The second Pannonian Super-Basin volume focuses on the geo-energy aspects in separate sections dedicated to geothermal energy, CCUS, hydrogen and natural gas storage and critical mineral exploration. The Pannonian Basin is the hottest sedimentary basin in mainland Europe, providing a useful template for geothermal exploration and utilization projects worldwide.

The first Pannonian Superbasin volume is dedicated to the regional geology of various Neogene extensional basins surrounded by the Alps, Carpathians and Dinarides. All these subbasins developed on highly extended continental crust, providing the locus typicus for the general evolution of extensional basins developed in a back-arc basin setting.

The Eastern Carpathian fold and thrust belt of Romania is one of the oldest oil and gas producing areas in the world. Numerous fields have been discovered in this region since the 1850s, however, their distribution is irregular with most of them clustered in the Moinesti area. Our analysis suggests that although aspects of hydrocarbon generation, reservoir presence and quality are rather similar along the strike of the entire thrust belt, recent uplift and erosional unroofing of the Carpathians ultimately controlled the preservation of oil and gas fields. Areas with the highest amount of exhumation and associated trap breaching, seem to have suffered more intense deformation due to late inversion, which in turn, reflects the rheology of the various basement units of the East European Margin underlying the Carpathians.

The Carpathians are part of the Alpine orogen, and the Getic Depression (or Getic fold belt) is located to the south of the South Carpathian. Underthrust beneath the fold belt is the Moesian Platform lower plate. This foreland depocenter can reach a depth of up to 10 km and evolved in an oblique convergent setting from latest Cretaceous-Paleogene and was shortened during the Badenian-middle Sarmatian (middle to late Miocene, 16-8 Ma) and Pliocene to recent. Thus far, in previous publications, the role of the structural grain of the lower plate was poorly constrained. For the fold belt, contrasting interpretations implied a range of shortening magnitudes and con-trasting fault pattern. This contribution shows seven balanced cross sections that rely on seismic reflection and well data. One section, just outside and to the south of the fold belt, gives insights into the fault network of the Moesian Platform. In that section we see 35 km of north westward directed normal sense extension that creates a set of rotated fault blocks. Growth strata within the half grabens attest to Permo-Lower Triassic extension age. The individual normal faults merge at depth into a common detachment that rises monotonously towards the east and forms a domal-shaped, arched detachment. This is the structural grain that we project down plunge towards the north beneath the fold belt. The interpreted six sections that lie in the tectonic transport direction show that structures in the western part of the Getic fold belt are compatible with the inversion on the underlying Permo-Lower Triassic extensional fault. Ubiquitous truncation of Oligocene strata by overlying units suggest inversion started during late Oligocene (intra-Burdigalian). The Badenian-Sarmatian shortening further deforms the pre-existing contractional features and the shortening increases from 5 km on the west to at least 17 km on the east. NW-SE oriented transfer zones with normal faults separate the fold belt domains with diverging displacement vectors and eastward increasing shortening. Two main salt levels within the fold belts' sediment pile are laterally discontinuous hence they only have local significance in the deformation. The frontal part of the fold belt consists predominantly of Badenian-Sarmatian synkinematic units as the fold belt propagated into the foredeep units, this interpretation requires less shortening in the frontal structures compared to earlier solutions. Due to the lack of characteristic features on the studied sections, we infer that the Getic fold belt did not evolve as a transtensional depocenter during the lower Miocene as suggested by earlier publications.

Reconstructing orogenic systems made up dominantly by sediments accreted in trenches is challenging because of the incomplete lithological record of the subducted oceanic domain and its attached passive continental margin thrusted by collisional processes. In this respect, the remarkable ~600 km long continuity of sediments exposed in the Eastern Carpathian thin‐skinned thrust and fold belt and the availability of quantitative reconstructions for adjacent continental units provide excellent conditions for a paleogeographical study by provenance and sedimentological techniques constraining sediment routing and depositional systems. These sediments were deposited in the Ceahlău‐Severin branch of the Alpine Tethys Ocean and over its European passive continental margin. We report sedimentological, paleomagnetic, petrographic, and detrital zircon U‐Pb data of Lower Cretaceous sediments from several thin‐skinned tectonic units presumably deposited in the Moldavides domain of the Eastern Carpathians. Sedimentological observations in the innermost studied unit demonstrate that deposition took place in a deepwater basin floor sheets to sandy turbidite system. Detrital zircon age data demonstrate sourcing from internal Carpathian basement units. The sediment routing changes in more external units, where black shales basin floor sheets to sandy mud turbidites were sourced from an external, European continental area. Although some degree of mixing between sources located on both margins of the ocean occurred, constraining a relatively narrow width of the deep oceanic basin, these results demonstrate that the internal‐most studied unit was deposited near an Early Cretaceous accretionary wedge, located on the opposite internal side relative to the passive continental margin domain of other Moldavides units.

Filipescu, S., Tãmaê, D.M., Bercea, R.-I., Tãmaê, A., Bãlc, R., £abãrã, D., Bindiu-Haitonic, R., Silye, L., Auer, A., Krézsek, C., Schléder, Z., Sãsãran, E., 2020. Biostratigraphic re-eval u a tion of the lower to mid dle Mio cene suc ces sion in the East ern Carpathians: a case study re lated to the oil fields of the Diapir Fold Zone, Ro ma nia. Geo log i cal Quar terly, 64 (3): 781–800, doi: 10.7306/gq.1554

The Carpathian Bend Zone is part of the Eastern Romanian Carpathians. The stratigraphic profile contains two levels of salt: Lower Miocene (Lower Burdigalian) and Middle Miocene (Badenian). The studied segment of the fold belt was deformed during the Middle Miocene (Badenian-to-Middle Sarmatian phase) and during the Late Miocene to present (Wallachian phase). During this latter phase, the Lower Burdigalian salt was remobilized and reached the surface on several locations piercing through 2–3 km-thick post-tectonic deposits. The salt outcrops and contractional structures now form a 30 km long, NE–SW lineament at the surface. This contribution proposes kinematic models for the Lower Burdigalian salt movement during both tectonic phases. The lineament was a detachment fold in the Middle Miocene phase. Thickened Burdigalian salt and Oligocene s.l. duplex filled the core of the detachment fold. The detachment fold was subsequently peneplained with the Burdigalian salt exposed on the paleo-surface that locally redeposited during the Badenian. The Wallachian evolution is less clear and we propose two viable kinematic models. It is possible that the salt rise kept up with sedimentation and halokinetic sequences formed at the salt–sediment interface. Alternatively, the area was reactivated in a thin-skinned, right-lateral strike–slip manner with local pull-apart basins (1–2 km across) providing space for salt plugs. Currently available data do not allow us to pick a preferred model for the kinematics during the Wallachian phase. Both kinematic models are novel and are in contrast with earlier ideas.

Abstract It is generally believed that the western part of the Black Sea opened during the Early Cretaceous. However, recent data and interpretation from the Turkish margin suggest rifting continued into the Coniacian or Santonian. In this review, the evidence related to the Black Sea rifting on the conjugate Romanian margin is reassessed. Our integrated interpretation of this region, supported by outcrop observations, core and detrital zircon data, suggests that rifting started during the Aptian and continued intermittently until the mid-Turonian in two distinct stages. These stages are bounded by significant unconformities and reflect the progressive widening of the rift system. The first synrift stage started in the Aptian with the deposition of fluvial and lacustrine clastic successions, and locally marine carbonates in semi-isolated depocentres. These sinks began to coalesce during the latest Aptian–Albian with shallow-marine transgression from the east, and deposition of coastal swamp, deltaic and littoral facies. The second phase of rifting during the Cenomanian was marked by transgressive shallow-marine deposits overstepping the earlier Albian depocentres. Continental break-up followed in the mid-Turonian associated with regional uplift and erosion of the basin margin and the local deposition of fluvial conglomerates.

Hydrocarbon discoveries in the Western Black Sea have proved the presence of both thermogenic and biogenic petroleum systems. The presence of Tertiary biomarkers in oils from the Romanian part of the Western Black Sea sub‐basin, and correlation with Oligocene to Lower Miocene black shales, suggests that the thermogenic petroleum system is sourced mainly by the Oligocene – Miocene Maikop Group. Older source rocks may also be present locally in other parts of the sub‐basin, but their contribution is currently poorly understood.This paper presents the results of 3D basin modelling which was intended to evaluate charge models for prospects in the Western Black Sea sourced by the Maikop Group shales. The model is built on the regional‐scale interpretation of recently acquired, long‐offset 2D reflection seismic data, and was calibrated with proprietary and published well, geochemical and temperature data. The sensitivity of the thermal models on source maturity was tested. The basin models investigated two end‐member heat‐flow scenarios, “hot” and “cold”. Whereas the “hot” model more successfully reproduces the field and well data in shelfal areas of the Western Black Sea, the “cold” model is considered to be more valid for deeper‐water areas. Hydrocarbon expulsion maps were calculated for both scenarios at key stratigraphic levels, with preferential migration routes identified.The results of the basin modelling suggest that the most likely source rocks for the oils in accumulations offshore Romania are located in the mid‐Maikop Group (Upper Rupelian? to Chattian). Core data from offshore wells indicate that the source rocks consist of black shales with fair to good oil generation potential (TOC ∼ 0.5 to 4.5%, HI <600 mg/g TOC, and mixed Type II/III kerogen). At the present day, these shales are in the early oil window offshore Romania to the SE of the producing fields, and in the wet gas window further to the east. Hydrocarbon expulsion from the mid‐Maikop interval began during the Middle Miocene, but significant volumes of liquids were generated only in the Late Miocene with the peak of expulsion not yet reached. Charging the accumulations on the Romanian Shelf requires lateral migration along the base‐Oligocene unconformity over distances of about 20–50 km. In addition, hydrocarbons have charged underlying Eocene and Cretaceous reservoir sections by lateral downward migration, filling structural traps and spilling over to higher structural levels. The results highlight the underexplored potential associated with the Maikop Group in the Western Black Sea.

The mid Cretaceous is characterized by high eustatic sea-levels with widespread oxic conditions that made possible the occurrence of globally correlated Oceanic Red Beds. However, very often, these eustatic signals have been overprinted by local tectonics, which in turn resulted in Lower Cretaceous closed and anoxic basins, as in the Eastern Carpathians. There, the black shale to red bed transition occurs in the latest Albian up to the early Cenomanian. Although earlier studies discussed the large-scale basin configuration, no detailed petrography and sedimentology study has been performed in the Eastern Carpathians. This paper describes the Hauterivian to Turonian lithofacies and interprets the depositional settings based on their sedimentological features. The studied sections crop out only in tectonic half windows of the Eastern Carpathians, part of the Vrancea Nappe. The lithofacies comprises black shales interbedded with siderites and sandstones, calcarenites, marls, radiolarites and red shales. The siliciclastic muddy lithofacies in general reflects accumulation by suspension settling of pelagites and hemipelagites in anoxic (black shale) to dysoxic (dark gray and gray to green shales) and oxic (red shales) conditions. The radiolarites alternate with siliceous shales and are considered as evidence of climate changes. The sandstones represent mostly low and high-density turbidite currents in deep-marine lobes, as well as channel/levee systems. The source area is an eastern one, e.g., the Eastern Carpathians Foreland, given the abundance of low grade metamorphic clasts. The Hauterivian – lower Albian sediments are interpreted as deep-marine, linear and multiple sourced mud dominated systems deposited in a mainly anoxic to dysoxic basin. The anoxic conditions existed in the early to late Albian, but sedimentation changed to a higher energy mud/sand-dominated submarine channels and levees. This coarsening upwards tendency is interpreted as the effect of the Aptian to Albian compressional tectonics of the Carpathians. The deepening of the Moldavide Basin from the Cenomanian is most probably linked to a significant sea-level rise.

The Messinian sea-level fall in the western Black Sea is poorly understood and often debated. We provide evidence for the sea-level fall, offshore Romania. There, the Messinian sedimentation is closely related to the gravitational collapse of the basin margin above the Maykop shales. This thin-skinned system controlled the Messinian lowstand depocentres. We estimated about 500-600 m of sea-level drop based on the erosional valleys cut into the formed lower Pontian slope and the Messinian erosional surface (MES).The Messinian lowstand sediments are delimited by the basal erosional surface (BES) formed at the onset of the sea-level fall and by the MES related to transgressive wave erosion during the initial slow rise in sea level. Subsequent rapid sea-level rise drowned the remaining erosional topography on the lower Pontian palaeo-shelf. Similar features have been described in the Mediterranean Basin.

Miocene sediments of the western Black Sea failed gravitationally during the intra-Pontian (Messinian) sea-level fall. In the region of the Histria Trough, this generated two independent collapse systems detaching on the upper part of Oligocene–Lower Miocene shale. This contribution focuses on the eastern system. The eastern linked system is approximately 60 km long in the dip direction, containing about 10 major extensional faults in the updip domain, with a cumulative extension (heave) of 11.4 km. This extension is accommodated downdip partially by 6 – 7 km of lateral compaction and on a single toe thrust with 4.8 km of shortening. The thin-skinned extension generated both basinwards-dipping faults and counter-regional faults (dip towards the basin margin), with associated rollovers, tilted fault blocks and keystone graben. Broad shale pillow (3 km across) and cuspate shale upwelling developed due to reactive shale diapirism. The collapse of the rollover anticlines into the half-graben suggests a high deformation rate. Downdip, the thrust follows the top of the Oligocene–Lower Miocene unit and steps up into the top of Sarmatian. The thrust hanging-wall anticline collapsed and triggered a mass transport complex (MTC). The top of the MTC is a rugose surface, and we suggest that it remained under water during the Messinian event due to its lack of visible erosion.

Abstract The present day collage of various Silurian basin fragments in Central and Eastern Europe (CEE) is the result of several orogenic and rifting/drifting episodes. The proper paleogeographic reconstruction of a single, very large Silurian foredeep basin in the context of regional geology has a major impact on the ongoing unconventional shale gas exploration efforts in the region, including Poland, Ukraine, Romania and Moldova. The distal segments of a large Silurian foreland basin associated with the Caledonian collisional orogene, along the perimeter of the East European Craton, can be reasonably followed along strike from NW to SE, from Poland all the way to the Ukrainian Black Sea coast. The foredeep basin sequence onlaps to the NE the various pre-Silurian and crystalline basement units. The Silurian basin of the CEE is interpreted here as a pro-foreland basin, with short-lived (less than 15 m.y.) and extremely rapid (locally more than 1,500 m per m.y.!), accelerating subsidence histories recording a portion of the orogenic history of the broader Caledonian orogeny. Besides the typical subsidence curves and the very prominent onlap of successive Silurian lithostratigraphic units onto the craton, the flexural origin is also supported by the general lack of normal-faulting within the basin, contradicting some interpretations suggesting deposition on the extensional continental margin of the Rheic Ocean. The map-view distribution of the lithofacies within the basin, such as clastic turbidites in the southwestern perimeter of the basin, deepwater shales in the center and neritic carbonates on the northeastern foreland margin, is also consistent with the flexural basin interpretation.

Summary The main objective of this project is to study the development and the architecture of extensional forced folds. Such structures usually develop above reactivated extensional basement fault. It is important to understand the evolution of reverse folds as they can trap hydrocarbons. We used wet kaolin clay models to observe the development of forced folding and the associated faults. Many of the features seen in the analogue models can be identified also on seismic reflection data. Therefore, the analogue experiments were successfully used as a template to interpret the Jurassic extensional fault system from the Moesian Platform, Southern Romania.

The geological understanding of the Black Sea Basin appears quite far from being reasonably resolved. During the last two decades many contrasting points of views were published regarding the kinematics, mechanism and timing of the opening of both the Western and Eastern Black Sea basins (Fig. 1). Whereas the academia mostly focused on the basin margins, the oil and gas industry produced lots of geological and geophysical data in the shelf and, just recently, in the deepwater part of the basin providing critical insights. The present work is an attempt to summarize the pros and contras of the various models suggested to date, in light of the deepwater reflection seismic and well data acquired in the last few years. The overview below is addressing three open-ended subjects related to the opening of the Western Black Sea: kinematics, timing and mechanism.

The Moesian Platform of Romania and Bulgaria is well known as a prolific and mature petroleum province (Paraschiv, 1974; Georgiev and Atanasov, 1993). Moesia, as a continental platelet, is bordered to the north and to the west by the Southern Carpathians, to the south by the Balkanides and to the west by the Black Sea.

Abstract This study integrates seismic interpretation and 3D analogue experiments monitored by digital image correlation techniques to investigate the evolution of the salt structures and the related depositional systems in the Laurentian Basin offshore Atlantic Canada. During the late Triassic, a layer of more than 3 km thick salt was deposited locally in a set of interconnected rift half-grabens forming a 50–70 km wide evaporite basin in the northern part of the Scotian Basin salt provinces. High sediment input in the Jurassic and early Cretaceous mobilized the salt into complex salt tectonic features, which suggest four kinematic domains with: (1) salt welds and pillows; (2) extensional diapirs and canopies; (3) contractional diapirs and folds; and (4) allochthonous salt nappe. The landward grabens trapped most of the Early Jurassic sediments by passive downbuilding into the salt with local extension. The expelled salt has been evacuated basinwards into a large contractional salt massif. The rapid advance of the allochthonous nappe was coeval with the Late Jurassic extensional collapse of the inflated salt massif due to seaward sediment progradation. Late Cretaceous and Tertiary progradation over the salt nappe caused extensional deformation with growth faulting and formation of minibasins on the secondary salt detachment level.

The Transylvanian Basin is a mature hydrocarbon province of Romania characterized by two petroleum systems: Mesozoic (thermogenic) and Miocene (biogenic). An extensive outcrop-based sedimentological and micropaleontological study correlated to seismic and well data discusses the elements of the Miocene petroleum system. The facies associations are indicative of alluvial, fandelta, shallow- and deep-marine settings. These are grouped into four different depositional systems (evaporite, mud-carbonate, sand-mud and sand-gravel). Their evolution in time and space shows large differences between various parts of the basin that have important consequences for exploration.The Transylvanian gas is formed by more than 99% methane of bacterial origin. This is sourced by low quality (<1% TOC) deep-marine shales. The shales contain Type II and Type III kerogen. The organic material is thermally immature. The best source rocks were deposited during major transgressions in the central-eastern parts of the basin. In general, reservoir quality is the best (porosity < 20%, permeability < 1 D) in the basin center, where reservoirs are deep-marine turbidite sandstones. Lower quality reservoirs are conglomerate-rich slope channels and various shallow-marine sandstones located near the basin margins. The seals are formed by shales that hold gas columns of up to 60 m. The most common structural traps are in 4-way dip closures related to salt-cored folds. Their timing is coeval with the late (post-Pannonian) exhumation of the basin and strongly linked to coeval salt tectonics. This requires a late charge and migration.The largest traps typically have multistory (up to 20) pay zones with a total of 100 BCF to 1 TCF reserves. Exploration to date has focused on structural traps, but most of the obvious structures have been drilled. It is argued that significant exploration potential lies in stratigraphic plays, including confined submarine fans, slope channels, detached lowstand prograding wedges, incised valleys, diapir flanks, salt-tectonics related unconformities and various sub-volcanic plays. Risks of the petroleum system elements associated to these plays in different areas of the basin are discussed. (C) 2009 Elsevier Ltd. All rights reserved.

Scaled analogue experiments with layered brittle and ductile materials have been used to simulate the development of listric growth-fault and expulsion rollover systems during gravitational spreading of a passive margin sedimentary wedge detached on salt. The experiments were performed with varying sedimentation patterns and rates to simulate different depositional scenarios. Deformation monitoring with 3D optical image correlation techniques was used to quantify the 3D surface evolution and strain history of model structures. Our results indicate that rollover structure kinematics is strongly coupled to sedimentation patterns and rates. Whereas differential loading governs the margin-scale state of stress and extensional spreading in the experiments, more localized feedback between the dynamic depositional systems, fault-controlled subsidence, and salt mobilization control the strain history of local fault structures. This is reflected in the characteristic succession of extensional structures that evolve from symmetrical grabens through early, mature and late (collapsed) basinward listric growth-fault and rollover systems into landward listric growth-fault and rollover systems. A lack of sedimentation enhances reactive diapir rise and passive diapirism, whereas low sedimentation rates favour development of long-lived basinward listric growth-fault or expulsion rollover systems. Conversely, high sedimentation rates lead to the development of landward listric growth-fault and rollover systems.

The history of Middle to Late Miocene evolution of the Transylvanian Basin was determined by the bordering Carpathian orogen evolution, the tectonic events being well recorded by the sedimentary history. The basin evolved in a back-arc setting, under a regional, compressional stress field. The major tectonic events produced during the Late Sarmatian and Post-Pannonian were related to the reactivation of the pre-Badenian fault systems. The Transylvanian Basin got uplifted after the Late Pannonian (? during the Pliocene), and at least 500 m of sedimentary cover was eroded. Based on seismic and well-log interpretation, core and outcrop sedimentology, and microfauna, eight sequences were defined. The early Middle Miocene sequences are roughly synchronous to five 3rd order global sea-level cycles. Most of the recognized sequence boundaries are enhanced by regional tectonic events. The sedimentary evolution was also strongly influenced by salttectonics, active starting with the Late Sarmatian. Two sequences were identified in the Lower Badenian deposits. The third sequence (late Early Badenian to early Mid Badenian) preserves information about deeper shelf settings. The lowstand of the following sequence was responsible for the deposition of the salt formation (late Mid Badenian), an important lithostratigraphic marker in the sedimentary record of the basin. In general, the Upper Badenian deposits (parts of the 4th and 5th sequences) belong to deep marine submarine fan systems. The Sarmatian (partially 5th, 6th and partially 7th sequences) was characterized by diverse salinity conditions, stretching from brackish to hypersaline, and by high tectonic instability, which induced several significant relative sea-level falls. During that time, deltaic north) and fandeltaic (east) systems fed submarine fans, stacked between salt-related submarine heights (“channeled” deepmarine depocenters). Most of the Pannonian deposits (partially 7th and 8th sequences) belong to submarine fan systems, but shallower facies were also found in the western and eastern part of the basin.