Palaeoproductivity and post-depositional aerobic organic matter decay reflected by dinoflagellate cyst assemblages of the Eastern Mediterranean S1 sapropel

Several significant hydrocarbon accumulations were discovered over the past decade in the Levant Basin, Eastern Mediterranean Sea. Onshore studies have investigated potential source rock intervals to the east and south of the Levant Basin, whereas its offshore western margin is still relatively underexplored. Only a few cores were recovered from four boreholes offshore southern Cyprus by the Ocean Drilling Program (ODP) during the drilling campaign Leg 160 in 1995. These wells transect the Eratosthenes Seamount, a drowned bathymetric high, and recovered a thick sequence of both pre- and post-Messinian sedimentary rocks, containing mainly marine marls and shales. In this study, 122 core samples of Late Cretaceous to Messinian age were analyzed in order to identify organic-matter-rich intervals and to determine their depositional environment as well as their source rock potential and thermal maturity. Both Total Organic and Inorganic Carbon (TOC, TIC) analyses as well as Rock-Eval pyrolysis were firstly performed for the complete set of samples whereas Total Sulfur (TS) analysis was only carried out on samples containing significant amount of organic matter (>0.3 wt.% TOC). Based on the Rock-Eval results, eight samples were selected for organic petrographic investigations and twelve samples for analysis of major aliphatic hydrocarbon compounds. The organic content is highly variable in the analyzed samples (0–9.3 wt.%). TS/TOC as well as several biomarker ratios (e.g. Pr/Ph < 2) indicate a deposition under dysoxic conditions for the organic matter-rich sections, which were probably reached during sporadically active upwelling periods. Results prove potential oil prone Type II kerogen source rock intervals of fair to very good quality being present in Turonian to Coniacian (average: TOC = 0.93 wt.%, HI = 319 mg HC/g TOC) and in Bartonian to Priabonian (average: TOC = 4.8 wt.%, HI = 469 mg HC/g TOC) intervals. A precise determination of the actual source rock thickness is prevented by low core recovery rates for the respective intervals. All analyzed samples are immature to early mature. However, the presence of deeper buried, thermally mature source rocks and hydrocarbon migration is indicated by the observation of solid bitumen impregnation in one Upper Cretaceous and in one Lower Eocene sample.

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Αλλαγές στις θαλάσσιες βακτηριακές κοινότητες σε συνθήκες εμπλουτισμού με θρεπτικά

10.12681/eadd/40875 ◽

2014 ◽

Author(s):

Στυλιανός Φοδελιανάκης

Keyword(s):

Organic Matter ◽

Water Column ◽

Nutrient Enrichment ◽

Eastern Mediterranean ◽

Community Diversity ◽

Coastal Sediment ◽

Common Source ◽

Composition And Structure ◽

Taxonomic Groups ◽

Bacterioplankton Communities

Nutrient enrichment is a common source of disturbance for marineecosystems. A prerequisite for the prediction of the effects of nutrient enrichment atthe ecosystem level is the understanding of the ecological mechanisms governingbacterioplankton communities, due to their high affinity with nutrients. The aim ofthis thesis was to examine changes in the composition and structure ofbacterioplankton communities of the water column and coastal sediment undernutrient enrichment. Three studies were conducted for that purpose: two in closedexperimental conditions and one examining changes in situ. In the first two studies,changes in the water column bacterioplankton communities were examined after Paddition and in nutrient enriched habitats, respectively. In the third study, changes inthe communities of coastal sediment were examined with and without the additionof organic matter and aeration of the water column. The main conclusions from theresults of this thesis were:a) Bacterioplankton communities of the Eastern Mediterranean show a high degreeof resistance to short-term P addition, although their biomass and production islimited by P.b) Five abundant taxonomic groups showed a similar pattern of change across threedifferent nutrient enriched habitats. These groups could be potentially used asindicators for monitoring nutrient enrichment at the water column.c) After incubation under presence or absence of organic enrichment, sedimentbacterial communities originating from different habitats clustered based on theincubation conditions rather than on the area of origin. That occurred faster for twoout of the three areas, where the amount of organic matter in the sediment wasinitially higher and bacterial community diversity was lower. These results indirectlysupport the theory of Baas-Becking that "everything is everywhere but theenvironment selects" and the positive correlation between diversity and communitystability.

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Diagenetic control of nitrogen isotope ratios in Holocene sapropels and recent sediments from the Eastern Mediterranean Sea

Biogeosciences Discussions ◽

10.5194/bgd-7-1131-2010 ◽

2010 ◽

Vol 7 (1) ◽

pp. 1131-1165 ◽

Cited By ~ 5

Author(s):

J. Möbius ◽

N. Lahajnar ◽

K.-C. Emeis

Keyword(s):

Organic Matter ◽

Primary Production ◽

Surface Sediments ◽

Eastern Mediterranean ◽

Nitrogen Isotope ◽

Organic C ◽

Deep Waters ◽

Spatially Distributed ◽

Temporal And Spatial ◽

Recent Sediments

Abstract. The enhanced accumulation of organic matter in Eastern Mediterranean sapropels and their unusually depleted δ15N values have been attributed to either enhanced nutrient availability which led to elevated primary production and carbon sequestration or to enhanced organic matter preservation under anoxic conditions. In order to evaluate these two hypothesis we have determined Ba/Al ratios, amino acid composition, N and organic C concentrations and δ15N on sinking particles, surface sediments, eight spatially distributed core records of the youngest sapropel S1 (10-6 ka) and older sapropels (S5, S6) from two locations. These data suggest that (i) temporal and spatial variations in δ15N of sedimentary N are driven by different degrees of diagenesis at different sites rather than by changes in N-sources or primary productivity and (ii) that present day TOC export production would suffice to create a sapropel like S1 under conditions of deep-water anoxia. This implies that both enhanced TOC accumulation and δ15N depletion in sapropels were due to the absence of oxygen in deep waters. Thus preservation plays a major role for the accumulation of organic-rich sediments casting doubt the need of enhanced primary production for sapropel formation.

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Dinoflagellate cyst based modern analogue technique at test — A 300 year record from the Gulf of Taranto (Eastern Mediterranean)

Palaeogeography Palaeoclimatology Palaeoecology ◽

10.1016/j.palaeo.2016.02.045 ◽

2016 ◽

Vol 450 ◽

pp. 17-37 ◽

Cited By ~ 4

Author(s):

Karin A.F. Zonneveld ◽

Michael Siccha

Keyword(s):

Eastern Mediterranean ◽

Dinoflagellate Cyst ◽

Modern Analogue Technique ◽

Modern Analogue

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Meiofauna of the deep Eastern Mediterranean Sea: distribution and abundance in relation to bacterial biomass, organic matter composition and other environmental factors

Progress In Oceanography ◽

10.1016/0079-6611(96)00002-x ◽

1995 ◽

Vol 36 (4) ◽

pp. 329-341 ◽

Cited By ~ 69

Author(s):

Roberto Danovaro ◽

Norberto Della Croce ◽

Anastasios Eleftheriou ◽

Mauro Fabiano ◽

Nadia Papadopoulou ◽

...

Keyword(s):

Organic Matter ◽

Environmental Factors ◽

Mediterranean Sea ◽

Eastern Mediterranean ◽

Bacterial Biomass ◽

Eastern Mediterranean Sea ◽

Organic Matter Composition

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Dating the Lascaux Cave Gour Formation

Radiocarbon ◽

10.1017/s0033822200034603 ◽

2011 ◽

Vol 53 (3) ◽

pp. 479-500 ◽

Cited By ~ 11

Author(s):

D Genty ◽

S Konik ◽

H Valladas ◽

D Blamart ◽

J Hellstrom ◽

...

Keyword(s):

Organic Matter ◽

Eastern Mediterranean ◽

Seepage Water ◽

Calibration Data ◽

Atlantic Period ◽

Carbonate Deposit ◽

Cave Paintings ◽

Geomorphological Changes ◽

Lascaux Cave ◽

First Time

Lascaux Cave is renowned for its outstanding prehistoric paintings, strikingly well-preserved over about 18,000 yr. While stalagmites and stalactites are almost absent in the cave, there is an extensive calcite flowstone that covered a large part of the cave until its opening for tourists during the 1950s. The deposit comprises a succession of calcite rims, or “gours,” which allowed seepage water to pond in large areas in the cave. Their possible role in preservation of the cave paintings has often been evoked, but until now this deposit has not been studied in detail. Here, we present 24 new radiocarbon accelerator mass spectrometry (AMS) and 6 uranium-thorium (U-Th) analyses from the calcite of the gours, 4 AMS 14C dates from charcoals trapped in the calcite, and 4 AMS 14C analyses on organic matter extracted from the calcite. Combining the calibrated 14C ages obtained on charcoals and organic matter and U-Th ages from 14C analyses made on the carbonate, has allowed the calculation of the dead carbon proportion (dcp) of the carbonate deposits. The latter, used with the initial atmospheric 14C activities reconstructed with the new IntCal09 calibration data, allows high-resolution age estimation of the gour calcite samples and their growth rates. The carbonate deposit grew between 9530 and 6635 yr cal BP (for dcp = 10.7 ± 1.8%; 2 σ) or between 8518 and 5489 yr cal BP (for dcp = 20.5 ± 1.9%; 2 σ). This coincides with humid periods that can be related to the Atlantic period in Europe and to Sapropel 1 in the eastern Mediterranean Sea. However, geomorphological changes at the cave entrance might also have played a role in the gour development. In the 1940s, when humans entered the cave for the first time since its prehistoric occupation, the calcite gours had already been inactive for several thousand years.

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Photochemical production of ammonium in the oligotrophic Cyprus Gyre (Eastern Mediterranean)

Biogeosciences Discussions ◽

10.5194/bgd-3-449-2006 ◽

2006 ◽

Vol 3 (3) ◽

pp. 449-474

Author(s):

V. Kitidis ◽

G. Uher ◽

R. C. Upstill-Goddard ◽

R. F. C. Mantoura ◽

G. Spyres ◽

...

Keyword(s):

Organic Matter ◽

Dissolved Organic Matter ◽

Significant Contribution ◽

Eastern Mediterranean ◽

Light Attenuation ◽

Euphotic Zone ◽

Surface Mixed Layer ◽

New Production ◽

Light Absorbance ◽

Local Noon

Abstract. We investigated the photoproduction of ammonium (NH4+) in surface waters of the Cyprus gyre in the central Eastern Mediterranean in May 2002, in 8 on deck irradiations with freshly collected, filtered samples. NH4+ photoproduction (photoammonification) increased with time-integrated irradiance during the course of irradiations. Photoammonification rates around local noon were 0.4–2.9 nmol L−1 h−1. Normalised to time integrated irradiance, these rates were 0.9–3.8 pmol L−1 h−1/(W m−2) and were significantly correlated with Chromophoric Dissolved Organic Matter (CDOM) absorbance at 300 nm normalised to Dissolved Organic Carbon (DOC). These results are consistent with the notion that successive CDOM photobleaching in the surface mixed layer results in decreased DOC-normalised light absorbance concurrent with decreased dissolved organic matter reactivity with regard to photochemical NH4+ release. Combining our experimental data with estimates of annual solar irradiance and water column light attenuation yields an annual photoammonification rate for the Cyprus Gyre of 40±17 mmol m−2 a−1, equivalent to ~12±5% of the previously estimated annual nitrogen requirement of new production in this region. Based on this analysis, NH4+ photoproduction makes a small, but significant contribution to the nitrogen budget of the euphotic zone in the oligotrophic Cyprus Gyre.

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Photochemical production of ammonium in the oligotrophic Cyprus Gyre (Eastern Mediterranean)

Biogeosciences ◽

10.5194/bg-3-439-2006 ◽

2006 ◽

Vol 3 (4) ◽

pp. 439-449 ◽

Cited By ~ 18

Author(s):

V. Kitidis ◽

G. Uher ◽

R. C. Upstill-Goddard ◽

R. F. C. Mantoura ◽

G. Spyres ◽

...

Keyword(s):

Organic Matter ◽

Dissolved Organic Matter ◽

Eastern Mediterranean ◽

Light Attenuation ◽

Euphotic Zone ◽

N Deposition ◽

Surface Mixed Layer ◽

Atmospheric N Deposition ◽

New Production ◽

Order Of Magnitude

Abstract. We investigated the photoproduction of ammonium (NH4+) in surface waters of the Cyprus gyre in the central Eastern Mediterranean in May 2002, in 8 on deck irradiations with freshly collected, filtered samples. NH4+ photoproduction (photoammonification) increased with time-integrated irradiance during the course of irradiations. Photoammonification rates around local noon were 0.4–2.9 nmol L−1 h−1. Normalised to time integrated irradiance, these rates were 0.9–3.8 pmol L−1 h−1/(W m−2) and were significantly correlated with Chromophoric Dissolved Organic Matter (CDOM) absorbance at 300 nm normalised to Dissolved Organic Carbon (DOC). These results are consistent with the notion that successive CDOM photobleaching in the surface mixed layer results in decreased DOC-normalised light absorbance concurrent with decreased dissolved organic matter reactivity with regard to photochemical NH4+ release. Combining our experimental data with estimates of annual solar irradiance and water column light attenuation yields an annual photoammonification rate for the Cyprus Gyre of 40±17 mmol m−2 a−1, equivalent to ~12±5% of the previously estimated annual nitrogen requirement of new production and in the same order of magnitude as atmospheric N deposition in this region. Based on this analysis, NH4+ photoproduction makes a small, but significant contribution to the nitrogen budget of the euphotic zone in the oligotrophic Cyprus Gyre.

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Productivity patterns and N-fixation associated with Pliocene-Holocene sapropels: paleoceanographic and paleoecological significance

Biogeosciences ◽

10.5194/bg-8-415-2011 ◽

2011 ◽

Vol 8 (2) ◽

pp. 415-431 ◽

Cited By ~ 12

Author(s):

D. Gallego-Torres ◽

F. Martinez-Ruiz ◽

P. A. Meyers ◽

A. Paytan ◽

F. J. Jimenez-Espejo ◽

...

Keyword(s):

Organic Matter ◽

Primary Production ◽

Late Quaternary ◽

Eastern Mediterranean ◽

N Fixation ◽

Accumulation Rates ◽

Ecological Changes ◽

Bottom Waters ◽

Mass Accumulation Rates ◽

Mass Accumulation

Abstract. We have studied a suite of 35 sapropel sequences from a transect of four ODP sites across the Eastern Mediterranean to explore for paleoproductivity patterns and provide new insights on ecological changes during their deposition. Paleoproductivity variations were identified using TOC and Babio mass accumulation rates and δ15Ntotal and δ13Corg values. Elevated Ba/Al and TOC mass accumulation rates record periods of basin-wide amplified productivity. Our data further support that sapropels were formed by cyclic increases in primary production of marine organic matter largely sustained by N-fixing bacteria. This productivity increase was triggered by climate factors leading to increased fluvial discharge and amplified nutrient input that also favored the establishment of N-fixing bacteria. Enhanced productivity led to depletion of deepwater dissolved oxygen and consequently improved organic matter preservation. Primary production was more intense during the middle to Late Pleistocene compared to Pliocene equivalents, coinciding with increasing total sedimentation rates. δ15N values are dramatically lower in the sapropels than in TOC-poor background sediments, indicating a major contribution from nitrogen-fixing bacteria to the higher productivity during sapropel deposition. Additionally, different degrees of denitrification occurred as a consequence of water column oxygenation which in turns evolved from stagnant anoxic bottom waters during Pliocene sapropels to oxygen depleted and sluggish circulation in late Quaternary layers. These differences between sapropel layers provide new evidences for the general evolution of the Eastern Mediterranean basin during the last 3 Mys in terms of paleoceanographic conditions and the intensity of climate variability leading to sapropel deposition.

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