The chemistry of brines from an Alpine thrust system in the central Pyrenees: An application of fluid inclusion analysis to the study of fluid behaviour in orogenesis

Journal Article · Mon Apr 01 00:00:00 EST 1991 · Geochimica et Cosmochimica Acta; (USA)

DOI:https://doi.org/10.1016/0016-7037(91)90160-7· OSTI ID:5600047

Banks, D A; Davies, G R; Yardley, B W.D.; McCaig, A M; Grant, N T ^[1]

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1. Univ. of Leeds (England)

Quartz filled veins and fractures which formed late in the Alpine thrusting of the Central Pyrenees contain inclusions of hypersaline Na-Ca-Cl brines with total dissolved salts of up to 25 wt{percent}. The total salinity is similar in all samples, irrespective of the vein or the wall rocks, but there are large variations in the chemistry of the fluids between samples. With one exception, each sample contains only a single dominant fluid population. Crush-leach extraction and chemical analysis of the inclusion electrolytes for Na, K, Ca, Mg, Ba, B, Li, Sr, Rb, Fe, Mn, Zn, Pb, F, Cl, Br, and Sr and Pb isotopes reveals that the fluid chemistry is strongly influenced by the local rocks. Of the four different lithologies in the thrust stack sampled, the Triassic mudstones and Cretaceous limestones or Silurian phyllites acted as sources for the vein fluids during the late thrusting. The composition of the fluid in the veins was dependent on the proximity to these lithologies. The similarity of the Br/Cl ratio (approximately twice seawater) and the consistent high salinity of all the inclusion fluids in the thrust stack indicate that they were all originally derived from a single source but progressively changed their cation and isotope chemistry through interaction with different host rocks. This ultimate source is likely to have been Triassic connate waters. The authors conclude that a local increase in permeability occurred when the veins formed and that fluid movement was over short distances. No evidence was found for a significant input of either surface or metamorphic fluids during thrusting.

• OSTI ID: 5600047
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Vol. 55:4; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
BRINES
GEOCHEMISTRY
ROCK-FLUID INTERACTIONS
FRANCE
GEOLOGIC DEPOSITS
QUARTZ
CHEMICAL ANALYSIS
INCLUSIONS
SPAIN
BARIUM ISOTOPES
BORON ISOTOPES
BROMINE ISOTOPES
CALCIUM ISOTOPES
CARBONATE ROCKS
CHEMICAL COMPOSITION
CHLORINE ISOTOPES
CONNATE WATER
CRETACEOUS PERIOD
ELECTROLYTES
FLUORINE ISOTOPES
GEOLOGIC FAULTS
GEOLOGIC HISTORY
IONIC COMPOSITION
ISOTOPE RATIO
LEAD ISOTOPES
LITHIUM ISOTOPES
MAGNESIUM ISOTOPES
MANGANESE ISOTOPES
METAMORPHIC ROCKS
MOUNTAINS
ORIGIN
OROGENESIS
POTASSIUM ISOTOPES
RUBIDIUM ISOTOPES
SILURIAN PERIOD
SODIUM ISOTOPES
STRONTIUM ISOTOPES
TRIASSIC PERIOD
ZINC ISOTOPES
ALKALI METAL ISOTOPES
ALKALINE EARTH ISOTOPES
CHALCOGENIDES
CHEMISTRY
DEVELOPED COUNTRIES
DEVELOPING COUNTRIES
EUROPE
GEOLOGIC AGES
GEOLOGIC FRACTURES
GEOLOGIC STRUCTURES
GROUND WATER
HYDROGEN COMPOUNDS
INTERSTITIAL WATER
ISOTOPES
MESOZOIC ERA
MINERALS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PALEOZOIC ERA
ROCKS
SEDIMENTARY ROCKS
SILICON COMPOUNDS
SILICON OXIDES
WATER
580000* - Geosciences