Origin of sulphur in minerals and fluids from Latium (Italy): isotopic constraints
Cavarretta, Giuseppe; Lombardi, Gianni
European Journal of Mineralogy Volume 4 Number 6 (1992), p. 1311 - 1330
published: Dec 15, 1992
manuscript accepted: Jan 17, 1992
manuscript received: Nov 23, 1990
ArtNo. ESP147050406011, Price: 29.00 €
Abstract Sulphur-bearing compounds from Latium are mainly Plio-Quaternary and occur in a variety of geological environments. Over 200 S isotope data (δ34S) are presented on a variety of mineral occurrences and aqueous species, both from the present work and from the literature. Results provide evidence of many successive phases of mineralization which occurred from depths of a few km to the surface. In the investigated area, the Messinian evaporites were involved in local phenomena. Triassic evaporites may have played an important role both in the subduction zone and at shallow depth. Anatectic and perpotassic magmas provided sulphur with δ34S higher than 0‰ to the mineralizing batches. On the basis of their isotopic characteristics and petrogenetic environment, four types of sulphide and five types of sulphates can be distinguished. Conditions are discussed under which equilibrium or disequilibrium reactions, chemical isotope fractionation and biological activity may have influenced the S isotope composition. For the overall volume of the mineralizations, the contribution of magmatic sulphur prevails over the sedimentary contribution. Isotope data suggest that mixing of "deep" and meteoric fluids may have occurred in the crust.