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A review of the stratigraphy of eastern paratethys (oligocene-holocene), with particular emphasis on the black sea
Abstract
A synopsis of the stratigraphy of Eastern Paratethys is provided. Particular emphasis is placed on the Black Sea. An attempt is made to place the regional stratigraphy in a (global) sequence stratigraphie framework for the first time.
... Middle to Late Miocene sedimentation in the western South Caspian Basin occurred in a progressively shallower-water setting, and evaporites are present in the upper Miocene Pontian Suite . The top of the Pontian can be correlated with the Messinian Salinity Crisis at ca. 5.5 Ma (Jones and Simmons, 1997). ...
... The overlying unit in the Miocene of the northern Alborz includes early and middle Sarmatian (equivalent to Tortonian) sandstones, marls and mudstones (Fig. 5) (Yassini, 1981). The late Sarmatian to Pannonian (equivalent to the Messinian) was a period of nondeposition in the northern Alborz (Yassini, 1981), coeval with a major drop in the relative sea level of the South Caspian (Jones and Simmons, 1997). ...
The South Caspian Basin, the northern Alborz Mountains, the Gorgan plain and the Moghan plain constitute the northernmost and youngest petroleum system in Iran. This region was part of the Paratethys realm from Oligocene to Pliocene time. The Oligocene – Miocene Maikop/Diatom Total Petroleum System of the South Caspian Basin produces major volumes of hydrocarbons in Azerbaijan and Turkmenistan, and the Iranian sector of the basin has consequently undergone exploration due to its generally similar geology. The 20 km thick, dominantly Cenozoic sedimentary cover in the basin is reduced to less than 3 km in the northern foothills of the Alborz Mountains, and scattered surface oil seepages in the latter region are believed to be generated by Cretaceous and Miocene source rocks. In the Moghan plain to the southwest of the South Caspian Basin, anticlinal folds of Oligo‐Miocene Zivar Formation sandstones may be prospective for hydrocarbon exploration. Mud volcanoes in the Gorgan plain and in adjacent offshore regions at the SE margin of the South Caspian Basin are associated with hydrocarbon seepages, and appear to be sourced by Cretaceous and Cenozoic shales and mudstones. Major structural features in the southern part of the South Caspian Basin include Cenozoic mud diapirs, folds and gravity structures.
... Oolites seed in agitated shallow, super-saturated saline water. The Babajan Formation that resides in the Bosphorian substage in the Caspian Sea contains shallow marine carbonates and evaporites that have been considered a stratigraphic equivalent of those in the Mediterranean Messinian [383]. The Caspian ostracods include the same Paratethys species as Leptocythere and Loxoconcha that are diagnostic of the Stage 3 Lago-Mare sediments [329,330,368,384]. ...
The first deep-sea drilling expedition in the Mediterranean chanced upon unanticipated discoveries when recovering deeply buried sediments of Late Miocene age that had once accumulated in ultra-shallow water and had later experienced subaerial exposure. Among these deposits were potassium and magnesium chlorides, desiccation cracks, fluvial gravels and shale bearing bottom-dwelling diatoms requiring sunlight, all indicative that the Mediterranean had evaporated one or more times to near dryness during what became called the Messinian Salinity Crisis. The initial presentation of these findings in 1973 was met with hesitancy. Had the present 2 to 4 km deep Mediterranean Basins been much shallower? How does one explain sediment sandwiched between beds of anhydrite and gypsum that hosted microfossils belonging to both ocean seawater and species that lived in fresh-to-brackish water lagoons? Did all of the evaporites originate on salt pans rimmed by alluvial aprons, or was there a deep-water period during which most of the 1 to 2 km thick layer of salt layer had arrived? How do the Late Miocene evaporites and mudstones outcropping in mobile belts along numerous Mediterranean margins fit with the scenario of a near empty Mediterranean? These inquiries are addressed in the style of a historical narrative reviewing 50 years of investigations by researchers turning their attention to the peripheral deposits, including those from the Paratethys. The stable isotopes of oxygen, carbon, sulfur, deuterium and strontium become crucial evidence in support of a substantial Mediterranean desiccation that harmonizes what appears to be unresolved conflicts among prior and even contemporary interpretations.
... They produce scenic landscapes and morphological features on the Earth's surface, such as gryphons, mud and scoria cones, salses, springs and fire columns [3][4][5][6]. However, the release of toxic and radioactive elements (arsenic, As; barium, Ba; copper, Cu; strontium, Sr; uranium, U; zinc, Zn, etc.) and (a) biogenic gases (e.g., methane, CH 4 and minor carbon dioxide, CO 2 ) during the active and dormant periods of volcanoes can impact the chemistry of local surface water, groundwater, interstitial solutions and sediments, as well as the Earth's atmospheric gas budget [7][8][9][10][11][12][13][14][15][16]. In many places, mud volcanic activity is triggered by the rapid subsidence of soft, fine-grained sediments rich in water and organic matter in a compressive tectonic setting, which promotes the generation of hydrocarbons and, subsequently, the formation The widespread, active and passive mud volcano systems located onshore in East Azerbaijan are relatively well documented with respect to their fluid and solid ejects [4,11,[26][27][28]. ...
We present geochemical and mineralogical datasets for five new mud volcanoes in continental Azerbaijan (Hamamdagh and Bendovan) and the adjacent Caspian Sea (Khara-Zire, Garasu and Sangi-Mughan). The fluid ejects have a Na–Cl-type composition and are generated by the mixing of evaporated Caspian seawater and low- to high-salinity pore waters, as indicated by Br–B and Cl–B systematics and Na–K and SiO2 geo-thermometers. The fluids contain high concentrations of As, Ba, Cu, Si, Li, Sr and Zn (60 to 26,300 ppm), which are caused by surface evaporation, pyrite oxidation, ion exchange reactions and hydrocarbon maturation in Oligocene-Miocene ‘Maykop’ shales. The solid ejects comprise liquid, oily and brecciated mud, mud/claystones and sandstones. The mud heterogeneity of the volcanoes is related to the geological age and different sedimentological strata of the host rocks that the mud volcanoes pass through during their ascent. All ejects show evidence of chemical alterations via water–rock–gas reactions, such as feldspar weathering, smectite illitization and the precipitation of Fe-(hydr)oxides, calcite, calcian dolomite, kaolinite and smectite. The studied localities have petrographic similarities to northern extending mud volcano systems located on Bahar and Zenbil islands, which suggests that mud volcanoes in the Caspian Sea region are sourced from giant shallow mud chambers (~1–4 km depth) located in Productive Series strata. Our results document the complex architecture of the South Caspian Basin—the most prolific hydrocarbon region in the world.
... From the Miocene times onward, the compressional deformation within pro-wedge foreland basin and the onset of Middle Miocene syn-tectonic sedimentation took place (Alania et al., 2021a). Within the RFFTB are distinguished three major changes in basin-fill dynamics: 1) marine/regressive stage (Middle Miocene-Early Pliocene), 2) marine/transgressive stage (Late Pliocene), and 3) marinecontinental/transgressive-regressive cycle (Pleistocene-Holocene) (Jones and Simmons, 1997). Unfortunately, the study area lacks any detailed sedimentological studies of syntectonic strata, although the basin-fill dynamics could be reconstructed taking into account basin geometry and depositional conditions. ...
The Rioni foreland fold-and-thrust belt is part of the Greater Caucasus pro-wedge and is one of the most important examples of the collision-driven far-field deformation of the Arabia-Eurasia convergence zone. Here we show the deformation structural style of the Rioni foreland fold-and-thrust belt based on seismic reflection profiles and regional balanced cross-section. The main style of deformation within the Rioni foreland fold-and-thrust belt is represented by a set of fault-propagation folds, duplexes, and triangle zone. The regional balanced cross-section shows that fault-propagation folds above the upper detachment level can develop by piggyback and break-back thrust sequences. Formation of fault-bend fold duplex structures above the lower detachment is related to piggyback thrust sequences. A balanced section restoration of compressional structures across the Rioni foreland fold-and-thrust belt provides a minimum estimate of shortening of −40%, equivalent −42.78 km. The synclines within the Rioni foreland fold-and-thrust belt are filled by the Middle Miocene-Pleistocene shallow marine and continental syn-tectonic sediments, forming a series of typical thrust-top basins. Fault-propagation folds and duplex structures formed the main structure of the thrust-top basin. The evolution of the thrust-top basins was mainly controlled by the kinematics of thrust sequences. Using end-member modes of thrust sequences, the thrust-top basins are divided into: 1) Type I-piggyback basin, 2) Type II-break-back basin, and 3) Type III—formation of thrust-top basin characterized by bi-vergent geometry and related to combined, piggyback and piggyback back thrust sequences.
... Vulkanların gündəlik fəaliyyəti dövründə maye və qaz fazalı komponentlər əksəriyyəti gil minerallardan təşkil olunmuş brekçiyadan ayrılırlar. Bu da öz növbəsində, məhz qrifon-salza fəaliyyəti nəticəsində palçıq vulkanının morfoloji strukturunun formalaşmasına gətirib çıxarır [25]. ...
Məqalədə, Azərbaycan palçıq vulkanlarının intişar tapdığı sahələrin geoloji, dərinlik-stratiqrafik, tektonik səciyyələri ilə bərabər, onların daxili quruluşları, püskürmələri haqqında seysmik stansiyaların qeydləri, həmçinin süxur tullantılarının vizual və geokimyəvi xarakteristikaları araşdırılır. Kompleks məlumatlar əsasında vulkan köklərinin maksimal dərinliyinin Təbaşir və Eosen yaşlı çöküntülər yerləşən intervallarla mümkün assosiasiyaları korrelyasiya olunur. Şıxzərlinin Üst Maykop yaşlı kəsilişindən götürülən yanar şistdən reper kimi istifadə edilməklə, vulkan tullantılarının zəngin üzvi maddə saxlayan (> 8 %), lakin geoloji yaşları mübahisə doğuran şistli süxurlarının üzvi-geokimyəvi göstəriciləri, tərkiblərində adsorbsiya sularının miqdarca paylanması və paleohövzə əmələgəlmə şəraitləri müqayisəli şəkildə öyrənilmiş, nəticə etibarı ilə onların Üst Maykopa və Orta Eosenə bağlılıqları ilə əlaqədar geoloji qanunauyğunluq müəyyənləşdirilir.
... Swath cross-section (10 km wide) through the transition zone between Siret Plateau and Jijia Hills (Cohen et al. 2013) is established based on information from Pevzner and Vangengeim (1993), Jones and Simmons (1997), and Rögl (1998) and is shown in Fig. 4. The most detailed lithostratigraphic column was created by Ștefan (1989) and began with Late Volhynian rocks ( Fig. 4): the Oneaga Clays Formation and the overlapping Lespezi-Tudora Sands (Fig. 5b) and Sandstones Formation. The Oneaga Clays Formation (220 m thick) comprises compacted and stratified mudstones in the basal part, which has sand lenses or layers in the upper part, and appears tilted in some sectors (Ștefan 1989 -as is the case also in Fig. 5a). ...
The Bahluieț Valley at Costești village geosite has recently been studied and proposed as a geoheritage site. Previous investigations of the study area were focused on the Costești-Cier archaeological site, which is currently integrated into the National Archaeological Repertoire. In this archaeological site, different levels of populations have been studied (Eneolithic Cucuteni A, Cucuteni AB, and Horodiștea-Erbiceni Culture populations) as well as an earth wall from La Tene (8th-10th/eleventh century BC) and a 15th-seventeenth century AD necropolis. In the area of the present-day Costești village, Bahluieț River leaves the Suceava Plateau area (with altitudes of 350-550 m a.s.l.) and enters the Jijia Hills (with altitudes of 50 to 200 m a.s.l.), flowing between Ulmiș Hill (306 m a.s.l., at north) and Ruginii Hill (326 m a.s.l., at the south). This valley, which is incised more than 100 m below the plateau level, suddenly becomes broader because of massive Late Pleistocene landslides that covered the former Bahluieț river floodplain and are now fossilized by fluvial deposits. During the Holocene, river incision detached paleochannels and fluvial terraces, while the landslides reactivated through retrogressive mechanisms, creating a complex landslide. A cutoff meander island hosts the Costești-Cier archaeological site, which is currently being actively eroded by the river. In the riverbank of this island, a multi-layered stratigraphy can be seen, consisting of landslide and flu-vial deposits, palaeosols, and archaeological remains. The layered deposits, the complex landslide, and the fluvial processes have the potential to become one of the most representative Quaternary sites of the Moldavian Plateau and Romania. By using geomorphosite assessment, geomorphological mapping, optically stimulated luminescence dating, and concepts of geoconservation, I show (i) the importance of the geosite due to the presence of the oldest dated fossil landslide in Romania and to the landslide-fluvial-archaeological relations and (ii) the need for protection at local, regional, and national levels considering the active processes that affect the site. I propose a geoconservation strategy for management and promotion of the geoheritage site.
Identifying the optimal azimuth and inclination for wellbore drilling in sandy formations can be considered a valuable aid in reducing sand production risks, lost time, and decreasing drilling costs in the petroleum industry. Therefore, a numerical systematic approach was provided to predict sand production in wellbore SDX-5, drilled in a deep-water sandstone reservoir in the Shah-Deniz gas field (South Caspian Basin), which has never been done previously. Additionally, this systematic approach uses geomechanical and geodynamical criteria, along with petrophysical information (density and sonic log) and tectonic characteristics of the study area, which are influenced by the active tectonic stresses of the Apsheron-Balkhan zone. The subsurface data sources employed are more eco-friendly, available, and continuous than experimental tests. The computations conducted achieved azimuth, inclination, polar, and depth profile plots for the Lower Balakhany Formation. The calculations reveal that the optimum azimuth for the wellbore drilling trajectories is parallel to SHmax and oblique drilling to near horizontal is the result of optimum inclination. Polar plots showed optimum azimuth, inclination, and effect of wellbore trajectory on critical collapse pressure and collapse drawdown pressure with pressure values simultaneously, which identify safer alternatives for achieving higher petroleum production rates without sanding. Depth profile plots provide a simultaneous overview of the values of critical collapse pressure, critical sanding pressure for instantaneous drawdown, and optimum wellbore production pressure during drilling and production operations. Moreover, optimum reservoir fluid production (maximum discharge) rates can be identified and imposed as upper limits to prevent sand production.
At the end of the Eocene, the demise of the Tethys Ocean led to the formation of one of the largest anoxic seas in the last 50 million years of Earth history. This long-lived anoxic water body, named Paratethys, covered large parts of central Eurasia and functioned as a major carbon sink for 15-20 million years, characterised by the deposition of cherts, anoxic turbidites and black shales. The anoxic episode was followed by a phase of instable connectivity where full marine episodes alternated with evaporitic crises and lacustrine episodes, resulting in the deposition of marine molasses, evaporites and continental-lacustrine sediments. Finally, Paratethys transformed into a megalake that progressively filled with clastic sediments from the neighbouring mountain ranges.
Paratethys was tectonically fragmented in numerous sub-basins that spread W-E from the Alpine and Carpathian orogens to the East European Platform. Most Paratethyan stratigraphic records from Central and Eastern European tectonically-active regions are not complete and thus hamper paleogeographic and paleoenvironmental reconstructions. The only exception is the Outer Carpathian Basin, located in the external part of the Carpathian arc in Central Europe, that preserved a complete record of Tethys demise and the rise and fall of Paratethys. The Outer Carpathians sedimentary successions show various lithologies that reflect an interplay of interbasinal connectivity and water exchange with the global ocean.
Here we review the stratigraphic schemes of the different tectonic domains of the Outer Carpathians and describe the most complete records to produce a Carpathian-wide framework for the Eocene to Miocene evolution of Paratethys, the lost sea of Eurasia. Finally, we focus on the paleogeographic reconstructions of the interbasinal Paratethys connections and discuss how marine connectivity influenced anoxia and hypersalinity and impacted the Cenozoic depositional environments in central Europe.
Mud volcanoes are natural phenomena that provide an essential source of information about subsurface sediments and deep structures. The phenomenon is usually associated with hydrocarbon accumulations in deep-seated strata. More than 30% of all mud volcanoes in the world are concentrated in the South Caspian Basin. Gorgan plain, as a part of the south Caspian lowland, is a transition zone between uplifting zones of the Alborz and Kopet Dagh and the subsiding basin of the south Caspian. Four active mud volcanoes in the western parts of the Gorgan Plain have extrusion of gas and mud. The existence of the possible hydrocarbon
contents in this plain caused a reflection seismic survey and exploratory wells were performed in this area by the National Iranian Oil Company. In this paper, we used 2-D reflection seismic data and well top data for the investigation of stratigraphy and structural setting of the Neftlijeh and Gharnyaregh mud volcanoes. According to the Well Report, the area sediments are composed of the Tertiary to Quaternary sediments of the SCB and underlying pre-Tertiary sequence of the Kopet-Dagh basin and a missing Oligocene, Eocene, Paleocene and upper Cretaceous deposition are observed in the well. The interpretation of the seismic section shows that the Caspian basin deposits reveal a partial deformation and increasingly sloping toward the depocenter, while the sequence of Kopet Dagh is folded.
The Neftlijeh and Gharnyaregh mud volcanoes occurred on subsurface anticline axes of the Kopet Dagh and a cluster of conjugate normal faults developed into the Cenozoic formations above the hinge zone of these anticlines. The subsidence pattern is observable at the summit of the anticlines. The structure suggests the presence of a chamber within the crest of the anticline. It seems extrusion and material removal from this chamber caused subsidence and forming of the structure. The Oligo-Miocene Maykop Formation is the significant source of both the extruded mud and the petroleum in the south Caspian basin, which is not observed in the studied well due to later regional erosion. However, the Cheleken and Apsheron deposits, known as reservoir rocks, have a large thickness in the area. The Kashafrud Formations are considered as the main source rock for the Kopet Dagh basin and the Mozduran and Tirgan formations are known as reservoir rocks. The occurrence of the Late Eocene compressional tectonic phase and following the folding of the Mesozoic sedimentary created structural traps at the strata. In addition, continued diapirism and uplifting of the deep-seated strata led to the growth of extensional faults and fractures over the hinge zones. These structures provide effective pathways for gas and fluid ascent from deep reservoirs to the surface. Generally, the results suggest that these mud volcanoes have a spatial and genetic relationship with buried folds. It seems the location of Gharenyaregh and Neftelijeh mud volcanoes is controlled by subsurface anticlines and their feeding source originated from both the Tertiary (SCB) and Pre-Tertiary (Kopet Dagh) units.
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