El Batolito de Colangüil (29-31°S) cordillera frontal de Argentina: estructura y marco tectonico

摘要: ABSTRACT. The Colanguil Batholith (CB) is located on the eastern border of Cordillera Frontal (29-31°S), northern San Juan Province. Intrusion took place between 264 and 247 Ma, after Rafael orogenic phase (SROP). It consists 61 % granodiorites 39% granites silicic longitudinal dike swarms with minor mafic dikes. Global composition different from circumpacific batholiths which are more mafic. Most CS was intruded into Rio Blanco-Agua Negra sedimentary basin Upper Carbonilerous-Asselian age. SROP end sedimentation in this (Asselian) beginning intrusion CB, being 280-270 Ma its most probable first batholith intrusions granodiorites, roughly coeval eruptions Choiyoi volcanics, consist andesitic to dacitic ignimbrites. Both sequences evolved intermediate high composition. compressive stresses folded thrusted a wide belt along Frontal. Degree deformation decreased gradually east, thus Precordillera Sierras Pampeanas were not deformed. selective control favored by thermal weakening. As consequence SROP, crust thickened giving rise an extensional regime enhanced gradient. CB following tensional fractures. Thus, relationship subsequent explains localization Permian magmatism Frontal, deformed belts. Previous emplacement subducting active probably ended at same time no longer active. related subductive because when motion slab subducted stopped, it became thermally equilibrated, dehydration processes ceased, convective flow astenospheric wedge stopped. However, anomaly generated during process preserved even though subducing unimportant. Heating account motionless state lithosphere basic underplate melted base crust.