Zenith Plateau

The Zenith Plateau is a large bathymetric high in the Indian Ocean, located about west-northwest of the Wallaby Plateau, west-northwest of Carnarvon, Western Australia, and north-west of Perth, Western Australia. The summit of the Zenith Plateau lies below sea level and its base is at about below sea level. It is about long and wide. In the east, the Zenith Plateau is separated from the Wallaby (Cuvier) Plateau by a wide, north to northeast-trending bathymetric trough.British Oceanographic Data Centre, 2003, ''GEBCO Digital Atlas.'' British Oceanographic Data Centre, National Environment Research Council, United Kingdom. The Zenith Plateau lies outside of the Australian Exclusive Economic Zone.Sayers, J., I. Borissova, D. Ramsay and P. A. Symonds. 2002, ''Geological framework of the Wallaby Plateau and adjacent areas.'' Record no. 2002/21. Petroleum & Marine Division, Geoscience Australia, Canberra, West Australia.

As discussed by AmosAmos, J., 2014
''Malaysia Airlines MH370: Searching in an ocean of uncertainty.''
BBC news, April 9, 2014. Retrieved April 13, 2014 and Beaman,Beaman, R., 2014

Retrieved April 13, 2014
Deep Reef Explorer
James Cook University, Queensland, Australia. Retrieved April 13, 2014. the bathymetry of the Zenith Plateau is very poorly mapped. Precise ocean floor depth data from bathymetric surveys, which used modern acoustic echosounders, across this undersea plateau are lacking. Transects across it by older, less precise singlebeam echosounder are few and insufficient to provide bathymetric data of significant detail. The bulk of the mapping is based upon coarse interpretation of satellite altimetry data in which the ocean floor bathymetry is inferred from measured variations in the elevation of the overlying sea surface.Sandwel, D. T., and W. H. F. Smith, nd
''Exploring the Ocean Basins with Satellite Altimeter Data.''
National Oceanic and Atmospheric Administration, United States Department of Commerce, Washington, D.C. Retrieved April 13, 2014

Name

The Zenith Plateau is named after the cable ship ''Zenith'', which discovered it while surveying the cable route from Cocos (Keeling) Islands to Fremantle, Western Australia.British Oceanographic Data Centre, 2010, ''IHO-IOC GEBCO Gazetteer of Undersea Feature Names,'' August 2010 version. British Oceanographic Data Centre, National Environment Research Council, United Kingdom. It was initially known as the Zenith Seamount as shown in the 1933 DMA Chart 5446 and the May 1975 Australian INT 708 chart. The Zenith Plateau is incorrectly designated as the ''Wallaby Plateau'' by a few official charts, some popular maps, American Association of Petroleum Geologists' maps, and the ACUF Gazetter. This confusion likely is the result of maps by Heezen and TharpHeezen, B.C. and M. Tharp, 1965, ''Physiographic Diagram of the Indian Ocean (with descriptive sheet). '' Geological Society of America Inc., New York.Heezen, B.C. and M. Tharp, 1966., ''Physiography of the Indian Ocean.'' Philosophical Transactions of the Royal Society of London, A 259:137-149. that incorrectly show the Zenith Plateau and the Wallaby Plateau as a single, composite bathymetric feature.Colwell, J. B., P. A. Symonds and A. J. Crawford, 1994, ''The nature of the Wallaby (Cuvier) Plateau and other igneous provinces of the west Australian margin.'' AGSO Journal of Australian Geology & Geophysics, 15(11):137-156.

Geology

Because the Zenith Plateau has not been studied in any detail, its internal structure and origin has largely been a matter of speculation and indirect inference from magnetic and satellite gravity studies and research involving adjacent bathymetric highs. It is generally inferred to be of the same geologic structure and origin as the adjacent and better studied Quokka Rise. Initially, the Zenith Plateau, along with the adjacent Wallaby Plateau, was thought to be part of a short-lived hotspot. As the result of detailed studies of the Wallaby Plateau, this hypothesis has been largely abandoned. Later, it was proposed that the Zenith Plateau, like the adjacent Wallaby Plateau, consists of a continental fragment of highly attenuated, stretched, and faulted continental crust that has been extensively intruded by magmatic rocks and deeply buried by volcanic rocks during the initial breakup of East Gondwana.Planke, S., P. A. Symonds, and C. Berndt, 2002, ''Volcanic rifted margin structure and development: A comparison between the NE Atlantic and western Australian continental margins.'' Paper no. 90022, AAPG Hedberg Conference, Stavanger, Norway, 8–11 Sept. American Association of Petroleum Geologists, Tulsa, Oklahoma. More recently, the Zenith Plateau is inferred to be a volcanic plateau that consists of a thick sequence of highly attenuated, stretched, and faulted volcanic margin crust formed during the time of the continental break-up of Gondwana. This crust is inferred to be buried by voluminous volcanic deposits that immediately followed its formation. Later on, complicated tectonic activity that was associated with local rifting and sea floor spreading separated the Wallaby and Zenith plateaus from Australia and each other.Gibbons, A. D., U. Barckhausen, P. van den Bogaard, K. Hoernle, R. Werner, J. M. Whittaker, and R. D. Muller, 2012, ''Constraining the Jurassic extent of Greater India: Tectonic evolution of the West Australian margin.'' Geochemistry, Geophysics, Geosystems. 13(5) article Q05W13. 25 pp.Hall, L. S. A. D. Gibbons, G. Bernardel, J. M. Whittaker, C. Nicholson, N. Rollet, and R.D. Müller, 2013, ''Structural Architecture of Australia’s Southwest Continental Margin and Implications for Early Cretaceous Basin Evolution.'' The Sedimentary Basins of Western Australia 4: Proceedings of the Exploration Society of Australia Symposium. Perth. 22 pp.

Judging from research conducted for adjacent oceanic rises and plateaus, it is presumed that the volcanic rocks, which comprise the Zenith Plateau are covered by a blanket of Cenozoic and older deep sea sediments of unknown thickness. Research conducted during the 25th cruise of the R/V Dmitriy Mendeleyev indicates that the deep sea sediments covering the Zenith Plateau consist of calcareous ooze. One core, core 2036, recovered during that cruise penetrated of rather compact light pale yellow pelitic, coccolith-foraminiferal ooze. Radiocarbon dating of samples from the upper of the core yielded dates ranging from 9790±750 to greater than 28,500 years radiocarbon. The average sedimentation rate calculated for sediments in this core is to per thousand years. According to these rates and the core description, the sediments covering this plateau are likely well-consolidated and possibly quite stiff.Ivanov, Ye. I., V. I . Kiselev And A.M. Palkina, 1985, ''Temperatures in the Indian Ocean during the Quaternary.'' Oceanology. 25(4):499-503.

Malaysia Airlines Flight 370

The northern flank of the Zenith Plateau underlies the part of the Indian Ocean that was initially suspected to be the final resting place of Malaysia Airlines Flight 370. According to the ''GEBCO Digital Atlas,'' the depth of the ocean bottom within the area that the ADV ''Ocean Shield'' detected acoustic signals that once were thought to be consistent with those emitted by underwater locator beacons (ULBs) mounted on flight recorders ranges from about to . However, lengthy searches of parts of the Zenith Plateau found nothing.

Except for its depth, the blanket of foraminiferal ooze, which likely covers the Zenith Plateau, provides an environment that should be helpful for searching for any aircraft wreckage lying on the ocean bottom. According to William Sager, a professor of marine geophysics at the University of Houston in Texas, the surface of ocean bottom covered with foraminiferal ooze is soft enough to squeeze between a person's toes, but it's not so soft that airplane wreckage would sink into it. He stated: "Something big like pieces of an airplane, it's going to be sitting on the surface."The Associated Press, 2014
''Seabed of jet hunt zone mostly flat. ''
March 31, 2014, The Dispatch Columbus, Ohio. Retrieved April 16, 2014. In addition, Robin Beaman, a marine geologist at James Cook University, Queensland, Australia, noted that any large metallic object lying on an ocean bottom covered by foraminiferal ooze would be readily recognizable on an autonomous underwater vehicle's sidescan sonar.Reuters, 2014
''Undersea drone hunt may take two months.''
The Huffington Post, April 16, 2014. Retrieved April 16, 2014. Sidescan sonar can be quite good at differentiating the acoustic return of a hard, metallic object compared to that of an ocean floor covered by ooze.Blondel, P., 2009, ''The Handbook of Sidescan Sonar.'' Springer Praxis Books, United Kingdom. 316 pp.

References

External links

Beaman, R., 2014
Deep Reef Explorer
James Cook University, Queensland, Australia.

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Plateaus of the Indian Ocean