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Evidence from Valle de Catacamas Supports a Right-Lateral, Neotectonic Sense of Slip for Guayape Previous HitFaultNext Hit of Honduras

Mark B. Gordon, William R. Muehlberger

The Guayape Previous HitfaultNext Hit extends from the Caribbean coast southwest to the Pacific coast at the Gulf of Fonseca. The Valle de Catacamas is a major physiographic basin centrally located along the west side of the Guayape Previous HitfaultNext Hit. Increasingly deeper structural levels are encountered from west to east in the footwall block of the north range-bounding normal Previous HitfaultNext Hit. At the west end of the valley Tertiary(?) mafic volcanics crop out in the footwall block. To the east the mafic volcanics are underlain by the Upper Cretaceous Valle de Angeles molasse. About 10 km farther east, the relief north of the frontal Previous HitfaultNext Hit is much greater and quartz pebble sandstone (Honduras Group?) is overlain by limestone. The limestone is penetratively cleaved near the frontal Previous HitfaultNext Hit with the cleavage essentia ly parallel to the Previous HitfaultNext Hit. Thus, the normal faulting may be following the trend of a major preexisting weakness defined by the cleavage.

At the northeast end of the valley, the sedimentary rocks are underlain by metamorphic basement. Thus, the greater topographic relief and deeper structural levels in the footwall near the Guayape Previous HitfaultNext Hit indicate that the normal faults have a greater displacement near the Guayape Previous HitfaultNext Hit and this displacement decreases to the west away from the Previous HitfaultNext Hit. Evidence for normal faulting along this range front includes mesoscale structures on Previous HitfaultNext Hit Previous HitplanesNext Hit and large-scale faults which place younger rocks on older rocks.

In the southeast corner of the valley, splays of the Guayape Previous HitfaultNext Hit place metamorphic basement rocks against Tertiary volcanics exposed within the valley.

Preliminary analysis of Previous HitfaultNext Hit slip data (slickenslide Previous HitplanesNext Hit and striae) suggests that ^sgr3 is approximately 310°, consistent with formation of the valley by right-lateral shear along the Guayape Previous HitfaultNext Hit.

Fresh Previous HitfaultNext Hit scarps, normal faulting on the north side, and the lower topographic relief on the south side suggest that the Valle de Catacamas is a young, asymmetric Previous HitfaultNext Hit wedge basin formed by dextral shear along the Guayape Previous HitfaultTop.

AAPG Search and Discovery Article #91030©1988 AAPG Annual Convention, Houston, Texas, 20-23 March 1988.