The metamorphic basement of the Alboran Basin at Site 976 yields high-grade schists, gneiss, migmatitic gneiss, marble, calc-silicate rocks, and granites. In the Alboran Domain, lithologic sequences composed mainly of this set of high-grade metamorphic rocks only occur in the Jubrique and Blanca Group units belonging to the Alpujárride Complex (Sebtide in the Rif). These rocks show a complex tectonometamorphic evolution in which different events accompanied by different stages of mineral growth with variable pressure-temperature conditions can be noted. Studies of the lithologic and metamorphic characteristics of the samples from Site 976 and comparison with the western Alpujárride rocks have allowed us to propose a position for the drilled basement sequence within the Alpujárride Complex. We conclude that the basement sampled at Site 976 corresponds to rocks belonging to the Blanca Group, cropping out onshore below the peridotite bodies and/or in an imbricate zone between two peridotite slices (Montemayor slices). The tectonic exhumation of the Blanca Group units, partially contemporary with Upper Serravallian-Tortonian sediments, was produced during the rifting (northeast-southwest extension direction) of the Alboran Basin.
1Examples
of how to reference the whole or part of this volume can be found under "Citations"
in the preliminary pages of the volume.
2Instituto
Andaluz de Ciencias de la Tierra-Departamento de Geodinámica, C.S.I.C.,
Universidad de Granada, Campus Fuentenueva s/n, 18071 Granada, Spain. jazanon@goliat.ugr
Date of
initial receipt: 27 May 1997
Date of acceptance: 2 December 1997
Reproduced online: 13 January 2004
Ms 161SR-225