Estratigrafía secuencial del Terciario superior marino de Patagonia: un equivalente de la "crisis del Messiniano"?

• C. Zavala ^[2] ; H. Freije ^[1]
  1. [1] Universidad Nacional del Sur

     Universidad Nacional del Sur

     Argentina

     
  2. [2] Consejo Nacional de Investigaciones Científicas y Técnicas
• Localización: Geotemas (Madrid), ISSN 1576-5172, Nº. 2, 2000 (Ejemplar dedicado a: IV Congreso del Grupo Español del Terciario (Tremp, 19-21 septiembre, 2000)), págs. 217-221
• Idioma: español
• Enlaces
  • Texto Completo Ejemplar
• Resumen

  • The Mio-Pliocene continental and marine deposits of the Río Negro Formation, in northern Patagonia, provide excellent exposures to analyse in detail late Tertiary evolution. This unit extensively crop-out in a near-tabular setting as continuous marine cliffs along a distance in excess of 100 km, with an average thickness ot 50 meters. This paper deals on the sequence stratigraphy of a marine level assigned to the Tortonian, using field data. This level has a large- scale wedge geometry within continental (aeolian) deposits, displaying a maximum thickness ot about 10 meters. It is internally composed of dark-grey mudstones and bioclastic sandstones deposited in a shallow and partially confined sea, with evidences of wave reworking processes. It integrates a single complete depositional sequence, having well-defined transgressive and highstand systems tracts. At the top of the sequence, a forced regressive set can be recognised, which is in turn followed by lacustrine deposits with desiccation cracks. The last evidence indicates a fast relative sea-level drop, which is here thought as eustatic in origin. Time- stratigraphy suggests a post-Tortonian / pre Early Pliocene Age for this sea-level fall, thus allowing a possible correlation with that responsible of the Messinian crisis in the Mediterranean.