OXIDE AND SULFIDE ASSOCIATIONS IN BASIC DYKES FROM TANDIL HILLS, BUENOS AIRES PROVINCE. ARGENTINA.

Authors

  • Horacio Echeveste
  • Raúl Fernandez

Keywords:

Oxides, Sulfides, Basic Dykes, Basement, Tandil,

Abstract

OS AIRES PROVINCE. ARGENTINA. The opaque mineral associations found in basic rock dykes in the vicinities of the city of Tandil makc tour groups. The main minerals of these groups arc: 1) Titanomagnetite-Ilmenite; 2) Ilmenite-Rutile-Pyrite; 3) Pyrrothite-Chalcopyrite-Co and Ni minerals; and 4) Ilmenite-Pyrrothite-Pentlandite. The dykes occur as intrusions in the crystalline basement 01' Northern Hills of the province 01' Buenos Aires, and the identified minerals form associations 01' an, in general, accessory character that lodge in diabases, titaniferous basalts, basaltic andesites and gabbroid, respectively. Microscopic studies and electronic microprobe determinations allow to state that the mineral associations, as well as the chemical composition 01' the studied species, represent different formation conditions and/or posthumous phenomena, which took part in the evoluLion 01' each rock type, resulting in definite paragenesis.

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