Bulletin of the Mineral Research and Exploration (BMRE)
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GEOCHEMICAL PROPERTIES AND RODINGITIZATION OF DIABASE DYKES CUTTING PERIDOTITES IN YÜKSEKOVA COMPLEX (ÖZALP, VAN - TURKEY)
No full textIn this study, the geology of diabase dykes which cut peridotites of Yüksekova complex (Özalp, Van, Turkey) and the effects of Ca metasomatism that caused the metamorphism of these peridotites were investigated. Within the light of mineralogical and petrographical studies and geochemical data; it was determined that diabase dykes that cut peridotites in Yüksekova complex had shown rodingitization in various degrees due to Ca metasomatism. Depending on this metasomatism, Ca-Al-Mg rich silicates were formed. The mineralogy of rodingitized dykes with ophitic texture is composed of diopside, plagioclase, hydrogrossularite, chlorite, epidote and in minor amounts phlogopite, prehnite, apatite, calcite, opaque minerals. Metasomatism caused enrichment of Ca and depletion of SiO2 in whole rock major oxides of dykes in tholeiitic character. So, dykes were divided into three different subgroups. The first group is formed from high grade rodingitized diabase dykes (~38.0–42.0 wt. % in SiO2; 19.0–26.0 wt. % in CaO). The grade of rodingitization in diabase dykes forming the second group is relatively low (~42.5–43.0 wt. % in SiO2; 14.5–15.0 wt. % in CaO). However, the effect of rodingitization has not been encountered due to results of both petrographical and geochemical analyses in diabase dykes which form the third group (~47.0–50.0 wt. % in SiO2; 10.0–12.0 wt. % in CaO). It is considered that in rodingitized dykes of which are enriched by trace and REE (Rare Earth Element) contents, the fluids affecting the metasomatic source have developed as a result of interactions with other rocks which were enriched more in these elements. It is also contemplated that the local geology, tectonical structure of the environment and the heat, oxygen fugacity and chemical composition in fluids which would develop due to those factors are significant in this interaction
THE GEOLOGY, GEOCHEMISTRY AND GENETICAL FEATURES OF THE ORMANBAŞI HILL (SİNCİK, ADIYAMAN) COPPER MINERALIZATION
No full textThe study area covers Ormanbaşı Hill of Adıyaman–Sincik County and its vicinity. Regional geological locations of Cu mineralizations that lie between the Southeastern Anatolian Foothill Belt and Taurus Orogenic Belt are conformable with thrust planes approximately extending in E-W directions. Cu mineralizations are observed in the form of lenses and layers within mudstone, diabase, spilite and claystone - shales of the Koçali complex. The primary genetic relations of these formations have completely been disappeared but have only been traced along thrust planes that are conformable with general tectonic lineaments. The ore structure is generally massive but is stockwork and disseminated in some zones. The ore bearing layer with pyrite towards deeper parts is observed, while the mineralization is observed in the form of iron ore cap (gossan) at surface. Ore paragenesis consists of pyrite, marcasite, chalcopyrite, sphalerite, bornite, chalcosine - covelline and native copper. All samples belonging to ore mineralizations plot on Cyprus type volcanogenic massive sulfide (VMS) area in Cu – Pb - Zn and Au - (Cu + Pb + Zn) - Ag ternary diagrams. All samples in Pb, Cu, Ag, Au and Zn spider diagrams which were normalized to primary mantle show a trend similar to VMS deposits. Besides, analyses carried out in massive pyrites indicated that these had Ni/Co ratio higher than 1% and less Ni content. Therefore; it was detected that hydrothermal processes had been affective in ore mineralizations. S32/S34 ratios were obtained as 6.9 and 7.6 in sulfur isotope analyses performed by using pyrite and chalcopyrite samples. These values are both compatible with sulfur ratios in hydrothermal solutions related to volcanism and show a similar composition with that of Cyprus type VMS deposits on the world
CONODONT FAUNA AND BIOSTRATIGRAPHY OF THE EARLY-MIDDLE DEVONIAN UNITS IN BEYKOZ, ŞILE AND KURTDOĞMUŞ AREAS, İSTANBUL, TURKEY
No full textThe conodont faunas defi ning the delta-pesavis zones (upper Lochkovian, Lower Devonian) were obtained from Beykoz and Karamandere sections of the İstinye Formation (the Yumrukaya group) and the conodont faunas of the laticostatus, serotinus, patulus and partitus zones (upper Emsian-lower Eifelian, Lower-Middle Devonian) were obtained from the Büyükdere and Kokarpınar sections of the Kozyatağı member of the Kartal Formation. A total of 22 species/subspecies were described belonging to the genera Neopanderodus (2), Icriodus (8), Pelekysgnathus (1), Lanea (1), Polygnathus (4), Ozarkodina (2), Pseudooneotodus (2), Belodella (2)
THE INFLUENCES OF OCEANOGRAPHICAL CHARACTERISTICS OF THE NORTH COASTS OF KARABURUN PENINSULA ON THE BENTHIC FORAMINIFERAL AND OSTRACOD ASSEMBLAGES
No full textMajor differences in foraminiferal assemblages have been observed between the eastern and western coasts on the northern part of the Karaburun Peninsula. In contrast to the rich fauna of the western coast, a poor assemblage was found on the western coast, which is located in the Gulf of İzmir. A great difference in population sizes have also been observed in Amphistegina lobifera Larsen assemblages found on the Aegean coasts of Karaburun Peninsula and Gulf of Izmir. In the frame work of this study, 84 foraminifer species were identifi ed. The most abundant species were Peneroplis pertusus (Forskal), P. planatus (Fichtel and Moll), Amphistegina lobifera Larsen, Elphidium crispum (Linné). Highest heavy metal pollution was observed in the inner part of the gulf, where least number of foraminifera species observed. 24 ostracod species were identifi ed. Our fi ndings showed that the number of genera and species of ostracods increases with the increasing depth and the distance to the shoreline on the NW of Karaburun Peninsula. Loxoconcha rhomboidea (Fischer), Xestoleberis communis Müller and X. depressa Sars were found to be dominant species on the NW of the peninsula, whereas on the NE of the peninsula Xesteleberis dispar Müller dominated the fauna, Xestoleberis communis Müller and X. depressa Sars were the other abundant species. The aim of this study is to investigate the foraminiferal assemblages of the north coasts of Karaburun Peninsula and fi gure out the effects of mercury mine and other elements on these assemblages. Two mercury mines are found on the north of the peninsula, “Karareis” located on the northwestern of Tuzla Cove and “Kalecik” on the southwestern of Karaburun. Both mines have been economically operated since ancient times until 1970s. However, mercury mineral has not been observed in the muck found in the vicinity. The piles of muck may be washed with rains, resulting in the draining of the acidic solutions with Hg, As and Fe to the nearby seasonal stream, which are then possibly carried to the sea. The sea water samples collected from the two locations showed differences in their heavy metalsand trace element contents, such as Al, Si, Cr, Mn, Fe, Co, Ni, Cu, Zn and As, but no signifi cant difference was observed in Hg. The aim of this study is to fi gure out the effects of the heavy metals, which were carried from the land, on the benthic foraminiferal assemblages
STRATIGRAPHY OF THE PAN - AFRICAN BASEMENT OF THE MENDERES MASSIF AND THE RELATIONSHIP WITH LATE NEOPROTEROZOIC/CAMBRIAN EVOLUTION OF THE GONDWANA
No full textThe Menderes Massif, exposed in the Western Anatolia, is tectonically overlain to the north by the Afyon Zone and to the south by the Lycian Nappes. In the northwest, two high-pressure units, the Cycladic Complex and overlying the Lycian Nappes, as well as the nappes of Ýzmir - Ankara Zone tectonically overlay the Menderes Massif. The metamorphic rock succession of the Massif can be divided into two main units: 1-PanAfrican basement (core series) and 2-Paleozoic - Early Tertiary metasedimentary rocks (cover series). The PanAfrican basement shows a stratigraphy consisting of a partly migmatized metaclastic sequence and polymetamorphic basic and acidic igneous rocks that intruded into these metaclastics. This metaclastic sequence, which is composed of paragneiss and conformably overlying schist units reaches a minimum thickness of eight kilometers and forms the oldest rocks of the Pan-African basement of the Menderes Massif. Field studies and geochronological data suggest that the protoliths of the paragneisses are predominantly clastic sediments of litharenitic composition. Frequently, the paragneisses alternate and interfinger in all directions with micaschists and biotite-albite schists, originating from mudstone and subarkosic sandstone, respectively. The paragneisses are conformably overlain by a schist unit. The originally gradual sedimentary contact is represented by a paragneiss and schist intercalation. The schists are dominated by micaschists with biotite-albite schist layers, derived from mudstone and subarkose, respectively. In the Menderes Massif, the paragneisses are generally extensively migmatized. Widespread anatectic granites occur as irregular-shaped bodies with migmatized margins. The detrital zircons of the paragneisses yielded ages scattered between 610 - 2558 Ma. Detrital zircons of the schist unit of the PanAfrican basement were dated at 592 - 3239 Ma. The intrusion ages of the orthogneiss showing clear intrusive contact relationship with metaclastic sequence range from 570 to 520 Ma. The granulite facies metamorphism of the paragneiss unit was dated at 583±5.7 Ma. These geochronological evidence and the contact relationships clearly reveal that the deposition age of the protoliths of the metaclastic sequence of the Pan-African basement can be constrained to Late Neoproterozoic between ca 590 - 580 Ma. The metaclastic sequence is intruded by large granitoid bodies and gabbroic stocks. The intrusion ages of the granitic precursors now represented by orthogneisses with changed mineralogical compositions and primary textures range from 520 to 570 Ma with a major event at about 550 Ma. These granites, which can be divided into three main groups (biotite orthogneiss, amphibole orthogneiss and tourmaline leucocratic orthogneiss) are the products of a poly-phase Pan-African acidic magmatic activity that intruded the metaclastic sequence. They are syn- to post- metamorphic intrusions with respect to the Pan-African orogeny. The basic meta- igneous rocks occurring in the Pan-African basement have gabbroic to noritic composition. They display massive cores and foliated margins that consist mainly of garnet amphibolites with relics of eclogites revealing the polymetamorphic history of the Pan-African basement. Field evidence and radiometric age data indicate that the primary contact relationship between the Pan-African basement and the Paleozoic cover series in the Menderes Massif was an unconformity (Supra-Pan-African unconformity) and the cover series were sourced from the Pan-African basement. The protoliths of the paragneiss and schist of the Pan-African basement were deposited on the passive continental margin of a basin occurring between East and West Gondwana during the Late Neoproterozoic time (Mozambique ocean). All the magmatic and metamorphic ages obtained from Pan-African basement coincide with the closure of this ocean and the final assemblage of the Gondwana supercontinent during Late Neoproterozoic - Cambrian time
SOME STRUCTURAL CHARACTERISTICS OF AZMAR ANTICLINE - NE IRAQ
No full textThe purpose of this study is to elucidate the structural style of Azmar structure, a major anticlinorium within the imbricate partition of Zagros fold-thrust belt in northeastern Iraq. Structural analysis of this anticlinorium demonstrated that it consists of four main NNW-SSE trending anticlines. They are imbricated SW ward through NE dipping reverse faults merge to a deep seated detachment. Furthermore, analysis of minor folds on hinge and limbs of the main Azmar anticline revealed the versatile style of such minor folds and their opposing vergencies. These features emphasize the role of faulting in development of the major fold and the minor folds. This interpretation has been supported by hinge angularity, as well as by association of hinge and limb disrupting reverse slip mesofaults with those minor folds. Therefore a progressive fault related folding is proposed for Azmar structure in this work
HEAT FLOW OF THE KIRŞEHİR MASSIF AND GEOLOGICAL SOURCES OF THE RADIOGENIC HEAT PRODUCTION
No full textIt is not often easy to distinguish the components of the mantle originated heat flow and radiogenic heat generation from each other. Surface heat flow is composed of two components. The first is the radiogenic heat source and the second is the heat flow originated from the upper mantle and the lower crust. In this study, heat flow and the radiogenic heat production of the Kýrþehir Massif and its geological sources were investigated. Curie point depths were calculated from aeromagnetic data. Geothermal gradient values were formed by considering the medium as homogenous and isotropic. The heat flow of the region was calculated using the heat transfer values of rock samples collected from field and it was determined that this value had ranged between 53 mWm-2 and 108 mWm-2. As a result of the evaluation of heat flow and heat production maps together, it was calculated that 60-92% of the average heat flow values of the region are mantle and 8-38% are radiogenic sourced. The radiogenic heat production in the study area, generally showed high anomaly values in young granitoids as predicted
GEOLOGY OF THE KÜTAHYA-BOLKARDAĞ BELT
No full textKütahya-Bolkardağ Belt is one of the subunits of the Tauride-Anatolide Terrane extending from the Aegean Sea to the Hınzır Mountains. It includes numerous tectonic slices, formed during the closure of the İzmirAnkara Oceanic branch of the Neotethys. The tectonic slices are mainly derived from three different tectonic settings: i- rocks representing the oceanic lithosphere and subduction- accretion prism of the İzmir-Ankara Ocean (ophiolites and ophiolitic mélanges), ii- flysch-type deposits that were formed in foreland-basins on the northern and passive edge of the Tauride-Anatolide platform in front of the southward advancing nappes (olistostromes with olistoliths, sedimentary mélanges), and iii- successions, in some cases with HP/LT metamorphism, representing the slope margin and external platform of the northern Tauride-Anatolide margin. Rock-units of the Kütahya-Bolkardağ Belt surround the HT/LP Menderes Core Complex and are also observed as slices or klippen in the massif , or as nappes to the south of it. The rocks of the İzmir-Ankara oceanic lithosphere occur as huge allochthonous bodies/tectonic slices and blocks within the mélange and olistostromes. The fossil data and geochemical data obtained suggest the following: The earliest oceanic volcanism commenced during middle Carnian, the generation of ocean island-type (OIB) volcanics lasted from Bajocian to Abtian, where as the MORbasalts spread from Aalenian to Turonian. Supra-subduction- and island-arc type basalts of Albian to Cenomanian age indicate an intra-oceanic subduction within the İzmir-Ankara Ocean. The mélanges are characterized by HP/LT metamorphism with a LP/LT overprint. Middle Maastrichtian olistostromes with olistoliths formed in foreland basins in front of the nappes include blocks of all kind of tectonic settings mentioned above. The flysch rocks are in depositional contact with the underlying platform and/or slope rocks of the Tauride-Anatolide passive margin. The Tauride-Anatolide slope and external platform deposits are partly affected by HP/LT metamorphism and occur as slices along the belt and as blocks within the flysch-basins. In Afyon area the Late Permian transgresses onto the Precambrian basement, whereas in Konya, more internal in regard to the platform, the Devonian carbonate platform is drowned and covered by back-arc-type sediments and volcanism of Carboniferous age. All along the belt, early Late Permian unconformably covers a slightly metamorphosed and deformed basement, attributed to a Variscan event within the Tauride-Anatolide platform. The Early Triassic sequences unconformably covering the older units and starting with volcanogenic continental clastics, pass into the marine carbonates by Anisian. In the allochtonous belonging to the more internal platform, the Ladinian-Lower Cretaceous sequences are represented with thick platform carbonates. The first deep marine sediments take place in some slices of these sequences which is interpreted as the initial rifting of the Ýzmir-Ankara oceanic branch. While only the slope sediments accompanying with transitional ocean crust volcanic are observed in the allochtonous derived from the northernmost part of the Taurid-Anatolid platform, the Ladinian-Lover Cretaceous sequences are represented by thick platform carbonates in the allochtonous of the inner platform. The transition from platform to slope-type deposits is in Malm in the allochtonous of the external platform, but Abtian in more internal parts. This indicates a stepwise deepening of the platform-margin. The presence of HP/LT metamorphic platform-margin sediments is indicative for a deep subduction of the attenuated continental-crust of the TaurideAnatolide margin. The initial compression-slicing and nappe-emplacement must have realized prior to Middle Paleocene. Middle Paleocene-Middle Eocene in the Kütahya-Bolkardag Belt is characterized by shallow-marine or continental molasse-type deposition in the remnant basins on the platform
HISTORICAL EVOLUTION OF THE GEOLOGICAL RESEARCHES IN THE MENDERES MASSIF
No full textThe Pan-African basement of Menderes Massif is made up of homogenous paragneiss and schist units (metaclastic sequence) which are intruded by metagabbros and gneisses derived from different types of granites. The basement is unconformably overlain by Early Palaeozoic metaclastic series consisting of quartzite and metaconglomerate at the lowest level. They show a transition into schists, and the Palaeozoic sequence ends with Permo-Carboniferous black marbles of Göktepe formation. Both basement and Palaeozoic sequence are intruded by Early Triassic leucocratic granites which were converted into orthogneisses by Alpine metamorphism. The Mesozoic series of the Menderes Massif begins with Late Triassic meta-sandstone/metaconglomerate intercalation and continues with Jurassic to Cretaceous dolomites and massive marbles. Platform-type massive marbles with metabauxite lenses and well-preserved rudist fossils at the uppermost levels are conformably overlain by late Campanian - late Maastrichtian reddish pelagic marbles. Flysch-type middle Paleocene metaolistostrome forms the uppermost unit of cover series. The protoliths of clastic sediments of the Pan-African basement consisting of paragneiss and conformably overlying schist units were deposited on a passive continental margin. The zircon ages of the granitoids intersecting this clastic sequence are restricted to a time range between 570 and 520 Ma with an average of about 550 Ma. The polyphase metamorphic evolution of the basement under granulite (583 ±5,7 Ma), eclogite (529,9 ±22 Ma) and Barrowian-type medium-pressure conditions (average 540 Ma) are related with the Pan-African Orogeny. The isotopic data including the ages of detrital zircons (592-3229 Ma) of paragneiss and schist units, the intrusion ages of granitoids and the age of granulite facies metamorphism constrain an age for the deposition of protoliths of metaclastic sequence between 592-580 Ma, Lower Late Neoproterozoic. In Eocene time, Pan-African basement and cover series were affected by Barrowian-type Alpine metamorphism under greenschist, lower amphibolite facies conditions, traditionally called as the \u27Main Menderes Metamorphism. However, new HP/LT evidence found in Mesozoic cover series reveals that this metamorphism is more complex than it was considered. It is generally accepted by many researchers that the exhumation of the Menderes Massif as a core complex is related with the extensional tectonic regime. It is assumed that there is a genetic relation between the intrusion of Eðrigöz - Koyunoba granites and the detachment fault in the northern part of the Menderes Massif. Furthermore; to the South of the Massif, it is suggested that the old thrust fault between the Menderes Massif and Lycian Nappes reworked as a detachment fault during the exhumation. The reason of extension in the region is the thermal weakness in the thickened crust made by the magmatism developed after the the collusion of Anatolide-Tauride platforms and the Sakarya continent. The intrusion ages of Eðrigöz and Koyunoba granitoids are 20-21 Ma and the detachment fault was active during 25-19 Ma. In addition, the symmetric core complex formation in the central submassif was carried out in the middle-late Miocene. Pliocene to recent active graben faults intersect the detachment faults
POLYMETAMORPHIC EVOLUTION OF THE PAN-AFRICAN BASEMENT AND PALAEOZOIC-EARLY TERTIARY COVER SERIES OF THE MENDERES MASSIF
No full textThe Menderes Massif exposing in the Western Anatolia substantially presents a complex tectonostratigraphy as a result of Late Alpine compressional tectonism. The lithostratigraphical succession of this crystalline complex can be divided into two units: 1- The Pan-African basement (core series) and 2-Palaeozoic - Early Tertiary metasedimentary rocks (cover series). The Pan-African basement of the Menderes Massif is made up of a Late Neoproterozoic metaclastic sequence consisting of paragneisses and conformably overlying micaschists. This high-grade metaclastic sequence is extensively migmatized and intruded by the syn- to post-PanAfrican gabbros and granitoids. The primary contact relationship between the core and cover series is a regional unconformity in character. The Palaeozoic (?Upper Devonian - Permian) cover units, which are cut by the intrusion of Triassic leucocratic metagranites are consisted of phyllites, quartzites and marbles. The Mesozoic cover units are characterized by Triassic to Upper Cretaceous platform-type thick marbles at lower levels of the sequence. Upper Campanian - Upper Maastrichtian pelagic carbonates and the overlying Middle Palaeocene - Eocene flysch-type blocky unit constitute the uppermost units of cover series. Relic mineral assemblages observed in the Pan-African basement reveal a complex polyphase metamorphic evolution of this basement under granulite, eclogite and amphibolite-facies conditions. The high temperature metamorphism developing under granulite facies is characterized by the presence of hypersthene type pyroxene. Pelitic granulites, orthopyroxene gneisses, orthopyroxene paragneisses and metagabbroic / metanoritic rocks form typical granulitefacies relics observed in the massif. Geothermobarometric estimations characterize an average temperature of 730 °C and pressure of 6 kbar for the granulite-facies metamorphism. By means of SHRIMP II method, clustering ages of 583±5.7 Ma were dated from the outer parts zircons in pelitic granulites which have no zoning but have overgrown under granulite facies. High grade metamorphism relics in the Pan-African basement are characterized by eclogite and eclogitic metagabbros. Fully recrystallized, fine grained massif eclogites, with non bearing relic texture belonging to protolith are composed of \u27omphacite (jd40-52) + garnet + clinozoisite + amphibole + quartz + rutile\u27. However; relic texture and minerals are extensively observed in metagabbros derived from eclogitic gabbros. The pressure-temperature (P-T) conditions of the Pan-African high-pressure metamorphism were estimated as 644°C with a minimum pressure of about 15 kbar, which corresponds to a burial depth of about 50 km. 206Pb/ 238U zircon ages obtained from eclogitic metagabbros by TIMS yield 529.9±22 Ma, reveal the high-pressure metamorphism as Pan-African in age. The Barrowian type medium pressure metamorphism reaching up migmatization stage in which anatectic granites developed caused extensive retrogradations. Geothermobarometric estimates from garnet amphibolites, retrograded from eclogites indicate that this metamorphism developed under P/T conditions of 7 kbar in pressure and 628°C in temperature. The crystallization ages of these anatectic granites range from 551 to 540 Ma. They were generated by migmatization of paragneisses and reveal that this medium-pressure event is related to the last stage of polyphase Pan-African metamorphism. All metamorphic ages obtained from the Pan-African basement are compatible with the latest stages of assemblage of Gondwana super continent. It is considered that protoliths of paragneisses and schists of the PanAfrican basement were deposited on a passive continental margin of a basin occurring between East and West Gondwana during the Late Proterozoic time (Mozambique Ocean). The Pan-African basement of the Menderes Massif was deeply buried and metamorphosed under granulite, eclogite and amphibolite-facies conditions as aresult of the closure of this basin and collision of East and West Gondwana during Late Neoproterozoic time. Both core and cover series of the Menderes Massif were affected by an Alpine aged old regional metamorphism. In the Palaeozoic sequence of cover series, this metamorphism is characterized by a Barrowian type medium-pressure metamorphism. This metamorphism developed under greenschist to lower amphibolite-facies (6 kbar in pressure / 430-550 °C in temperature) and described by the occurrences of garnet, staurolite and kyanite (disthene) in phyllites. Mesozoic-Early Tertiary cover series at the southern part of Çine submassif contain data associated with Alpine aged HP/LT metamorphism. Carpholite-kyanite assemblage within Triassic quartz metaconglomerates shows a metamorphism under a pressure of 10-12 kbar and temperature of 440 °C corresponding to a minimum depth of 30 km. So far, there has not been detected any data for an Alpine HP / LT metamorphism, neither in the Pan-African basement nor in the Palaeozoic sequence of the Menderes Massif. Based on the fossil content obtained from youngest unit of the cover series and from the oldest non metamorphic sedimentary cover on the massif, the Alpine metamorphism can biostratigraphically be constrained into Eocene and Oligocene time interval. Few isotopic data (37±1 Ma, Late Eocene Rb/Sr biotite age; 36±2 Ma, Middle Eocene Ar/Ar muscovite age; 43 - 37 Ma, Eocene Ar/Ar muscovite age) related to Alpine metamorphism are compatible with the related time interval. The Alpine metamorphisms of tectonical zones belonging to Anatolides is substantially associated with the closure of the northern branch of Neothethys Ocean and with the collision in Palaeogene. In such a tectonic model, the segment of the Anatolide-Tauride platform corresponding to the Menderes Massif was subjected to intense internal imbrication during the subduction process of the northern branch of Neotethys and the following period in which the continental collision occurred. The tectonical slices being formed were buried at different depths and metamorphosed under varying conditions related with burial depths under the load of Afyon zone at north in Eocene-Oligocene times, and of Lycian nappes passing south and of ophiolites