Abstract

A seismic-reflection survey along the continental margin of Honduras has uncovered an assemblage of diapirlike bodies. Features such as disrupted and upturned flank reflectors as well as a domed and faulted overburden suggest that the bodies are truly piercement structures. Although unequivocal evidence is lacking, the diapirs are probably salt. The bodies are shallow and corroboration could be obtained by drilling (Fig. 1).

The Cayman Trough is a locus of intense tectonism along which the Caribbean plate is considered to be decoupled from the North America plate. Salt offshore Honduras (Caribbean plate) may have been displaced eastward by about 1,000 km relative to presumably equivalent salt deposits in Guatemala (North America plate). Hence, slip rates for the lithospheric plates in the northwestern Caribbean can be estimated to lie between 1 and 2 cm/yr, depending on whether the transcurrent motions were initiated in the mid-Mesozoic or the mid-Cenozoic.

The bulk of the data available from this and other studies convinces one that the Cayman Trough is a strike-slip feature. Consequently, a sphenochasm model for the structural evolution of the Gulf of Honduras that delegates strike-slip faulting to a subordinate role is improbable. A model involving the relative clockwise rotation of Honduras from Yucatan in the mid-Mesozoic followed in the mid-Tertiary by roughly 300 km of sinistral, strike-slip displacement localized along the Cayman Trough is conceivable but unlikely. Additional magnetic surveying will probably be needed to test this model.

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