Upper Cretaceous foraminifera and palynomorphs from Ekelöf coast Section, Ekelöf Point, Eastern James Ross Island, Antarctic Peninsula.

AMENABAR, C.R.; CARAMÉS, A.; CONCHEYRO, A.

AMEGHINIANA

ASOCIACION PALEONTOLOGICA ARGENTINA

Lugar: Buenos Aires; Año: 2016 vol. 53 p. 333 - 357

0002-7014

A micropaleontological analysis of foraminifera and palynomorphs obtained from a partial sedimentary section cropping out at EkelöfPoint, eastern James Ross Island, Antarctic Peninsula, is presented. The section, named Ekelöf Coast, includes the lowest levels of the Upper CretaceousHamilton Point Member of the Snow Hill Island Formation. Among the foraminifera, 18 benthic taxa including 10 agglutinated and eightcalcareous are recognized. Palynomorphs include continental and marine species. The continental assemblage contains 44 spore and pollenspecies. The marine assemblage consists of 10 peridinioid dinoflagellate cysts species, dominating in number of specimens, and 10 gonyaulacoids.Although the palynomorph assemblage supports a late Campanian age for the section, an earliest Maastrichtian age is not excluded. Thepaleoenvironmental interpretation based on the distribution of foraminiferal morphogroups indicates an outer shelf-upper bathyal environmentin agreement with sedimentological data. The paleoenvironmental inference based on the S/D ratio (sporomorph versus dinoflagellate cysts) andthe P/G ratio (peridinioid versus gonyaulacoid cysts) suggest a coastal to inner neritic setting with a continuous continental supply from the continentto the marine environment, evidenced by the slight dominance of the peridionoids over gonyaulacoids cysts. The discrepancy observedbetween palynological and micropaleontological-sedimentological data may be linked to the development of a narrow continental shelf duringthe Late Cretaceous. In such continental shelf, terrestrial palynomorphs and peridinoid cysts would quickly run down the slope and would bedeposited in the deep marine environment together with gonyaulacoid cysts.