Last glacial–Holocene paleoceanography of the Black Sea and Marmara Sea: stable isotopic, foraminiferal and coccolith evidence

Aksu, Ali E; Hiscott, Richard N.; Kaminski, Michael A.; Mudie, Petra J.; Gillespie, Helen; Abrajano, T.A.; Yaşar, Doğan

doi:10.1016/s0025-3227(02)00345-6

Cited by 153 publications

(78 citation statements)

References 51 publications

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“…Our suspicions are based on the occurrence of these form in core-top sediments with an abundance trend opposite to that of E. huxleyi and to Gephyrocapsa species (Aksu et al, 1995b, their Figs. 10 and 11) and to that of E. huxleyi (Aksu et al, 2002). Ziveri et al (2000a), observed a few overgrown specimens of Emiliania huxleyi in deep sediment trap samples (3000 m water depth) and more common specimens in core-top sediments with variable abundance at different sampling stations (their Fig.…”

Section: Are There Reticulofenestra Coccoliths In the Holocene -Late mentioning

confidence: 88%

“…(Aksu et al, 2002) respectively, are in part overgrown coccoliths of E. huxleyi and/or of Gephyrocapsa. Our suspicions are based on the occurrence of these form in core-top sediments with an abundance trend opposite to that of E. huxleyi and to Gephyrocapsa species (Aksu et al, 1995b, their Figs.…”

Section: Are There Reticulofenestra Coccoliths In the Holocene -Late mentioning

confidence: 99%

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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

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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

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Section: Are There Reticulofenestra Coccoliths In the Holocene -Late mentioning

confidence: 88%

Section: Are There Reticulofenestra Coccoliths In the Holocene -Late mentioning

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

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“…Furthermore, in order to characterise the exchanges between the Mediterranean-Marmara-Black Seas during the last 30 ka, in particular during the early Holocene, a multiproxy approach has documented outflow phases of the Black Sea (e.g. Aksu et al, 2002;Hiscott et al, 2002Hiscott et al, , 2006). …”

Section: Dinocysts In the Caspian Sea And Neighbouring Seasmentioning

confidence: 99%

River inflow and salinity changes in the Caspian Sea during the last 5500 years

Leroy

Marret

Gibert

et al. 2007

Quaternary Science Reviews

116

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Pollen, spores and dinoflagellate cysts have been analysed on three sediment cores (1.8 to 1.4 m-long) taken from the south and middle basins of the Caspian Sea. A chronology available for one of the cores is based on calibrated radiocarbon dates (ca 5.5-0.8 cal. ka BP). The pollen and spores assemblages indicate fluctuations between steppe and desert. In addition there are some outstanding zones with a bias introduced by strong river inflow. The dinocyst assemblages change between slightly brackish (abundance of Pyxidinopsis psilata and Spiniferites cruciformis) and more brackish (dominance of Impagidinium caspienense) conditions. During the second part of the Holocene, important flow modifications of the Uzboy River and the Volga River as well as salinity changes of the Caspian Sea, causing sea-level fluctuations, have been reconstructed. A major change is suggested at ca 4 cal. ka BP with the end of a high level phase in the south basin. Amongst other hypotheses, this could be caused by the end of a late and abundant flow of the Uzboy River (now defunct), carrying to the Caspian Sea either meltwater from higher latitudes or water from the Amu-Daria. A similar, later clear phase of water inflow has also been observed from 2.1 to 1.7 cal. ka BP in the south basin and probably also in the north of the middle basin.

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“…There fore, I as sumed that the BFOI proxy should be of po ten tial util ity for in ter pret ing the his tory of bottom wa ter ven ti la tion in the Marmara Sea. Aksu et al (2002a) cal cu lated BFOI val ues in sam ples col lected from a pis ton core from the south ern Marmara Shelf and showed that the Ho locene val ues of the in dex have been fairly con stant since the reflooding of the sea fol low ing the last deglaciation. In this piston core col lected at 111 m depth on the south ern Marmara Shelf the core-top BFOI value faith fully re pro duced the modern sea-floor dis solved ox y gen value mea sured at the same local ity, which strongly sug gested the proxy could be used to inter pret the Ho lo cene his tory of the Marmara Sea.…”

Section: Discussionmentioning

confidence: 97%

Calibration of the Benthic Foraminiferal Oxygen Index in the Marmara Sea

Kaminski¹

2012

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Ben thic foraminifera (to tal as sem blages) were stud ied from 30 sea-floor sam ples col lected along a bathymetric transect on the south ern shelf of the Marmara Sea from depths of 15-350 m. At each sta tion, Kaiho's Ben thic Foraminiferal Ox y gen In dex (BFOI) was cal cu lated based on spe cies abun dances us ing the meth ods out lined by Kaiho (1994). The cal cu lated BFOI val ues were con verted to an a logue ox ygen val ues, and cal i brated to the dis solved ox y gen val ues mea sured 1 m above the sea-floor at each sta tion. In the sur face wa ters and central part of the Marmara Shelf transect, the BFOI val ues re pro duce the mea sured dis solved ox y gen val ues with a re mark able de gree of ac cu racy. Be neath the pycnocline at depths of 30 to 75 m, the BFOI un der es ti mated the mea sured ox y gen val ues. This dis crep ancy is attrib uted to sea son ally higher sum mer ox y gen val ues within the chlo ro phyll max i mum, cor re spond ing to the po si tion of the Med i ter ranean In flow Wa ter (MIW) pres ent dur ing sum mer. In the deeper part of the transect (be low 140 m), BFOI val ues over es ti mated the mea sured ox y gen val ues. This dis crep ancy is at trib uted to the pres ence of denser MIW that cas cades down the sub ma rine can yon beneath the Marmara ship chan nel dur ing win ter, ven ti lat ing the deep Marmara Sea. The BFOI ac cu rately points out the sea sonal dif ferences in the po si tion and depth of the MIW in the south west ern Marmara Sea. The BFOI likely re flects the lon ger-term ox y gen val ues av er aged over the span of many years. Mi chael

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Last glacial–Holocene paleoceanography of the Black Sea and Marmara Sea: stable isotopic, foraminiferal and coccolith evidence

Cited by 153 publications

References 51 publications

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

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

River inflow and salinity changes in the Caspian Sea during the last 5500 years

Calibration of the Benthic Foraminiferal Oxygen Index in the Marmara Sea

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