Degree of pyritization (DOP) as a paleoenvironmental indicator: Revisited

Conference · Wed Jan 01 04:00:00 EST 1992 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:5806744

Canfield, D E ^[1]; Raiswell, R ^[2]

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1. Georgia Inst. of Tech., Atlanta, GA (United States)
2. Leeds Univ. (United Kingdom)

The degree to which reactive'' iron minerals become pyritized (DOP) has proven to be a useful indicator of bottom water O[sub 2] conditions when applied to ancient sediments. The argument is that the lower bottom water O[sub 2], the greater the extent to which Fe becomes pyritized, and the greater DOP. Modern sediment studies suggest, however, that a direct correlation between bottom water O[sub 2] and DOP may not exist in all cases, and hence, that DOP may not be a universal indicator of bottom water O[sub 2]. The authors cite first the modern euxinic Black Sea whose sediment DOP's range from 0.2 to 0.8, with an average of 0.45. Most of these values fall outside of the accepted range for euxinic sediments. Next, they note that at the FOAM site in Long Island Sound, DOP is 0.43 at 10 cm depth and remains unchanged as sediment is buried to 3 meters, despite prolonged contact with high concentrations of sulfide. Factors other than bottom water O[sub 2] must be controlling DOP at FOAM. They suggest that DOP is controlled by the factors of sulfide exposure time and iron mineralogy. These factors are not necessarily constrained and their combined influence can cause nonsystematic variations of DOP with bottom water O[sub 2]. So, they argue that in the Black Sea, the wide range in DOP values reflect the rather constant sedimentation of a reactive'' iron phase, diluted to various extents by relatively unreactive iron. DOP in this case responds to the systematics of iron sedimentation rather than to bottom water O[sub 2]. At FOAM, the relatively unreactive HCL-extractable Fe found there reacts too slowly to causes changes in DOP with depth, despite continuous sulfide contact.

• OSTI ID: 5806744
• Report Number(s): CONF-921058--
• Conference Information: Journal Name: Geological Society of America, Abstracts with Programs; (United States) Journal Volume: 24:7
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
ATLANTIC OCEAN
BLACK SEA
CHALCOGENIDES
COMPARATIVE EVALUATIONS
DEPTH
DIMENSIONS
ECOLOGICAL CONCENTRATION
ELEMENTS
ESTUARIES
EVALUATION
IRON COMPOUNDS
LONG ISLAND SOUND
MINERALOGY
MINERALS
NONMETALS
OXYGEN
PALEOCLIMATOLOGY
PALEONTOLOGY
PYRITE
SEAS
SEDIMENTS
SULFIDE MINERALS
SULFIDES
SULFUR COMPOUNDS
SURFACE WATERS
TRANSITION ELEMENT COMPOUNDS