GEOLOGY AND ISOTOPIC STUDIES OF SICILIAN SULFUR DEPOSITS
Stable isotopic studies of carbon and sulfur in correlation with geologic information have provided substantial evidence for a biogenic origin for native sulfur in salt domes. Similar studies on the Sicilian sulfur deposits indicate a biogenic syngenetic origin. Sulfur in Sicily occurs in a lagoonal evaporitic sequence of formations known as the Gypsum-Sulfur series of late Miocene age. The series, begins with the Diatomite formation that is overlain by the Basal limestone. Commercial quantities of sulfur occur in the next youngest formation known as the Sulfur limestone, the limestone of which is composed of white granular calcite. Alternating above the Sulfur limestone are the sulfurbarren Gypsum Beds formation and the Globigerina mail. The sigma S34 composition of the native sulfur in the sulfur limestone roughly varies between +l0 to --l0 permil, in contrast to differences between +20 to +30 permil for the sulfur in gypsum and anhydrite from which it is inferred the sulfur has been derived. These differences of a few permil to more than 20 permil are typical isotopic fractionations obtained during the reduction of sulfate to hydrogen sulfide by anaerobic bacteria. It is inferred that energy for the bacterial reduction was most likely provided by organic material that was oxidized by the bacteria to carbon dioxide which then reacted with calcium ions, made available by the reduced sulfate, to form calcite. This biological derivation of carbon dioxide, resulting in calcite in the Sulfur limestone, is suggested by sigma C/ sup 13/ variations between -20 to -30 permit for this formation, in contrast to typical sigma C/sup 13/ compositions of about -5 permil for carbonates in the other sulfur-barren formations. The almost complete lack of iron in the sediments that formed the sulfur limestone explains the lack of ferrous sulfide. Instead, it is inferred that the hydiogen sulfide was oxidized to native sulfur, in a suitable Eh environment having a limited supply of oxygen, by the expected exothermic reaction. It is, therefore, theorized that the Sicilian sedimentary sulfur deposits have a biogenic syngenetic origin. (auth)
- Research Organization:
- Yale Univ., New Haven; and Universita, Pisa, Italy
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-16-022418
- OSTI ID:
- 4827000
- Journal Information:
- Economic Geology and the Bulletin of the Society of Economic Geologists (U.S.), Vol. Vol: 57; Other Information: Orig. Receipt Date: 31-DEC-62
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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Related Subjects
BACTERIA
CALCITE
CALCIUM
CALCIUM CARBONATES
CARBON 13
CARBON DIOXIDE
CARBON ISOTOPES
CONFIGURATION
DEPOSITS
DISTRIBUTION
GEOCHEMISTRY
GEOLOGY
HYDROGEN SULFIDES
IRON SULFIDES
ITALY
LIMESTONE
MINERALS
ORGANIC COMPOUNDS
OXIDATION
QUANTITY RATIO
REDUCTION
SULFATES
SULFUR
SULFUR 34
SULFUR ISOTOPES