Fernández, F. J., I. Rodríguez, J. Escuder-Viruete, and A. Pérez-Estaún (2016), Exhumation of high-P marbles of the Samaná Terrane (Northern Hispaniola): Insights from paleostress and microstructural imprints, Tectonophysics, 686, 116-131, doi: http://dx.doi.org/10.1016/j.tecto.2016.07.025.


Paleostress variations and microstructural imprints of a subducted carbonate slab record changes in mechanical strength during its exhumation. The slab studied here forms part of the high-P Samaná Terrane located on the north-eastern margin of the Hispaniola Island. Cold-cathodoluminescence images reveal relict cataclastic fabrics within the highest-pressure marbles of the Punta Balandra and Santa Bárbara Schists structural units, formed in the early stages of exhumation at P-T conditions ca. 2.0 GPa − 500 °C. Cataclastic flow was triggered after a moderate increase of water content (1.2% < w.t. H2O < 1.8%). Accordingly, grain sizes larger than equivalent radius ri = 40 μm preserve distribution of power law type with fractal dimensions D2 = 2.43 in Punta Balandra unit and D2 = 2.72 in Santa Bárbara unit. After cataclastic flow, the stress dropped and grain comminution conducted the marbles to the dissolution-precipitation domain. Then, as exhumation progressed, the effective stress increased and calcite intracrystalline plasticity process dominated. Calcite-twinning incidence and recrystallized grain-size indicate maximum paleostress ca. 350 MPa and mean flow paleostress ≈ 130 MPa. SEM-EBSD analyses show similar weak type-c calcite fabrics in all high-P carbonate units, even though they record different metamorphic P peak. Therefore, intracrystalline plasticity was probably dominant during the development of the final tectonic fabric. Finer grain-size distributions are out of fractal range, with D1 < 1, because of the further superposed deformation. Most of the data are consistent with an initial forced exhumation model of the carbonate slab in a brittle-ductile rheology of the confined plate interface.

Reference article


We use cookies to improve our website and your experience when using it. Cookies used for the essential operation of this site have already been set. To find out more about the cookies we use and how to delete them, see our privacy policy.

  I accept cookies from this site.
EU Cookie Directive plugin by www.channeldigital.co.uk