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Titolo:
MINERALOGY AND PARENTAL BRINE EVOLUTION IN THE PEDRO DE VALDIVIA NITRATE DEPOSIT, ANTOFAGASTA, CHILE
Autore:
PUEYO JJ; CHONG G; VEGA M;
Indirizzi:
UNIV BARCELONA,FAC GEOL,ZONA UNIV PEDRALBES E-08028 BARCELONA SPAIN
Titolo Testata:
Revista geologica de Chile
fascicolo: 1, volume: 25, anno: 1998,
pagine: 3 - 15
SICI:
0716-0208(1998)25:1<3:MAPBEI>2.0.ZU;2-K
Fonte:
ISI
Lingua:
SPA
Keywords:
NITRATES; IODATES; SALINE MINERALS; BRINE EVOLUTION; PETROGRAPHY; NORTHERN CHILE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
15
Recensione:
Indirizzi per estratti:
Citazione:
J.J. Pueyo et al., "MINERALOGY AND PARENTAL BRINE EVOLUTION IN THE PEDRO DE VALDIVIA NITRATE DEPOSIT, ANTOFAGASTA, CHILE", Revista geologica de Chile, 25(1), 1998, pp. 3-15

Abstract

The Chilean nitrate deposits have been formed by a complex paragenesis of saline minerals that infill the porosity and open spaces of different country rocks. The study of the mineral infilling sequences in the rock porosities at the Pedro de Valdivia deposit has enabled to gaininformation about the evolution of the parental brines of the saline (nitrate bearing) paragenesis. This evolution is revealed by the precipitation of a sequence of progressively more soluble minerals: silicates (zeolites); calcite; Ca-, Na-, (K-) and Mg-sulphates; Na- and KMg-nitrate-sulphates; nitratine; and small amounts of iodates, Na- and KMg-iodate-sulphates, chromates, berates and perchlorates. Two specific trends have been distinguished in the general sequence. A Na- trend characterised by the association glauberite-darapskite-(hectorfloresite),and a KMg-Na- trend related to alite-humberstonite-niter-(fuenzalidaite).Parental brines of the deposit were related to the phreatic systemfrom which saline associations precipitate. Regional data drive the authors to consider as Oligocene-Miocene (but older that 6 Ma) the age of the mineralisation. The main physiographic features were similar tothe recent ones in this period, the climate being more humid. The genesis of the parental brines of the Chilean nitrate deposits is assumedto include thermal processes and recycling by leaching of previous salts formed in the arid environment of the Atacama Desert. Evaporation has also been involved in their genesis. It is the on ly mechanism effective enough to saturate the brines in very soluble minerals. Nevertheless, the nitrate ores cannot be considered as true evaporites owing to their arrangement infilling veins land porosities) and the almost complete absence of displacive growths las nodules or enterolithes) andother typical structures of evaporites.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 25/09/20 alle ore 07:04:38