The Conlara Metamorphic Complex: a Pampean metamorphic event in the Sierra de San Luis, Argentina. 17º Congreso Geológico Argentino, J

LÓPEZ DE LUCHI, M. G.; CERREDO, M.E.; STEENKEN, A.; SIEGESMUND, S.; WEMMER,K.; MARTINO, R.D.

San Salvador de Jujuy

Congreso; 17º Congreso Geológico Argentino; 2008

The Sierra de San Luis consists of NNE trending metamorphic complexes named Nogolí, Pringles and Conlara (Sims et al., 1997). These units are separated by the two narrow phyllite belts of the San Luis Formation (SLF, Prozzi and Ramos 1988). The Conlara Metamophic Complex (CMC) is the easternmost of these complexes. The western margin of the CMC is affected by the mylonitic Río Guzmán shear zone whereas its eastern margin to the Sierra de Comechingones (Sims et al., 1997) is controlled by the Las Lajas and Guacha Corral shear zones. The metamorphic series of CMC comprises both metasedimentary and metaigneous rocks. The former are dominated by metagreywackes and scarce metapelites with lesser amounts of tourmaline schists and turmalinites. Likely controlled by a D3 related major structure (fold?) distinct metasedimentary assemblages are recognized on cartographic plan: in the central northern areas of CMC fine-grained schists, banded medium-grained schists with subordinated interlayers of tourmaline schists dominate, whereas along the eastern and southeastern areas medium-grained schists (either banded or not) with rare amphibolite interlayers crop out. The central fine to medium-grained schist association is characterized by S2 oriented biotite-quartz-plagioclase±muscovite ± garnet assemblages, whereas the eastern medium-grained schists bear the non-diagnostic biotite (S2 oriented)-plagioclase assemblage, rarely garnet occurs as a prograde phase displaying post S2 plagioclase replacement. Muscovite blasts overprinting S2 planes are widely distributed on M domains of all schist types. The metaigneous components of CMC encompass basic terms (likely emplaced as sills within the sedimentary pile) and granitic rocks. These in turn, belong to two distinct groups: an earlier one which underwent all the prograde metamorphic evolution of the CMC being emplaced between D1-D2, and a later one which were emplaced later synkinematically with the late D3 deformation and displays a down-T path of deformation microstructures (from the submagmatic stage to low-T greenschist facies conditions).