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| Loisels Seamounts | |
|---|---|
| Name | Loisels Seamounts |
| Location | South Pacific Ocean |
| Type | Seamount chain |
Loisels Seamounts are an undersea chain of volcanic edifices located in the South Pacific Ocean. The feature forms a linear group of guyots and conical seamounts that rise from the seafloor and have been the subject of geological, oceanographic, and biological studies. The seamounts are notable for their role in regional plate interactions and for supporting diverse benthic and pelagic communities.
The Loisels Seamounts lie on the Pacific Plate flank near lithospheric features associated with the East Pacific Rise, proximate to Ōjin Seamount and other chains such as the Hawaiian–Emperor seamount chain, the Line Islands, and the Society hotspot. Their coordinates situate them within the jurisdictional waters adjacent to the exclusive economic zones of states including French Polynesia and near oceanographic survey regions managed by institutions like the National Oceanic and Atmospheric Administration and the Institut polaire français Paul-Émile Victor. Nautical charts produced by the International Hydrographic Organization and bathymetric compilations such as the GEBCO grid contextualize their relation to nearby features like the Mariana Trench abyssal plain and the Pitcairn Islands plateau.
The seamounts were formed by intraplate volcanism linked to mantle plume activity comparable in process to the formation of the Hawaiian Islands and the Easter Seamounts. Petrologic analyses compare rock types from ocean drilling and dredge samples with specimens from the Kerguelen Plateau and the Galápagos Islands to infer mantle source characteristics. Geochronologic techniques such as argon–argon dating and uranium–lead dating have been applied alongside seismic reflection profiles used by institutions like the Woods Hole Oceanographic Institution and the Scripps Institution of Oceanography to constrain the timing of edifice construction relative to regional tectonic events like the Cretaceous Normal Superchron and the opening of the South Pacific Basin.
Morphologically, the chain includes flat-topped guyots that record paleo-shoreline erosion events similar to features found near the Great Meteor Seamount and steep-sided volcanic cones analogous to Loihi Seamount. Hydrothermal alteration and secondary volcaniclastic deposits have been identified using remotely operated vehicles operated by research vessels such as the RV Thomas G. Thompson and the RV Roger Revelle. Studies referencing eruption products link the seamounts to mantle plume flux variations discussed in literature involving the Mantle plume hypothesis and tectonic stress fields monitored by the International Seismological Centre.
Biological surveys revealed that the seamounts host high-density sessile communities including reef-forming corals comparable to assemblages documented at Apo Reef Natural Park and sponge grounds resembling those studied near the Azores and the Rockall Trough. Mobile fauna such as deepwater sharks, tunas, and cetaceans show usage patterns analogous to observations from the Line Islands Marine National Monument and the Papahānaumokuākea Marine National Monument. Biodiversity assessments led by teams from the Monterey Bay Aquarium Research Institute and the Bishop Museum employed DNA barcoding, stable isotope analysis, and ROV video transects to compare faunal endemism with that reported for the Juan Fernández Islands and the Galápagos Marine Reserve.
Initial charting by hydrographic expeditions of the 19th century gave way to systematic multibeam mapping in the 20th century by navies and research programs including surveys by the US Geological Survey and collaborative campaigns with the International Ocean Discovery Program. Scientific cruises involving the Alfred Wegener Institute and the National Institute of Water and Atmospheric Research used dredging, coring, and in situ experiments to build lithostratigraphic frameworks. Key publications appeared in journals associated with the American Geophysical Union and the Geological Society of America summarizing stratigraphy, geochemistry, and ecology.
Human impacts from deep-sea fishing fleets targeting species with behavior patterns similar to those around the Phoenix Islands Protected Area and from exploratory mineral interests echo pressures documented for the Clarion-Clipperton Zone. International governance instruments such as the United Nations Convention on the Law of the Sea and regional agreements involving France and Pacific island states inform conservation measures. Proposals for protection have cited models from the Convention on Biological Diversity and management frameworks used in the Micronesia Challenge and the Coral Triangle Initiative to mitigate threats like bottom trawling and potential polymetallic nodule mining.
Bathymetric data for the seamounts derive from multibeam echosounder surveys conducted from vessels affiliated with the NOAA Ship Okeanos Explorer, the French Research Vessel L'Atalante, and national research fleets. Datasets have been incorporated into products by the Global Multi-Resolution Topography (GMRT) Synthesis and the International Bathymetric Chart of the Southern Ocean for regional modeling. Mapping efforts utilize software and standards promulgated by the Open Geospatial Consortium and data repositories maintained by the National Centers for Environmental Information and the European Marine Observation and Data Network.
Category:Seamount chains Category:Underwater volcanoes Category:South Pacific Ocean