Strike-slip faulting and basin formation at the Guayape Fault--Valle de Catacamas intersection, Honduras, Central America

Abstract

The Valle de Catacamas forms a major basin along the central portion of the Guayape fault, the most prominent tectonic element of the Chortís block. The Guayape fault extends 290 km southwest from the Caribbean coast to the region of El Paraíso, Honduras, and may continue to the Pacific coast along a related prominent topographic feature, the Choluteca linear. Basins presently forming along the Guayape fault indicate that the fault is currently experiencing right-slip. The active features of the Valle de Catacamas displace older folds and reverse faults which apparently formed during an earlier period of sinistral shear. Thus, the Guayape fault has undergone at least two phases of movement, post-Cenomanian left-slip followed by the present right-slip. The geology of the valley suggests multiple stages of evolution. These include at least one period of thrust and reverse faulting, possibly associated with sinistral shear along the Guayape fault, and a recent episode of normal faulting associated with dextral shear on the Guayape fault. Thrusting of basement rocks over Jurassic strata on the south side of the valley was the earliest deformation to affect Mesozoic or Cenozoic rocks. The event can only be dated as post-Jurassic in age. The Cretaceous rocks of the Sierra de Agalta on the north side of the Valle de Catacamas are much more strongly deformed than similar rocks in central Honduras. In this range, the Aptian-Albian Atima Limestone commonly has a pervasive pressure solution cleavage which has not been reported from other locations on the Chortís block. The cleavage is apparently axial planar to the folds. The age of this deformation is constrained only as post-Cenomanian. SIR data indicate that these folds are deflected in sinistral shear near the Guayape fault. In addition, a major structural contact has a large left-lateral separation. The folds in the Sierra de Agalta are cut by the range-bounding normal fault of the Sierra de Agalta. Younger rocks are placed on older rocks by this normal fault, and fault slip data from small fault planes in the footwall block indicate normal faulting. The N 65° E strike of this normal fault, the N 35° E strike of the Guayape fault, and stress orientations inferred from fault slip data indicate that the present movement on the Guayape fault is right-slip. Fault slip data from the Guayape fault zone is heterogeneous as would be expected if two stage slip has occurred.