CONTROLS ON CLAY MINERALS IN AN EARLY PALEOGENE NONMARINESUCCESSION: IMPLICATIONS FOR VOLCANIC AND PALEOCLIMATIC RECORD OF EXTRA-ANDEAN PATAGONIA, ARGENTINA

M. S. RAIGEMBORN, L.E. GÓMEZ PERAL, M. KRAUSE, S.D. MATHEOS

JOURNAL OF SOUTH AMERICAN EARTH SCIENCES

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2014 p. 1 - 23

0895-9811

The distribution of clay minerals into fine-grained samples of the NT-RC succession, a Danian?middle Eocene mainly continental siliciclastic-volcaniclastic sequence exposed between the Atlantic coast and the San Bernardo Range in the Golfo San Jorge Basin is assessed in order to establish the possible origin of the clays and non-clay minerals, constrain the influence of the source area, volcanic activity, paleoclimate and weathering conditions on their genesis, considering sedimentological facies. A general vertical trend in the arrangements of the clay minerals along the studied succession shows an upward decrease in smectite, coeval with an increase in kaolinite. XRD combined with SEM analysis provide new very useful data about the composition and micromorphology of non-clay minerals as Opal-CT, zeolites, volcanic glass, and specially from clay minerals as smectite, kaolinite, halloysite among others. The detailed micromophologic analysis from clay minerals allow to establish a distinction beween authigenic (in situ) and volcanogenic genesis for the clays. The paleoclimatic information provided obtained from the clay minerals of the NT-RC succession of Central Patagonia (~ 46° LS) seems to constitute one of the most complete temporary recorded of the hyperthermal events of the EPWG in South America.