Mehmet Cemal Göncüoğlu

Stratigraphy, correlations and palaeogeography of Palaeozoic terranes of Bulgaria and NW Turkey: a review of recent data

Abstract Within the Alpine tectonic units SE of the European Variscan Orogenic Belt in Bulgaria and NW Turkey several crustal blocks are identified. Although their contact relations with surrounding units are obscured by Alpine events, the differences in the succession of events, stratigraphy, sedimentology and palaeobiogeographical distribution within them permits recognition of the Moesian, Balkan, Istanbul and Zonguldak Terranes. The Moesian terrane corresponds to the pre-Variscan Palaeozoic and Neoproterozoic rocks of the Moesian microplate in north Bulgaria and south Romania. The Balkan Terrane in Bulgaria incorporates Neoproteozoic and Palaeozoic sequences in the Western Balkanides (part of the Carpathian-Balkan orogen) and another three allochthonous units (Kraishte, Central Balkanides and Strandzhides). In NW Anatolia in Turkey, the Caledonian basement and Ordovician to Carboniferous sedimentary succession are divided into the Istanbul Terrane and the Zonguldak Terrane. With the exception of the Moesian Terrane in the Bulgarian area, they all comprise a Cadomian basement with relicts of oceanic lithosphere, volcanic arc and a continental crust of unknown affinity. Based on characteristic features within their Palaeozoic successions, there terranes are correlated with the main terrane assemblages in Central and Eastern Europe. It is suggested that they all are of peri-Gondwanan origin but behaved independently while drifting towards Laurussia. During the Early Devonian the Zonguldak Terrane docked to Baltica, whereas the others were still at similar palaeolatitudes to the Central European terranes (e.g. Saxo-Thuringian). This was followed by the successive accretion of the Moesian Terrane to Laurussia along the Rhenohercynian suture at the end of Devonian-Early Carboniferous and of the Balkan and Istanbul Terranes the Early and Late Carboniferous.

Petrogenesis and geodynamic evolution of the Late Neoproterozoic post-collisional felsic magmatism in NE Afyon area, western central Turkey

Abstract In western Turkey, Late Neoproterozoic basement rocks are represented by variably deformed metasedimentary and meta-igneous rocks within different tectonostratigraphical units that make up the Alpine Tauride–Anatolide Platform. In the Kütahya–Bolkar Dagı unit to the NE of Afyon this basement mainly includes garnet-bearing mica schists intruded by metamorphic granitic rocks with relict porphyritic textures. The youngest zircon ages obtained from the granitic rocks by the single zircon evaporation method are 542±5.0 Ma on average, which correlate with the Late Pan-African–Cadomian granitic magmatism. The granitic rocks are rhyodacitic or dacitic and peraluminous in composition, and display geochemical characteristics of I-type (tonalite–trondhjemite–granodiorite (TTG) source) felsic intrusive rocks. Trace and rare earth element patterns with distinct depletion in Rb, K, Nb, Sr, P and Ti relative to the other trace elements correlate very well with a Proterozoic TTG source. The petrogenetic modelling also implies that they were developed by partial melting of a TTG source by 20% fractional melting plus 20% Rayleigh fractional crystallization. The emplacement temperatures estimated by using zircon (790–820 °C), apatite and monazite saturation thermometry are about 827–1035 °C; these are in accordance with I-type rather than S-type granite melts. A geochemical comparison of the NE Afyon granitic rocks with the coeval quartz-porphyries in the Sandikli area of the Geyik Dag tectonic unit suggests that the latter may represent the more evolved felsic part of the Cadomian magmatism. Hence, both basement complexes are parts of the same Gondwanan terrane and represent the eastern continuation of the North African–Southern European terrane assemblage.

The geodynamic evolution of the Intra-Pontide suture zone, Central Turkey: evidence from the ophiolite bearing Arkot Dağ Mélange

Lucchi, Renata G. ... et. al.-- 87° Congresso della Societa Geologica Italiana e 90° Congresso della Societa Italiana di Mineralogia e Petrologia, The Future of the Italian Geosciences - The Italian Geosciences of the Future, 10-12 September 2014, Milan, Italy.-- 1 pageThe Montellina Spring (370 m a.s.l.) represents an example of groundwater resource in mountain region. It is a significant source of drinking water located in the right side of the Dora Baltea Valley (Northwestern Italy), SW of Quincinetto town. This spring shows a morphological location along a ridge, 400 m from the Renanchio Torrent in the lower sector of the slope. The spring was investigated using various methodologies as geological survey, supported by photo interpretation, structural reconstruction, NaCl and fluorescent tracer tests, discharge measurements. This multidisciplinary approach, necessary due to the complex geological setting, is required for the importance of the Montellina Spring. It is interesting in the hydrogeological context of Western Alps for its high discharge, relatively constant over time (average 150 l/s), and for its location outside a fluvial incision and suspended about 40 m above the Dora Baltea valley floor (Lasagna et al. 2013). According to the geological setting, the hydrogeological reconstruction of the area suggests that the large amount of groundwater in the basin is essentially favoured by a highly fractured bedrock, covered by wide and thick bodies of glacial and gravitational sediments. The emergence of the water along the slope, in the Montellina Spring, is essentially due to a change of permeability between the deep bedrock and the shallow bedrock and/or surficial sediments. The deep bedrock, showing closed fractures and/or fractures filled by glacial deposits, is slightly permeable. The shallow bedrock, strongly loosened as result of gravitational phenomena, and the local gravitational sediments are, on the contrary, highly permeable. The concentration of water at the spring is due to several reasons. a) The spring is immediately downward a detachment niche, dipping towards the spring, that essentially drains the water connected to the change of permeability in the bedrock. b) It is along an important fracture, that carries a part of the losses of the Renanchio Torrent. c) Finally, it is favored by the visible and buried morphology. Although it is located along a ridge, the spring occurs in a small depression between a moraine and a landslide body. It also can be favored by the likely concave trend of buried base of the landslide. At last, tracer tests of the Renanchio Torrent water with fluorescent tracer are performed, with a continuous monitoring in the Montellina Spring. The surveys permit to verify and quantify the spring and torrent hydrogeological relationship, suggesting that only a small fraction of stream losses feeds the spring.