Abstract

ARAYA-VERGARA, José F.. The genetical problem of the North Patagonic fjord bottoms. Investig. mar. [online]. 1998, vol.26, pp. 71-81. ISSN 0717-7178.  doi: 10.4067/S0717-71781998002600007.

It is an attempt of founded discussion on the genesis of the fjord bottoms of Northern Patagonia. Even though the operation of a Pleistocene glacial piedmont in this region has been demonstrated, its submarine effect on the fjord basins was until now ignored. The longitudinal high resolution 3.5 k Hz echo-sounder records, show two types of fjord basins: uniform ponding esplanade and ponding esplanade alternating with chaotic accumulations. In the first, two evolutive phases are indentified; the beds of the lower phase are remolded and the source of its material is conjectural; in exchange, the laminated beds of the upper phase are intact and fill depressions on materials of the lower phase, with sediments supplied by slopes. In the second, there is synchronical construction between chaotic accumulations and the beds of ponding esplanade. Consequently, for the basins with uniform esplanade, the genesis of the lower phase is ignored yet; in exchange, a good part of the upper phase can be reconstructed; the dating of its superficial beds indicates Holocene age. For basins with chaotic accumulations, models for construction of submarine moraines can be applied. The concept of polyphasic moraines is proposed