Article

Palaeogeographic environment during the desiccation of the Black Sea

September 1983
Palaeogeography Palaeoclimatology Palaeoecology 43(3-4):195-204

September 1983
43(3-4):195-204

Authors:

During the latest Chersonian (about 10.3 m.y. ago) tectonic movements took place leading to an elevation of the Crimean-Caucasian chain and to an isolation of the Fore-Caucasian part of the Black Sea Basin. This part of the basin had been draining the rivers of the Russian Platform and after the isolation it became desalinized, while the main part of the Black Sea Basin was almost desiccated and evaporites, mainly dolomites, formed in it due to the predominant calciummagnesiumcarbonate composition of the Chersonian Sea waters. These dolomites are found in the drillings of DSDP Leg 42B and are confirmed geophysically.The tectonic movements during the latest Chersonian led to the formation of a series of grabens along which the Mediterranean Sea invaded the north Aegean area and a little later (during the Early Maeotian) the Black Sea.

The end of the Great Khersonian Drying of Eurasia: Magnetostratigraphic dating of the Maeotian transgression in the Eastern Paratethys

Article

Full-text available

Jul 2018

Central Eurasia underwent significant paleoclimatic and paleogeographic transformations during the middle to late Miocene. The open marine ecosystems of the Langhian and Serravallian seas progressively collapsed and were replaced in the Tortonian by large endorheic lakes. These lakes experienced major fluctuations in water level, directly reflecting the paleoclimatic conditions of the region. An extreme lowstand of the Eastern Paratethys lake (‐300 m) during the regional Khersonian stage reveals a period of intensely dry conditions in Central Eurasia causing a fragmentation of the Paratethys region. This period of “Great Drying” ended by a climate change towards more humid conditions at the base of the Maeotian stage, resulting in a large transgressive event that reconnected most of the Paratethyan basins. The absence of a robust time frame for the Khersonian‐Maeotian interval hampers a direct correlation to the global records and complicates a thorough understanding of the underlying mechanisms. Here we present a new chronostratigraphic framework for the Khersonian and Maeotian deposits of the Dacian Basin of Romania, based on integrated magneto‐biostratigraphic studies on long and continuous sedimentary successions. We show the dry climate conditions in the Khersonian start at 8.6‐8.4 Ma. The Khersonian/Maeotian transition is dated at 7.65‐7.5 Ma, several million years younger than previous estimates. The Maeotian transgression occurs later (7.5‐7.4 Ma) in more marginal and shallower basins, in agreement with the time transgressive character of the flooding. In addition, we date a sudden water level drop of the Eastern Paratethys lake, the Intra‐Maeotian Event (IME), at 6.9 Ma, and hypothesize that this corresponds to a reconnection phase with the Aegean basin of the Mediterranean. Finally, we discuss the potential mechanisms explaining the particularities of the Maeotian transgression and conclude that the low salinity and the seemingly “marine influxes” most likely correspond to episodes of intrabasinal mixing in a gradual and pulsating transgressive setting. This article is protected by copyright. All rights reserved.

Paratethys response to the Messinian salinity crisis

Article

Jul 2017
EARTH-SCI REV

The Black Sea and Caspian Sea are the present-day remnants of a much larger epicontinental sea on the Eurasian continental interior, the Paratethys. During the late Miocene Messinian Salinity Crisis (MSC), a unique oceanographic event where 10% of the salt in the world's ocean got deposited in the deep desiccated basins of the Mediterranean, the Paratethys Sea was connected to the Mediterranean Sea. Unlike the Mediterranean, no salt is known to have been deposited in the Paratethys region at this time, yet a similar mechanism of deep desiccation (with a water level drop of up to 2 km occurring at 5.6 Ma) has been proposed in the past to explain the late Miocene and Pliocene Paratethys basin evolution.

The Tertiary stratigraphy and the Messinian erosional surface on the Black Sea western margins, high-resolution seismic stratigraphy

Thesis

Full-text available

Nov 2004

Gillet Herve

The Tertiary paleogeographic evolution of the Black Sea, within the paratethys realm, was characterised by several periodic isolation episodes. The eutatic responses of the Black Sea to these de-connexions, and especially those related to the Mediterranean Messinian crisis, are still not clearly established. The high resolution seismic stratigraphy study we present is based on interpretation of multichanel HR seismic data correlated with drillings recovered on the occidental Black Sea margin. Our investigations were concentrated on the identification of erosional surfaces, interpreted as markers of eustatic falls, linked to the basin isolation phases. On the Romano-Ukrainian shelf, the seismic profiles display six major discontinuities regarded as Tertiary erosional surfaces : (1) the surfaces underlined at the base of the Eocene (E), at the base of the Oligocene (O), in the Middle Miocene (M) and at the base of the Pontian (P); (2) and two intra-Pontian erosional unconformities (L.IPU and IPU). On the other hand, the Messinian erosional surface was clearly identified on the Bulgaro-Turckish margin. Recent correlation between the Paratethysian and Mediterranean stratigraphic scale suggest that the IPU surface recognised on the Romano-Ukrainian shelf is equivalent to the Messinian erosional surface. Among the five ante-Messinian erosional surfaces described, we interpret the M surface as the signature of a catastrophic sea level fall related to the Upper Burdigalian isolation phase. We propose that the four other surfaces correspond either to submarine erosion episodes, or to transgressive events. The discovery of the Messinian erosional surface in Black Sea constituting the major result of this study, enables to validate the assomption about the Messinian Dessiccation of the Black Sea [Hsü and Giovanoli, 1979].

Is the impact of the Messinian Salinity Crisis in the Black Sea comparable to that of the Mediterranean?

Article

Full-text available

Apr 2015

Erosional features have been observed along the Black Sea shelf in wells and on seismic reflection profiles that are broadly similar to the seismic stratigraphic signature of the Messinian Salinity Crisis (MSC) in the Mediterranean. In particular, the intra- (or Middle) Pontian unconformity has been suggested by some as the manifestation of the MSC in the Black Sea Basin. Missing strata and prominent lithological changes associated with the inferred MSC unconformity indicate erosional removal of parts of the underlying Cenozoic deposits in the shelf areas of the entire Black Sea. The magnitude of the relative sea level drop associated with this unconformity has been much debated, and ranges from tens of meters to thousands of meters.

Recurrent phases of drought in the upper Miocene of the Black Sea region

Article

Jan 2015
PALAEOGEOGR PALAEOCL

Late Oligocene and Miocene climate and vegetation in the Eastern Paratethys area (northeast Bulgaria), based on pollen data

Article

Nov 2007
PALAEOGEOGR PALAEOCL

The results of palynological studies of the Oligo-Miocene in the western part of the Euxinian Basin (Eastern Paratethys) are based on the analysis of 57 samples from core C-136A drilled near the town of Balchik, Varna district. Some samples were barren or contained very little pollen and were not included in the analysis. Quantitative data are thus confined to 26 polleniferous samples. We present results for the Upper Oligocene as well as the Tarkhanian, Karaganian, Bessarabian, and Chersonian stages of the middle to upper Miocene.Mixed deciduous forests were widespread during the time period studied. Swamp forests are also recorded, with distribution maxima observed in the Oligocene and in the Bessarabian. The widest extent of herbaceous vegetation is recorded in the late Bessarabian and Chersonian, when it occupied open landscapes after a marine regressional phase.The climatic data reconstructed by the Coexistence Approach indicate mean annual temperatures (MATs) of ca. 15–17 °C and mean annual precipitation (MAPs) of 800–1300 mm for the Upper Oligocene. The narrowest coexistence intervals of the Tarkhanian and Karaganian display MATs of 14–17 °C and MAPs of 800–1300 mm. The most substantial data are for the Bessarabian, in which the lower part is characterized by MATs of 15.6–16.6 °C and MAPs from 800–1200 (1300) mm. The results for the upper part of the Bessarabian are more variable, especially with respect to precipitation that is generally lower (700–800 mm). The same is true for the Chersonian, where besides lower precipitation, lower annual temperature and temperature of coldest month are observed. These results correlate with previous vegetation and palaeoclimate data from the Forecarpathian Basin (NW Bulgaria).

Miocene connectivity between the Central and Eastern Paratethys: Constraints from the western Dacian Basin

Article

Oct 2014
PALAEOGEOGR PALAEOCL

The Oligo-Miocene stratigraphy and the Messinian erosional surface in Black Sea, high-resolution seismic stratigraphy

Article

Full-text available

Oct 2003
CR GEOSCI

The stratigraphy of the Black Sea western margin is revisited through seismic data acquired during two French-Romanian surveys. These data are calibrated by industrial and DSDP drillings; they display several major discontinuities regarded as Tertiary erosional surfaces. The major seismic discontinuity underlines the base of Miocene formations and corresponds to a composite surface including at least three erosional phases ranging from Oligocene to Pontian times. Moreover, a Messinian erosional surface is clearly identified. This is in agreement with the Hsü's proposition [Palaeogeogr. Palaeoclimatol. Palaeoecol. 29 (1979) 75-93] suggesting a Messinian sea-level drop of Black Sea related to the Messinian Salinity Crisis described in the Mediterranean Sea. To cite this article: H. Gillet et al., C. R. Geoscience 335 (2003).

Holocene paleo?environment from the southwest Black Sea: a reconstruction based on dinoflagellate cysts and other palynomorphs

Article

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Holocene dinoflagellate cysts as salinity indicators from the southwestern Black Sea

Article

Full-text available

Messinian-Pontian Crisis in the Black Sea: Constraining the magnitude of sea level drop

Article

Full-text available

Apr 2009

It has been proposed that the Black Sea suffered a desiccation period during the Messinian Salinity Crisis (MSC) of the Mediterranean Sea. This is based on the finding of shallow water deposits at 2107 meter below current sea level, a regional erosional surface in seismic sections and on a Pontian low stand in the Dacic basin. If true, and if low stand persisted for longer than a couple of thousand years, the removal of the water column is expected to have evoked an isostatic/flexural response of the solid earth. We use flexural modelling to calculate this response of the solid earth and to constrain the magnitude of sea level drop and its impact on the connectivity with surrounding basins. To reproduce the observations, the sea level in the Black Sea should have dropped between 1730 and 2230 meter. The transitional position of the Aegean region between the Mediterranean and Black Sea and the presence of Miocene and Pliocene fauna suggest that this region acted as an intermediate basin linking both water masses. The large sea level drop during the MSC in the Mediterranean caused a similar isostatic/flexural response of the solid earth. Hence, the transitional position of the Aegean region means that flexural uplift in response to both sea level drops contributed to the strait connectivity: Govers et al., (2008) predicted an uplift between 100 and 200 meter in the Aegean region due sea level drop of the Mediterranean Sea and our results show an uplift between 1 and 50 meter of the southwestern margin of the Black Sea in response to the sea level drop in this basin. We speculate that the limited water depth of the Aegean region during the MSC and uplift due to one of the sea level drops resulted in the disconnection of the Mediterranean and Black Sea. This disconnection turned the Black Sea into an isolated basin in which the sea level is controlled by balance of evaporation, precipitation and river input which are in turn directly controlled by climate. We therefore propose that a change in climate, possible induced by the sea level drop in the Mediterranean, resulted in the installation of a negative water balance and desiccation of the Black Sea.

Opening History of the Eastern Black Sea From Wide-angle Seismic Refraction Data and Subsidence Analysis

Article

Dec 2006

To investigate the contribution of depth-dependent stretching to the formation of the eastern Black Sea, we examine this extensional basin using wide-angle seismic refraction data and subsidence analysis. Wide-angle seismic data can constrain variations in thinning within the crust, while subsidence analysis can extract information on thinning throughout the lithosphere. The eastern Black Sea is an ideal location for this study because it contains 8-10 km of sediments that record the Cenozoic subsidence history. In addition to providing generic insights into rifting processes, this study also provides new constraints on the controversial tectonic history of this region. New onshore-offshore wide-angle seismic refraction data were acquired in Feb.-March 2005 along four transects that survey thin crust in the center of the eastern basin, the mid-Black Sea High (a basement ridge that separates the eastern and western basins), Sinop Trough (a sub-basin south of the basin center), and the Turkish margin. Velocity models created by first arrival tomography (FAST) show that the crust thins abruptly from the margins into the center of the basin, from ~32-33 km to ~7-8 km over a lateral distance of only ~30 km, implying a stretching factor (beta) of ~4.5. Thin crust in the basin center is 7-9 km thick and has velocities consistent with either thinned continental crust or oceanic crust formed in a back-arc basin. We will present new velocity models created by joint reflection/refraction (JIVE) tomography that will provide further information on the affinity of crust in basin center and the structure of the margin. We have also analyzed the subsidence history using two strain rate inversion algorithms: 1) a model that assumes pure-shear extension, and 2) a model that allows extension to vary with depth without assuming the existence or form of depth-dependence. The results suggest that the stratigraphy of this basin can be explained by a predominantly pure-shear stretching history. The timing of opening has also been the subject of intense debate; our work indicates that extension likely continued into the early Cenozoic, as suggested by stratigraphic relationships and the timing of arc magmatism. The basin-wide pattern in stretching implied by our subsidence analysis suggests increasing extension to the east, which is consistent with the opening of the eastern Black Sea by the rotation of Shatsky Ridge away from the mid-Black Sea High. The beta derived from subsidence analysis (~4.8) is similar to that calculated from the crustal velocity model.

Birth, life and death of the Pannonian Lake

Article

Full-text available

Jul 1990
PALAEOGEOGR PALAEOCL

Miklos Kazmer

The Miocene-Pliocene Pannonian Lake formed in an extensional basin system behind the compressional arc of the Carpathians. Its size and depth were comparable to those of the Caspian Sea. Subsidence began in Middle Miocene times, forming deep, pelagic basins, separated by reef-bearing ridges. Clastic influx filled the marginal basins during Middle Miocene time. Prograding deltas dissected the lake and completed the infilling of the basin system by the end of the Pliocene. Basin plain, prodelta, delta front, delta plain, beach, fluviatile, and marsh environments can be recognized.

Cenozoic evolution of the eastern Black Sea: A test of depth-dependent stretching models

Article

Jan 2008
EARTH PLANET SC LETT

Subsidence analysis of the eastern Black Sea basin suggests that the stratigraphy of this deep, extensional basin can be explained by a predominantly pure-shear stretching history. A strain-rate inversion method that assumes pure-shear extension obtains good fits between observed and predicted stratigraphy. A relatively pure-shear strain distribution is also obtained when a strain-rate inversion algorithm is applied that allows extension to vary with depth without assuming its existence or form. The timing of opening of the eastern Black Sea, which occupied a back-arc position during the closure of the Tethys Ocean, has also been a subject of intense debate; competing theories called for basin opening during the Jurassic, Cretaceous or Paleocene/Eocene. Our work suggests that extension likely continued into the early Cenozoic, in agreement with stratigraphic relationships onshore and with estimates for the timing of arc magmatism. Further basin deepening also appears to have occurred in the last ∼ 20 myr. This anomalous subsidence event is focused in the northern part of the basin and reaches its peak at ∼ 15–10 Ma. We suggest that this comparatively localized shortening is associated with the northward movement of the Arabian plate. We also explore the effects of paleowater depth and elastic thickness on the results. These parameters are controversial, particularly for deep-water basins and margins, but their estimation is a necessary step in any analysis of the tectonic subsidence record stored in stratigraphy.

Organic petrology, mineralogy and depositional environment of the Kipra lignite seam, Maritza-West basin, Bulgaria

Article

Aug 2007
INT J COAL GEOL

The aim of the present study is to provide additional information about the properties and depositional environment of the Kipra lignite seam, which was deposited during the regressive stage of development of the Maritza-West basin. Petrographical and mineralogical data, along with ash yields and sulphur contents of 24 samples from a seam profile, have been used to study the vertical variation of the depositional settings during peat accumulation and subsequent coalification.The Kipra lignite is characterized by high ash yields and sulphur contents. It formed in a rheotrophic, low-lying mire with alkaline pH value. Vegetation with low preservation potential dominated within the palaeomire. During peat formation, frequent changes of the water level controlled the depositional environment. During the deposition of units 1 and 2, high water energy caused the transportation of high amounts of inorganic material into the mire, resulting in the formation of weakly gelified mineral-rich lignite. The organic matter from units 3 and 4 is characterized by enhanced gelification, which probably reflects the decreasing energy of the system. Good positive correlation between sulphur contents and the GI values was established in units 4, indicating that the gelification of the tissues was probably mainly controlled by the bacterial activity. In contrast, the gelification of the samples from unit 3 of the Kipra seam was probably governed by the redox conditions. The organic matter deposited under relatively wet conditions, in which the thermal and oxidative destruction of the tissues, was limited.A variety of major, minor and accessory minerals are present in Maritza-West lignite. The mineral composition is dominated mainly by pyrite, gypsum and calcite, and to a lesser extent limonite, quartz, kaolinite, montmorillonite, illite, chlorite and plagioclase. Jarosite, hematite, halloysite, mica, K-feldspar, aragonite, siderite, and dolomite were also determined in very low concentrations. These minerals formed syngenetically and epigenetically. The syngenetic stage is characterized mainly by the formation of pyrite, carbonates, silicates and sulphates, whereas the Fe-oxyhydroxides, partially the carbonates and almost all silicates are of detrital origin. During the epigenetic stage, carbonates, sulphates, clay minerals, pyrite, and Fe-oxyhydroxides were formed. Alteration products like gypsum, jarosite, limonite, chlorite, kaolinite, illite, mica, and calcite were generated due to the transformation of detrital and authigenic minerals.

Flexure due to the Messinian-Pontian sea level drop in the Black Sea

Article

Full-text available

Oct 2009
GEOCHEM GEOPHY GEOSY

Paleowater depth observations suggest that a large sea level drop occurred in the Black Sea coeval with the Messinian salinity crisis in the Mediterranean Sea. This sea level drop would have induced vertical motions of the solid earth, which influenced strait dynamics with major implications for the hydrological regime of the region. Using three-dimensional flexure models we find that a sea level drop between 1730 and 2230 m is required to reproduce the observed paleowater depths. The models predict that uplift reduced the seaway connectivity between the Black Sea and the Mediterranean Sea (Aegean region) and between the Black Sea and the Caspian Sea (Stavropol Highlands). The Miocene Paratethys Sea consequently became fragmented, and the remaining subseas likely became more sensitive to climate change. This agrees with the discovery of erosional surfaces in the Caspian Sea and in the Pannonian Basin. To explain the synchronicity of the sea level lowering in the Black Sea and the Mediterranean, we speculate that a regional shift toward a drier climate occurred in response to the Messinian salinity crisis in the Mediterranean, which led to a fall in sea level within the Black Sea.

Cetacean and hipparion fossils from the upper Miocene near General Marinovo Village, NW Bulgaria

Conference Paper

Full-text available

Dec 2023

The fossils of cetaceans are common in the Miocene marine deposits of North Bulgaria and along the Black Sea coast, however, they had received little attention until now. We report on abundant whale fossil material from the area near General Marinovo Village, NW Bulgaria. The finding of a hipparion tooth in the same area as the rest of the material implies a late Miocene age for the fossils. Taphonomical, XRD, and palaeohistological analyses reveal details about the pre-burial history and palaeobiology of part of the studied cetacean fossils.

Characterisation of ecological and conservational status of Common Wall Lizard (Podarcis muralis) in Vojvodina province, Serbia

Thesis

Full-text available

Jun 2021

Marko Mirč

This thesis provides description of the ecological niche space of the Common Wall Lizard (Podarcis muralis) in the Vojvodina region of Serbia with a detailed presentation of its distribution in the area. Additionally, a quantification of the developmental stability of the wall lizard in Vojvodina on an urbanization gradient is given. Finally, the ecological and conservational status of the species in the Vojvodina region is described. The species’ ecological niche space was analysed using the ENFA and MaxEnt modelling approaches, with ecogeographical variables derived from bioclimatic, atmospheric water regime, orographic, and land cover habitat variables. The obtained models were compared with models for peripanonian and mountainous Serbia since we believe the current distribution of the wall lizard in Vojvodina depends on ecological signals specifically present in the Vojvodina region but are absent in the two other ecogeographical regions of Serbia. Niche models for lizards in Vojvodina were significantly different from models for the peripanonian and mountainous regions of Serbia. The differences in ecological niche space were interpreted and related to the bionomy of the species. Ecological niche models revealed a wide distribution of the wall lizard across urban habitats of the Vojvodina region and a clear association with habitats of this type. Specifically, we identified a pattern of the close association of species’ presence with edge habitats of urban and industrial sites, and a general avoidance of agricultural habitats. In the other two regions, this signal was less pronounced with different habitat and orographic variables becoming more important. Overall, bionomic signals related to habitat structure were more important than scenopoetic signals related to abiotic conditions in defining the ecological space of this species in Serbia. Since urban habitats are generally believed to be stressful environments with numerous challenges to species’ overall fitness, we analyzed developmental stability of lizards across a gradient of urbanization to provide insight into the possible coping mechanisms of this species. Developmental stability was described by analyzing fluctuating asymmetry in qualitative characters of the pholidosis, as well as fluctuating asymmetry, allometry, modularity and integration of the pileus and frequency of phenodeviants in the pileus region of the lizard. Developmental stability results showed that urban and suburban lizard populations do not develop under more stressful conditions than populations from natural habitats, while they do have a more canalized developmental response. The wide distribution and a close connection to urbanized habitats with successful adaptation to new environments lead to the conclusion that the Common Wall Lizard should be considered as an indigenous species for the Vojvodina region, contrary to proposed qualifications.

Tephrochronology of a distal tonstein layer within the Maritsa East lignite basin, Bulgaria: Potential sources of the Miocene large explosive eruption

Article

Full-text available

Sep 2022
GEOL CARPATH

Late Miocene megalake regressions in Eurasia

Article

Full-text available

Jun 2021

The largest megalake in the geological record formed in Eurasia during the late Miocene, when the epicontinental Paratethys Sea became tectonically-trapped and disconnected from the global ocean. The megalake was characterized by several episodes of hydrological instability and partial desiccation, but the chronology, magnitude and impacts of these paleoenvironmental crises are poorly known. Our integrated stratigraphic study shows that the main desiccation episodes occurred between 9.75 and 7.65 million years ago. We identify four major regressions that correlate with aridification events, vegetation changes and faunal turnovers in large parts of Europe. Our paleogeographic reconstructions reveal that the Paratethys was profoundly transformed during regression episodes, losing ~ 1/3 of the water volume and ~ 70% of its surface during the most extreme events. The remaining water was stored in a central salt-lake and peripheral desalinated basins while vast regions (up to 1.75 million km ² ) became emergent land, suitable for development of forest-steppe landscapes. The partial megalake desiccations match with climate, food-web and landscape changes throughout Eurasia, although the exact triggers and mechanisms remain to be resolved.

IOP Conference Series: Earth and Environmental Science Concentration, distribution, and mode of occurrence of mercury in Bulgarian high-sulphur coals Concentration, distribution, and mode of occurrence of mercury in Bulgarian high-sulphur coals

Article

Full-text available

Dec 2020

The goal of this study is to determine the mercury content, distribution, and modes of occurrence in high-sulphur coals from the Maritza-West, Maritza-East, and Stanyantsi basins in Bulgaria. The investigation is based on 51 samples representing the whole coal beds. The average concentration of Hg for all studied samples is 0.34 ppm and the values vary from 0.07 to 1.20 ppm; the average is 6.8-times higher than the Hg value in the upper continental crust and 3.4-times higher than the average values for world coals. The highest average Hg concentration (0.57 ppm) was found in the Maritza-West samples, followed by the Maritza-East (0.30 ppm), and the Stanyantsi (0.15 ppm) lignite. These data correspond with the sulphur content, i.e, the highest-Hg lignite has the highest S content. A weak positive correlation between Hg and the total and sulphide S and a negative correlation between Hg and the organic S content for the Maritza-West lignite were observed. It is suggested that the Hg is predominantly incorporated in pyrite, which is present in high amount in these coals. The tendency in the distribution of Hg and S forms for the Maritza-East and Stanyantsi basins shows that Hg may be closely connected with S-bearing organic compounds, especially for the Maritza-East lignite. Consequently, the main part of Hg in the highS coals from the Maritza-East and Stanyantsi basins is closely connected with organic sulphur complexes and may be with inorganic matter other than sulphide minerals. The data determined from this study partially confirms the results for other highS world coals reported earlier. For the typical highS Maritza-West lignite it may be suggested that there is a strong connection between Hg and pyrite and especially with epigenetic pyrite infilling the coal veins and cleats, while for highS Maritza-East and Stanyantsi lignite the Hg is predominantly incorporated in organic matter and especially in sulphur-bearing organic compounds.

Changing seas in the late Miocene Northern Aegean: A Paratethyan approach to Mediterranean basin evolution

Article

Full-text available

Sep 2020
EARTH-SCI REV

The Northern Aegean region evolved during the Miocene as a restricted land-locked basin with small ephemeral connections to both the Eastern Paratethys (former Black Sea) and Mediterranean. Its biostratigraphic data show mixed Paratethys-Mediterranean components, but the Paratethys fauna has generally been neglected for chronologic reconstructions. Here, we review this biostratigraphic data from a Paratethyan perspective and present revised paleogeographic reconstructions of the Northern Aegean throughout the late Miocene. In the Tortonian, all sub-basins show mainly fluvio-deltaic terrestrial environments with a series of scattered lakes that are predominantly fed by local rivers and short-lived Paratethys connections. The first persisting marine conditions, still alternating with brackish Paratethyan environments, indicate a middle Messinian (late Maeotian) age (6.9–6.1 Ma), when the region formed a semi-isolated (Egemar) sea with multiple marine influxes. The termination of marine conditions is very well documented by a marked palaeoenvironmental change to the brackish water environments that correlate to the Maeotian/Pontian boundary (6.1 Ma) in Eastern Paratethys. During the Messinian Salinity crisis (5.97–5.33 Ma), the Northern Aegean was a brackish water system (Lake Egemar) that formed a passageway for Paratethyan overspill waters towards the Mediterranean. We conclude that the thick evaporites of the Northern Aegean domain do not reflect the classic Mediterranean MSC sequences, but are more likely related to older (Badenian or Maeotian) salinity incursions.

Implications for peat formation in Maritsa-West Basin, SE Bulgaria: Insights from organic petrology, palynology and biomarker assemblage

Article

Mar 2020
INT J COAL GEOL

The paper reports the results of the organic petrological, palynological and geochemical characterization of lignite samples from the Kipra lignite seam (Late Miocene, Maritsa-West Basin, Bulgaria). The bulk of the organic matter (OM) is represented by highly gelified detrohuminite with locally abundant leaf-derived ulminite. Liptinite group is characterized by predominance of microsporinite and liptodetrinite, locally with cutinite and fluorinite. Terpene resinite and suberinite are rare. Low TPI and high GI indices indicate peat formation from vegetation with low preservation potential, deposited under water-logged environment of marsh- or fen-type. The palynological results reveal a vegetational community representing different habitats (i.e. mesophytic, marginal and aquatic). The relatively poor preservation of the palynomorphs, however, suggests vegetation that was more diverse during peat formation. Although gymnosperm palynomorphs predominate, the gymnosperm organic matter contribution was probably minor as indicated by the low contents of sesqui- and diterpenoid biomarkers. Because of the absence of triterpenoid biomarkers of neither oleanane, nor lupane or ursane-type, it is considered that angiosperms that do not synthesize their precursors predominated, or the depositional environment had unfavorable characteristics, which prevented the transformation of the triterpenoid precursors. The extractable organic matter yield from the Kipra lignite is low, and dominated by saturated compounds, while polar compounds and asphaltenes occur in low amounts. Aromatic compounds are completely absent. The saturated hydrocarbons are mainly composed of n-alkanes, accompanied by minor amounts of branched- (including isoprenoids) and cycloalkanes, sesqui- and diterpenoids, steroids and hopanoids. Straight chain alkanes are prevailed by long-chain homologues, but show rather mature distribution with CPI ~ 1. Biological (e.g. bacterial) activities and/or environmental control are considered as the main factor/s controlling the observed uncommon n-alkane distributions. A rather uncommon pentacyclic terpenoid, i.e. onocerane I, was tentatively identified in one sample, based on its characteristic fragmentation pattern. Based on its presence, a very specific plant community is considered, and/or specific palaeoenvironmental conditions occurred at least temporarily during the peat formation. However, the responsible plants could not be identified. The low amounts of hopanoid biomarkers, together with the low amounts of n-alkanones, are consistent with limited aerobic biodegradation of the plant remains. The mature 22S/(22S + 22R) C30 hopane ratio (~ 0.55), as well as the random huminite reflectance values (~0.3–0.4%), which are more than twice higher than previously reported, argue for local a increase of coalification degree, presumably due to increased thermal influx around major faults.

Supplementary Material

Data

Full-text available

May 2019

Late Miocene stratigraphy, palaeoclimate and evolution of the Sandanski Basin (Bulgaria) and the chronology of the Pikermian faunal changes

Article

Aug 2018
GLOBAL PLANET CHANGE

We study the sedimentology, palaeontology and palaeomagnetism of the 500 m thick sedimentary sequence in the Gorna Sushitsa gorge in the Sandanski Basin (southwest Bulgaria), which is exceptionally rich in fossil mammals of Pikermian type. Magnetostratigraphy indicates that this section was deposited within 2 myrs, between 8.5 Ma and 6.5 Ma (late Tortonian to early Messinian). Our investigations reveal that the Sandanski Basin infill represents two stacking synrift phases (Delcevo and Kalimantsi formations), with an intervening tectonic quiescence package (Sandanski Formation). Kalimantsi Formation deposition ends with the cessation of slip on basin-bounding faults at 6.9 Ma, probably caused by a switch from regional E-W to N–S extension between 7 and 6.5 Ma. High slip rates compared to hanging wall sedimentation rates induced the development of mega-breccia dominated substantial fault scarps during the younger synrift phase (8.2 to 6.9 Ma). Tectonic changes are superimposed by several climatic changes. Moderately humid conditions prevail from 8.5–8.2 Ma, followed by relatively dry period from 8.2 to 7.8 Ma. A second humid interval from 7.74–7.56 Ma, which may be responsible for the Maeotian transgression in the Eastern Paratethys lake, is followed by a significant trend in local and supra-regional aridization, indicated by the onset of orbital driven aeolian dust deposition at 7.42 Ma. Our new data expand the Northern Mediterranean Sahara-born dust record at the Tortonian-Messinian transition to at least 600 kyrs (7.42 to 6.85–6.8 Ma). Coeval with the onset of dust deposition we observed evolutionary changes in the large mammal record, leading to the classical Pikermian association dated to between 7.42 and 7.27 Ma. We interpret faunal changes at the Tortonian-Messinian transition in the Eastern Mediterranean as driven by global cooling and mid-latitudinal desertification.

Early diagenetic greigite as an indicator of paleosalinity changes in the middle Miocene Paratethys Sea of central Europe

Article

Full-text available

Jul 2017
GEOCHEM GEOPHY GEOSY

The Miocene epicontinental Paratethys Sea of central Eurasia has experienced multiple restriction and reconnection events to the open ocean. Magnetostratigraphy is an important dating tool to better understand the temporal and spatial paleoenvironmental variations associated with these changes. Magnetostratigraphy in the Paratethys domain, however, is complicated by the presence of greigite (Fe3S4). Here, we report rock magnetic and X-ray fluorescence data of the Tisa section (Romania) which was previously magnetostratigraphically dated at the middle Miocene (base at 12.8 Ma and top at 12.2 Ma). This section comprises the Badenian Sarmatian Extinction Event (BSEE), which is marked by a major salinity change from marine to brackish environments, related to the opening of the connection between the Central and the Eastern Paratethys basins. In the marine Badenian sediments below the BSEE, the pyritization process is shown to be complete because of abundant sulfate supply. In the brackish Sarmatian deposits, four intervals with early diagenetic greigite are observed, and linked to insufficient sulfate in the water column. These four greigite intervals appear to correspond to maxima in the ∼100 kyr eccentricity cycle. We propose that increased fresh water from the Eastern Paratethys basin during eccentricity maxima restricted the sulfate availability in the Tisa area, leading to a reduced HS- production and enhanced greigite preservation. The early diagenetic formation of greigite enables a quasi syn-depositional recording of the paleomagnetic field, which allows reliable paleomagnetic dating in this section. Our results further suggest greigite as a potential indicator for salinity changes during marine/brackish transitions.

Why are there no Messinian evaporites in the Black Sea?

Article

Full-text available

Sep 2016

An unconformity has been observed along the Black Sea shelf on seismic reflection profiles and wells which is broadly similar to the one associated with that formed during the Messinian salinity crisis (MSC) in the Mediterranean. Therefore, this intra- (or Middle) Pontian unconformity has been traditionally interpreted as the manifestation of the MSC in the Black Sea Basin. However, the magnitude of the sea-level fall associated with this erosive surface does not appear to be nearly as significant as was assumed previously. Also, the inferred MSC surface itself cannot be easily followed into the palaeo-deepwater basin as a regional unconformity in the same manner as in the Mediterranean. Moreover, around the Black Sea, there is no evidence of major river incisions during the MSC, unlike the well-documented cases in the Mediterranean region. If the MSC evaporites in the Mediterranean indeed deposited in a subaerial setting at the basin floor, the lack of a major drawdown in the Black Sea explains why there are no Messinian evaporites in the Black Sea. Owing to the approximately 500 m MSC sea-level drop the Black Sea basin system, this basin did not even get close to the conditions required for the formation of evaporites in the basin centre. As the magnitude of the sea-level drop and the overall impact of the MSC in the Black Sea is interpreted to be less significant than in the Mediterranean, the risk of breaching pre-existing hydrocarbon traps during the MSC is less than has been suggested before. © 2016 The Author(s). Published by The Geological Society of London for GSL and EAGE. All rights reserved.

A Greigite-Based Magnetostratigraphic Time Frame for the Late Miocene to Recent DSDP Leg 42B Cores from the Black Sea

Article

Full-text available

May 2016

Throughout the Late Neogene, the Black Sea experienced large paleoenvironmental changes, switching between (anoxic) marine conditions when connected to the Mediterranean Sea and (oxic) freshwater conditions at times of isolation. We create a magnetostratigraphic time frame for three sites drilled during Deep Sea Drilling Project (DSDP) Leg 42B to the Black Sea (drilled in 1975). At the time, magnetostratigraphic dating was impossible because of the presence of the little understood iron sulfide mineral greigite (in sediments a precursor to pyrite) as magnetic carrier. Our rock-magnetic results indicate that only anoxic conditions result in poor magnetic signal, likely as a result of pyrite formation in the water column rather than in the sediment. The magnetostratigraphic results indicate that Hole 379A, drilled in the basin center, has a continuous sedimentary record dating back to 1.3 Ma. Hole 380/380A is subdivided into three consistent intervals, 0–700 mbsf, 700–860 mbsf, and 860–1075 mbsf. The top unit covers the Pleistocene but the magnetostratigraphy is likely compromised by the presence of mass transport deposits. The middle unit spans between 4.3 and 6.1 Ma and records continuous deposition at ~10 cm/kyr. The lower unit lacks the independent age constraints to correlate the obtained magnetostratigraphy. Hole 381 is drilled on the Bosporus slope and as a result, hiatuses are common. A correlation to the nearby Hole 380/380A is proposed, but indicates deposits cannot straightforwardly be traced across the slope. Our improved age model does not support the original interpretation based on these cores of a desiccation of the Black Sea during the Messinian salinity crisis.

Palaeontology of the upper Miocene vertebrate localities of Nikiti (Chalkidiki Peninsula, Macedonia, Greece). Synthesis

Article

Mar 2016

The study of the new and old collections of the Nikiti vertebrate localities included in this volume provides several new evidences for the taxonomy, composition, chronology and palaeoecology of these late Miocene mammal faunas. The faunal list of both primate bearing localities is enriched and improved by addition of new taxa and revision of older identifications; two new species are recognized in the Nikiti 2 (NIK) fauna (two hipparionine horses) and one subspecies from Nikiti 1 (NKT) is upgraded to the species level. The NKT and NIK faunas include 15 and 19 mammalian taxa, respectively. The mammalian faunas from both sites consist of almost the same families; the absence of some of them in NKT or NIK is most probably artificial. The chronology of the Nikiti mammal assemblages is based on biochronological data only, which allow the correlation of NKT to the terminal Vallesian (between 9.3 and 8.7 Ma) and that of NIK to the earliest Turolian (between 8.7 and 8.3 Ma). Concerning their age in relation with other neighboring mammal assemblages, NKT is younger than Ravin de la Pluie (Axios Valley, Greece) and isochronous or slightly older than Grebeniki (Ukraine). The NIK assemblage is older than Ravin des Zouaves 5 (Axios Valley) and Sivas (Turkey), dated at 8.2 Ma and 8.3 Ma, respectively. The available morphoecological, dental microwear-mesowear, and enamel isotopic analyses of the herbivores, as well as study of the phytolites suggest an open-light cover landscape for both localities. As documented previously in the Axios Valley, the Nikiti mammal fauna exhibits a significant reorganization through the Vallesian/Turolian boundary, including the Ouranopithecus/Mesopithecus replacement. However, this faunistic event is not consistent with the results of independent studies (isotope, dental wear, etc.) that fail to confirm significant climatic or vegetational changes across the same time interval.

Middle Miocene (Badenian) vegetation and climate dynamics in Bulgaria and Poland based on pollen data

Article

Feb 2016
PALAEOGEOGR PALAEOCL

The Miocene represents a time in Eurasia when evergreen and thermophilous dominated Paleogene vegetation was replaced by deciduous and temperate plants. Climatically, it is the transition from a greenhouse to an icehouse world, with the middle Miocene Climatic Optimum as the last warm episode of Earth history. Processes of plant evolution, transformation of vegetation and coenotic structure were significantly forced by both, changes in the global climate system, and also by significant palaeogeographic reorganizations. To give new insight in the middle Miocene evolution of European ecosystems and climate dynamics, we compared plant assemblages from northern Bulgaria and southern Poland (southern Paratethyan and Polish Lowlands realms).

Novel Polar Biomarkers of the Miocene Maritza-East Lignite, Bulgaria

Article

Mar 2016
ORG GEOCHEM

The present study provides further insight into the composition of polar compounds in the Miocene Maritza-East lignite, Bulgaria. Samples from two coal seams and interbedded claystone layers have been analyzed by geochemical proxies for polar constituents, consisting of n-alkan-2-ones, n-alkanols, n-alkanoic acids, polar sesqui-, di-, and triterpenoids, steroids, hopanoid acids, etc. These series are quantified, correlated vs. depth, and various ratios calculated. Polar diterpenoids predominate in the soluble organic matter. Several new compounds were identified, i.e. 7,11-dehydro-12-oxoabieta-7,9(11),13-triene, salvinolone, and chamaecydins. The preferential contribution of Cupressaceae/Taxodiaceae in the palaeoflora is confirmed by the significant abundance of polar diterpenoids (200-600 μg/g Corg), and is further supported by the presence of chamaecydins (3-9 μg/g Corg). The polar lupane assemblage attests that Betulaceae also was an important input from angiosperm vegetation to the palaeomire. The related new compounds are 24,25-bisnoroxyallobetula-1,3,5(10)-triene and 24,25-bisnorallobetula-1,3,5(10)-triene, which further support this point. This investigation increases the knowledge on floral progenitors and provides further proof of the input from the Cupressaceae/Taxodiaceae or Podocarpaceae families as the most abundant trees in the peat-forming environment of the Miocene Maritza-East Basin.

The Badenian–Sarmatian Extinction Event in the Carpathian foredeep basin of Romania: Paleogeographic changes in the Paratethys domain

Article

Oct 2015
GLOBAL PLANET CHANGE

The Badenian–Sarmatian boundary interval is marked by a major extinction event of marine species in the Central Paratethys. The exact age of the boundary is debated because many successions in marginal basins show erosional features and fauna reworking at the boundary level. Here, we selected the Tisa section in the Carpathian foredeep basin of Romania, which is continuous across this Badenian–Sarmatian Extinction Event (BSEE). Quantitative biostratigraphic records of planktic and benthic foraminifera and calcareous nannofossils allow to accurately locate the Badenian–Sarmatian boundary and indicate a major paleoenvironmental change from open marine to brackish water conditions. Magnetostratigraphic results reveal a polarity pattern that uniquely correlates to the time interval between 12.8 and 12.2 Ma. Interpolation of constant sedimentation rates determines the age of the BSEE in the Carpathian foredeep at 12.65 ± 0.01 Ma, in good agreement with several earlier estimates. We conclude that the extinction event took place in less than 10 kyr, and that it was most likely synchronous across the Central Paratethys. It corresponds to a major paleogeographic change in basin connectivity with the Eastern Paratethys, during which the nature of the Barlad gateway switched from a passive to a full connection.

Catastrophic Flooding of the Black Sea

Article

Full-text available

May 2003

William Ryan

Decades of seabed mapping, reflection profiling, and seabed sampling reveal that throughout the past two million years the Black Sea was predominantly a freshwater lake interrupted only briefly by saltwater invasions coincident with global sea level highstand. When the exterior ocean lay below the relatively shallow sill of the Bosporus outlet, the Black Sea operated in two modes. As in the neighboring Caspian Sea, a cold climate mode corresponded with an expanded lake and a warm climate mode with a shrunken lake. Thus, during much of the cold glacial Quaternary, the expanded Black Sea's lake spilled into to the Marmara Sea and from there to the Mediterranean. However, in the warm climate mode, after receiving a vast volume of ice sheet meltwater, the shoreline of the shrinking lake contracted to the outer shelf and on a few occasions even beyond the shelf edge. If the confluence of a falling interior lake and a rising global ocean persisted to the moment when the rising ocean penetrated across the dividing sill, it would set the stage for catastrophic flooding. Although recently challenged, the flood hypothesis for the connecting event best fits the full set of observations.

Paleogeographic evolution of the Late Miocene Lake Pannon in Central Europe

Article

Mar 1999
PALAEOGEOGR PALAEOCL

The paleogeographic evolution of Lake Pannon within the Pannonian basin is reconstructed with eight maps, ranging from the Middle Miocene to the Early Pliocene. The maps are based on the distribution of selected biozones and specific fossils, and on complementary sedimentological and seismic information. Our reconstruction shows that the history of Lake Pannon can be divided into three distinct intervals: an initial stage with low water level, which resulted in isolation from the sea at about 12 Ma and might have led to temporary fragmentation of the lake; an interval of gradual transgression lasting until ca. 9.5 Ma; and a long late interval of shrinkage and infilling of sediments that persisted into the Early Pliocene. The deep subbasins of the lake formed during the transgressive interval, in more basinward locations than the deep basins of the preceding Sarmatian age. The southern shoreline, running parallel with the Sava and Danube rivers along the northern foot of the Dinarides, changed very little during the lifetime of the lake, while the northern shoreline underwent profound changes.

PALAEOENVIRONMENT AND ARCHAEOLOGY: THE USE OF DIATOM ANALYSIS IN ARCHAEOLOGY

Article

Full-text available

Jan 2008

Nadja Ognjanova-Rumenova

Diatoms are being used increasingly to assess short- and long-term environmental change, because they are informative, versatile, flexible, and powerful ecological indicators. Diatoms respond rapidly to changes in many ecological characteristics. The assemblages are usually diverse and therefore contain considerable ecological information. For this reason, and because it is easy to obtain large numbers of individuals, robust statistical and multivariate procedures can be used to analyze assemblage data. Methods for collecting, analyzing, and presenting data have advanced rapidly in the past 10 years.

Miocene vegetation and climate dynamics in Eastern and Central Paratethys (Southeastern Europe)

Article

May 2011
PALAEOGEOGR PALAEOCL

Influence of floral assemblage, facies and diagenesis on petrography and organic geochemistry of the Eocene Bourgas coal and the Miocene Maritza-East lignite (Bulgaria)

Article

Nov 2005
ORG GEOCHEM

Numerous differences in the petrography and organic geochemistry of two Tertiary, low rank coal deposits of Bulgaria, formed within comparable depositional environments, are outlined. Different floral assemblages are indicated as the main sources of organic matter. For the Eocene Bourgas sub-bituminous coals a warm climate plant community dominated by angiosperms is reflected in the biomarker composition, whereas a coniferous flora was the main source of the resinous organic matter of the Miocene Maritza-East lignite. The results are in agreement with palaeobotanical data. These differences in the peat forming vegetation of the Paleogene compared to the Neogene of Bulgaria are attributed to decreasing temperature during the Tertiary. The abundance of resinous compounds relative to lipids from plant waxes (long chain n-alkanes), as well as the preservation of plant tissue, are mainly controlled by gymnosperm/angiosperm ratios.Pristane/phytane and diasterenes/sterenes ratios reflect variations in redox conditions and the pH of the depositional environments, caused by eustatic sea level changes, freshwater inflow, or varying (ground)water table. Changing Eh and pH values are associated with differences in microbial activity controlling the extent of gelification of plant tissue. Bacteria most probably contributed to the aromatisation of triterpenoids in the mire.Enhanced thermal maturation of organic matter during diagenesis is reflected in higher contents of n-alkanes and the presence of alkyl naphthalenes in the Bourgas coals. Alkyl naphthalenes are thought to have been formed from pentacyclic triterpenoids rather than from resinous compounds.

Stratigraphic evolution of the Black Sea: inferences from basin modelling

Article

Dec 1995
MAR PETROL GEOL

A modelling simulation of the syn-rift and post-rift stratigraphies and subsidence history of the Western and Eastern Black Sea basins is described. The model uses the initial lithospheric conditions and rifting parameters (thinning factors, effective elastic thickness and depth of necking) derived by large-scale lithospheric deformation modelling. Using a stratigraphic modelling approach, supported by a large and high-quality data set, constraints on the palaeo-water depth evolution of the basin and associated basement subsidence are provided. The model reproduces and provides explanations for several features of the stratigraphy of the Black Sea: the apparent near-absence of syn-rift strata (other than in the Western Pontides); thin to condensed early post-rift sequences in both basins; a thick Upper Eocene sequence in the Eastern Black Sea; a relatively thin Oligocene to Miocene sequence and a very thick Quaternary sequence. It also predicts the geometry and depth of the lake that developed in the centre of the Black Sea when the sea level fell by 1500 m during the Late Miocene.

Late Miocene-Quaternary sedimentary environment evolution of the Kerch seep area, Black Sea

Article

Jun 2022
MAR GEOL

A set of 2D high resolution seismic lines was acquired near the Kerch Peninsula during R/V Meteor Cruise M72/3 in March/April 2007 to the Eastern Black Sea. The high resolution seismic data were used for analysis of seismic facies and seismic sequences to gain insight into the sedimentary evolution of the study area. Seven seismic facies types were identified and six seismic units could be mapped. Based on seismic line interpretation, isopach and seismic facies distribution maps, a chronostratigraphic framework could be established for the study area. The study reveals that the sediment deposits were influenced by syndepositional tectonic movements, sea level and climate. During the late Miocene and the early Pliocene, possible slope fan deposits developed. At the boundary between the Miocene and Pliocene, the Messinian erosional truncation surface was observed. After the Messinian sea level fall, accompanied by a major transgressional phase during the Pliocene, the Paleo-Don and Kuban Rivers delivered a large terrigenous input to the Black Sea from the uplifted Crimean Mountains. This formed thick submarine fan deposits near the mouth of Kerch Strait during the late Pliocene. Facies variations within the seismic units are related to the sea-level and climate curves, and are reflected by grain size variations in the sediments and the shift of the river mouth. During the Quaternary, hemipelagic sediments interbedded with coarse-grained fluvial sediments developed in the study area, along with slumps, river channels and fan deposits.

A Late Maeotian age (6.7–6.3 Ma) for the enigmatic “Pebbly Breccia” unit in DSDP Hole 380A of the Black Sea

Article

Jul 2019
PALAEOGEOGR PALAEOCL

Various hypotheses exist on the age and origin of the so-called “Pebbly Breccia” unit in the deep-sea record of DSDP Hole 380A of the Euxinian (Black Sea) Basin. Here, we present a detailed study of diatom and nannofossil assemblages of Hole 380A. Our diatom records show a characteristic sequence of appearance of markers species, which we can correlate to the recently established bio-magnetostratigraphic time frame of the Zheleznyi Rog section on the Black Sea coast of the Taman Peninsula (Russia). It shows that the Pebbly Breccia is sandwiched between Upper Maeotian deposits, and must have been deposited at an age between 6.7 and 6.3 Ma. The appearance of nannoplankton and the marine diatom association at above the Pebbly breccia (Unit IVc) suggests a short-term incursion of marine conditions. The age of Unit IVc, based on diatom data, is 6.3-6.1 Ma. The nannoplankton record is mainly represented by species that do not have stratigraphic value. The previously reported presence of Ceratolithus acutus in the Black Sea is explained by misinterpretation of destructed elements of ascidian spicules. We conclude that the Pebbly Breccia is not related to a desiccated Black Sea at Messinian Salinity Crisis times, but it corresponds to a late Maeotian episode of gravitational instability in the SW Black Sea region.

Sedimention and Plate Tectonics

Chapter

Jan 2000

Andrew D. Miall

Until the 1960s, sedimentary basins were explained and categorized in terms of geosyncline theory (Dott 1974, 1978; Mitchell and Reading 1978). Such classic books as those by Kay (1951), Krumbein and Sloss (1963), and Aubouin (1965) had a profound impact on geologists and formed the basis for all large-scale interpretations. However, we can now see that these and other studies, although meticulously descriptive, could not ultimately explain why or how most basins formed or why there were recurrent structural styles or lithofacies assemblages. Beginning with the development of plate tectonics in the 1960s, much has now become clear. The kinematics of modern plate movements have been documented in some detail and have provided geologists and geophysicists with a reliable data bank from which to build and constrain models of deep-lithospheric behavior. Beginning with the basin models of McKenzie, Beaumont, and others in the late 1970s (Chap. 7), our understanding of crustal and mantle processes has led to the development of the science of geodynamics, by which surface tectonic processes and events may be related to processes deep in the earth’s interior.

Sedimentation and plate tectonics

Chapter

Jan 1990

Andrew D. Miall

Until the nineteen sixties sedimentary basins were explained and categorized in terms of geosynclinal theory (Dott, 1974, 1978; Mitchell and Reading, 1978). Such classic books as those by Kay (1951), Krumbein and Sloss (1963) and Aubouin (1965) had a profound impact on geologists and formed the basis for all large-scale interpretations. However, we can now see that these and other studies, although meticulously descriptive, could not ultimately explain why or how most basins formed or why there were recurrent structural styles or lithofacies assemblages. With the development of plate tectonics much has become clear. The kinematics of modern plate movements have been documented in some detail, and have provided geologists and geophysicists with a reliable data bank from which to build and constrain models of deep crustal behavior. Most sedimentary basins can now be explained in terms of plate margin or plate interior processes, and their structure and stratigraphy have become more comprehensible. This has led to the growth, in the last ten years, of a brand new terminology for types of basin. For miogeosyncline we now have divergent margin basin, for exogeosyncline we have retroarc basin, and so on. In fact, it is recommended that the old terminology be entirely abandoned. Such terms as eugeosyncline and geanticline now serve only to confuse, because we can study many features so described and recognize that these terms fail to distinguish between several subtly, but importantly, different types of plate setting. Other general terms, including intermontane basin and successor basin, are also so imprecise as to be of little value. The papers by Dickinson (1974) and Bally and Snelson (1980) provide the best general basin descriptions and classifications using this new terminology. They are referred to extensively in this chapter.

Land Mammal Distribution in the Mediterranean Neogene: A Consequence of Geokinematic and Climatic Events

Chapter

Jan 1985

European Neogene mammal ages are based on the evolution of different mammal groups and migrational events. The correlation of these mammal ages with the marine stages, the palinspastic reconstruction of circum-Mediterranean seas and seaways, and knowledge of continental and marine climates have allowed for a better understanding and timing of Neogene mammal faunal evolution. The most significant events influencing the faunal composition in the circum-Mediterranean area are discussed: the Oligocene-early Miocene Eurasian-African separation and the early Miocene Bering land-bridge connection; the Afro-Eurasian faunal exchange around 19 million years (m.y.); the early middle Miocene interruption of this Eurasian-African corridor; the Hipparion event in late Miocene-Tortonian time, and the generation of the Turolian circum-Mediterranean chronofauna in Messinian time. Pliocene to Pléistocène climatic oscillations and tectonic events finally shaped the Mediterranean mammal distribution of today, before the impact of mankind.

Peculiarities of sulphur functionalities in the Thracian coal province, Bulgaria

Article

Full-text available

Jan 2005

The Thracian coal province in Bulgaria is comprised of three main coal basins, Maritza East, Maritza West and Elhovo, with extremely immature coals (Rr = 0.18–0.21%). These Miocene-Pliocene aged low rank coals (lignites) are characterized by high ash and sulphur contents, and low calorific values. Temperature programmed reduction/oxidation at atmospheric pressure (AP-TPR/TPO), coupled with on-line mass spectrometer(AP-TPR/TPO-MS) and with an off-line gas chromatograph-mass spectrometer (GC-MS), were applied to the qualitative and semi-quantitative analysis of sulphur functionalities in representative samples from each basin of the coal province. Carbonates and mineral sulphur were removed by preliminary treatment with diluted acids at mild conditions to prevent effects on the TPR kinetograms. This treatment mainly removed the mineral sulphur, and its effects on organic sulphur were insignificant. Most of the organic sulphur in the Thracian lignites occurs in thiophenic structures (~ 60%). The TPR-MS profiles showed the presence of alkyl and aryl thiols, dialkyl and aryl-alkyl sulphides and thiophenes. The main organic sulphur compounds registered by the off-line AP-TPR-GC-MS were highly volatile compounds (thiols, sulphides, disulphides), alkylated thiophenes, and a lesser proportion of benzothiophenes. The disulphides (-SS-) are relatively abundant in the Maritza East and Elhovo lignites. They are probably the main aliphatic sulphur species in the coal’s organic matter. Aliphatic chains with sulphur bridges are also principal structural functionalities in the Maritza West organic matter. Aromatic compounds with two aromatic rings and high degrees of substitution could be key organic structures in the studied lignites.

Black Sea desiccation during the Messinian Salinity Crisis: Fact or fiction?

Article

Full-text available

May 2014
GEOLOGY

The late Miocene Messinian Salinity Crisis (MSC) was an extraordinary geologic event in the Mediterranean Basin marked by massive salt accumulation and presumably basin desiccation as a consequence of the reduced water exchange with the Atlantic Ocean. The discovery of a desiccation deposit in the Black Sea, the so-called Pebbly Breccia unit, was used to claim that the Black Sea also became desiccated during the MSC. Erosional features interpreted from seismic profiles of the Black Sea margin, correlated by some to the Pebbly Breccia unit, were used to support this hypothesis. However, the age of the Pebbly Breccia is poorly constrained, and its origin and relevance to the MSC subject to controversy. Here we present new biostratigraphic (dinoflagellate cyst) data from two key sedimentary successions located in a deep and a marginal setting of the Black Sea Basin. These records demonstrate that the Pebbly Breccia predates the Mediterranean water-level drop during the MSC. We argue that the presumed erosional features in the Black Sea Basin are not related to the MSC and likely represent an older Miocene event.

Bulgarian low rank coals: Geology and petrology

Article

Jan 1997

George D. Šiškov

The largest coal-forming maximum in Bulgaria took place during the Neogene. Fifteen coal deposits are located in four coal-bearing provinces. The coal deposits south of the Balkan Mountains were formed in small grabens and depressions filled with molasse. Only the coals in Northern Bulgaria were formed in a small palaeodelta. The coal measures are of varying thickness and contain a few coal seams, with compact to complex structure and a range of thickness. Three groups are defined on the basis of maceral composition, allowing a reconstruction of the coal-forming ecosystems and the genesis of the genotypes during biochemical coalification. According to Alpern's classification the coals have middle to high ash content (ashy to coaly facies). They are of huminite type with low liptinite and inertinite content, and of low rank - lignite and mat brown coals.

Organic sulphur as a main index for determining the genetic type of low-rank coals

Article

Full-text available

Jan 2005

Astatistical analysis of the quality of Donetz low-rank coals has been carried out using catalogue data and freshly-sampled coals. Thirty seven samples of bituminous coals with volatile matter contents ranging from 37.2% to 44.2% were used. All coals are closely clustered into groups of samples with different ranges of (O+N)daf/Cdaf atomic ratio. It has been shown that linear correlations exist between the Sî daf and Sî daf /Cdaf ratio and Vdaf. The correlation coefficients within the different sample groups have been found to be r1=0.87; r2=0.92, and r3=0.98. They increase as the O daf /Cdaf inter- val is narrowed down, i.e. as the coal rank is more exactly defined. Similarly, a statistical dependence between the volatile matter yield and the organic sulphur content has been found for the Donetsk DG and G brand coals, with the correlation coefficients being r = 0.91 and r = 0.95, respectively. It was also found that some structural parameters of the coals correlate with So daf . 13 C-isotopes

The endemic molluscs of the Late Miocene Lake Pannon: Their origin, evolution, and family-level taxonomy

Article

Mar 2007
Lethaia

Long-lived lakes are often sites of spectacular endemic radiations. During the Oligocene to recent history of the Paratethys, large, long-lived (more than a million years) lakes with endemic faunas formed three times, in three different basins: the first in the Pannonian basin, the second in the Euxinian (Black Sea) basin, and the third in the Caspian basin. Because the Euxinian lake inherited much of the fauna of Lake Pannon, the three lakes together hosted two endemic radiations of molluscs. The most long-lived lake in the region was Lake Pannon, which persisted approximately seven million years from the late Middle Miocene to the Early Pliocene. Lake Pannon was formed by isolation from the sea. Changes in hydrological regime and/or water chemistry in addition to the relative lowstand which accompanied (or caused) the isolation almost completely exterminated the restricted marine fauna of the basin. A few highly euryhaline and marginal marine cardiids, dreissenids, and hydrobiids survived this environmental change. As in other fossil and extant long-lived lakes, the originally low-diversity fauna radiated into a high number of related endemic species (‘species flocks’) and genera in the expanding and ecologically vacated lake. Many originally freshwater taxa (unionids, sphaeriids, viviparids, valvatids, melanopsids, lymnaeids, planorbids) entered the lake as well, and some of them also gave rise to endemic clades. Evolution in both relict and freshwater immigrant groups led to the appearance of highly unusual shell shapes. Many lineages exhibit gradual morphological changes over one to several million years. More than 900 endemic mollusc species have been described from Lake Pannon, although this number includes junior synonyms, invalid species names, and highly similar chronospecies. Applying a conservative taxonomy, all these species belong to four bivalve and eight gastropod families. The high degree of endemism, however, is reflected by proposals of some authors to establish as many as five new families based on Lake Pannon endemics.

Petroleum geology of the Black Sea

Article

Mar 1996
MAR PETROL GEOL

The Black Sea comprises two extensional basins formed in a back-arc setting above the northward subducting Tethys Ocean, close to the southern margin of Eurasia. The two basins coalesced late in their post-rift phases in the Pliocene, forming the present single depocentre. The Western Black Sea was initiated in the Aptian, when a part of the Moesian Platform (now the Western Pontides of Turkey) began to rift and move away to the south-east. The Eastern Black Sea probably formed by separation of the Mid-Black Sea High from the Shatsky Ridge during the Palaeocene to Eocene. Subsequent to rifting, the basins were the sites of mainly deep water deposition; only during the Late Miocene was there a major sea-level fall, leading to the development of a relatively shallow lake. Most of the margins of the Black Sea have been extensively modified by Late Eocene to recent compression associated with closure of the Tethys Ocean. Gas chromatography—mass spectrometry and carbon isotope analysis of petroleum and rock extracts suggest that most petroleum occurrences around the Black Sea can be explained by generation from an oil-prone source rock of most probably Late Eocene age (although a wider age range is possible in the basin centres). Burial history modelling and source kitchen mapping indicate that this unit is currently generating both oil and gas in the post-rift basin. A Palaeozoic source rock may have generated gas condensate in the Gulf of Odessa. In Bulgarian waters, the main plays are associated with the development of an Eocene foreland basin (Kamchia Trough) and in extensional structures related to Western Black Sea rifting. The latter continue into the Romanian shelf where there is also potential in rollover anticlines due to gravity sliding of Neogene sediments. In the Gulf of Odessa gas condensate has been discovered in several compressional anticlines and there is potential in older extensional structures. Small gas and oil discoveries around the Sea of Azov point to further potential offshore around the Central Azov High. In offshore Russia and Georgia there are large culminations on the Shatsky Ridge, but these are mainly in deep water and may have poor reservoirs. There are small compressional structures off the northern Turkish coast related to the Pontide deformation; these may include Eocene turbidite reservoirs. The extensional fault blocks of the Andrusov Ridge (Mid-Black Sea High) are seen as having the best potential for large hydrocarbon volumes, but in 2200 m of water.

Calcareous nannofossil biostratigraphy and magnetostratigraphy of the Upper Miocene and Lower Pliocene of the Northern Aegean (Orphanic Gulf - Strimon Basin areas), Greece

Article

Aug 2006
PALAEOGEOGR PALAEOCL

The transitional position of the Northern Aegean makes it an important area for studying the relation between the Mediterranean and the Eastern Paratethys. A chronostratigraphic framework has been obtained for the Late Neogene deposits along the Orphanic Gulf and in the Strimon Basin of Northern Greece by analysing calcareous nannofossil data and paleomagnetic results from eight sections. The local formations and major lithological units have been correlated with the Upper Miocene and Lower Pliocene stages. Furthermore, the obtained framework has facilitated a more detailed reconstruction of the effects of the Messinian salinity crisis on the sedimentary record.

Black Sea: Geological Setting and Recent Deposits Distribution from Seismic Reflection Data

Article

Full-text available

Apr 1978

The origin of the Black Sea is discussed in the framework of the evolution of the Mediterranean Alpine area since the beginning of the Mesozoic. The Black Sea is considered to be a marginal basin formed between Lias to Upper Cretaceous times, behind the Pontides Range relative to the consumption of the Tethys. Land geological data and multichannel seismic reflection profiles show that later compressional movements occurred at the northeastern and southern margin of the Black Sea depression. In the abyssal plain, basement reliefs are buried by a thick horizontal sequence of mainly post-Eocene sediments. Mud diapiric phenomena of deep layers, related to undercompaction, and covered by rapidly deposited thick sediments, are observed southeast of Crimea. It appears that, during Pliocene-Quaternary times, sedimentation and subsidence strongly increased. Sedimentation was controlled by fans related to the main deltas. Correlations of DSDP holes with seismic reflection profiles allow better interpretation of the sedimentation pattern in the Black Sea.

Stratigrafija verhnekainozoiskih otlogenii po diatomejam

Article

Jan 1980

Middle-Upper Neogene and early Quaternary chronology from the Dacic Basin and correlation with neighbouring areas

Article

Jan 1981

Andreescu Ion

Paleogeographic implications of Late Miocene deposits in the Aegean region

Article

Jan 1979

La sedimentation Neogene dans le Fosse Nord Egeen

Article

Jan 1979

Black Sea Geophysical Framework

Article

Apr 1978

Das Neogen im Strimon-Becken (Griechisch-Ostmazedonien)

Article

Jan 1969

F. Gramann

Critical notes on the stratigraphy of Black Sea boreholes (Deep Sea Drilling Project, Leg 42B)

Article

Jan 1979

E. Kojumdgieva

Stratigraphy of the Lacustrine Sedimentation in the Black Sea

Article

Apr 1978

K.J. Hsü

Die Molluskenfauna der Neogenen Formation Der Halbinsel-Gelibolu

Article

Jan 1979

G. Taner

Stratigraphy of the Neogene in Sandanski Graben

Article

Jan 1982

Messian event in the Black Sea

Article

Jan 1979
PALAEOGEOGR PALAEOCL

Three holes were drilled during the 1975 DSDP Leg 42B drilling the Black Sea. A section from Hole 380, at 2107 m water depth on the western edge of the abyssal plain, is 1074 m thick, and provides the most complete stratigraphic section. Dating of the sediments is based upon (1) fossil evidence from pollen, crustaceans, benthic foraminifera, and diatoms, (2) correlation with climatic changes and with unusual isochronous events that have been dated elsewhere, (3) paleomagnetic data, and (4) estimates of sedimentation rate.The history of Black Sea sedimentation recorded by the DSDP cores includes black shale sedimentation during the Late Miocene, followed by periodic chemical sedimentation from Late Miocene to Early Quaternary, and a change to dominantly terrigenous sedimentation from the Middle Quaternary. These hemipelagic and turbiditic sediments were deposited in lacustrine and brackish marine environments. The Messinian sediments, however, consist of stromatolitic dolomite, oolitic sands, and coarse gravels, deposited in supratidal and intertidal environments. The intercalation of the shallow-water sediments in a deep-water sequence suggests a drastic lowering of the water-level within the Black Sea basin during the Messinian so that the edge of the present abyssal plain was then the edge of a shallow lake.The Messinian draw-down phase of the Black Sea was in existence for about 100,000 years during the Lago-Mare stage of the salinity crisis. The evaporated waters formed an alkaline lake before it was drowned by a brackish marine transgression correlative to the Trubi transgression of the Mediterranean.

Le faciostratotype du Malvensien de la zone de courbure des Car-pates orientales

Jan 1972
58-157

I Andreescu

Andreescu, I., 1972. Le faciostratotype du Malvensien de la zone de courbure des Car-pates orientales. Dari de Seama Sedin., Inst. Geol., Bucuresti, 58(9): 157--176.

Opresnjalos li yugnooukrainskoe sarmatskoe more?

Jan 1967
97

Belokrys

Belokrys, L. S., 1967. Opresnjalos li yugnooukrainskoe sarmatskoe more? Sov. Geol., 7: 97--110.

Sarmat yuga SSR. In: Stratigrafia kainozoja Sev

Jan 1976
1-21

L S Belokrys

Belokrys, L. S., 1976. Sarmat yuga SSR. In: Stratigrafia kainozoja Sev. Prichernomorja i Krima, 1. Dnepropetrovsk, 1--21.

Biostratigraphic correlations between the Neogene land mammal faunas of the East and Central Paratethys. Ann. G4ol. Pays Hell6n

Jan 1979
411-423

L K Gabunia

Gabunia, L. K., 1979. Biostratigraphic correlations between the Neogene land mammal faunas of the East and Central Paratethys. Ann. G4ol. Pays Hell6n., H. S., 411--423.

On the absolute age of the Hipparion from Saro

Jan 1977
7

Gabunia

Gabunia, L. K. and Rubinstein, M. M., 1977. On the absolute age of the Hipparion from Saro. Geol. S., Bratislava, 21(1): 7--11 (in Russian with English summary).

Zakonomernosti razvitija molluskov v opresnennih basseinah neogene Evrazii

Jan 1976
288

Ilina

Ilina, L. B., Nevesskaya, L. A. and Paramonova, N. P., 1976. Zakonomernosti razvitija molluskov v opresnennih basseinah neogena Evrazii. Nauka, Moscow, 288 pp.

Stratigrafija verhnekainozoiskih otlogenii po dia-tomejam. In: Geologicheskaja istorija Chernogo morja po resultatam glubokovodnogo burenija

Jan 1980
52-65

A P Jous
V V Mukhina

Jous6, A. P. and Mukhina, V. V., 1980. Stratigrafija verhnekainozoiskih otlogenii po dia-tomejam. In: Geologicheskaja istorija Chernogo morja po resultatam glubokovodnogo burenija. Nauka, Moscow, pp. 52--65.

Strukturnaja poverhnost sarmatskih otlogenii severozapadnoi chasti shelfa Chernogo morja

Jan 1975
149-158

I G Morgunov
V P Vorobiov
A V Kalinin
I I Kovalskaja
P N Kuprin
V L Pivovarov

Morgunov, I. G., Vorobiov, V. P., Kalinin, A. V., Kovalskaja, I. I., Kuprin, P. N. and Pivovarov, V. L., 1975. Strukturnaja poverhnost sarmatskih otlogenii severozapadnoi chasti shelfa Chernogo morja. Kompleksn. Issled. Prirodi Okeana, 5: 149--158.

Die neogene Carpoflora aus dem Melnik-Becken

Jan 1982
3

Palamarev

Palamarev, E., 1982. Die neogene Carpoflora aus dem Melnik-Becken. Paleontol., Stratigr. Lithol., 16:3--44 (in Bulgarian with German summary).

Asupra limitei Sarmatian-Meotian din regiunea euprinsa intre Valea Buzaului si afluentul sau Balaneasa

Jan 1964
35

Pana

Pana, I., 1964. Asupra limitei Sarmatian--Meotian din regiunea euprinsa intre Valea Buzaului si afluentul sau Balaneasa. Anal. Univ. Bucuresti, Ser. Stiint. Nat. (Geol.-Geogr.), 13(2): 35--46.

Paleomagnitnie issledovanija verhnemiocenovih i nignepliocenovih morskih otlogenii Tamanskogo poluostrova

Jan 1978
5

Pevzner

Pevzner, M. A. and Chikovani, A. A., 1978. Paleomagnitnie issledovanija verhnemiocenovih i nignepliocenovih morskih otlogenii Tamanskogo poluostrova, Izv. Akad. Nauk SSSR, Ser. Geol., 1: 5--15.

Opit prjamoi korrelacii mio-pliocena Vostochnego Paratetisa i Tetisa

Jan 1978
95

Semenenko

Semenenko, V. N. and Ljulieva, S. A., 1978. Opit prjamoi korrelacii mio-pliocena Vosto-chnego Paratetisa i Tetisa. In: Stratigrafia kainozoja Sev. Prichernomorja i Krima, 2. Dnepropetrovsk., pp. 95--105.

Istoria flori i rastitelnosti yuga Evropeiskoi chasti SSSR v pozdnem miocene-rannem pliocene

Jan 1979
197

Shchekina

Shchekina, N. A., 1979. Istoria flori i rastitelnosti yuga Evropeiskoi chasti SSSR v pozd-nero miocene-rannem pliocene. Naukova Dumka, Kiev, 197 pp.

Izvestkovie nanofossilii v kernah glubokovodnogo burenija

Jan 1980
71

Shumenko

Shumenko, S. I. and Ushakova, M. G., 1980. Izvestkovie nanofossilii v kernah glubokovod-nogo burenija. Nauka, Moscow, pp. 71--73.

Zonation of the Sarmatian sediments in northeastern Bulgaria on ostracod fauna

Jan 1976
53

Stancheva

Stancheva, M., 1976. Zonation of the Sarmatian sediments in northeastern Bulgaria on ostracod fauna. Geol. Balcanica, 6(1): 53--59.

Beitrag zur kenntnis der pontischen Molluskenfauna aus Griechenland und ihre stratigraphische Bedeuting

Jan 1963
73

Stevanovic

Stevanovic, P. M., 1963. Beitrag zur Kenntnis der pontischen Molluskenfauna aus Griechenland und ihre stratigraphische Bedeuting. Bull. Acad. Serbe Sci. Arts, 32, Classe Sci. Math. Nat., N. S., 9:73--93 (in Serbian with German summary).

Le faciostratotype du Malvensien de la zone de courbure des Carpates orientales. Dari de Seama Sedin.

Jan 1972
157

Andreescu

Das Neogen im Strimon-Becken (Griechisch-Ostmazedonien)

Jan 1969
445

Gramman

Les communautés des Mollusques du Sarmatien et leur importance stratigraphique

Jan 1980
72

Kojumdgieva

Strukturnaja poverhnost sarmatskih otlogenii severozapadnoi chasti shelfa chernogo morja

Jan 1975
149

Morgunov

Biostratigraphic correlations between the Neogene land mammal faunas of the East and Central Paratethys

Jan 1979
411

Gabunia

Palaeogeographic environment during the desiccation of the Black Sea

Abstract

No full-text available

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