Tectonic blocks in serpentinite melange (eastern Cuba) reveal large-scale convective flow of the subduction channel
Abstract
Detailed petrological study of mid-oceanic ridge basalt−derived high-pressure amphibolite blocks from a fragment of the Caribbean subduction channel (La Corea serpentinite-matrix mélange, eastern Cuba) has revealed contrasted zoning patterns of garnet porphyroblasts, including well-defined complex oscillatory prograde-retrograde concentric zoning in one sample. Calculated pressure-temperature (P-T) conditions for this sample using mineral inclusion assemblages and isochemical P-T projections reveal large P-T recurrences best explained by large-scale convective movement of the tectonic block in a serpentinitic subduction channel. The P-T conditions attending garnet growth followed an overall counterclockwise path as a consequence of continued refrigeration of the subduction channel during ongoing underflow after its onset ca. 120 Ma. These findings constitute the first report of large-scale convective circulation of deeply subducted material in the subduction channel, and are consistent with the thermomechanical behavior of the channel predicted by numerical models.
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To Cite this article: Blanco-Quintero, I.F., García-casco, A., Gerya, T. (2011): Tectonic blocks in serpentinite melange (eastern Cuba) reveal large-scale convective flow of the subduction channel. Geology, 39, 79-82.
DOI: 10.1130/G31494.1
