Mygdonia Basin Research Articles

Bone modifications by the giant hyaena Pachycrocuta brevirostris on large-sized ungulate carcasses from the Lower Pleistocene site of Tsiotra Vryssi (Mygdonia Basin, Greece)

ABSTRACT The Early Pleistocene mammal communities of Europe are characterised by a great diversity of large carnivorans. Among them, the largest ever hyaenid, Pachycrocuta brevirostris, a fierce predator with great bone-cracking adaptations that has left its taphonomic signature on several fossiliferous sites. Here, we perform a rigorous taphonomic analysis focusing on bone surface modifications and damage patterns on large-sized ungulate bones from the site Tsiotra Vryssi (1.78 to ~1.5 Ma; Mygdonia Basin, Greece), aiming to identify the main biotic agent responsible for the modifications. Results reveal significant carnivore ravaging of the assemblage, and selective consumption of bones/bone portions related to nutrient value. Comparisons with modifications on similar-sized ungulate carcasses produced by extant and extinct predators, and similarities with Pachycrocuta-modified assemblages, indicate that Pachycrocuta was the principal agent of modification. Overall, this study not only provides taphonomic evidence for the interpretation of Tsiotra Vryssi, but also offers insights into the palaeobiology, and particularly carcass consumption behaviour of the giant hyaena. Hence, it advances our knowledge on carnivoran guild dynamics and prey–predator relationships during this epoch and has important implications for the investigations of the subsistence behaviour of the meat-eating hominins, who entered Eurasia at ~1.8 Ma, roughly synchronously with Pachycrocuta.

The new fossil site Krimni-3 in Mygdonia Basin and the first evidence of a giant ostrich in the Early Pleistocene of Greece

The new fossil site Krimni-3 in Mygdonia Basin and the first evidence of a giant ostrich in the Early Pleistocene of Greece

Active faults, Paleoseismological trenching and seismic hazard assessment in the Northern Mygdonia Basin, Northern Greece: The Assiros-Krithia fault and the Drimos fault zone

The Plio-Quaternary Mygdonia Basin in Northern Greece is bounded by active normal faults that can host significant earthquakes and produce considerable damage to the city of Thessaloniki (the second biggest city in Greece – 1 million population), located only 15–20 km away. In 1978, a damaging M = 6.5 earthquake occurred along a fault in the southern part of the basin, generating primary and secondary surface ruptures. This manuscript offers the results of the first detailed geomorphological and paleoseismological investigations in the northern part of the basin. As a result: i) a new active normal fault has been mapped, the Assiros-Krithia fault (AKF); and ii) another fault zone that has been assessed with probable activity in the literature, the Drimos fault zone (DFZ), has been confirmed active and mapped in detail. Paleoseismological trenching investigations supported by radiometric dating were carried out along both structures. The AKF and DFZ form the northern and northwestern boundaries of the Mygdonia Basin, respectively. The AKF deflects the local drainage network and is expressed as a single north dipping localised fault trace, gently uplifting the northern part of the Mygdonia Basin. The last event produced 48 cm of vertical displacement around 4540 cal. yrs BP, and the fault has an estimated slip rate of ∼0.1 mm/yr. The DFZ is an 8-10 km-long NW-SE trending normal fault that dips and downthrows to the NE (045o-050o). It is characterised by distributed deformation across eight major and secondary fault planes. Four of these planes have been activated over the last 9000 years, therefore the structure is Holocene active. The DFZ has an estimated slip rate of 0.1–0.3 mm/yr and may merged with the Liti-Gerakarou fault zone in multi-segment ruptures. The DFZ highlights that NW-SE trending faults are potentially active in Northern Greece. Their long recurrence intervals justify why they were not activated during the period covered by the historical record and emphasise, once again, the necessity of paleoseismological studies and the implementation of fault specific approaches in seismic hazard assessment.

Reconsidering the Equids from the Early Pleistocene Fauna of Apollonia 1 (Mygdonia Basin, Greece)

The remains of equids are abundant in the Early Pleistocene faunas of Greece. “Apollonia-1” is one of the richest localities from the latest Villafranchian, providing eight skulls, mandibular remains and plenty of postcranial material during several field campaigns. This study focuses mainly on the skulls, mandibular remains and metapodials from the old and new collection described in detail. The specimens are compared with equids from several Greek and European fossiliferous localities dating from the late Villafranchian to the middle Galerian. The systematic position of Equus apolloniensis is also discussed. Based on its basicranial proportions, E. apolloniensis is considered a true Equus. A second species has also been identified recently, here referred to as Equus sp.; it is poorly represented, and it is even larger and more robust than E. apolloniensis based on a single metacarpal and third phalanges. The presence of two equid species in Apollonia 1 validates its Epivillafranchian (=latest Villafranchian) age.

Dating of the Lower Pleistocene Vertebrate Site of Tsiotra Vryssi (Mygdonia Basin, Greece): Biochronology, Magnetostratigraphy, and Cosmogenic Radionuclides

Background and scope: The late Villafranchian large mammal age (~2.0–1.2 Ma) of the Early Pleistocene is a crucial interval of time for mammal/hominin migrations and faunal turnovers in western Eurasia. However, an accurate chronological framework for the Balkans and adjacent territories is still missing, preventing pan-European biogeographic correlations and schemes. In this article, we report the first detailed chronological scheme for the late Villafranchian of southeastern Europe through a comprehensive and multidisciplinary dating approach (biochronology, magnetostratigraphy, and cosmogenic radionuclides) of the recently discovered Lower Pleistocene vertebrate site Tsiotra Vryssi (TSR) in the Mygdonia Basin, Greece. Results: The minimum burial ages (1.88 ± 0.16 Ma, 2.10 ± 0.18 Ma, and 1.98 ± 0.18 Ma) provided by the method of cosmogenic radionuclides indicate that the normal magnetic polarity identified below the fossiliferous layer correlates to the Olduvai subchron (1.95–1.78 Ma; C2n). Therefore, an age younger than 1.78 Ma is indicated for the fossiliferous layer, which was deposited during reverse polarity chron C1r. These results are in agreement with the biochronological data, which further point to an upper age limit at ~1.5 Ma. Overall, an age between 1.78 and ~1.5 Ma (i.e., within the first part of the late Villafranchian) is proposed for the TSR fauna. Conclusions: Our results not only provide age constraints for the local mammal faunal succession, thus allowing for a better understanding of faunal changes within the same sedimentary basin, but also contribute to improving correlations on a broader scale, leading to more accurate biogeographic, palaeoecological, and taphonomic interpretations.

Regional tectonic model of Southern, Central part of the Mygdonian basin (Northern Greece) by applying 3D Transient Electromagnetic Modeling

This study aims to define the geotectonic characteristics of the Mygdonia basin by using 3D Transient Electromagnetic (TEM) technology. The Mygdonian basin is located between Volvi and Langada lakes around 45 km North-East of Thessaloniki city in northern Greece and presents very high seismicity. To define the tectonic regime of the area, a detailed electromagnetic survey was performed along with the geological and lithological study of the area. The TEM data were acquired using the TEM-FAST 48 instrument for 485 soundings in 159 locations. The 1-D and 2-D interpretation of the TEM data indicate the tectonic characteristics of the area. 3D modeling applied to TEM data highlighted the fracture zone in the investigated area. The geothermal field of Apollonia is also depicted. The results are validated with the previous EM (AMT, RMT, and MT) data acquired in the study area studies.

Mammuthus meridionalis (Nesti, 1825) from Apollonia-1 (Mygdonia Basin, Northern Greece) and its importance within the Early Pleistocene mammoth evolution in Europe

In the present article, we study the mammoth remains from the late Villafranchian (Early Pleistocene) locality Apollonia-1 (Mygdonia Basin, Northern Greece). The material consists of a hemi-mandible with the m3, isolated m3/M3 and a maxilla fragment with DP2-DP3. The mandibular and dental features permit their attribution to the southern mammoth Mammuthus meridionalis (Nesti, 1825). Yet, the dental features indicate an evolutionary stage somewhat more derived than the Upper Valdarno mammoth (beginning of late Villafranchian) in terms of the higher number of plates in the DP3 and the marginally higher hypsodonty index in the M3. This is also revealed by the application of a Principal Component Analysis, where several dental features are combined. Moreover, the relatively deep mandibular corpus is a derived feature. In these aspects, the Apollonia-1 sample fits better with corresponding specimens from European localities correlated to the second part of the late Villafranchian and the Epivillafranchian. From this period, two subspecies have been proposed from Western Europe: M. m. vestinus (Azzaroli inAmbrosetti, Azzaroli, Bonadonna & Follieri, 1972) from Italian localities correlated to the Farneta Faunal Unit and M. m. deperetiCoppens & Beden, 1982 from Saint-Prest (France). We propose that M. m. vestinus can be regarded a valid subspecies of the southern mammoth and that M. m. depereti is possibly a junior synonym. The results of this study are in agreement with the existing biochronological correlation of the Apollonia-1 fauna and further support the potential biostratigraphic significance of M. meridionalis within the Early Pleistocene, albeit conclusions based on limited/fragmentary sample should always be taken with caution.

Integrated Water Management Approach for Adaptation to Climate Change in Highly Water Stressed Basins

Adaptation aims at increasing the resilience of natural and human systems to current and future impacts of climate change. The main objective of the current research is to introduce an innovative methodological framework which can effectively assess adaptation measures in basins with severe water deficits by coupling hydrology, climate change and management scenarios, leading to accurate decision making. In this paper, both supply and demand adaptation measures were proposed in line with various regional, national and European policies in order to improve the severe water problem of the Mygdonia basin. The overexploitation of the surface water systems (Lakes Koronia and Volvi) and groundwater resources of the Mygdonia basin during the previous decades, along with the projected decrease of the future water availability, due to climate change, accentuate the need for concerted action towards adaption to climate change. The measures include the increase of a stream diversion towards Lake Koronia, the increase of the embankment elevation at the outfall point of Lake Volvi, the restructuring of crops and their combinations. The measures were examined in terms of their sustainability and effectiveness in the short-term (2020–2050) and long-term (2050–2080) future periods under the most reliable climatic model. The results indicate that the application of demand management measures is more efficient compared to supply oriented solutions for addressing the future water deficit of the Mygdonia water system. The combination of crop restructuring and the decrease of agricultural land proved to be the most efficient and sustainable solution.

Integrated hydrological modelling of surface water and groundwater under climate change: the case of the Mygdonia basin in Greece

Abstract Lakes Volvi and Koronia are located in the Mygdonia basin and constitute the second and fifth largest natural lakes in Greece, respectively. The lakes along with the Mygdonia basin aquifer have undergone severe quantitative and qualitative degradation, while Lake Koronia has been totally depleted in recent years. In this study, a fully integrated hydrological analysis of the Mygdonia basin for historical and future periods is carried out. Future climatic data were derived and analyzed from a Regional Climate Model, while the implications of climate change on the water balance of both lakes and the Mygdonia basin aquifer until 2100 were projected by developing a modelling system which includes coupled hydrological and hydraulic models, such as UTHBAL, MIKE SHE, MIKE HYDRO River and the MIKE HYDRO Basin. The results indicated that the precipitation is expected to decrease by 17%, the temperature to increase by 2.90 °C and as a result, the surface runoff is projected to decrease by 21% and the groundwater recharge to decrease by 38% in the Mygdonia basin at the end of the century. The above changes would have a direct negative impact on the Lakes Koronia and Volvi and the Mygdonia basin aquifer future water balance necessitating adaptation measures.

Mammuthus meridionalis from Apollonia-1 (Mygdonia Basin, Northern Greece) and its importance within the Early Pleistocene Mammoth Evolution in Europe

Mammuthus meridionalis from Apollonia-1 (Mygdonia Basin, Northern Greece) and its importance within the Early Pleistocene Mammoth Evolution in Europe

Recursive anisotropy: a spatial taphonomic study of the Early Pleistocene vertebrate assemblage of Tsiotra Vryssi, Mygdonia Basin, Greece

By applying advanced spatial statistical methods, spatial taphonomy complements the traditional taphonomic approach and enhances our understanding of biostratinomic and diagenetic processes. In this study, we elaborate on a specific aspect – spatial anisotropy – of taphonomic processes. We aim to unravel the taphonomic history of the Early Pleistocene vertebrate assemblage of Tsiotra Vryssi (Mygdonia Basin, Greece). Circular statistics are used for the fabric analysis of elongated elements; geostatistics (directional variograms), wavelet and point pattern analyses are applied for detecting anisotropy at the assemblage level. The anisotropy of magnetic susceptibility (AMS) of sedimentary magnetic minerals is also investigated. The results, integrated with preliminary remarks about the differential preservation of skeletal elements, sedimentological and micromorphological observations, suggest multiple dispersion events and recurrent spatial re‐arrangement of a lag, (peri)autochthonous assemblage, consistent with the cyclical lateral switching of a braided fluvial system. Furthermore, this study offers a contribution to the building of a spatial taphonomic referential framework for the interpretation of other fossil vertebrate assemblages, including archaeo‐palaeontological ones.

Compendium of data, source code and text associated with the publication: D. Giusti et al., "Recursive anisotropy: A spatial taphonomic study of the Early Pleistocene vertebrate assemblage of Tsiotra Vryssi, Mygdonia Basin, Greece"

Compendium of data, source code and text associated with the publication: D. Giusti et al., "Recursive anisotropy: A spatial taphonomic study of the Early Pleistocene vertebrate assemblage of Tsiotra Vryssi, Mygdonia Basin, Greece"

Early bison remains from Mygdonia Basin (Northern Greece)

The continuous enrichment of the European Pleistocene mammal fossil record leads inevitably to a comprehensive forthcoming review of the biogeographic and evolutionary history of bisons on the continent. New and revised data from the post-Olduvai (<1.8 Ma)-pre-Jaramillo (>1.0 Ma) time span of the Mygdonia basin (N. Greece), exposed here, indicate the presence of a small bison referred to as Bison cf. degiulii (Masini, Palombo & Rozzi, 2013) due to its similarities with the contemporaneous type material from the Italian Peninsula. A series of minor morphometrical changes detected across chronologically successive Mygdonia bison populations is interpreted as local adaptations to harsher environmental conditions. A re-evaluation of several morphological and biometrical features of the European early bison populations in comparison with later and extant taxa leads to the reconfirmation of some characters as taxonomically and phylogenetically important, while questioning others. The results allow recognizing B. degiulii as most likely member of the true bison clade Bison (Bison) Hamilton Smith, 1827 and reconsidering the current B. (Eobison) Flerov, 1972 concept. The data from Mygdonia basin and Northern Greece confirm the short co-occurrence of Bison Hamilton Smith, 1827 and Leptobos Rütimeyer, 1877-1878 in the Balkans and suggest the appearance of at least two bison lineages in Southern Europe between 1.7-1.5 Ma.

Extraction and Validation of Geomorphological Features from EU-DEM in The Vicinity of the Mygdonia Basin, Northern Greece

The European Union Digital Elevation Model (EU-DEM) is a relatively new, hybrid elevation product, principally based on SRTM DEM and ASTER GDEM data, but also on publically available Russian topographic maps for regions north of 60° N. More specifically, EU-DEM is a Digital Surface Model (DSM) over Europe from the Global Monitoring for Environment and Security (GMES) Reference Data Access (RDA) project - a realisation of the Copernicus (former GMES) programme, managed by the European Commission/DG Enterprise and Industry. Even if EU-DEM is indeed more reliable in terms of elevation accuracy than its constituents, it ought to be noted that it is not representative of the original elevation measurements, but is rather a secondary (mathematical) product. Therefore, for specific applications, such as those of geomorphological interest, artefacts may be induced. To this end, the purpose of this paper is to investigate the performance of EU-DEM for geomorphological applications and compare it against other available datasets, i.e. topographic maps and (almost) global DEMs such as SRTM, ASTER-GDEM and WorldDEM™. This initial investigation is carried out in Central Macedonia, Northern Greece, in the vicinity of the Mygdonia basin, which corresponds to an area of particular interest for several geoscience applications. This area has also been serving as a test site for the systematic validation of DEMs for more than a decade. Consequently, extensive elevation datasets and experience have been accumulated over the years, rendering the evaluation of new elevation products a coherent and useful exercise on a local to regional scale. In this context, relief classification, drainage basin delineation, slope and slope aspect, as well as extraction and classification of drainage network are performed and validated among the aforementioned elevation sources. The achieved results focus on qualitative and quantitative aspects of automatic geomorphological feature extraction from EU-DEM at a water basin level, with the use of Geographical Information Systems (GIS).

Revisiting Ursus etruscus (Carnivora, Mammalia) from the Early Pleistocene of Greece with description of new material

The Villafranchian ursids of Greece are scanty, represented by a few isolated teeth and bones. During our last field campaigns in the Mygdonia Basin (Macedonia, Greece) we discovered an almost complete cranium, as well as some cranial, dental and postcranial remains, which are presented in this article. The new material originates from the locality Tsiotra Vryssi (TSR), dated to the late Villafranchian (1.8–1.2 Ma). The specimens are described and compared with ursids from various European localities; their morphological characters and dimensions place it with Ursus etruscus Cuvier, 1823, while the dental features are most similar to the specimens from Pietrafitta (Italy). The TSR cranium was CT-scanned in order to create a 3D virtual model and study its internal anatomy. Its observed endocranial traits exhibit primitive conditions, confirming the basal position of U. etruscus among the Pleistocene European ursids. Most of these features are shared with U. arctos and clearly differ from U. deningeri and U. spelaeus. Finally, we provide a revision of the known Greek material of U. etruscus and the biostratigraphic distribution of the Miocene–Pleistocene ursids of Greece. The earliest secure appearance of Ursus etruscus in Greece is found in the locality Dafnero 1 (Western Macedonia), dated to the end of the middle Villafranchian at ∼2.0 Ma, whereas its probable last occurrence is known from the locality Apollonia 1 of the Mygdonia Basin, dated to the latest Villafranchian at ∼1.2 Ma.

STRESS EVOLUTION ONTO MAJOR FAULTS IN MYGDONIA BASIN

Stress transfer due to the coseismic slip of strong earthquakes, along with fault population characteristics, constitutes one of the most determinative factors for evaluating the occurrence of future events. The stress Coulomb (ΔCFF) evolutionary model in Mygdonia basin (N.Greece) is based on the coseismic changes of strong earthquakes (M≥6.0) from 1677 until 1978 and the tectonic loading expressed with slip rates along major faults. In the view of stress transfer mechanisms, ΔCFF is also calculated onto fault planes, along with the segmented fault zone from Thessaloniki to Gerakarou and N.Apollonia (TG-NAp FZ). Normal fault segments bound the basin from the south and currently compose the most active neotectonic zone. The association of the spatial distribution of seismicity (2000-2014) with the stress enhanced areas is also investigated. Results demonstrate that the earthquake locations are strongly influenced by the stress transfer from past strong earthquakes and their focal properties. Since the stress build-up occurs fast, results are discussed in terms of hazard assessment by defining potential locations for future events.

The web portal of the EUROSEISTEST strong ground motion database.

Strong motion data that have been recorded during the 20-years of operation of the permanent network of EUROSEISTEST (Mygdonia basin, Northern Greece) have been homogenized and organized in an easily accessible, via the web, database. The EUROSEISTEST web portal and the application server running underneath are based solely on free and open source software (F/OSS; MySQL v5.5; RubyOnRails,SAC, Gnuplot and numerous GNU supporting utilities). Its interface allows the user to easily search strong motion data from approximately 200 events and 26 strong motion stations using event-related, record-related or station-related criteria. Further investigation of the data is possible in a graphical environment which includesplots of processed and unprocessed acceleration waveforms, velocity and displacement time histories, amplitude Fourier and response spectra and spectrograms. A great effort was directed toward the inclusion of accurate and most updated earthquake metadata, as well as a wealth of stations related information such as geotechnicaland geophysical site characterization measurements, subsoil structure and site effects. Acceleration data can be easily downloaded in either SAC or ASCII format, while all stations metadata are also available to download.

Fault population recognition through microseismicity in Mygdonia region (northern Greece)

Seismicity in the area of Mygdonia basin (northern Greece) is lately characterized by a lack of strong events (M≥5.0) on the seismogenic faults known to have been repeatedly activated in the past. Only small to moderate magnitude earthquakes (M≤4.8) have occurred since 2000 in the area. Therefore, microseismicity is the only available information to be exploited for the identification of active faults and hazard assessment, since it may occur everywhere, as well as onto the major hazardous faults. Earthquakes recorded between 2000 and 2014 by the Hellenic Seismological Network were relocated by using the available P- and S-seismic wave arrivals in order to improve location accuracy. The VP /VS velocity ratio which was found equal to 1.78, along with station time delays, were all included in the Hypoinverse computer program. In the case of strong spatial or temporal clustering the HypoDD algorithm was employed for further improving location accuracy. The relocated seismicity was used to outline the geometrical properties of the local fault population and identify seismogenic faults deprived of a clear surface expression. Cross-sections made perpendicular to the main axis of the seismicity alignments, shed more light to the local fault network.

Two new vertebrate localities from the Early Pleistocene of Mygdonia Basin (Macedonia, Greece): Preliminary results

Two new vertebrate fossiliferous localities from the Pleistocene of the Mygdonia Basin (Macedonia, Greece), Tsiotra Vryssi (TSR) and Platanochori-1 (PLN), are presented in this article. TSR belongs to the Gerakarou Formation and its preliminary faunal list includes the corvid Corvus pliocaenus, the hyaenid Pachycrocuta brevirostris, the canid Canis etruscus, the rhinoceros Stephanorhinus sp., two species of Equus, the bovid Bison sp., the cervid Metacervocerus rhenanus and the giraffid Palaeotragus sp. PLN belongs to the Platanochori Formation (overlying Gerakarou Formation) and its fauna includes the following taxa: Stephanorhinus hundsheimensis, Equus apolloniensis, Bison sp. and Pontoceros ambiguus. The preliminary comparison of these faunal assemblages with the already known localities from the Mygdonia Basin and the wider region, combined with the geological data, suggest a Late Villafranchian age for TSR, chronologically intermediate between the localities Gerakarou-1 and Apollonia-1, while the fauna from PLN is indicative of a Latest Villafranchian age, similar to that of Apollonia-1. These new localities will enhance our understanding of the crucial time period of the earliest dispersal of hominins into Europe.

Three‐dimensional shallow structure from high‐frequency ambient noise tomography: New results for the Mygdonia basin‐Euroseistest area, northern Greece

AbstractWe examine the use of ambient noise cross‐correlation tomography for shallow site characterization using a modified two‐step approach. Initially, we extract Rayleigh wave traveltimes from correlation traces of vertical component seismic recordings from a local network installed in Mygdonia basin, northern Greece. The obtained Rayleigh wave traveltimes show significant spatial variability, as well as distance and frequency dependence due to the 3‐D structure of the area, dispersion, and anelastic attenuation effects. The traveltime data sets are inverted through a surface wave tomography approach to determine group velocity maps for each frequency. The proposed tomographic inversion involves the use of approximate Fresnel volumes and interfrequency smoothing constraints to stabilize the results. In the last step, we determine a final 3‐D velocity model using a node‐based Monte Carlo 1‐D dispersion curve inversion. The reliability of the final 3‐D velocity model is examined by spatial and depth resolution analysis, as well as by inversion for different model parameterizations. The obtained results are in very good agreement with previous findings from seismic and other geophysical methods. The new 3‐D VS model provides additional structural constraints for the shallow sediments and bedrock structure of the northern Mygdonia basin up to the depth of ∼200–250 m. Present work results suggest that the migration of ambient tomography techniques from large scales (tens or hundreds of km) to local scales (few hundred meters) is possible but cannot be used as a black box technique for 3‐D modeling and detailed geotechnical site characterization.