Palinología del Paleogeno tardío-Neo geno temprano, pozo Aries x-l, Plataforma Continental Argentina, Tierra del Fuego

Abstract

Nineteen cutting samples from the Aries x-I well, drilled in the Argentine continental shelf, offshore Tierra del Fuego, were analized for palynology. Marine and terrestrial palynomorph assemblages, fairly well preserved, though neither diverse nor abundant, were recovered throughout the studied interval, comprising depths between 240-640 m. Four sections, D, e, B and A from botton to top are informally proposed on the basis of the palynological content. Sections D through B are considered Oligocene in age, most probably Upper Oligocene, whereas section A yielded Early Miocene assemblages, according to previously recorded species distribution in nearby areas. Two marine events were recognized in sections e and A respectively. The first is characterized by the presence of high amounts of protoperidinioid dinoflagellate cysts (up to 98%) mostly Brigantedinium sp., and the second, by equivalent amounts of both major dinocyst groups-gonyaulacoids, protoperidiniods- with absolute dominance of Nematosphaeropsis rigida Wrenn (32 % of the assemblage). An environmental trend from estuarine- transitional restricted (section C) to neritic nearshore marine (section A) is suggested. Terrestrial palynomorphs are abundant in sections e and A. Levels 500-550 m have large amounts of Nothofagidites spp., pterydophyte spores and fungal rernains, probably reflecting forest vegetation in the surrounding area. The interva1260-300 m, section A, yielded a diverse pollen grain assemblage mostly composed of the herbaceous and shrubby families Cyperaceae, Asteraceae, Chenopodiaceae and Anacardiaceae.