Sulfur isotope composition of orogenic spinel lherzolite massifs from Ariege (north-eastern pyrenees, France): An ion microprobe study

Journal Article · Mon Oct 01 04:00:00 EDT 1990 · Geochimica et Cosmochimica Acta; (USA)

DOI:https://doi.org/10.1016/0016-7037(90)90018-G· OSTI ID:6262118

Chaussidon, M ^[1]; Lorand, J ^[2]

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1. Centre de Recherches Petrographiques et Geochimiques, Vandoeuvre-les-Nancy (France)
2. Unite associee au CNRS, Paris (France)

The orogenic spinel lherzolite massifs from Ariege, which represent tectonically emplaced fragments of the sub-continental upper mantle, are composed mainly of variously depleted peridotites. These rocks are crosscut by two generations of pyroxenites. The first is made up of layered pyroxenites, which are interpreted either as crystal segregates from Triassic continental tholeiites or as subducted parts of the oceanic crust re-injected within the upper mantle. The second consists of amphibole-rich dikes separated from Cretaceous alkali basalts. Forty sulfide grains, occurring either as inclusions within silicates or as interstitial grains, were investigated by ion microprobe for their sulfur isotopic compositions. Comparison between sulfide inclusions in silicates and interstitial sulfide grains strongly suggests that serpentinization and pyrenean metamorphism had no significant effect don the {delta}{sup 34}S values. Likewise, these values are broadly independent of the degree of partial melting. The negative {delta}{sup 34}S values of the massive peridotites could represent an ancient depletion event in the upper mantle. By contrast, the positive {delta}{sup 34}S values observed in the layered pryoxenites and the amphibole-rich dikes indicate that the two parent magmas had in common a mantle source variously enriched in {sup 34}S. Therefore, the present study reveals two extreme reservoirs characterized by different {delta}{sup 34}S values in the upper mantle. This range of variations can explain most {delta}{sup 34}S values found in MORB, continental tholeiites, and alkali basalts.

• OSTI ID: 6262118
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Journal Name: Geochimica et Cosmochimica Acta; (USA) Vol. 54:10; ISSN GCACA; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
BASALT
CHEMICAL ANALYSIS
CHEMICAL COMPOSITION
CHEMISTRY
EARTH CRUST
EUROPE
FRANCE
GEOCHEMISTRY
GEOLOGIC HISTORY
IGNEOUS ROCKS
INCLUSIONS
ION MICROPROBE ANALYSIS
ISOTOPE RATIO
ISOTOPES
MICROANALYSIS
NONDESTRUCTIVE ANALYSIS
OCEANIC CRUST
PERIDOTITES
PETROCHEMISTRY
PETROGENESIS
PLUTONIC ROCKS
ROCKS
SULFUR ISOTOPES
VOLCANIC ROCKS
WESTERN EUROPE