Evolution of the Danube Deep-Sea Fan since the Last Glacial Maximum: new insights into Black Sea water-level fluctuations

Constantinescu, Adriana Maria; Toucanne, Samuel; Dennielou, Bernard; Jorry, Stéphan; Mulder, Thierry; Lericolais, Gilles

doi:10.1016/j.margeo.2015.05.007

Cited by 42 publications

(19 citation statements)

References 77 publications

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“…We also computed the predicted BGHSZ for past conditions during the LGM period (Constantinescu et al, 2015). The sea level reached a low value down to −100/−150 m (Demirbağ et al, 1999;Winguth et al, 2000), and the seawater temperature at the seafloor was estimated to be 4°C by Soulet et al (2011).…”

Section: Base Of Gas Hydrate Stability Zone Modelingmentioning

confidence: 99%

Anomalously Deep BSR Related to a Transient State of the Gas Hydrate System in the Western Black Sea

Ker

Thomas

Riboulot

et al. 2019

Geochem Geophys Geosyst

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A comprehensive characterization of gas hydrate system offshore the western Black Sea was performed through an integrated analysis of geophysical data. We detected the bottom‐simulating reflector (BSR), which marks, in this area, the base of gas hydrate stability. The observed BSR depth does not fit the theoretical steady state base of gas hydrate stability zone (BGHSZ). We show that the disparity between the BSR and predicted BGHSZ is the result of a transient state of the hydrate system due to the ongoing reequilibrium since the Last Glacial Maximum. When gas hydrates are brought outside the stability zone due to changes in temperature and sea level, their dissociation generates an increase in interstitial pore pressure. This process is favorable to the recrystallization of gas hydrates and delays the upward migration of the hydrate stability zone explaining the anomalously deep BSR. The BSR depth, which is commonly used to derive geothermal gradient values by assuming steady state conditions, is used here to derive the maximum excess pore pressure at the BGHSZ. Derived excess pore pressure values of 1–2 MPa are probably the result of the low permeability of hydrate‐bearing sediments. Higher pore pressure values derived at the location of a fault system could cause hydrofracturing enabling the free gas to cross the gas hydrate stability zone and emerge at the seafloor, forming the flares observed in close vicinity to where the shallow gas hydrates were sampled.

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Section: Base Of Gas Hydrate Stability Zone Modelingmentioning

confidence: 99%

Anomalously Deep BSR Related to a Transient State of the Gas Hydrate System in the Western Black Sea

Ker

Thomas

Riboulot

et al. 2019

Geochem Geophys Geosyst

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“…If the tectonic subsidence is fast enough to maintain high sedimentation rates, sediment overspill may never occur, and the system remains balanced. The isolated nature of these balanced system often enhance their sensitivity to forcing factors (Müller et al, 2001;Abels et al, 2009Abels et al, , 2010Leroy et al, 2014;Litt and Anselmetti, 2014;Wagner et al, 2014;Constantinescu et al, 2015;Neubauer et al, 2016).…”

Section: Restricted Basins Form Unusual Depositional Environmentsmentioning

confidence: 99%

Sedimentary architecture and depositional controls of a Pliocene river-dominated delta in the semi-isolated Dacian Basin, Black Sea

Jorissen

Leeuw

Baak

et al. 2018

Sedimentary Geology

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Sedimentological facies models for (semi-)isolated basins are less well developed than those for marine environments, but are critical for our understanding of both present-day and ancient sediment records in restricted depositional environments. Our proposed facies model considers an 835m-thick sedimentary succession, accumulated in a semi-isolated brackish embayment of the mid-Pliocene Black Sea. We investigated the sedimentary processes and depositional controls responsible for the sedimentary architecture of a delta flowing into this semi-isolated basin. The deltaic progradation caused a regressing from distal shelf deposits with brackish-water faunas to proximal fluvial deposits with freshwater faunas. The observed facies architecture is typical for a river-dominated delta. The deltaic progradation into a restricted depositional environment probably resulted in the river domination and in a near-absence of sediment redistribution by wave-or tidal processes. The basin was filled with brackish-water, enhancing frequent hyperpycnal plumes, ichnofossils activity, enrichment in organic material and the preservation of in situ brackish-and freshwater faunas. The delta prograded into a shallow basin on a low-gradient slope, creating thin sharp based sand bodies in numerous thin parasequences, due to a multiplication of the terminal distributary channels, covering a wide depositional area. The parasequences are bounded by reddish oxidized shell-rich indurated flooding surfaces, formed by sediment starvation on the top of the abandoned delta lobes, due to frequent delta-lobe switching. As a result, a succession of 64 parasequences occurs, with a thinning from 15 to 95m from towards the top of the section. These high-frequency parasequences combine into nine low-order regressive sequences of around 83m and into three high-order regressive sequences of around 300m. A robust magnetostratigraphic time frame permitted to compare the observed sedimentary cyclicity with the amplitude and the frequency of various climatic cycles including astronomical forcing. Our results show that the frequencies of the parasequences and sequences are not in line with any Milankovitch climatic cycle. This suggests that astronomical climate forcing didn't influence autogenic delta-lobe switching.

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“…The timing and nature of lake/sea transition and associated rates of inundation have been a hotly debated topic (A. E. Constantinescu et al, 2015;Giosan et al, 2009;Hiscott et al, 2007;Lericolais, 2017;Ryan, 2007;Ryan et al, 2003;Turney and Brown, 2007;Yanchilina et al, 2017;Yanko-Hombach et al, 2007a;Yanko-Hombach, 2007). As (Yanchilina et al, 2017, p. 15) note, four differing hypothesis are currently offered:…”

Section: The Black Seamentioning

confidence: 99%

The next frontiers in research on submerged prehistoric sites and landscapes on the continental shelf

Sturt¹,

Flemming²,

Carabias³

et al. 2018

Proceedings of the Geologists' Association

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Submerged prehistory has emerged as a key topic within archaeology over the last decade. During this period the broader academic community has become aware of its potential for revolutionising our understanding of the past. With recent technological and scientific developments has come an opportunity to investigate larger areas and learn more than previously thought possible. When charting the future of the subject, however, it is also necessary to consider its historical trajectory. This sense of opportunity and optimism has been experienced before, but not sustained. As such, our greatest challenge lies not in adopting technological developments, but in maintaining momentum.

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Evolution of the Danube Deep-Sea Fan since the Last Glacial Maximum: new insights into Black Sea water-level fluctuations

Cited by 42 publications

References 77 publications

Anomalously Deep BSR Related to a Transient State of the Gas Hydrate System in the Western Black Sea

Anomalously Deep BSR Related to a Transient State of the Gas Hydrate System in the Western Black Sea

Sedimentary architecture and depositional controls of a Pliocene river-dominated delta in the semi-isolated Dacian Basin, Black Sea

The next frontiers in research on submerged prehistoric sites and landscapes on the continental shelf

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