Palynofacial approach across the K/P boundary in Marambio (Seymour) Island, Antarctic Peninsula.

RODRÍGUEZ BRIZUELA, R.; MARENSSI, S.; BARREDA, V.; SANTILLANA, S.

Revista de la Asociación Geológica Argentina

Año: 2007 vol. 62 p. 236 - 241

Abstract. This study attempts to analyze optically the palynological organic matter behavior throughout the Cretaceous- Paleogene boundary in Marambio (Seymour) Island, Antarctic Peninsula. The boundary is located in the upper part of the López de Bertodano Formation, coinciding with a widespread glauconitic level. Fifteen samples were analyzed and associated in four palynofacies. Defined palynofacies indicate an inner shelf marine environment of sedimentation. The palynofacial assemblages permitted discriminating the studied section into three minor stratigraphical intervals related to three sea-level stages. The integration of these stages results in an hypothetical sea-level curve, that reflects a minor transgressive - regressive pulse into a general regressive trend. The maximun water depth is about 1 m below the postulated K/P boundary. Palinofacial recognition of this pulse supports the earlier idea of a slow transgressive-regressive event with minor internal transgressive-regressive cycles. Palynofacial data indicates preservation of the organic matter across the K-P boundary, and therefore do not suggest any local effect of the hypothetical global catastrophic K/P event. Considering the monotonous lithology of the López de Bertodano Formation that makes the recognition of unconformities difficult, this work opens the possibility of applying a sequence stratigraphic approach based on the recognition of maximum flooding surfaces for future investigations.