Fossil cold-water corals (Scleractinia and Gorgonacea) from the Burdwood reef, Argentina

LAMARCHINA SALVADOR; ZAMPONI M; ISLA, F.; MARTIN J

Vigo

Congreso; International Symposiun on narine sciences; 2018

Universidad de Vigo

The Burdwood Bank is a rocky platform emerging from abyssal plains to depths of 50-100 m between the South Atlantic Ocean and the Drake Passage. Regarding its geological affinity, it has a composition similar to the Staten Island (Isla de los Estados), aligned to the Andes-Darwin Cordillera. It is crossed from south to north by oceanic currents very cold and rich in nutrients. Rocks dredged from the shallower portions of its western portion are composed of carbonatic blocks. The analyses indicate fossil specimens of Desmophyllum sp. (Order Scleractinia) and Gorgonacea palmatum (Order Alcyonacea or Gorgonacea), genera living today in the region. In this sense, sectors of this western portion should be considered as an ancient reef composed mostly of cold-water corals. The major consequences are assigned to oceanographic and climatic implications. During the Upper-Pleistocene lowstand, sunlight was more available at the shallower depths and therefore corals were very frequent at the former wave-dominated areas. Sea-level variations have therefore strong influence on cold-water coral growths in the sense that nutrient availability by currents can significantly changed between glacial and interglacial periods.