Bulletin of the Mineral Research and Exploration (BMRE)
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WHOLE ROCK GEOCHEMISTRY AND TECTONIC SETTING OF JURASSIC AGED LISAR GRANITE, TALESH MOUNTAINS, NORTH IRAN
No full textThe Late Jurassic aged Lisar granite in North Iran is in tectonic contact of the form of thrust and strike slip faults with Upper Cretaceous sandy limestone and is covered by Paleogene polygenetic conglomerate in the Talesh Mountain at the western continuation of the Alborz range. The rock samples of the granite are pink coloured and coarse-gained with K-feldspar, quartz, plagioclase, biotite and amphibole. The Lisar granite is more likely emplaced in an extensional environment indicated with numerous space filling silica-rich aplitic veins in the rocks. The granite samples are moderately altered and feldspars are changed to sericite and clay minerals and biotite is partially converted to chlorite. The Lisar granite has derived from a high K magma and is A-type in nature, belonging to A2 subgroup. The rock samples of granite are characterized by distinct negative Eu anomaly and a decrease from LREE to HREE contents. The parental melts of the granite were generated from partial melting of a lower continental crustal source with possible contribution from the mantle materials. The Lisar granite represents Cimmerian post-collision magmatism in north Iran following closure of Palaeotethys Ocean and subsequent collision.
DOI: 10.19111/bulletinofmre.33649
MOLLUSCAN ASSEMBLAGE AND PALEOECOLOGY OF LOWER MIOCENE SEQUENCES OF THE MUNZUR MOUNTAINS (EASTERN ANATOLIA, TURKEY)
No full textThe research subject is the Miocene aged units that located in the Munzur Mountains at the Ovacik district of Tunceli province. There is a continued sediment deposits from Paleozoic to Cenozoic at the Munzur Mountains. The neritic limestones of the Miocene Başpınar Formation outcropping in the Ovacık district are rich in fossil groups of gastropods and bivalves. In this study, 336 samples from the Başpınar Formation have been evaluated. Seven species of Gastropoda (Globularia carlei, Granulolabium plicatum, Granulolabium (Tiaracerithium) thiarella, Tympanotonus margaritaceus, Terebralia subcorrugata, Nassarius erunalae, Cerithium vulgatum,) and four species of Bivalvia (Cardita rusticana, Anadara aquitanica, Cubitostrea digitalina, Ostrea lamellosa) were identified. One more species of Bivalvia was identified by using open nomenclature (Chlamys sp.). The studied fossil assemblage of the Başpınar Formation indicates a Lower Miocene. Furthermore, for the first time in this study, paleoecological species diversity is calculated by using the Simpson, Shannon-Wiener, Epilou and Margalef indices for the locations where the fossils were collected. Numerical results are obtained by comparing bivalves and gastropods. According to these results, the Gastropoda specimens shows that the more dominancy (Simpson index D = 0,82), the more species diversity (Shannon-Wiener index H = 2,53) and the higher species richness (Margalef index M = 1,23) than the Bivalvia specimens. The Epilou index value (Ep = 0,9) gives the result that the species numbers in the gastropods are approximately equal to each other. DOI: 10.19111/bulletinofmre.33424
STRUCTURAL FEATURES OF THE NİĞDE MASSİF İN THE ÇAMARDI (NİĞDE) DİSTRİCT
No full textIn the Çamardı (Niğde) region, Niğde Massif is composed of Palaeozoic-Mesozoic marble, gneiss and quartzite. The high-grade metamorphic rocks of the Massif are cut by Cretaceous granodiorites. These rocks are unconformably overlain by Paleocene-Eocene low-grade metamorphic rocks. Upper Cretaceous-Eocene flysch and island-arc type volcanic rocks tectonically overlie the above mentioned units. The youngest rocks in the area are Oligocene-Quaternary continental sedimentary and volcanic rocks. The rocks of the massif have been subjected to at least four ductile deformational events, that are designated as D1, D2, D3 and D4. The first phase of deformation produced recumbent isoclinal folds (F1-F2 folding) which are often intrafolial and rootless, and pervasive axial-planar foliation. Bedding in the metasedimentary rocks of the massif is almost completely transposed into S1-foliation. D2 event generated northeast-southwest trending and variably plunging folds (F3 folding) on the map scale. The superposition of F3 folds over the F1-F2 folds generated Type-2 mushroom fold interference patterns. The second generation inclined folds (F2) are very tight to isoclinal and generally asymmetric. D3- event formed a large dome structure, possibly related to the granodioritic intrusions in the studied area. D4-event is characterised by northwest-southeast trending and southeast plunging map scale synformal and antiformal folds. During the D4-event both the rocks of massif and its Paleocene-Eocene cover rocks are folded (F5- folding). High competency contrast of the lithologies existing across the boundary between the massif and the cover during F5- folding has led to the formation of map scale cuspate-lobate folds. Microscopic observations have shown that the cover rocks of the massif are metamorphosed under the very low grade metamorphic conditions and gained cleaved structures, during the D4-event
THE GEOLOGICAL EVOLUTION OF SORGUN (YOZGAT)-YILDIZELİ (SİVAS) FORELAND BASIN, PETROGRAPHIC, GEOCHEMICAL ASPECTS AND GEOCHRONOLOGY OF VOLCANISM AFFECTING THE BASIN
No full textSorgun-Yıldızeli basin is an east-west trending asymmetric marginal foreland (peripheral foreland basin) formed as a result of the consumption of oceanic crust of the northern branch of Neotethys due to the collision of Sakarya continent in the north and Kırşehir Block in the south. It provides much information about the geodynamic evolution of the region. The basement of the study area consists of Late Palaeozoic-Mesozoic Akdağmadeni Massif. Akdağmadeni Massif was intruded by Cenomanian-Maastrichtian granitoids and is overlain tectonically by Late Cretaceous Artovaophiolitic melange within the İzmir-Ankara-Erzincan suture zone and by Cenomanian-Maastrichtian Darmik Formation. The volcano-sedimentary sequence deposited in Sorgun-Yıldızeli foreland basin developed on the relicts of the İzmir-Ankara-Erzincan Suture Zone along the northern margin of Kırşehir Block and was named the Boğazköy Formation. The pelitic, clastic and coarse clastic levels of Upper Palaeocene-Middle Eocene Boğazköy Formation including İzmir-Ankara-Erzincan Suture Zone slices and olistostromes are differentiated as the Dolak member. Toward the inner part of the basin, a turbiditic sequence of conglomerate, sandstone, claystone including rare limestone beds was deposited, consisting of conglomerate, sandstone, claystone, rarely limestone and alternations of three different volcanic rocks (acidic, basic and intermediate) related to subduction and/or collision. Calc-alkaline lava and pyroclastics of basaltic and basalt-andesite composition were differentiated as the Pazarcık volcanic member, with lava and pyroclastics of dacitic and rhyolitic composition called the Sarayözü volcanic member and calc-alkaline lava and pyroclastics of andesitic, trachyandesitic and dacitic composition called Kiremitlik volcanic member in Sorgun-Yıldızeli basin. According to the 40Ar/39Ar geochronologic method, the ages of 57.2±2.0 Ma and 56.7±1.8 Ma were obtained for Pazarcık volcanics, 48.8±1.5 Ma for Sarayözü volcanics and 45.1±1.3 Ma and 47.3±0.6 Ma for Kiremitlik volcanics. The reefal limestones which are not thick and occur in higher parts of the Boğazköy Formation were called the Limestone member. The uppermost section of the sequence which consists of generally clastic and coarse clastics is named the Konacı member. When the sedimentation and volcanism continued in the basin, gabbroic intrusions occurred as sills and laccoliths cutting the Boğazköy Formation. These gabbroic rocks were named the Yaycılar Gabbro. The age of 51.0 ± 0.7 Ma was found for the Yaycılar Gabbro with the 40Ar/39Ar geochronologic method. As a result of slab breakoff, the relicts of the consumed oceanic crust and the released massif were uplifted rapidly and the units of Middle-Late Eocene Tokuş Formation were deposited transgressively on the Boğazköy Formation and on outcropping basement rocks in the basin which was controlled by an extensional tectonic regime. Upper Miocene-Pliocene (İncesu Formation), Pliocene and Quaternary terrestrial sediments were deposited unconformably on all older units
WHEN DID THE PLATE TECTONICS BEGIN? THE INCEPTION OF PLATE TECTONICS BASED ON THE EXISTENCE OF KOMATIITES AND THEIR MgO VARIATIONS
No full textThe geoscientists have always wondered what evolutionary processes the Early Earth went through until it reached today. The beginning of the plate tectonics poses another matter of debate in these processes. Yet, the debates on when the plate tectonics began have not been resolved. In this sense, especially the lack of records regarding the period of time before the Cambrian Era is considered the biggest obstacle against resolution of these debates. The geoscientists have befitted from various methods to come up with different proposals about the beginning of the plate tectonics. The most notable rock type among the ones produced by the mantle is the komatiites. While the oldest datable komatiite is 3.82 Ga; the youngest is 0.86 Ga. With the high content of magnesium they contain, their special texture and the geological setting, the komatiites are not similar to any other rock groups which can currently be examined. Though they were produced in different geological times, no up - to - date forms of these rocks have been observed. Given the formation conditions of komatiites, recorded time intervals and the content of magnesium they contain, they might indicate when the plate tectonics began. DOI: 10.19111/bulletinofmre.31422
ALTERATION ZONES ASSOCIATED WITH EOCENE MAGMATISM IN THE OLUR (ERZURUM) AREA, EASTERN PONTIDES AND THEIR SIGNIFICANCE
No full textThe Alpine Orogenic Belt with numerous porphyry Cu-Mo-Au mineralizations, starts from Eastern Europe continues through Turkey and the Caucasus and extends into Iran and Afghanistan. The study area of the Eastern Pontides is in this orogenic belt. Using fi eld and laboratory studies an attempt has been made to establish the origin of Yeşilbağlar, Kaban and Köprübaşı alteration zones in the Olur area (Erzurum). In the study area Early Eocene Coşkunlar volcanics and sub volcanic rocks have contact with the Oltu çayı volcanics of Early-Middle Jurassic. Alteration in the study area effects these Oltuçayı and Kaban volcanics. In the study area mineralizations are present in the alteration zones. Disseminated, stockwork, vein/veinlet and fi ssure type mineralizations are present in the Coşkunlar dacite. Paragenesis in the alteration zones are pyrite, chalcopyrite, sphalerite, galena, pyrrohotite, quartz, calcite and barite. FT-IR and XRD studies showed the presence of clay, sulphate, sulphur, carbonate, silicate and oxide minerals in the alteration zones. Field and petrographical studies showed that alteration types in the Yeşilbağlar, Kaban and Köprübaşı areas are, advanced argillic-argillic, pyropylitic and sericitic. They are similar to the alterations present in the upper part of the mineralizations in the porphyry systems of the Alpine Orogenic Belt. In the Eastern Pontides starting in Early Jurassic, continuation of subductions resulted in closure of the İzmir-Ankara- Erzincan ocean and in Early Eocene the Taurid platform collided with the Eurasian active continental margin. Data from the study area indicate the presence of alteration zones in the upper part of the buried porphyry system and the possibility of mineralized parts in the deeper parts of the system
PERMEABILITY OF SAVCIBEY DAM (BİLECİK) AXIS LOCATION AND DESIGN OF GROUT CURTAIN
No full textThis study comprise the design of the planned grout curtain in Savcıbey Dam (Söğüt/Bilecik) in order to provide impermeability along the dam axis. Within the context of field studies, engineering geology map was generated, ground investigation drilling was realized and permeability tests were performed. Within the field studies, the joint conditions of the geological units (Triassic aged Bozüyük Metamorphic schists) under the dam axis and its effect on permeability was observed considering the positions of the discontinuities with regard to the dam axis location. Orientation of discontinuities generally have strikes changing between N – S and NNE – SSW. 5 boreholes on dam axis, 2 boreholes on cofferdam, 3 boreholes on diversion tunnel and 2 boreholes on spillway total 245 m ground investigation borehole were drilled. In order to determine the permeability profile of dam axis and design the grout curtain, Lugeon tests in Bozüyük Metamorphic units observed in dam axis, falling head permeability tests in alluviums observed in thalveg and slope debris observed in right abutment were performed. Lugeon tests realized in Bozüyük Metamorphic units show that the unit is generally permeable and partly low permeable. Alluvium and slope debris are highly permeable. In addition, drilling works realized in dam axis shows that the augmentation of the weathering degree cause an increase of permeability in Triassic aged Bozüyük Metamorphic schists. As a result of these studies information about the permeability of Savcıbey Dam was collected and the grout curtain hole was designed. Accordingly, it is predicted that approximately 40 m depth of grout curtain from the stripping excavation with the depth of 1.50 m would prevent the possible leakage
TECTONIC GEOMORPHOLOGY OF BAŞKALE FAULT ZONE
No full textBaşkale Fault Zone is located between Şemdinli-Yüksekova fault zone in southeast Turkey and Guilato–Siahcheshmeh–Khoy fault system in southeast Iran. The fault zone starts from Yavuzlar town extending to Işıklar village in southwest. The BFZ is composed of three different segments which have orientations varying N75°E to N 80°E. Offset streams, fault-controlled drainage system such as Çığılsuyu stream, alluvial fans which line up parallel to the fault and contain deformation structures, fault flats, Plio-Quaternary volcanic rocks and volcanic structures, and fissure ridge travertines with formation continuing today are among morphotectonic characteristics that indicate the BFZ is active.
The objective of the investigation is to determine the effect of Başkale Fault Zone on morphotectonic evolution of the region. With this aim, morphometric indices such hypsometric integral, drainage basin asymmetry, the ratio between the width and the height of valley and sinuosity of mountain fronts were produced with a Digital Elevation Model of study area and were interpreted. Depending on the results of morphometric models, it appears that the region has young topography and is actively rising. It was concluded that the rate of topographic uplift in the region increases from east to west and typically rates are greater than 0.5 mm per year in the west.
DOI: 10.19111/bulletinofmre.31575
ONE OF THE MAİN NEOTECTONİC STRUCTURES İN THE NW CENTRAL ANATOLİA: BEYPAZARI BLİND THRUST ZONE AND RELATED FAULT-PROPAGATİON FOLDS
No full textThis paper suggests that the structure known as “Beypazarı flexure / monocline” in the Turkish geology literature should be named as “Beypazarı fault-propagation folds”. Beypazarı, Kilci and Başören blind thrusts together with Erenler back thrust constitute the Beypazarı Blind Thrust Zone which is an active neotectonic structure as indicated by earthquake activity. NW-SE contraction created by the interaction between the North Anatolian Fault Zone, the Kırıkkale-Erbaa Fault Zone and the Eskişehir Fault Zone produced the Eldivan-Elmadağ Pinched Crustal Wedge, the Abdüsselam Pinched Crustal Wedge and the Beypazarı Blind Thrust Zone. These structures take up the internal deformation of the Anatolian Plate
MOLLUSCAN BİOSTRATİGRAPHY OF EARLY MİOCENE DEPOSİTS OF THE KALE-TAVAS AND ACIPAYAM BASİNS (DENİZLİ, SW TURKEY)
No full textIn the present work, a stratigraphic framework of the early Miocene units of the Kale-Tavas and Acıpayam deposits is proposed.Two stratigraphic sections from the brackish-marine deposits of Aquitanian (Yenidere formation) and three sections from the shallow marine units of late Burdigalian (Kale formation) age have been logged. In total 26 mollusc species are identified similar to those of the areas in the Mediterranean province. The fauna indicates that the Mediterranean Tethys occupied the southwestern part of the Denizli region only during the early Miocene. A tectonic pulse in the basin during the early Miocene may have been very important to understand the limits of marine Tethyan influence in the area