Resumo

ATENCIO, Mario et al. Geomorfología sísmica de la última transgresión lacustre de la formación pozo D-129 en la región de la faja plegada, cuenca del golfo San Jorge. Rev. Asoc. Geol. Argent. [online]. 2015, vol.72, n.1, pp.136-147. ISSN 0004-4822.

The Golfo San Jorge Basin records a hydrocarbon production history of more than 100 years. The Pozo D-129 Formation, which is the main source rock of the basin, is a lacustrine unit with high pyroclastic participation that spreads over a wide extension within the subsurface of the basin; its thickness increases toward the central area of the basin, reaching up to 1500 meters. In the San Bernardo Fold Belt of Santa Cruz province, more than 200 wells were analyzed and three main sections in the Pozo D-129 Formation were recognized, based on lithological and geochemical variations. In the uppermost section of the unit an stratigraphic interval characterized by black shales rich in organic matter is interpreted as the last and most extended lacustrine transgression of this unit, informally named "cuello pelítico". The analysis and characterization of this interval becomes the main objective of the present study. 3D seismic visualization and seismic facies identification allowed the recognition of the main geomorphologic patterns associated with the last lacustrine transgressive event. A strong thickness variation could be recognized mainly related to the distribution within isolated depocentres. The depositional characterization of the "cuello pelítico" in the area improves the knowledge of the current paleoenvironmental model of the unit.

Palavras-chave : Pozo D-129 Formation; Golfo San Jorge Basin; Seismic facies; Lacustrine transgression; Black shales.

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