Northern Central America is of exploration interest both for its hydrocarbon potential, and for the critical information which it can provide to evaluate the hydrocarbon potential of other parts of the tectonically complex western Caribbean. The Mesozoic strata overlying the Chortis Block of northern Central America, especially the thick and widespread Lower Cretaceous carbonates, are similar to highly productive strata in southeastern Mexico. Recent palinspastic reconstructions suggest that the Chortis Block may have been plucked from southern Mexico and transported to its present location through a series of complex plate interactions, and the possibility that the prolific Mexican hydrocarbon province extends into Honduras and northern Nicaragua has not been adequately tested onshore.

The structure of western Honduras is dominated by WNW- to NW- trending dextral wrench faults as inferred from the orientation of en echelon folds and thrusts and from the geometries of associated north-trending pull-apart basins. The faults form major shear zones spaced from 30 to 50 km apart in western and central Honduras. Detailed mapping at a scale of 1:50,000 has been concentrated along one of these shear zones, the Montana de Comayagua structural belt, discussed in detail below. East-central Honduras is characterized by a transition from dominantly NW to NE-trending faults. The major NE-trending faults are probable sinistral wrench faults, and are spaced approximately 50 80 km apart. The zone of complex interaction between the NW- and NE-trending faults is beyond the area of reliable geologic coverage, and should be the focus of future mapping studies.

The Montana de Comayagua structural belt is a N60W-trending wrench zone which has a documented length of 130 km and a width of 30 km in central Honduras. The Montana de Comayagua structural belt may extend into unmapped areas to the northwest toward Guatemala and to the southeast toward Nicaragua. Mapping of the Agalteca quadrangle has clarified that the Montana de Comayagua structural belt consists of a series of left-stepping, strike-slip faults produced by probable dextral cretaceous to early Tertiary. Associated with these strike-slip faults are syntectonic high-angle reverse faults, thrust faults, folds and antithetic shears. The assemblage is a "flower structure" in cross section, and is believed to be the product of transpression. The Late Cretaceous-early Tertiary wrench structures of central Honduras are overprinted and locally reactivated by north-trending grabens of the Honduras Depression which began to form in the mid-Miocene and are still active.

The axis of the N60W-trending wrench zone in the Agalteca quadrangle is structurally high and exposes an apparently conformable sequence of deformed Mesozoic sedimentary rocks. A Paleozoic (?) metamorphic basement, the Cacaguapa Schist, is known to unconformably underlie the Mesozoic sequence in central Honduras, but is not exposed in the Agalteca quadrangle. The Mesozoic sedimentary rocks include Upper Jurassic (?) to Lower Cretaceous conglomerates of the Honduras Group which are overlain by Valanginian (?) to Albian limestones of the Yojoa Group. The Yojoa Group is overlain by Albian to Late Cretaceous red beds of the Valle de Angeles Group, which include an intercalated limestone member, the Cenomanian Esquias Formation. The Mesozoic sedimentary rocks are intruded by mafic to felsic stocks and dikes of Late Cretaceous to Tertiary age, and are unconformably overlain by Tertiary volcanic rocks.

The geologic database for northern Central America is limited, and varies greatly in detail and reliability across international boundaries, hampering regional tectonic and stratigraphic analysis. Honduras has the poorest published geologic coverage of the Central American republics. An in-progress compilation from original sources of the geology of western and central Honduras provides the basis for a series of preliminary geologic quadrangle sheets at a scale of 1:25,000. The compilation is based on all available nonproprietary geologic maps at a scale of 1:250,000 or larger. It comprises a much needed partial update to the published geologic map of Honduras, and is merged with the published maps of adjacent Guatemala, El Salvador and Nicaragua.

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