciences, 2022
Site 259, in the easternmost Perth Abyssal Plain has basement of basalt breccia and brecciated basalt, overlain by thick lower Aptian black clay, Albian nannofossil clay, Upper Cretaceous zeolitic clay, and upper Paleocene to Quaternary clayey nannofossil ooze. This dated the oldest basement in the plain as probably early Aptian (ca 120 Ma).