Origen alóctono del gabro del Cerro San Lorenzo, Sierra de Comechingones, Córdoba

CHINCARINI, ALEJANDRO; MARTINO, ROBERTO DONATO; GUERESCHI, ALINA BEATRIZ

Revista de la Asociación Geológica Argentina

Asociación Geológica Argentina

Lugar: Buenos Aires; Año: 1998 vol. 53 p. 435 - 444

0004-4822

The isolated and layered Cerro San Lorenzo gabbro is the largest body of basic rocks recognized at Sierras de Córdoba. In section viewed toward the south is strongly asymmetric with abrupt slope on the west side and a more smooth one on the east side. In map view has an oval shape (2700 x 1600 m = 4,32 Km2, major axis oriented NNW-SSE). Surrounding rocks are mainly composed by garnetiferous-biotitic gneisses in which tabular bodies of marbles, amphibolites and acidic igneous rocks are intercalated along with small ultramafics and eyed gneisses. Using traverse orthogonal profiles and mapping is possible to integrate a three dimensional view of the encasement gneisses which adopt a concave form like a trough defined by its dipping inward foliation. In the middle of this trough rest the lens-like gabbroic body in which igneous lamination and layering recognized throughout form a convex arch dipping to the east and bent around an axis oriented N 229°/85°. Both, the gneisses and gabbro foliations are strongly non concordant. An hypothesis of an allochtonous origin with a progressive evolution composed by (a) deep intrusion, (b) shear deformation, (c) dismembering of the body that produced a large porphyroclast of gabbro and (d) tectonic transport up to its final place are considered for the Cerro San Lorenzo´s gabbro. Finally, rigid body translation carried the body to the current position.