We present a map that correlates tectonic units between Alps and western Turkey accompanied by a text providing access to literature data, explaining the concepts used for defining the mapped ...tectonic units, and first-order paleogeographic inferences. Along-strike similarities and differences of the Alpine-Eastern Mediterranean orogenic system are discussed. The map allows (1) for superimposing additional information, such as e.g., post-tectonic sedimentary basins, manifestations of magmatic activity, onto a coherent tectonic framework and (2) for outlining the major features of the Alpine-Eastern Mediterranean orogen. Dinarides-Hellenides, Anatolides and Taurides are orogens of opposite subduction polarity and direction of major transport with respect to Alps and Carpathians, and polarity switches across the Mid-Hungarian fault zone. The Dinarides-Hellenides-Taurides (and Apennines) consist of nappes detached from the Greater Adriatic continental margin during Cretaceous and Cenozoic orogeny. Internal units form composite nappes that passively carry ophiolites obducted in the latest Jurassic–earliest Cretaceous or during the Late Cretaceous on top of the Greater Adriatic margin successions. The ophiolites on top of composite nappes do not represent oceanic sutures zones, but root in the suture zones of Neotethys that formed after obduction. Suturing between Greater Adria and the northern and eastern Neotethys margin occupied by the Tisza and Dacia mega-units and the Pontides occurred in the latest Cretaceous along the Sava-İzmir-Ankara-Erzincan suture zones. The Rhodopian orogen is interpreted as a deep-crustal nappe stack formed in tandem with the Carpatho-Balkanides fold-thrust belt, now exposed in a giant core complex exhumed in late Eocene to Miocene times from below the Carpatho-Balkan orogen and the Circum-Rhodope unit. Its tectonic position is similar to that of the Sakarya unit of the Pontides. We infer that the Rhodope nappe stack formed due to north-directed thrusting. Both Rhodopes and Pontides are suspected to preserve the westernmost relics of the suture zone of Paleotethys.
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•Tectonic map correlates tectonic units between Alps and western Turkey.•Profiles visualize architecture of Alpine-eastern Mediterranean orogens.•Review provides overview of Alpine-type orogens across national boundaries.
The Dinarides fold-thrust belt on the Balkan Peninsula resulted from convergence between the Adriatic and Eurasian plates since Mid-Jurassic times. Under the Dinarides, S-wave receiver functions, ...P-wave tomographic models, and shear-wave splitting data show anomalously thin lithosphere overlying a short down-flexed slab geometry. This geometry suggests a delamination of Adriatic lithosphere. Here, we link the evolution of this continental convergence system to hitherto unreported sets of extensively uplifted Oligocene-Miocene (28-17 Ma) marine terraces preserved at elevations of up to 600 m along the Dinaric coastal range. River incision on either side of the Mediterranean-Black Sea drainage divide is comparable to the amounts of terrace uplift. The preservation of the uplifted terraces implies that the most External Dinarides did not experience substantial deformation other than surface uplift in the Neogene. These observations and the contemporaneous emplacement of igneous rocks (33-22 Ma) in the internal Dinarides suggest that the Oligo-Miocene orogen-wide uplift was driven by post-break-off delamination of the Adriatic lithospheric mantle, this was followed by isostatic readjustment of the remaining crust. Our study details how lithospheric delamination exerts an important control on crustal deformation and that its crustal signature and geomorphic imprint can be preserved for millions of years.
The Cenozoic foreland fold and thrust belt of the external Dinarides along the eastern shore of the Adriatic Sea shows an overall NW-SE structural strike that changes to E-W in its central part, ...between Zadar and Mostar. This change is associated with a dextrally transpressive zone, named Split-Karlovac Fault. Segments of this fault straddle the Eo-Oligocene flexural foreland basin system of the external Dinarides. Two balanced cross-sections across the northern and southern segments of this transverse fault zone document highly contrasting styles of deformation and amount of shortening. The northern segment across Velebit Mountain is characterized by a triangle structure with a minimum shortening of 44 km. This triangle structure is formed by a set of thick-skinned top-SW thrust duplexes, topped by a thin-skinned passive top-NE roof backthrust. By contrast, the southern segment, traversing north of Split, shows a thin-skinned top-SW to top-S directed nappe stack, associated with a minimum shortening of 127 km and rooting into a basal detachment in the Paleozoic basement.
To better understand parameters controlling these contrasting styles of deformation, we modelled the flexural response of the foreland lithosphere that provided the accommodation space for the Eocene to Oligocene syn-orogenic Promina Beds, a prevailingly carbonate-clastic and conglomerate-bearing sequence making a part of the foreland basin fill. Tectonic load exerted by the hinterland nappe stack was estimated using the two balanced cross-sections. Estimates of tectonic load allowed modelling the amount of flexural response that yielded depth and shape of the basin containing the Promina Beds. The best fitting modelling results provided additional confidence in the validity of the balanced cross-sections.
It is shown that shortening in the two structurally contrasting segments of the thick-skinned thrust belt were contemporaneous with dextral strike-slip along the thick-skinned Split-Karlovac Fault and coeval with sedimentation of the Promina Beds. We propose that the Velebit triangle structure acted as a back-stop that prevented the propagation of the deformation front towards the SW. Instead shortening was transferred along the Split-Karlovac Fault into the southern transect, where deformation propagated towards the foreland along a successively shallowing stepped detachment. The contrasting style of Eo-Oligocene deformation probably resulted from the interplay of Permo-Triassic evaporites with the reactivation of inherited Middle Triassic normal faults to both sides of the transpressive zone.
•Nappe stack vs. triangle structure in the external Dinarides fold and thrust belt.•Substantial along-strike difference of crustal shortening.•Effects of mechanically weak lithologies on the style of deformation.•Lithosphere deflection modelling in combination with balanced cross-sections.•Impacts of a transverse zone on the flexural foreland basin system geometry.
The External Dinarides fold-thrust belt formed during Mid-Eocene–Oligocene times by SW-propagating thrusting from the Internal Dinarides towards the Adriatic foreland. Although previously considered ...as structurally quite uniform, recent work reported along-strike contrasting deformation styles in two structural domains within this fold-thrust belt. The two areas with very contrasting deformation styles are separated by the N–S-striking dextral Split-Karlovac Fault, a 250 km long, transpressive transfer fault. The southeastern domain is characterized by a thin-skinned SW-vergent nappe stack in contrast to the northwestern domain, where a set of blind, thick-skinned top-SW thrust duplexes prevail underneath the passive NE-vergent backthrusts. To better understand why the External Dinarides underwent such contrasting along-strike deformation, we reconsidered a temporal and spatial along- and across-strike distribution of Paleo-Mesozoic lithofacies to both sides of the Split-Karlovac Fault and estimated the role of mechanical stratigraphy on deformation styles in this part of the fold-thrust belt. Therefore, we constructed a new 2D kinematic forward model in the western backthrust-dominated domain. Our best-fit forward-modelled balanced cross section across the central Velebit Mtn. portrays a 75 km wide triangle zone. This zone took up at least 47 km of shortening during Eo-Oligocene times. It comprises a set of thin-skinned NE-vergent backthrusts detached in the upper Paleozoic atop a SW-vergent thick-skinned antiformal stack detached in the lower Paleozoic Adriatic basement. The NE-vergent backthrusts likely nucleated at lateral facies boundaries related to extensional half grabens that locally formed during Middle Triassic and Late Jurassic passive margin extension. During the Eo-Oligocene folding and thrusting, the selective inversion of inherited Mesozoic half grabens boundary faults into the NE-vergent backthrusts in the northwestern domain led to the observed along-strike changes in the deformation style of the External Dinarides. A seismotectonic analysis of instrumentally recorded earthquakes suggests contrasting seismic behaviour along the central and southern Velebit transects within the northwestern structural domain. The central Velebit Mtn. triangle structure appears to currently accommodate dominantly strike-slip motion, with reverse faulting being confined to east of the Split-Karlovac Fault. In contrast, seismicity along the southern Velebit cross section appears to be confined to the structurally lowermost parts of the triangle zone and the foreland, while it´s structurally higher parts are less seismically active. Also, a predominance of reverse faulting along this transect suggests ongoing accommodation of shortening in this part. Our results indicate that both the variations in the mechanical stratigraphy and the pre-orogenic structural inheritance obtained during rifting and passive margin stages exert control on contractional structures within the External Dinarides, including the distribution of present-day seismicity.
The Southern Adriatic is recognized as one of the most seismically active regions of the Central Mediterranean. It hosted the strongest historically known and instrumentally recorded earthquakes in ...Croatia and Montenegro. We conducted a detailed study of algal rims and tidal notches along the Dubrovnik–Konavle coastal area, aimed to contribute in reconstruction of relative sea level (RSL) change, palaeoearthquakes and neotectonics during the last 4500 years. The RSL reconstruction based on high-resolution geochronology showed that the spatial variability of RSL change is largely controlled by local tectonics, leading generally to an alternation of periods of RSL rise and rapid falls caused by coseismic uplift events. During the interseismic periods RSL rose at rates from 1.03 to 0.7 mm/yr before AD, followed by a slowdown to ~0.43 mm/yr, and reaching ~1.3 mm/yr after 1850s. The only exception relates to a period of slow RSL drop probably related to the 3.2 ka cold event. Rapid RSL falls caused by coseismic uplift indicate the occurrence of several large-scale events during the 4th–6th centuries AD, the 800–1360 cal AD period, and in 1395, with hints of earlier events between 1395 cal BC and 565 cal AD. These instances correspond to either unknown or insufficiently documented earthquakes. Conversely, the earthquakes in 1520 and 1667 have been clearly identified. The most compelling evidence of coseismic uplift is associated with the 1667 Dubrovnik earthquake, with an estimated uplift of 40–60 ± 15 cm documented along 40 km of coastline. Analyses of multiple sites with the same high-resolution marker show that Holocene tectonic deformations vary along different fault segments with minimum uplift rates ranging from ~0.3 to ~0.9 mm/yr over ~1.5 ka. The main seismogenic source responsible for coseismic uplifts is attributed to the Dalmatian unit basal thrust and its NE-dipping splays at the Adria-Dinarides boundary.
•We provide the relative sea-level reconstruction based on 66 new sea-level index points.•We show significant variability of relative sea-level change due to local tectonic contributions.•New evidence of spatial effects of 1667 AD Dubrovnik earthquake is presented.•The Dalmatian unit basal thrust is a composite seismogenic source responsible for coastal uplifts.•Our data show relative sea-level drop related to 3.2 ka cold event well marked in the Mediterranean.
The seismicity of NW Croatia, seismically the most vulnerable part of the country is presented based on historical records and reanalysed and relocated earthquakes occurring after 1908. The improved ...picture of the distribution of seismicity shows consistent grouping of foci in space, mostly within eight epicentral areas. The database of fault-plane solutions has been considerably enlarged, and now lists 22 earthquakes. The earthquake mechanisms consistently reveal the subhorizontal to moderately dipping
P-axis, predominantly N–S directed in the central part of studied area, to NW–SE and NE–SW directed in the western and eastern parts, respectively. They indicate the prevalence of compressional tectonics with reverse faulting in the central part versus strike-slip motions in the western and eastern sectors. These data are in agreement with stress calculations and kinematics of Quaternary structures obtained by geological studies. The completeness of the catalogue, estimated by comparing the cumulative activity rate for a large number of subcatalogues to the reference, contemporary rate, exhibits large spatial heterogeneity. Taking this into account, we have computed and mapped the parameters of the frequency-magnitude recurrence relation (the
b-value and the activity rate).
Comprehensive glacial Quaternary studies involving geochronological methods, modelling of ice topography with the support of field geomorphological and geological data in the Balkan Peninsula are ...relatively scarce, although there is evidence of past glaciations in several mountain ranges. Here, we present research on the extent and timing of past glaciations on the northern Velebit Mt. in coastal Croatia and inferences of the climate during that time. Based on geomorphological and sedimentological evidence and using cosmogenic 36Cl surface exposure dating of moraine boulders, we provide an empirical reconstruction of past glaciers and compare this with the Parallel Ice Sheet Model (PISM) simulations under different palaeoclimate forcings. The dating results show that the northern Velebit glaciers reached their maximum extent during the last glacial cycle before the global Last Glacial Maximum (LGM). Maximum ice extent likely correlates with Marine Isotope Stage 5–4, although the exact timing cannot be determined at this point due to poorly known site- and time-specific denudation rates. Empirical reconstruction of the maximum extent suggests that the area covered by glaciers was ~116 km2. The-best fit PISM simulation indicates that the most likely palaeoclimate scenario for the glaciers of this size to form is a cooling of ~8 °C and a 10% reduction in precipitation from present-day levels. However, the best-fit simulation does not correctly model all mapped ice margins when changes in climatological parameters are applied uniformly across the model domain, potentially reflecting a different palaeoprecipitation pattern to today.
•The Northern Velebit glaciers reached their maximum extent before the global LGM.•The minimum moraine ages are 16.5 ± 1.6 ka, 52.6 ± 9.3 ka, 57.0 ± 11.0 ka and 94.0 ± 24.0 ka.•The maximum ice limit likely correlates with MIS 5–4.•The palaeoclimate was ~8 °C colder and ~10% drier than today.
New high-resolution relative sea-level (RSL) proxy data obtained from Lithophyllum rims in the Adriatic allow us to distinguish major local, regional and global RSL driving processes during the past ...two millennia. RSL change on the Elafiti islands in the Dubrovnik archipelago (Southern Adriatic) has been significantly affected by local tectonic contributions, which vary spatially and increase southeastwards from Jakljan to Grebeni. Consequently, the RSL change on northwestward islands, Jakljan and Šipan, is still dominantly driven by linear regional glacio-isostatic adjustment (GIA) processes estimated at ∼0.34 mm/yr. However, GIA effects are occasionally cancelled out by local, non-linear coseismic uplifts of small magnitude and by variations in the global mean sea level (GMSL). Thus the rapid fall in GMSL of 0.26 mm/yr offset the GIA effects between approximately ∼1000–1250 cal CE, resulting in temporal hiatuses in algal rim formation. After ∼1800 cal CE, GIA rates were significantly amplified by GMSL rise, which exceed 0.9 mm/yr at Jakljan and Šipan and goes up to 1.4 mm/yr at Koločep and Grebeni, confirming the acceleration of RSL rise over the past two hundred years.
The new GMSL records from the northern and southern Adriatic, allow us to reconstruct the first high-resolution GMSL curve for the Adriatic. We show that GMSL variability is in-phase with solar activity during the last two millennia, acting on cycles of ∼350, 220 and 100-yrs. We also show that increased GMSL fall, which stopped the formation of algal rims around ∼1000 and ∼1600 cal CE, coincides with the global reduction in radiative forcing associated with the Oort and Maunder minima, with a drop in sea surface temperature (SST) and with increased salinity. Thus, our analyses revealed a consistent periodicity between the Adriatic GMSL signal, solar forcing, SST and salinity, with the most important cycle being the 350-year Great Solar Cycle.
•We provide first data on global mean sea level (GMSL) variation in the Adriatic.•GMSL signal phases with solar forcing, sea surface temperature (SST) and salinity.•Rapid GMSL drop cancelled out GIA rates and temporarily stopped algal rim formation.•Local tectonic contributions in the Dubrovnik archipelago progress southeastwards.•Coseismic uplift rate at Elafiti in last 1.6 ka varies from 0.1 to 0.2 to 0.6–0.8 mm/yr.
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