Marine Geology and Paleoceanography

Paleoceanography is the study of the sedimentary record of the ocean, the history of tectonic plate motions, glacial changes and recognised linkages between contemporary sedimentation patterns and environmental circumstances.

Marine Geology:-

The study of the history and structure of the ocean floor is known as marine geology or geological oceanography. The ocean floor and coastal zone are investigated using geophysical, geochemical, sedimentological and paleontological methods. Geophysics and physical oceanography are closely related to marine geology.

In the years following World War II, marine geology research was crucial in giving important evidence for seafloor spreading and plate tectonics. The deep ocean floor is the final mostly uncharted frontier, and extensive mapping is being done to assist both military (submarine) and economic (petroleum and metal mining) goals.

Oceanography:-

Oceanography, often known as oceanology, is the study of the oceans from a scientific standpoint. Ecosystem dynamics, waves, ocean currents, and geophysical fluid dynamics; the geology of the seafloor and the plate tectonic; and fluxes of diverse chemical compounds and physical qualities inside the ocean and across its limits are all issues covered by this essential Earth science. Oceanographers use a variety of disciplines to gain a better understanding of the world ocean, including astronomy, biology, chemistry, climatology, geography, geology, hydrology, meteorology, and physics. Paleoceanography is the study of the geologic history of the oceans. An oceanographer is a scientist who specialises in ocean sciences such as marine geology, physics, chemistry and biology.

Modern Oceanography:-

The oceans’ knowledge was limited to the top few fathoms of water and a small portion of the bottom, mostly in shallow locations. The ocean depths were almost completely unknown. In the mid-nineteenth century, the British Royal Navy’s attempts to chart all of the world’s coastlines confirmed the vague notion that most of the ocean was very deep, while nothing more was known. The mysteries of the uncharted ocean’s sparked popular and scientific curiosity in the same way that exploration sparked interest in the polar regions and Africa.

Other Western nations carried out scientific expeditions in the late 1800s (as did private individuals and institutions). Albatros, the first purpose-built oceanographic ship, was launched in 1882. Fridtjof Nansen permitted his ship, Fram, to be trapped in Arctic ice in 1893. This allowed him to collect oceanic, meteorological, and astronomical data at a fixed location across time.

Paleoceanography:-

Paleoceanography is the study of the geologic history of the seas in terms of chemistry, circulation , geology, biology , sedimentation patterns etc. Paleoceanographic studies, which use environment models and multiple proxies to reconstruct past climates at various intervals, allow scientists to analyse the influence of marine processes in global climate. Paleoclimatology and paleoceanography are inextricably linked.

Source and methods of information:-

Paleoceanography uses proxy methods to infer information about the status and evolution of the world’s oceans in the past. Long-chain organic compounds (e.g. alkenones), stable and radioactive isotopes, and trace metals are all geochemical proxy techniques. Furthermore, sediment cores can be valuable; paleoceanography is intimately related to sedimentology and palaeontology.

• Sea Surface Temperature:-

The ratio of magnesium to calcium (Mg/Ca) in plankton shell secretions, long-chain organic compounds such as alkenone, tropical corals near the sea surface, and mollusk shells can be used to recover sea-surface temperature (SST) records from deep-sea sediment cores.

• Bottom Water Temperature:-

Mg/Ca ratios in benthic foraminifera and ostracodes are the most often utilised proxy for inferring deep-sea temperature history. Temperatures deduced from Mg/Ca ratios have indicated a cooling of the deep ocean of up to 3°C during late Pleistocene glacial episodes. The work of Lear et al. [2002] to calibrate bottom water temperature to Mg/Ca ratios in 9 places covering a variety of depths from up to six different benthic foraminifera is noteworthy (depending on location)

• Sediment Record:-

Sediment records can tell us a lot about the past and help us make predictions about the future. Paleoceanography is not a new field, with some study dating back to the 1930s and earlier. Sediment core-scanning methods have advanced modern time scale reconstructive research. These approaches have permitted research similar to that done with Antarctic ice core records. Paleoproductivity approaches such as assessing total diatom abundance can be used to infer the relative abundance of species existing at a given epoch from these records. Deschamps et al. highlighted how sediment records from the Chukchi-Alaska and Canadian Beaufort Margins can provide information on previous weather patterns and ocean circulation.

• Salinity:-

The inference of salinity from paleorecords is more difficult. Due to the relative abundances of diatoms that are limited to certain salinity regimes, deuterium excess in core records can provide a stronger inference of sea-surface salinity than oxygen isotopes can provide a semiquantitative salinity record. The global water cycle and ocean salinity balance have shifted, with the North Atlantic becoming more salinized and the subtropical Indian and Pacific oceans becoming less so. As the water cycle has changed, the vertical distribution of salt and haloclines has changed as well. Sea ice extent can be reduced as a result of large freshwater incursions and changing salinity.

Conclusion:-

Provides information on how the Earth was formed, how it has altered since formation, the components that make it up, and the processes that affect it. The deep ocean bottom, the shallower slopes and shelves that encircle the continents, and coastal features such as beaches and estuaries are all studied in marine geology. Some coastal river regions and major lakes are also studied by USGS marine geologists.