Active post-depositional oxidation of the most recent sapropel (S1) in sediments of the eastern Mediterranean Sea

Santvoort, P.J.M. van; Lange, Gert J. de; Thomson, J.; Cussen, Helen; Wilson, T.R.S.; Krom, Michael D.; Strohle, K

doi:10.1016/s0016-7037(96)00253-0

Cited by 213 publications

(149 citation statements)

References 39 publications

Supporting

Mentioning

129

Contrasting

Order By: Relevance

“…The Ba is in the form of biogenic barite and has been shown to be a reliable guide to the position of sapropels in which the initial high C org contents have been partly or completely removed by oxidation (Van Santvoort et al, 1996, 1997Langereis et al, 1997;Thomson et al, 1999). In core BC19, part of S1 is removed due to post-depositional downward oxidation (Van Santvoort et al, 1996;Slomp et al, 2002). The present-day redox front is located at the top of the visual sapropel and the Fe-oxide and Fe-bound P peaks are currently forming through precipitation of upward di¡using Fe 2þ and HPO 23 4 (porewater pro¢les in Slomp et al, 2002).…”

Section: Discussionmentioning

confidence: 99%

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

2004

View full text Add to dashboard Cite

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

show abstract

Section: Discussionmentioning

confidence: 99%

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

2004

View full text Add to dashboard Cite

show abstract

“…All cores from the Eastern Mediterranean recovered the Holocene sapropel S1, whereas cores from the Aegean Sea and Western Mediterranean contained no visual S1. The thickness of visual S1 and oxidised S1 (Van Santvoort et al, 1996;Thomson et al, 1999) …”

Section: Methodsmentioning

confidence: 99%

“…Moreover, within S1, we observed partial erosion and mechanical breakage of coccoliths (Plate II, figure 6) that together can be used as a proxy for coccolith dissolution (Ziveri et al, 1999a,b). The upper part of sapropel S1 has been subject to post-depositional downward oxidation that affected its original organic carbon and carbonate content (De Lange et al, 1989;Van Santvoort et al, 1996;Thomson et al, 1999;Mercone et al, 2000). However, the dark and oxidised portion of the sapropel is characterized by a similar abundance of the different LM morphotypes.…”

Section: Diagenetic History 451 Eastern Mediterraneanmentioning

confidence: 99%

Abnormal carbonate diagenesis in Holocene–late Pleistocene sapropel-associated sediments from the Eastern Mediterranean; evidence from Emiliania huxleyi coccolith morphology

Crudeli

Young

Erba

et al. 2004

Marine Micropaleontology

View full text Add to dashboard Cite

In studying the Holocene -late Pleistocene record of the Eastern Mediterranean, considerable Emiliania huxleyi size/shape variation not clearly assignable to primary or secondary calcification was observed. Accordingly, different morphotypes were distinguished by light microscope (LM).A subsequent scanning electron microscope (SEM) analysis of selected samples has indicated that Emiliania huxleyi coccoliths are variably affected by carbonate diagenesis in these sediments. A series of diagenetic stages were qualitatively defined, comprising well-preserved specimens, three overgrowth (OG1 to OG3) and one etching (E1) stage. Comparing SEM and LM observations, a tentative correlation between the E. huxleyi calcified LM-morphotypes and E. huxleyi SEM-overgrowth stages is proposed here.Our study not only indicates that Emiliania huxleyi coccoliths are strongly influenced by carbonate diagenesis, but also that they show effects of carbonate precipitation and dissolution much more clearly than other coccoliths. The relative abundances of the different LM-morphotypes were used to define an E. huxleyi overgrowth index (EXO) that qualitatively estimates carbonate precipitation/dissolution on coccoliths in this sediment. This resulted in definition of five ''Diagenetic'' intervals (D1 to D5). Deposition of sapropel S1 was a time of good preservation with variable dissolution and no overgrowth of E. huxleyi coccoliths, whereas calcite overgrowth was high during the Last Glacial Maximum (LGM) and interglacial period and, to a lesser extent, during the Younger Dryas and through the last 5 ka. D

show abstract

“…Nevertheless the Mn/Al profile shows a more articulated shape than the characteristic double peaks so far widely described (overview in Thomson et al, 1999). Van Santvoort et al (1996) already illustrated the importance of sampling resolution in order to detect early diagenetic signals. As a case study, they showed the different shape of the solid phase Mn profile at low (1 peak; from 1 to N2.5 cm resolution) and high high-resolution (0.5 cm) sampling (2 peaks) (boxcore BC 12, Eastern Mediterranean).…”

Section: Post-depositional Alteration Of Sapropel S1mentioning

confidence: 90%

“…Mn/Al peaks, and to a lesser extend the enrichment of Fe/Al observed in the oxidized sapropel, are linked to the downward penetration of the oxidation front (Van Santvoort et al, 1996), that led to postdepositional removal of organic matter, as evidenced in the uppermost part of the original sapropel. Nevertheless the Mn/Al profile shows a more articulated shape than the characteristic double peaks so far widely described (overview in Thomson et al, 1999).…”

Section: Post-depositional Alteration Of Sapropel S1mentioning

confidence: 97%

Geochemical evidence for high-resolution variations during deposition of the Holocene S1 sapropel on the Cretan Ridge, Eastern Mediterranean

Gennari

Tamburini

Ariztegui

et al. 2009

Palaeogeography, Palaeoclimatology, Palaeoecology

View full text Add to dashboard Cite

Major and minor element distributions and solid phase phosphorus contents were measured in a sediment core from the Cretan Ridge that contains the Holocene S1 sapropel. Micro-XRF ultra-high resolution analysis reveals multiple Mn peaks in the oxidized upper portion of the sapropel, which implies either a non-steadystate upward remobilization of Mn or not constant downward diffusion of bottom water oxygen. Sequential extraction allowed the identification of different phosphorus phases. Detrital phosphorus increases in the sapropel layer, suggesting enhanced delivery from land during sapropel deposition. Higher organic carbon to organic phosphorus ratios in the sapropel indicate enhanced regeneration of phosphorus relative to carbon under low-oxygen conditions. Fourier analysis on the ultra-high resolution XRF data reveals frequencies that are provisionally assigned to millennial to decennial solar cycles. Although these cycles have been reported from several continental and marine archives, they have never been documented from Sapropel S1 in the Eastern Mediterranean.

show abstract

Active post-depositional oxidation of the most recent sapropel (S1) in sediments of the eastern Mediterranean Sea

Cited by 213 publications

References 39 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

Abnormal carbonate diagenesis in Holocene–late Pleistocene sapropel-associated sediments from the Eastern Mediterranean; evidence from Emiliania huxleyi coccolith morphology

Geochemical evidence for high-resolution variations during deposition of the Holocene S1 sapropel on the Cretan Ridge, Eastern Mediterranean

Contact Info

Product

Resources

About