Modes of sapropel formation in the eastern Mediterranean: some constraints based on pyrite properties

Passier, Hilde F.; Middelburg, Jack J.; Lange, Gert J. de; Böttcher, Michael E.

doi:10.1016/s0025-3227(98)00081-4

Cited by 98 publications

(70 citation statements)

References 47 publications

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“…That the bottom water was dysoxic or semi-euxinic during S1 formation has been deduced from, e.g. the trace metal, Fe and S geochemistry, abundances of benthic foraminifera, evidence for occasional bioturbation and preservation e⁄ciencies of C org in this sapropel (Passier et al, 1999c;Mercone et al, 2001;Slomp et al, 2002). There is a close linear relation between C org and water depth during sapropel S1, which has been explained as the result of a decrease in availability of oxygen in the water column with water depth (Murat and Got, 2000).…”

Section: Methodsmentioning

confidence: 99%

“…Assuming all organic matter remineralization took place by sulfate reduction, the burial e⁄ciencies of C org in the sapropels can be calculated from the integrated amounts of C org and S in the sediments, using appropriate values for sul¢de reoxidation (Passier et al, 1999c):…”

Section: Reconstruction Of the Sedimentary P Cycle During Sapropel Fomentioning

confidence: 99%

“…we assumed either a sul¢de reoxidation percentage of 80%, which is a maximum value for sapropel S1 (Passier et al, 1999c), or no sul¢de reoxidation. Due to the more abundant presence of oxygen, sul¢de reoxidation probably was more important (i.e.…”

Section: Reconstruction Of the Sedimentary P Cycle During Sapropel Fomentioning

confidence: 99%

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Controls on phosphorus regeneration and burial during formation of eastern Mediterranean sapropels

2004

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The carbon (C) and phosphorus (P) geochemistry of sapropels from four sites in the eastern Mediterranean Sea was determined to obtain more insight into the role of differences in sediment accumulation rates and bottom water anoxia on P regeneration and burial in sediments. Sediment C org /P org (with org = organic) ratios above Redfield indicate enhanced regeneration of P relative to C from organic matter during formation of the most recent sapropel S1 and a Pliocene sapropel (ODP-site 969E; i-282c). Release of P from Fe-oxides was relatively unimportant. Increased burial of Ca-P (authigenic carbonate fluorapatite and/or biogenic hydroxyapatite) occurred but was of minor importance compared to the enhanced P release from organic matter. For sapropel S1, C org /P org and C org /P reac , (with reac = reactive, defined as the sum of organic, Fe-bound, authigenic and biogenic Ca-P) ratios decreased with increasing sedimentation rate and oxygen exposure and decreasing water depth. Whether the water column in the deep basin was dysoxic/semi-euxinic (S1) or euxinic (Pliocene) does not appear to affect the estimated burial efficiencies of P org and P reac . Enhanced C org burial under the euxinic water column explains the much higher C org /P org and C org /P reac ratios in the Pliocene sapropel (on average V2860 and V760, respectively) compared to sapropel S1 (on average V530 and V160, respectively). ß

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Section: Methodsmentioning

confidence: 99%

Section: Reconstruction Of the Sedimentary P Cycle During Sapropel Fomentioning

confidence: 99%

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Controls on phosphorus regeneration and burial during formation of eastern Mediterranean sapropels

2004

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“…Cyclical deposition of interbedded organic-rich sapropels and organiclean marls in the eastern Mediterranean has been linked to orbital forcing of the African monsoon [30][31][32] , with water-column stratification and inhibited deep-water renewal contributing to OM enrichment in sapropel intervals 32,33 . Sediment lamination, elevated concentrations of redox-sensitive trace elements 28 , an abundance of framboidal pyrite 34 and the presence of isorenieretane 35 , a biomarker characteristic of photosynthetic green sulphur bacteria, indicate that the ODP Site 969 Pliocene sapropels investigated here were deposited under anoxic and periodically sulfidic conditions. BSE imaging shows that OM in the lower-most part of the sapropels occurs mainly as 5-15 mm organoclay aggregates and grains.…”

Section: Resultsmentioning

confidence: 78%

Micro-trace fossils reveal pervasive reworking of Pliocene sapropels by low-oxygen-adapted benthic meiofauna

Löhr

Kennedy

2015

Nat Commun

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Animal burrowers leave an indelible signature on the sedimentary record in most marine environments, with the seeming exception of low-oxygen environments. In modern sedimentary settings, however, sub-millimetre-sized benthic animals (meiofauna) are adapted to low oxygen and even sulfidic conditions. Almost nothing is known about their impact on ancient marine sediments because they leave few recognizable traces. Here we show, in classic Pliocene-aged anoxic facies from the Mediterranean, the first reported trace fossil evidence of meiofaunal activity and its relation to changing oxygenation. A novel approach utilizing electron imaging of ion-polished samples shows that meiofauna pervasively reworked sediment under oxygen-depleted conditions that excluded macrofauna, fragmenting organic laminae and emplacing 15-to 70-mm-diameter faecal pellets without macroscopically influencing the fabric. The extent of reworking raises the question: how pervasively altered are other sediments presently assumed to lack animal influence and how far into the geological record does this influence extend?

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“…Previous studies in the eastern Mediterranean have shown that the proportion of quartz decreases in the sapropelic sediments as a result of low wind strength during times of sapropel formation (Calvert and Fontugne, 2001). Pyrite is also a common mineral of the sapropel deposits in the sediments of Eastern Mediterranean as a result of microbial SO4 reduction and subsequent reaction of reduced S with Fe, mainly during the formation of the layer (Passier et al, 1999;Calvert and Fontugne, 2001). Aragonite is also related to the sapropel formation and possible mechanisms for its presence are considered the high growth of Florisphaera profunda, the detrital origin and the sulphate reduction, during the sapropel interval (Thomson et al, 2004).…”

Section: Discussionmentioning

confidence: 98%

Preliminary Studies on Sediment Core From the Tyro Basin

et al. 2017

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Modes of sapropel formation in the eastern Mediterranean: some constraints based on pyrite properties

Cited by 98 publications

References 47 publications

Controls on phosphorus regeneration and burial during formation of eastern Mediterranean sapropels

Controls on phosphorus regeneration and burial during formation of eastern Mediterranean sapropels

Micro-trace fossils reveal pervasive reworking of Pliocene sapropels by low-oxygen-adapted benthic meiofauna

Preliminary Studies on Sediment Core From the Tyro Basin

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