Exposed in the core of a NNW-trending frontal anticline of the Laramide fold-thrust belt of northeastern Mexico, the Granjeno Schist comprises a polydeformed assemblage of Paleozoic metasedimentary and metavolcaniclastic rocks and serpentinized mafic-ultramafic units. The earliest deformation (D1) predates emplacement of a leucogranite at 351 ± 54 Ma and may record obduction of this oceanic unit. Subsequent deformations (D2a-D2c) record tectonic juxtapositioning of the Granjeno Schist against the ∼1 Ga Novillo Gneiss by NNW-directed dextral shear under conditions of decreasing temperature. Cooling ages of 313 ± 13 Ma and 300 ± 4 Ma are considered to date the onset of dextral motion, which continued into the Permian. These events are linked to the Late Paleozoic closing of the Rheic Ocean.
|Number of pages||18|
|Journal||International Geology Review|
|Publication status||Published - Sep 2005|