Rama Norte Vein, Agua de Dionisio mining district, Farallón Negro, Belén Department, Catamarca Province, Argentinai

Regional Level Types
Rama Norte Vein	Vein
Agua de Dionisio mining district	Mining District
Farallón Negro	Municipality
Belén Department	Department
Catamarca Province	Province
Argentina	Country

MINERALOGIC STUDY OF HYDROTHERMAL ALTERATION OF WALL ROCK OF THE FARALLÓN NEGRO RAMA NORTE VEIN, CATAMARCA PROVINCE, ARGENTINA:
The Distrito Minero Agua de Dionisio is located in Belén department, Catamarca province, at 2.600 m.a.s.l. The stratigraphic sequence is conformed by low-grade metamorphic rocks, continental clastic sedimentites, rocks of Farallón Negro volcanic complex, sandstones and tuffites. A preliminary study of mineralogy, texture and alteration characteristics of the wall rock of Farallón Negro Rama Norte vein was completed. The Farallón Negro Rama Norte vein has banding texture, with alternance of Mn oxides and quartz-calcite fined bands. The wall rock is a medium-grained, hypidiomorphic monzonite. This rock is composed by potash feldspar, plagioclase, biotite, pyroxene, quartz, apatite, and opaque minerals. Based on study it was determined that the monzonite wall rock presents sericitic and propylitic hydrothermal alteration of moderate intensity.
Grain Farallón Negro North Branch is a branch of the Farallón Negro grain Already exploited. It has a thickness ranging from 0.5 to 3 m approximately, a general direction N 40 ° W and 65 ° N E approximate tilt. Is engaged in a monzonitic rock that forms the intrusive body of Alto La Blenda. It was determined on the basis of samples taken in surface and its observation with magnifying glass the grain has a dark grey color given by grain manganese oxides very fine and a banded texture that is manifested by the staggered provision of these minerals with carbonate and quartz, both of whitish color. They are very common drusics cavities. Contacts of the grain with the monzonite are net, and in general, found that veins are located in areas of failure. In terms of the monzonite is a light gray rock. Microscopically found a phaneritic of grain texture media, holocrystalline, hipidiomorphic einequigranular. It consists of potassium feldspar, plagioclase, biotite, pyroxene(diopside-augite), quartz, apatite and opaque minerals. Potassium feldspar occurs in large masses anhedral without Crystal twinning, with a poikilitic, including abundant texture tablets of plagioclase. Plagioclase crystals have form subhedral, Crystal twinning albite and an elongated prismatic habit. The biotite is found in the form of aggregates laminar, is partially altered to chlorite and epidote at its edges and in their cleavage planes. Pyroxenes have form anhedral, abundant inclusions of opaque with a cubic habit and their edges are corroded. The scarce presence was observed anhedral in crystalline Quartz. The apatite is an accessory mineral rare and occurs in the form of small rounded sub crystals. Minerals of this rock alterations are in order of abundance: sericite, chlorite, epidote, carbonates, quartz and clay minerals, being the sericite alteration mineral more frequent close contact with the grain. With respect to the style of alteration, a pervasive selective alteration, where the sericite is defined as a product of feldspars, while the epidote and chlorite alteration is they are replacing the biotite. Carbonate and quartz are generally associated, forming thin veins that cross the rock.

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