Detrital zircon and apatite constraints on depositional ages,sedimentation rates and provenance: Pliocene Productive Series,South Caspian Basin,Azerbaijan

We used detrital zircon U/Pb geochronology and apatite (U–Th–Sm)/He thermochronology to better constrain depositional ages and sedimentation rates for the Pliocene Productive Series in Azerbaijan. U/Pb analysis of 1,379 detrital zircon grains and (U–Th–Sm)/He analysis of 57 apatite grains—from Kirmaky Valley and Yasamal Valley onshore sections, Absheron Peninsula—yielded two distinct sub‐populations: “young” Neogene grains and “old” Mesozoic, Palaeozoic and Proterozoic/Archean grains. The large numbers of Neogene age grains (around 10% of all grain ages) provided a new absolute age constraint on the maximum depositional age of the Lower Productive Series of 4.0 Myr. These “young” Neogene zircon grains most likely originated from volcanic ash falls sourced from the Lesser Caucasus or Talesh Mountains. In this paper we propose a timescale scenario using the maximum depositional age of the Productive Series from detrital zircon grain U/Pb constraints. Potential consequences and limitations of using apatite (U–Th–Sm)/He dating method in estimating maximum depositional ages are also discussed. These new age constraints for the Lower Productive Series gave much faster sedimentation rates than previously estimated: 1.3 km/Myr in the South Caspian Basin margin outcrops and up to 3.9 km/Myr in the basin centre. The sedimentation rates are one of the highest in comparison to other sedimentary basins and coeval to global increase in sedimentation rates 2–4 Myr. The older group of detrital zircon grains constitutes the majority of grains in all sample sets (~80%). These older ages are inferred to reflect the provenance of the Productive Series sediment. This sediment is interpreted to have been derived from the Proterozoic and Archean crystalline basement rocks and Phanerozoic cover of the East European Craton, Proterozoic/Palaeozoic rocks of the Ural Mountains and Mesozoic sedimentary rocks of the Greater Caucasus. This sediment was likely supplied from northerly sourced drainage that emptied into the South Caspian Basin.     

Late Miocene to Pliocene stratigraphy of the Kura Basin,a subbasin of the South Caspian Basin: implications for the diachroneity of stage boundaries

Relative ages of late Cenozoic stratigraphy throughout the Caspian region are referenced to regional stages that are defined by changes in microfauna and associated extreme (>1000 m) variations in Caspian base level. However, the absolute ages of these stage boundaries may be significantly diachronous because many are based on the first occurrence of either transgressive or regressive facies, the temporal occurrence of which should depend on position within a basin. Here, we estimate the degree of diachroneity along the Akchagyl regional stage boundary within the Caspian basin system by presenting two late Miocene‐Pliocene aged measured sections, Sarica and Vashlovani, separated by 50 km and exposed within the Kura fold‐thrust belt in the interior of the Kura Basin. The Kura Basin is a western subbasin of the South Caspian Basin and the sections presented here are located >250 km from the modern Caspian coast. New U‐Pb detrital zircon ages from the Sarica section constrain the maximum depositional age for Productive Series strata, a lithostratigraphic package considered correlative with the 2–3 Myr‐long regional Eoakchagylian or Kimmerian stage that corresponds to a period of extremely low (>500 m below the modern level) Caspian base level. This new maximum depositional age from the Productive Series at Sarica of 2.5 ± 0.2 Ma indicates that the regionally extensive Akchagyl transgression, which ended the deposition of the Productive Series near the Caspian coast at 3.2 Ma, may have appeared a minimum of 0.5 Myr later in the northern interior of the Kura Basin than at the modern Caspian Sea coast. The results of this work have important implications for the tectonic and stratigraphic history of the region, suggesting that the initiation of the Plio‐Pleistocene Kura fold‐thrust belt may have not been as diachronous along strike as previously hypothesized. More generally, these results also provide a measure of the magnitude of diachroneity possible along sequence boundaries, particularly in isolated basins. Comparison of accumulation rates between units in the interior of the Kura subbasin and the South Caspian main basin suggest that extremely large variations in these rates within low‐stand deposits may be important in identifying the presence of subbasins in older stratigraphic packages.     

Structure and evolution of mass transport deposits in the South Caspian Basin,Azerbaijan

The Quaternary to late Pliocene sedimentary succession along the margin of the South Caspian Basin contains numerous kilometre‐scale submarine slope failures, which were sourced along the basin slope and from the inclined flanks of contemporaneous anticlines. This study uses three‐dimensional (3D) seismic reflection data to visualise the internal structure of 27 mass transport deposits and catalogues the syndepositional structures contained within them. These are used to interpret emplacement processes occurring during submarine slope failure. The deposits consist of three linked structural domains: extensional, translational and compressive, each containing characteristic structures. Novel features are present within the mass transport deposits: (1) a diverging retrogression of the headwall scarp; (2) the absence of a conventional headwall scarp around growth stratal pinch outs; (3) restraining bends in the lateral margin; (4) a downslope increase in the throw of thrust faults. The results of this study shed light on the deformation that occurred during submarine slope failure, and highlight an important geological process in the evolution of the South Caspian Basin margin.     

Provenance of the Lower Triassic Bunter Sandstone Formation: implications for distribution and architecture of aeolian vs. fluvial reservoirs in the North German Basin

Zircon U–Pb geochronometry, heavy mineral analyses and conventional seismic reflection data were used to interpret the provenance of the Lower Triassic Bunter Sandstone Formation. The succession was sampled in five Danish wells in the northern part of the North German Basin. The results show that sediment supply was mainly derived from the Ringkøbing‐Fyn High situated north of the basin and from the Variscan belt located south of the basin. Seismic reflection data document that the Ringkøbing‐Fyn High was a local barrier for sediment transport during the Early Triassic. Hence, the Fennoscandian Shield did not supply much sediment to the basin as opposed to what was previously believed. Sediment from the Variscan belt was transported by wind activity across the North German Basin when it was dried out during deposition of the aeolian part of the Volpriehausen Member (lower Bunter Sandstone). Fluvial sand was supplied from the Ringkøbing‐Fyn High to the basin during precipitation events which occurred most frequently when the Solling Member was deposited (upper Bunter Sandstone). Late Neoproterozoic to Carboniferous zircon ages predominate in the Volpriehausen Member where the dominant age population with a peak age of 337 Ma corresponds to the culmination of Variscan high‐grade metamorphism, whereas a secondary age population with a peak at 300 Ma matches the timing of volcanism and magmatism at the Carboniferous/Permian boundary in the northern Variscan belt. Parts of the basement in the Ringkøbing‐Fyn High were outcropping during the Early Triassic and zircon ages similar to this Mesoproterozoic basement are present in the Bunter Sandstone. The heavy mineral assemblage of the Solling Member is uniform and has a high garnet content compared to the contemporaneous sediments in the Norwegian‐Danish Basin and in the southern part of the North German Basin. This finding confirms that a local source in the Ringkøbing‐Fyn High supplied most of the fluvial sediment in the northern part of the North German Basin. The northernmost part of the Bunter Sandstone is situated on a platform area that is separated from the basin area by a broad WNW–ESE‐oriented fault zone. The most promising reservoir in the basin area is the aeolian Volpriehausen Member since the sandstone has a wide lateral distribution and a constant thickness. The alluvial to ephemeral fluvial Solling Member may be a good reservoir in the platform area and marginal basin area, but the complex sand‐body architecture makes it difficult to predict the reservoir quality.     

Neogene tectonostratigraphic history of the southern Neuquén basin (39°–40°30′S,Argentina): implications for foreland basin evolution

Although the Neuquén basin in Argentina forms a key transitional domain between the south‐central Andes and the Patagonian Andes, its Cenozoic history is poorly documented. We focus on the sedimentologic and tectonic evolution of the southern part of this basin, at 39–40°30′S, based on study of 14 sedimentary sections. We provide evidence that this basin underwent alternating erosion and deposition of reworked volcaniclastic material in continental and fluvial settings during the Neogene. In particular, basement uplift of the Sañico Massif, due to Late Miocene–Pliocene intensification of tectonic activity, led to sediment partitioning in the basin. During this interval, sedimentation was restricted to the internal domain and the Collon Cura basin evolved towards an endorheic intermontane basin. From stratigraphic interpretation, this basin remained isolated 7–11 Myr. Nevertheless, ephemeral gateways seem to have existed, because we observe a thin succession downstream of the Sañico Massif contemporaneous with the Collon Cura basin‐fill sequence. Comparisons of stratigraphic, paleoenvironmental and tectonic features of the southern Neuquén basin with other foreland basins of South America allow us to classify it as a broken foreland with the development of an intermontane basin from Late Miocene to Late Pliocene. This implies a thick‐skinned structural style for this basin, with reactivation of basement faults responsible for exhumation of the Sañico Massif. Comparison of several broken forelands of South America allows us to propose two categories of intermontane basins according to their structural setting: subsiding or uplifted basins, which has strong implications on their excavation histories.     

Tectonostratigraphic framework and depositional history of the deepwater Ulleung Basin,East Sea/Sea of Japan

The Ulleung Basin, East Sea/Japan Sea, is a Neogene back-arc basin and occupies a tectonically crucial zone under the influence of relative motions between Eurasian, Pacific and Philippine Sea plates. However, the link between tectonics and sedimentation remains poorly understood in the back-arc Ulleung Basin, as it does in many other back-arc basins as well, because of a paucity of seismic data and controversy over the tectonic history of the basin. This paper presents an integrated tectonostratigraphic and sedimentary evolution in the deepwater Ulleung Basin using 2D multichannel seismic reflection data. The sedimentary succession within the deepwater Ulleung Basin is divided into four second-order seismic megasequences (MS1 to MS4). Detailed seismic stratigraphy interpretation of the four megasequences suggests the depositional history of the deepwater Ulleung Basin occurred in four stages, controlled by tectonic movement, volcanism, and sea-level fluctuations. In Stage 1 (late Oligocene through early Miocene), syn-rift sediment supplied to the basin was restricted to the southern base-of-slope, whereas the northern distal part of the basin was dominated by volcanic sills and lava flows derived from initial rifting-related volcanism. In Stage 2 (late early Miocene through middle Miocene), volcanic extrusion occurred through post-rift, chain volcanism in the earliest time, followed by hemipelagic and turbidite sedimentation in a quiescent open marine setting. In Stage 3 (late middle Miocene through late Miocene), compressional activity was predominant throughout the Ulleung Basin, resulting in regional uplift and sub-aerial erosion/denudation of the southern shelf of the basin, which provided enormous volumes of sediment into the basin through mass transport processes. In Stage 4 (early Pliocene through present), although the degree of tectonic stress decreased significantly, mass movement was still generated by sea-level fluctuations as well as compressional tectonic movement, resulting in stacked mass transport deposits along the southern basin margin. We propose a new depositional history model for the deepwater Ulleung Basin and provide a window into understanding how tectonic, volcanic and eustatic interactions control sedimentation in back-arc basins.     

Hinterland basin development and infilling through tectonic and eustatic processes: latest Messinian‐Gelasian Valdelsa Basin,Northern Apennines,Italy

This article reports a stratigraphic and structural analysis of the Neogene‐Quaternary Valdelsa Basin (Central Italy), filled with up to 1000 m of uppermost Miocene to lower Pleistocene strata. The succession is subdivided into seven unconformity‐bounded stratigraphic units (synthems, or large‐scale depositional sequences) that include fluvio‐deltaic and shallow‐marine deposits. Structures related to basin shoulders and internal boundaries controlled the Neogene location and geometry of different depocentres. During the Tortonian‐Messinian, a buried NE‐trending high related to regional, basin‐transverse lineaments separated two adjacent sub‐basins. During the lower Pliocene, compressional displacement along NW‐trending, thrust‐related highs controlled the distribution of depocentres and dispersal of sediment. Extensional tectonics, although previously considered the dominant deformation style affecting the rear of the Northern Apennines since the late Miocene, is no longer considered a dominant control on tectono‐sedimentary development of the Valdelsa basin. Instead, the Valdelsa Basin shares features with continental hinterland basins of orogenic belts where compression, extension, and transcurrent stress fields determine a complex spatial and temporal record of accommodation and sediment supply. In the Valdelsa Basin tectonics and eustatic sea‐level fluctuations were dominant in forcing the deposition of sedimentary cycles at several scales. Zanclean and Gelasian large‐scale depositional sequences were mainly controlled by crustal shortening, whereas a eustatic signal was preferentially recorded during the Piacenzian. Smaller scale depositional sequences, common to most synthems, were controlled by orbitally forced glacio‐eustatic cycles.     

South Caspian Oil Fields: Onshore and Offshore Reservoir Properties

Original field data reports from the Azerbaijan sector of the South Caspian Basin have been used to compile statistical histograms of reservoir characteristics for both onshore and offshore oil fields. Two groups of statistics are presented here: the first group discusses reservoir thickness, areas, volumes, and horizon depths for the onshore and offshore fields; the second group discusses permeability, porosity, oil viscosity, oil recovery factor, reserves, and production for the onshore and offshore fields. These statistical distributions have been constructed so that one has available an historical database for use in assessing the range of likely reservoir characteristics in exploration ventures in this basin.     

Strike‐slip tectonics and basin inversion in the Western Mediterranean: the Post‐Messinian evolution of the Alboran Sea

A comprehensive interpretation of single and multichannel seismic reflection profiles integrated with biostratigraphical data and log information from nearby DSDP and ODP wells has been used to constrain the late Messinian to Quaternary basin evolution of the central part of the Alboran Sea Basin. We found that deformation is heterogeneously distributed in space and time and that three major shortening phases have affected the basin as a result of convergence between the Eurasian and African plates. During the Messinian salinity crisis, significant erosion and local subsidence resulted in the formation of small, isolated, basins with shallow marine and lacustrine sedimentation. The first shortening event occurred during the Early Pliocene (ca. 5.33–4.57 Ma) along the Alboran Ridge. This was followed by a major transgression that widened the basin and was accompanied by increased sediment accumulation rates. The second, and main, phase of shortening on the Alboran Ridge took place during the Late Pliocene (ca. 3.28–2.59 Ma) as a result of thrusting and folding which was accompanied by a change in the Eurasian/African plate convergence vector from NW‐SE to WNW‐ESE. This phase also caused uplift of the southern basins and right‐lateral transtension along the WNW‐ENE Yusuf fault zone. Deformation along the Yusuf and Alboran ridges continued during the early Pleistocene (ca. 1.81–1.19 Ma) and appears to continue at the present day together with the active NNE‐SSW trending Al‐Idrisi strike‐slip fault. The Alboran Sea Basin is a region of complex interplay between sediment supply from the surrounding Betic and Rif mountains and tectonics in a zone of transpression between the converging African and European plates. The partitioning of the deformation since the Pliocene, and the resulting subsidence and uplift in the basin was partially controlled by the inherited pre‐Messinian basin geometry.     

A three‐dimensional stratigraphic model for the Messinian crisis in the Pannonian Basin,eastern Hungary

A three‐dimensional quantitative stratigraphic forward model is employed to investigate the controls leading to the Messinian events in the lacustrine Pannonian Basin of Central Paratethys, and the link between the Messinian salinity crisis in the Mediterranean and the late Miocene‐Pliocene stratigraphy of the Pannonian Basin. Subsurface geological data show that a prominent unconformity surface formed during Messinian time in the Pannonian Basin associated with a sudden forced regression, abrupt basinward shift of facies and a subsequent, prolonged lowstand normal regression. The lowstand prograding series filled up the shallow basin fast, while, at the same time, the marginal areas of the basin were subject to tectonic inversion. The Dionisos program used in this research is built on a nonlinear water‐driven sediment diffusion process, and it employs multiple sediment classes, basin flexure and compaction. Four different scenarios were built in the experiments to test possible basin histories with different rates and timing of tectonic inversion. Each scenario was modelled in two versions: including and not including a lake‐level fall in the Messinian. The results confirm that the Pannonian Basin in the study area has undergone a tectonic inversion since the Messinian, although the exact rates of uplift at different locations remain uncertain. The unconformity and the observed stratigraphic architecture and facies pattern could be modelled adequately only in the versions that applied a Messinian lake‐level fall. Our research concludes that the Messinian unconformity in the Pannonian Basin was caused by an absolute lake‐level drop, likely linked to the desiccation of the Mediterranean, followed by subsidence and normal regression in the basin centre and concomitant tectonic inversion and uplift along the basin margins.     

The evolution of the high‐elevated depocenters of the northern Sierras Pampeanas (ca. 28˚ SL), Argentine broken foreland,South‐Central Andes: the Pipanaco Basin

The Pipanaco Basin, in the southern margin of the Andean Puna plateau at ca. 28°SL, is one of the largest and highest intermontane basins within the northernmost Argentine broken foreland. With a surface elevation >1000 m above sea level, this basin represents a strategic location to understand the subsidence and subsequent uplift history of high‐elevation depositional surfaces within the distal Andean foreland. However, the stratigraphic record of the Pipanaco Basin is almost entirely within the subsurface, and no geophysical surveys have been conducted in the region. A high‐resolution gravity study has been designed to understand the subsurface basin geometry. This study, together with stratigraphic correlations and flexural and backstripping analysis, suggests that the region was dominated by a regional subsidence episode of ca. 2 km during the Miocene‐Pliocene, followed by basement thrusting and ca. 1–1.5 km of sediment filling within restricted intermontane basin between the Pliocene‐Pleistocene. Based on the present‐day position of the basement top as well as the Neogene‐Present sediment thicknesses across the Sierras Pampeanas, which show slight variations along strike, sediment aggradation is not the most suitable process to account for the increase in the topographic level of the high‐elevation, close‐drainage basins of Argentina. The close correlation between the depth to basement and the mean surface elevations recorded in different swaths indicates that deep‐seated geodynamic process affected the northern Sierras Pampeanas. Seismic tomography, as well as a preliminary comparison between the isostatic and seismic Moho, suggests a buoyant lithosphere beneath the northern Sierras Pampeanas, which might have driven the long‐wavelength rise of this part of the broken foreland after the major phase of deposition in these Andean basins.     

Basin filling evolution of the central basins of Mallorca since the Pliocene

A new compilation of data from 436 drill cores using decompaction and backstripping techniques was used to reconstruct the basin filling history from the Pliocene until the present day in the Palma, Inca and Sa Pobla Basins on the island of Mallorca (Spain). Calcareous rocks dominate the source area and provide a limited amount of clastic input to the basins that has resulted in an average accumulation rate of between 5 and 20 m/Ma during the last 5.3 Ma. Carbonate sediment production dominated the basin filling history during early‐mid Pliocene, but during the Quaternary, the sedimentation processes in the Palma Basin were probably enhanced by an evolution in the drainage network that increased the sediment supply and the accumulated thickness caused by stream capture. However, the maximum sedimentation rate filling the depocentres of the three basins has been decreasing since the Pliocene, showing that not only the catchment transport efficiency but also the relative sea level have been controlling the sediment accumulation in these carbonate basins. The isopach cross‐sections support the idea that a palaeorelief was generated during the Messinian sea level drop and that heterogeneities were filled in from the Pliocene to the Quaternary. We conclude that the central basins of Mallorca were filled heterogeneously due to tectonic and geomorphic processes that controlled sediment transport and production, resulting in different average sedimentation thicknesses that decreased since the Pliocene as the accommodation space became filled and the relative sea level dropped.     

The Western Irish Namurian Basin reassessed

ABSTRACT Current basin models for the Western Irish Namurian Basin (WINB) envisage an elongate trough along the line of the present‐day Shannon Estuary that was infilled with clastic sediments derived from a hinterland that lay to the W or NW. This paper argues for an alternative basin configuration with source areas to the SW supplying sediment to a basin where deepest water conditions were in northern County Clare. Rapid subsidence along the present‐day Shannon Estuary ponded sediment in this area throughout the early Namurian and, only with the rapid increase of sedimentation rates within the mid‐Namurian (Kinderscoutian Stage), were substantial amounts of sediment able to prograde to the NE of the basin. This alternative model better explains the overwhelming predominance of NE‐directed palaeocurrents in the Namurian infill, but requires fundamental revisions to most aspects of current depositional models. Deep‐water black shales (Clare Shale Formation) initially accumulated throughout the region and were progressively downlapped by an unconfined turbidite system (Ross Formation) prograding to the NE. This in turn was succeeded by an unstable, siltstone‐dominated slope system (Gull Island Formation) characterized by large‐scale soft‐sediment deformation, which also prograded to the NE. In the northern‐most basin outcrops, in northern County Clare, this early phase of basin infill was developed as a condensed succession of radiolarian‐rich black shales, minor turbiditic sandstones and undisturbed siltstones. The new basin model envisages the northern exposures of County Clare to be a distal, basin floor succession whereas the traditional model considers it a relatively shallow, winnowed, basin margin succession. Later stages of basin infill consist of a series of deltaic cycles that culminate in major, erosive‐based sandstone bodies (e.g. Tullig Sandstone) interpreted either as axial, deltaic feeder channels or incised valley fills genetically unrelated to the underlying deltaic facies. Within the context of the new basin model the former alternative is most likely and estimated channel depths within the Tullig Sandstone indicate that the basal erosive surface could have been generated by intrinsic fluvial scour without recourse to base‐level fall. The northerly flowing Tullig channels pass down‐dip into isolated channel sandbodies interbedded with wave‐dominated strata that suggest the deltas of the WINB were considerably more wave‐influenced than hitherto proposed. The retreat of the Tullig delta during sea‐level rise saw the rapid southerly retrogradation of parasequences, as may be expected if the basin margin lay to the SW of the present‐day outcrops.     

Tectonic and oceanographic control of sedimentary patterns in a small oceanic basin: Dove Basin (Scotia Sea,Antarctica)

Dove Basin, a small oceanic domain located within the southern Scotia Sea, evidences a complex tectonic evolution linked to the development of the Scotia Arc. The basin also straddles the junction between the main Southern Ocean water masses: the Antarctic Circumpolar Current (ACC), the Southeast Pacific Deep Water (SPDW) and the Weddell Sea Deep Water (WSDW). Analysis of multichannel seismic reflection profiles, together with swath bathymetry data, reveals the main structure and sediment distribution of the basin, allowing a reconstruction of the tectonostratigraphic evolution of the basin and assessment of the main bottom water flows that influenced its depositional development. Sediment dispersed in the basin was largely influenced by gravity‐driven transport from adjacent continental margins, later modified by deep bottom currents. Sediments derived from melting icebergs and extensive ice sheets also contributed to a fraction of the basin deposits. We identify four stages in the basin evolution which – based on regional age assumptions – took place during the early Miocene, middle Miocene, late Miocene–early Pliocene and late Pliocene–Quaternary. The onsets of the ACC flow in Dove Basin during the early Miocene, the WSDW flow during the middle Miocene, and the SPDW during the late Miocene were influenced by tectonic events that facilitated the opening of new oceanic gateways in the region. The analysis of Dove Basin reveals that tectonics is a primary factor influencing its sedimentary stacking patterns, the structural development of new oceanic gateways permitting the inception of deep‐water flows that have since controlled the sedimentary processes.     

Stratigraphic evolution of the upper slope and shelf edge in the Karoo Basin, South Africa

The Permian Ecca Group of the Karoo Basin, South Africa preserves an extensive well-exposed siliciclastic basin floor, slope and shelf-edge delta succession. The Kookfontein Formation includes multiple sedimentary cycles that display clinoform geometries and are interpreted to represent the deposits of a slope to shelf succession. The succession exhibits progradational followed by aggradational stacking of deltaic cycles that is related to a change in shelf-edge trajectory, and lies within two depositional sequences. Sediment was transferred to the slope via overextension of deltas onto and over the shelf edge, resulting in failure and re-adjustment of local slope gradients. The depositional facies and architecture of the Kookfontein Formation record the change from a bypass- to accretion-dominated margin, which is interpreted to reflect a decrease in sediment transport efficiency as the slope gradient decreased, slope length increased and shelf-edge trajectory rose. During this time the delivery system changed from point-sourced basin-floor fans fed by slope channels to starved basin-floor with sand-rich slope clinoforms. This is an example of a progradational margin in which the younger slope system is interpreted to be of a different style to the older slope system that fed the underlying sand-rich basin floor fans.     

Effects of large sea‐level variations in connected basins: the Dacian–Black Sea system of the Eastern Paratethys

Sea‐level changes provide an important control on the interplay between accommodation space and sediment supply, in particular, for shallow‐water basins where the available space is limited. Sediment exchange between connected basins separated by a subaqueous sill (bathymetric threshold) is still not well understood. When sea‐level falls below the bathymetric level of this separating sill, the shallow‐water basin evolution is controlled by its erosion and rapid fill. Once this marginal basin is filled, the sedimentary depocenter shifts to the open marine basin (outward shift). With new accommodation space created during the subsequent sea‐level rise, sediment depocenter shifts backwards to the marginal basin (inward shift). This new conceptual model is tested here in the context of Late Miocene to Quaternary evolution of the open connection between Dacian and Black Sea basins. By the means of seismic sequence stratigraphic analysis of the Miocene‐Pliocene evolution of this Eastern Paratethys domain, this case study demonstrates these shifts in sedimentary depocenter between basins. An outward shift occurs with a delay that corresponds to the time required to fill the remaining accommodation space in the Dacian Basin below the sill that separates it from the Black Sea. This study provides novel insight on the amplitude and sedimentary geometry of the Messinian Salinity Crisis (MSC) event in the Black Sea. A large (1.3–1.7 km) sea‐level drop is demonstrated by quantifying coeval sedimentation patterns that change to mass‐flows and turbiditic deposits in the deep‐sea part of this main sink. The post‐MSC sediment routing continued into the present‐day pattern of Black Sea rivers discharge.     

GLACIER TRENDS IN THE CAUCASUS, 1960s TO 1980s

Records of terminus positions for the 1960s to 1980s have been obtained for 51 glaciers in the Greater Caucasus Mountains between the Black Sea and Caspian Sea, between latitude 40° and 44° N and longitude 40° and 49° E. These records have been analyzed as percentage of glaciers observed retreating, advancing, and stationary, displayed as a five-year moving average. The main result is the absence of the clear trend towards glacier advance found in the Alps between the 1960s and 1980s by both Patzelt (1985) and Wood (1988), suggesting a phase difference in the climates of the Alps and the Caucasus. [Key words: glaciers, glaciology, Greater Caucasus Mountains, Alps.]