Sea water basalt interaction in spilites from the Iberian Pyrite Belt

✍ Scribed by J. Munhá; R. Kerrich

• Publisher: Springer
• Year: 1980
• Tongue: English
• Weight: 926 KB
• Volume: 73
• Category: Article
• ISSN: 0010-7999
• DOI: 10.1007/bf00371394

✦ Synopsis

Low grade hydrothermally metamorphosed mafic rocks from the Iberian Pyrite Belt are enriched in 1so relative to the oxygen isotopic ratio of fresh basalt (+ 6.5 _+ 1~

The observed 6180 whole rock values range from +10.87~ to +15.71~ corresponding to positive isotopic shifts of +5~ to + 10% o, thus requiring isotopic exchange with fluids under conditions of high water:rock ratios at low temperatures. The lowest 3180 observed corresponds to an albitized dolerite still and is compatible with independent geochemical data suggesting lower water: rock ratios for the alteration of these rocks.

The isotope data are consistent with the hypothesis that the spilites from the Pyrite Belt were produced by interaction of basaltic material with sea water.

Significant leaching of transition metals from the marie rocks during alteration coupled with available sulphur isotopic data for the sulphide ores also suggest that sea water may have played an important role in the formation of ore deposits in the Iberian Pyrite Belt.