THE CALLOVIAN UNCONFORMITY AND THE OPHIOLITE OBDUCTION ONTO THE PELAGONIAN CARBONATE PLATFORM OF THE INTERNAL HELLENIDES

The carbonate-platform-complex and the oceanic formations of the central Pelagonian zone of the Hellenides evolved in response to a sequence of plate tectonic episodes of ocean spreading, plate convergence and ophiolite obduction. The biostratigraphies of the carbonate platform and the oceanic successions, show that the Triassic-Early Jurassic platform was coeval with an ocean where pillow basalts and radiolarian cherts were being deposited. After convergence began during late Early- Jurassic - Middle Jurassic time, the oceanic leading edge of the Pelagonian plate was subducted beneath the leading edge of the oceanic, overriding plate. The platform subsided while a supra-subduction, volcanic-island-arc evolved. Biostratigraphic and geochemical evidence shows that the platform and the oceanic floor, temporarily became subaerially exposed during Callovian time. This “Callovian event” is suggested to have taken place as oceanic lithosphere first made compressional, tectonic contact with the carbonate platform, initiating a basal detachment fault, along which the platform was thrust upwards. The central Pelagonian zone became an extensive land area that was supplied with laterite from an ophiolite highland. A similar emergence of Vardar ophiolite most likely took place in the Guevgueli area. The Callovian emergence shows that the initial ophiolite obduction onto the platform took place about 25 million years before the final emplacement of the ophiolite during Valanginian time

Erratum to: Stratigraphy and tectonics of a time-transgressive ophiolite obduction onto the eastern margin of the Pelagonian platform from Late Bathonian until Valanginian time, exemplified in northern Evvoia, Greece

The obduction of an ophiolite sheet onto the eastern Pelagonian carbonate-platform-complex of the Hellenides began during the late Bathonian and ended with the final emplacement of the ophiolite during Valanginian time. The early stages of obduction caused sub-aerial exposure of the platform, recorded by an unconformity of Callovian age, which is marked by laterites overlying folded and faulted, karstic substrates. The laterites have distinct ophiolitic geochemical-signatures, indicating that emergent ophiolite had been undergoing lateritic weathering. This unconformity coincides with widespread western-Tethyan, Callovian gaps, indicating that the obduction in the Hellenides was probably related to far-reaching plate-tectonic processes. Resumed gravitational pull and rollback of the subducted, oceanic leading edge of the Pelagonian plate presumably initiated the early Oxfordian transgression of shallow marine carbonates and the inundation of the temporarily exposed ophiolite. Platform drowning continued into Tithonian–Valanginian time, documented initially by reefal carbonates and then by below-CCD, carbonate-free radiolarian cherts and shales. Subsequently, siliciclastic turbidites, which apparently originated from uplifted Variscan basement, were deposited together with and over the radiolarite as the ophiolite nappe-sheet advanced. The nappe substrate underwent tectonic deformations of varying intensity while, polymictic mélange and syn-tectonic sedimentary debris accreted beneath the ophiolite and at the nappe-front. The provenience of the ophiolite-nappe-complexes of northern Evvoia most probably has to be looked for in the Vardar ocean

Geoscience teaching and student interest in secondary schools-preliminary results from an interest research in Greece, Spain and Italy

The results of a topic-interest study on geosciences among 14- to 17-year-old school students are reported. The research was organized in the framework of the European project Geoschools to investigate the interest of students in the context of teaching strategies for geosciences in secondary schools. A questionnaire was designed as the main data-collection tool, based on the results of a comparison on geosciences curricula among the five European countries (Austria, Greece, Portugal, Italy, and Spain) which are the partners in the GEOschools project. The present study focuses on results from Greece and Spain but also includes preliminary results from Italy, for comparison purposes. Questionnaires were distributed in 20 schools (through 20 teachers with around 600 students) in each participating country. Specifically, a sample of 554, 14- to 15-year-old students were surveyed in 20 schools across Greece, a sample of 155, 14- to 17-year-old students was surveyed in seven schools in Aragón (Spain), and a sample of 624, 14- and 16-year-old children was surveyed in 11 schools in Sicily (Italy) to identify their main topics of interest in geosciences. Additional surveys in Spain in Castilla-La Mancha (Guadalajara), Madrid, Catalonia, and in the province of Gerona (134 students, 14–17 years old) and from Portugal (284 students) are still in the process of evaluation. Results indicate that the most attractive topics for children are Natural Hazards and Palaeontology. Teaching strategies also raise interest. Children from Spain generally show less interest in geosciences than do children of the same age from Greece. A discussion on the high educational potential of geological heritage is included, providing clear case examples for showing geological problems. © The European Association for Conservation of the Geological Heritage 2013