The region of Caçapava do Sul, in the State of Rio Grande do Sul, is characterized by the occurrence of a granite batholith (Granite Caçapava) that is surrounded by a belt of matamorphites belonging to the Porongos Group and attributed to the Upper Precambrian by RIBEIRO et alii (1966). Among the metamorphites there is a body of carbonate rocks of lenticular aspect, with clear contacts, interpenetrated by granitic apophyses and with outcrops of approximately 17 km 2 .
The study of metamorphism shows that these rocks were thermally affected by the Caçapava Granite and apófises, which is evidenced by the metamorphic zoning that goes from the facies pyroxene hornfels, in the vicinity of the contact, to the facies albite-epitope hornfels, in more distal positions.
The structure is generally isotropic, the preservation of the polymorph orthoclase, the contemporaneity of the granite and its nesting agents (Brasiliano Cycle) and considering that the nesting rocks belong to the schist facies (BITENCOURT, 1983), are facts that show the relatively shallow placement of Granite Caçapava and allow temperatures of the metamorphic apogee to be estimated at around 560 ° C.
The total pressure and fluid phase pressure were estimated in 1,000 baryons, a value compatible with the shallow (3 to 4 km) of the Caçapava Granite.
Analysis of these metamorphic rocks made based on diagrams T X - CO 2 for CaO-MgO-SiO system 2 -CO 2 -H 2 O, balance both showed parageneses as imbalance feature compatible with the nature of "granite magma Caçapava "that did not favor a homogeneous thermal distribution and of long duration.
