INVESTIGADORES
REMESAL Marcela Beatriz
congresos y reuniones científicas
Título:
The pumiceous levels interbedded in the paleobeaches of Half Moon
Autor/es:
REMESAL, M.B.; PARICA C.A.; CASELLI A.T.
Lugar:
Buenos Aires - Argentina,
Reunión:
Conferencia; SCAR XXXI & Open Science Conference; 2010
Resumen:
Deception Island is a young, active volcano located at the southwestern of the
Bransfield Strait, between the Antarctic Peninsula and the South Shetland archipelago.
The origin of the Deception volcano is related to a spreading centre in the Bransfield
Strait, which is responsible for a line of submerged seamounts. Decepcion is
characterized by explosive volcanism and emissions of pumiceous blocks. Deception
Island contains a wide range of magmatic compositions (basalt to dacites). After Le
Bas et al. (1986), the rocks are classified as basalts (mainly subalkali basalts, rare
alkali basalts), basaltic trachyandesites, trachyandesites and trachytes. Interbedded
in the paleobeaches of Half Moon Islands thin levels of pumiceous fragments had been
recognized. The pumiceous blocks founded in Half Moon Island are brownish with a
narrow variation in tones dark to light. Sizes oscillate between 3 cm to 8 cm. The
textures are highly vesiculated and vitroclastic. Pumiceous block from Half Moon Island
was classified as trachyte (65%SiO2, = 7%total alkalis, < 20%Q) bordering the limit of
the alkaline series. These samples have a good array in the tendency of a transitional
series of Deception Island very close to the new data presented for the pumiceous. The
over impose of the chondritic-normalize profile of the pumiceous blocks from Half Moon
Island define a trend close similar to differentiated rocks from Deception Island, with
enrichment in LREE ([Ce/Yb]cn 2), flat design for the HREE and the Eu anomaly.
48 Quaternary Southern Ocean intermediate and deep-water circulation