Relaciones entre tectónica y sedimentación en el Grupo Cuyo (Jurásico medio) en el área de quebrada del sapo, Cuenca Neuquina, Argentina.

AZÚA, G.; FREIJE, H.; PONCE, J.J.

La Habana, Cuba

Congreso; IV Congreso de Geología y Minería; 2001

The studied area is located on the southern margin of the Picún Leufú creek, in the zone named "Dorsal de Huíncul", 50 km south of Zapala City in Neuquén Province, Argentina. Based on field work, four detailed stratigraphic sections were measured (bed by bed) with a Jacob staff, covering a total thickness of 3107 m. A regional cross section of the Quebrada del Sapo area, correlating the detailed stratigraphic sections,using index horizons was made. Six unconformity-bounded stratigraphic units were recognized. They are partially equivalent to Los Molles Formation (Unit 1), Lajas Formation (Units 2 and 3), Challacó Formation (Unit 4), Tordillo Formation (Unit 5) and Vaca Muerta and Quintuco Formations (Unit 6). Two main structural systems are present in this area. The older one (pre Late Bajocian) is represented by a southeast-northwest anticline verging southwestward. The Los Molles Formation was affected by this structure. The second structure is an east-west anticline verging south and involving units 2 to 6. This structure was developed during Middle to Late Jurassic times (Late Bajocian – Early Tithonian) and performed a geometrical control on deposition of the above mentioned sequences. In the case of the younger structure was possible to recognize a composite progressive unconformity that display a round cycle of acceleration and deceleration of the diastrophism. In this scenario the angular unconformities represents the deformation climax. The first tectonic phase will be started with an accelerated diastrophism (Lajas Formation, Late Bajocian) represented by an angular increase of plain unconformities. After reach the maximum diastrophism (boundary between units 2 and 3; Bathonian?) a decelerated diastrophism during units 4 to 6 (Early Callovian-Early Tithonian) occurs. The structural patterns are indicative of of simultaneous deformation with the sedimentation during Jurassic times.