EMPLACEMENT OF THE OPHIOLITE COMPLEX IN EASTERN CUBA

KENYA ELVIRA NUÑEZ CAMBRA ¹, GARCÍA CASCO ANTONIO ², ITURRALDE VINENT MANUEL ³, MILLAN TRUJILLO GUILLERMO ¹

presenter's e-mail: kenya@igp.minbas.cu

1 - Geology and Paleontology Institute
2 - University of Granada
3 - National Museum of Natural History of Cuba

The ophiolite complexes in the east part of Cuba were emplaced in the Late Maastrichtian, generally as thrust slices of variable thickness over the cretaceous metavolcanic complex of Sierra del Purial. Structural measurements were taken and processed within the Moa-Baracoa ophiolite massif, recognizing the principal faults systems and stress directions. The internal structure of the massif is characterized by fragmentation zones, faults and open joints with different attitudes, indicating different stresses. The principal faults systems are grouped with strike WNW (285°).
The lineation structures on the main overthrust fault plane, as well as reverse shear zones clearly indicate a sense of tectonic transport (vergence) towards the NNE. These structures suggest cold (i.e., late) emplacement of the Moa Baracoa ophiolite over the cretaceous metavolcanic complex coming from the south.
The Güira de Jauco amphibolite body, located to the east of the Moa-Baracoa ophiolite, bear intercalations of serpentinite that, in turn, contains amphibolite blocks. Peak P-T attained were 600-650 °C and ca. 6 kbar. This body is interpreted as the metamorphic sole of the Moa-Baracoa ophiolite.
The general structure of this body is characterized by strongly deformed rocks, with close folds with axial planes dipping to the WNW. That fact suggests hot (i.e., early) emplacement of the Moa-Baracoa ophiolite coming from the WNW.
The ophiolite melange of the Sierra del Convento massif, located south of the Moa-Baracoa ophiolite, is a subduction complex that contains, within a serpentinite matrix, strongly deformed HP/HT metabasite rocks (amphibolite, eclogite, blueschist) and moderately deformed graintoids that intrude the HP/HT rocks but are also metamorphosed to HP/LT conditions. The sense of thrusting is from SE to NW. Structural features in the underlying metavolcanic rocks show micro- to meso-folds with vergence towards NNW. Also faults within the massif dip to the SSE. This suggests that this melange was emplaced coming from the SSE.

ACCEPTED as Poster Presentation
in session: "G20.11 - Caribbean plate tectonics"