4. Geological-Structural Mapping of Weathered Igneous and Metamorphic Rock Units

A summary of the main results achieved in the geological-structural mapping, from the data of potential fields and airborne gamma spectrometry, from units of igneous and metamorphic rocks in the western (Havana-Matanzas), central (Cienfuegos-Villa Clara-Sancti Spiritus), and central-eastern (Camagüey-Tunas-Holguín) regions of Cuba offers. The gravimetric data allow to identify different geological-structural traits: by lows, those associated with the Northern Cuban Thrusts Belt, the southern metamorphic massifs, the granitic igneous bodies and the synorogenic structural basins and depressions; by highs, those linked with powerful thickness of volcanic rocks and ophiolitic bodies; as well as geophysical alignments, major tectonic boundaries within the Cuban Orogen. Aeromagnetic data allow mapping the main tectonic boundaries; the southern metamorphic massifs; the synorogenic structural basins and depressions; granitoid belts; ophiolitic bodies and the development area of volcanic rocks. The faculty of lithological mapping that gives the differential distribution of magnetite in various rock units gives this possibility. The airborne gamma spectrometry identifies, by increased values of U(Ra), units with high contents of graphite (organic matter) and those associated with acid igneous rocks. Potassium increases are linked, mainly, to the alkaline and acidic medium-igneous rocks. Incremented values of thorium generally characterize the metamorphites and, U(Ra) and Th increments express some highly developed weathering crusts on ultrabasites.