Interstitial Water Studies, Deep Sea Drilling Project, Leg 75

Gieskes, Joris M.; Johnston, K.; Boehm, M.; Nohara, Masato

doi:10.2973/dsdp.proc.75.128.1984

Cited by 3 publications

(3 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These observations, in conjunction with the fact that sulfate was present in interstitial waters (Gieskes et al, 1984;Prell, Niitsuma, et al, 1989) and that DOP is rarely higher than 0.5, suggest that only a fraction of organic matter, whether it be labile or not, is utilized during bacterial sulfate reduction in the diagenetic environment of marine upwelling sediments. Pyrite production in these sediments does not proceed to depletion of one of the components of the system, and sulfate reduction and H 2 S production appear to be limited by an as yet unknown process.…”

Section: Discussionmentioning

confidence: 94%

“…These intermediate DOP values indicate that Fe was probably not limiting for pyrite formation in these sediments. Also, the sulfate concentrations are high enough (4.9-31 mmol/L) to indicate that it was not a limiting factor for pyrite formation (Gieskes et al, 1984;Berner, 1985). Organic matter character from pyrolysis in Hole 532B clusters in an area that is characteristic of immature marine organic matter in a plot of the HI vs. OI (Fig.…”

Section: Site 532mentioning

confidence: 99%

See 1 more Smart Citation

Organic Carbon, Reduced Sulfur, and Iron in Miocene to Holocene Upwelling Sediments from the Oman and Benguela Upwelling Systems

Emeis¹,

Morse²,

Mays³

1991

Proceedings of the Ocean Drilling Program

View full text Add to dashboard Cite

We examined sediments from Neogene and Quaternary sections of the Benguela and Oman upwelling systems (DSDP Site 532, ODP Sites 723 and 722) to determine environmental and geochemical factors which control and limit pyrite formation in organic-carbon-rich marine sediments.Those samples from the upwelling sites, which contained low to moderate concentrations of total organic carbon (0.7%-3%), had C/S ratios typical of normal marine sediments, i.e., around 2.8. In these sediments, TOC availability probably limited pyrite formation. Results that do not conform with accepted models were found for the sediments high in TOC (3^0-12.4%). The organic matter was of marine origin and contained considerable pyrolytic hydrocarbons, a fact that we take as a sign of low degradation, yet significant concentrations of dissolved sulfate coexisted with it (> 5 mmol/L in the case of Sites 532 and 723). Detrital iron was probably not limiting in either case, because the degree of pyritization was always less than 0.65. Therefore, controls on sulfate reduction and pyrite formation in the organic matter-rich sediments do not appear to conform simply to generally accepted diagenetic models. The data from these thermally immature, old, and organic-rich marine sediments imply that (1) the total reduced sulfur content of organic-rich marine upwelling sediments rarely exceeds an approximate boundary of 1.5% by weight, (2) the C/S ratio of these sediments is not constant and usually much higher than the empirical values proposed for marine sediments. We conclude that sedimentary pyrite formation in upwelling sediments is limited by an as yet unknown factor, and that caution is advised in using C/S ratios and C vs. S diagrams in paleoenvironmental reconstructions for organic-rich sediments.

show abstract

Section: Discussionmentioning

confidence: 94%

Section: Site 532mentioning

confidence: 99%

Organic Carbon, Reduced Sulfur, and Iron in Miocene to Holocene Upwelling Sediments from the Oman and Benguela Upwelling Systems

Emeis¹,

Morse²,

Mays³

1991

Proceedings of the Ocean Drilling Program

View full text Add to dashboard Cite

show abstract

“…Bacterial sulfate reduction in burial depths of up to 100 m (e.g. Gieskes et al 1984) is responsible for decreasing Eh. Bright-luminescent cement is volumetrically much less abundant than preceding nonluminescent scalenohedral cement and succeeding ferroan, moderate-to dull-luminescent cement (Figs.…”

Section: Depth Ofprecipitation and Timingofstrong-ferroan Dull-luminmentioning

confidence: 99%

Calcite cement successions in Middle Devonian (Givetian) carbonate mud buildups of the southern Ahnet basin (Algerian Sahara)

Kaufmann

Wendt

2000

Carbonates Evaporites

View full text Add to dashboard Cite

In the Ahnet Basin of southernAlgeria, carbonate mud buildups were establishedin a deeper subtidal environmentduring Givetiantimes. The primarycavity system(irregularcavities,stromatactis) of thesebuildupsexhibitsa calcitecement succession precipitated in marine-phreatic to deep-burialenvironments.Cementationstartedin the marine environment. Cloudy,radiaxial-fibrouscalcites(RFCs)of originallyhighMg-calcitecomposition coat the walls ofthe cavitiesand occupy 50-80%ofthe pore space. The carbon-and oxygen-isotopic signatureof these cements correspondsto that of co-occurring, nonluminescentbrachiopodshells and to that of coevalRFCs from the Mader Basin of Morocco. Average valuesof 8 180 = -2.6 (± 0.4)%0 PDBand 8 13C = +2.6 (± 0.4)%0 PDB are assumedto representthe Givetianstable-isotopicseawatersignatureof theNorthwestAfricancarbonateprovince. The exceptionalhigh 8 180 values,comparedto MiddleDevoniandata ofNorth America,are interpretedto result from the mid-latitudinal (about 40 0 S), colder-water settings of the Northwest-African carbonate buildups. The 87Srj86Sr ratios of RFCs (0.70802±17)and nonluminescentbrachiopodshells (0.70780±3) fit well into establishedSr-isotopiccurves of Devonian seawater.Cementation in the shallow-burial realm is characterizedby a typical non-bright-dull cathodoluminescence sequence of nonluminescent scalenohedral cements (dog-tooth cements) with bright-luminescent outer margins overgrown by slight-ferroan, moderate-luminescent cements. Meteoric influenceon this cement sequencecan be excluded.Deep-burialcementationfollowinga ratherlongperiodofnon-cementation is representedbystrong-ferroan, dull-luminescentblockycements. Alternatively to pressure solution, outgassingof CO 2 by decreasingpore-fluidpressure caused by Variscan fracturingcan be consideredas carbonatesourcefor ferroancalciteprecipitationin the remainingpore space. Strong8 18 0 depletion(-10.6to -14.8%0 PDB) of thesecements point to the influenceof hydrothermalfluidsrather than to a pure depth-related temperaturecontrol. 8 13 C values show a trend from a nearly marinesignatureto more negativevalues(upto -9.0%0 PDB)which suggeststhe inputof methaneby hydrocarbonmigrationduringVariscan compression. More radiogenic8 7 Srj86Sr ratios(0.70826to 0.71684)with respectto the marine compositionare probably causedby the input of radiogenicstrontiumfrom K-feldspardissolutionand/or clay recrystallization from adjacent siliciclasticunits.

show abstract

Archaebacterial ether lipids: Natural tracers of biogeochemical processes

Pauly

Vleet

1986

Organic Geochemistry

View full text Add to dashboard Cite

Interstitial Water Studies, Deep Sea Drilling Project, Leg 75

Cited by 3 publications

References 6 publications

Organic Carbon, Reduced Sulfur, and Iron in Miocene to Holocene Upwelling Sediments from the Oman and Benguela Upwelling Systems

Organic Carbon, Reduced Sulfur, and Iron in Miocene to Holocene Upwelling Sediments from the Oman and Benguela Upwelling Systems

Calcite cement successions in Middle Devonian (Givetian) carbonate mud buildups of the southern Ahnet basin (Algerian Sahara)

Archaebacterial ether lipids: Natural tracers of biogeochemical processes

Contact Info

Product

Resources

About