The Old Cryogenic Structures of Northern Patagonia: The Cryomere Penfordd

DARIO TROMBOTTO

ZEITSCHRIFT FUR GEOMORPHOLOGIE

GEBRUDER BORNTRAEGER

Lugar: Stuttgart; Año: 1996 vol. 40 p. 385 - 399

0372-8854

The processes of frezeeng and thawing that took place in the subregion of Northern Patagonia during the Quaternary Cryomere, are revealed today by traces of cryofragmentation, cryoturbation of polygons, ice wedge casts, folds, irregular structures, etc. imprinted in the fluvial deposits of Patagonian Gravel from the Plio-Pleistocene age and in the upper part of the Tertiary. During and after the deposition of the Patagonian Gravel cryoforms were built showing a characteristic structure related with the penetration and draining of water, possible freezing, and with the drying and cracking of the active paleo-layer. At the same time the cryogenic forms within the Patagonian Gravel are related with the forming of calcrete or ?tosca?, which consists mainly of CaCO3, quartzes and volcanic glass, giving the profiles their characteristic periglacial image: a vertically and laterally heterogeneous structure. This lithologic architecture of calcretes impregnating the Patagonian Gravel, creates a network-like system of ?columns?, horizontal layers and ?windows? according to the deposition and precipitation/or not of  CaCO3 which again each stand for different morphological types of calcretes. Puero Madryn is an area that is very representativ of old cryoforms.