The “chessboard” classification scheme of mineral deposits: Mineralogy and geology from aluminum to zirconium

High-Mg ultrapotassic volcanic rock occurrences of lamproitic affinity are exposed in southwestern Anatolia, mostly within the Menderes Massif. From north to south the lamproitic volcanism shows increasingly younger ages ranging from 20 to 4 Ma. Volcanism is contemporaneous with more voluminous shoshonitic, high-K calc-alkaline, and ultrapotassic magmatic activity in the Simav–Selendi, Usak, Kirka, Koroglu, Afyon and Isparta–Golcuk areas. The southward decrease in the age of the volcanism correlates with changes in geochemical composition, particularly a decrease in 87Sr/86Sr, 207Pb/204Pb, Zr/Nb and Th/Nb, and an increase in 143Nd/144Nd, 176Hf/177Hf, 206Pb/204Pb, 208Pb/204Pb and Ce/Pb, thus delineating a systematic change from orogenic (crust-like) to anorogenic (convecting mantle-like) signatures. Rare earth element compositions of clinopyroxene phenocrysts demonstrate an increasing role for residual garnet for locations in the central parts of the Menderes Massif, indicating a lithosphere thickness greater than 80 km. In contrast, K2O abundances remain nearly constant at around 7%, indicating buffering by phlogopite in the mantle source. Magma genesis in southwestern Anatolia is controlled by post-collisional extensional events initiated after major lithospheric thickening. Geochemical constraints suggest that the mantle source experienced two main geodynamic stages. The first stage caused ultradepletion of the mantle and subsequent metasomatic enrichment, which allowed coupling of the geochemical signatures of ultradepleted harzburgite with those of crust-derived sediments. This happened during the final closure stages of the southern Neotethys Ocean and the accretion of forearc oceanic lithosphere (island-arc type), as shallowly subducted material to the Anatolian lithosphere. The second stage is post-collisional, and is related to the collapse of the orogenic belt and the development of extension-related horst and graben structures. This stage is concurrent with the initiation of a thermal anomaly originating from a gap, identified by seismic tomography, in the subducted slab under western Anatolia. We propose that the lithospheric mantle underwent intense ‘asthenospherization’ owing to lithosphere–asthenosphere interaction, caused by the southward expansion of this gap during slab roll-back. The geochemical resemblance of the lamproites to more voluminous, contemporaneous shoshonitic magmas implies their derivation from a heterogeneous mantle source that had been affected by similar processes. These mantle processes may be closely associated with the major episode of uplift in the Menderes Massif.

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Ultrapotassic Mafic Rocks as Geochemical Proxies for Post-collisional Dynamics of Orogenic Lithospheric Mantle: the Case of Southwestern Anatolia, Turkey

Post-collisional magmatism in western Anatolia began in the Eocene, and has occurred in discrete pulses throughout the Cenozoic as it propagated from north to south, producing volcano- plutonic associations with varying chemical compositions. This apparent SW migration of magma- tism and accompanying extension through time was a result of the thermally induced collapse of the western Anatolian orogenic belt, which formed during the collision of the Sakarya and Tauride-Anatolide continental blocks in the late Paleocene. The thermal input and melt sources for this prolonged magmatism were provided first by slab break-off-generated aesthenospheric flow, then by lithospheric delamination-related aesthenospheric flow, followed by tectonic extension-driven upward aesthenospheric flow. The first magmatic episode is represented by Eocene granitoid plutons and their extrusive carapace that are linearly distributed along the Izmir- Ankara suture zone south of the Marmara Sea. These suites show moderately evolved com- positions enriched in incompatible elements similar to subduction zone-influenced subalkaline magmas. Widespread Oligo-Miocene volcanic and plutonic rocks with medium- to high-K calc- alkaline compositions represent the next magmatic episode. Partial melting and assimilation- fractional crystallization of enriched subcontinental lithospheric mantle-derived magmas were important processes in the genesis and evolution of the parental magmas, which experienced decreasing subduction influence and increasing crustal contamination during the evolution of the Eocene and Oligo-Miocene volcano-plutonic rocks. Collision-induced lithospheric slab break-off provided an influx of aesthenospheric heat and melts that resulted in partial melting of the previously subduction-metasomatized mantle lithosphere beneath the suture zone, producing the Eocene and Oligo-Miocene igneous suites. The following magmatic phase during the middle Miocene (16- 14 Ma) developed mildly alkaline bimodal volcanic rocks that show a decreasing amount of crustal contamination and subduction influence in time. Both melting of a subduc- tion-modified lithospheric mantle and aesthenospheric mantle-derived melt contribution played a significant role in the generation of the magmas of these rocks. This magmatic episode was attended by region-wide extension that led to the formation of metamorphic core complexes and graben systems. Aesthenospheric upwelling caused by partial delamination of the lithospheric root beneath the western Anatolian orogenic belt was likely responsible for the melt evolution of these mildly alkaline volcanics. Lithospheric delamination may have been caused by 'peeling off' during slab rollback. The last major phase of magmatism in the region, starting c.12 Ma, is represented by late Miocene to Quaternary alkaline to super-alkaline volcanic rocks that show OIB-like geochemical features with progressively more potassic compositions increasing toward south in time. These rocks are spatially associated with major extensional fault systems that acted as natural conduits for the transport of uncontaminated alkaline magmas to the surface. The melt source for this magmatic phase carried little or no subduction component and was pro- duced by the decompressional melting of aesthenospheric mantle, which flowed in beneath the atte- nuated continental lithosphere in the Aegean extensional province. This time-progressive evolution of Cenozoic magmatism and extension in western Anatolia has been strongly controlled by the interplay between regional plate-tectonic events and the mantle dynamics, and provides a realistic template for post-collisional magmatism and crustal extension in many orogenic belts.

http://www.users.miamioh.edu/dileky/publications/2009/duplicates/DilekAltunkaynak.GSL2009.pdf

Geochemical and temporal evolution of Cenozoic magmatism in western Turkey: Mantle response to collision, slab break-off, and lithospheric tearing in an orogenic belt

Sorption processes and XRD analysis of a natural zeolite exchanged with Pb(2+), Cd(2+) and Zn(2+) cations.

Pb–Nd–Sr isotope and trace element geochemistry of Quaternary extension-related alkaline volcanism: a case study of Kula region (western Anatolia, Turkey)

Petrology and geochemistry of potassic rocks in the Gölcük area (Isparta, SW Turkey): genesis of enriched alkaline magmas

Cappadocia is essentially covered by nine rhyolitic ignimbrite units, being the products of a multi-phase volcanism of Upper Miocene-Pliocene age. Around Urgup and the Kizilirmak River, these ignimbrites constitute a volcanic-sedimentary succession together with lacustrine sediments, called the Urgup formation. In the zeolite occurrences of Cappadocia that were found in the lacustrine parts of pyroclastics outcropping around the Tuzkoy, Sarihidir, Karain, Cokek, Ibrahim Pasa and Karadag areas, clinoptilolite is the most common mineral and is associated with chabazite, erionite and phillipsite in some areas. A gain of alkaline-earths from the lake water, which is compensated by a loss of alkalis from the glass, took place during the formation of the different zeolite assemblages, which were probably controlled by the composition of the parent glasses. The distribution of erionite confirms its relation with mesothelioma cases in Tuzkoy, Sarihidir and Karain villages that are located outside tourist areas. The high incidence of malignant mesothelioma in Karain may be explained by uncontrolled occupational exposure to erionite. The “fairy chimneys”, “canyons” and “underground cities”, which are situated in the unaltered or slightly altered parts of the Kavak, Zelve, Cemilkoy, Gordeles and Kizilkaya ignimbrites do not constitute any health risk for the inhabitants or for visitors.

Zeolite occurrences and the erionite-mesothelioma relationship in Cappadocia, central Anatolia, Turkey

The Bigadic, Emet and Kirka lacustrine basins of western Turkey may be considered as Tibet-type graben structures that were developed during the Miocene within the Izmir-Ankara suture zone complex. The volcanic-sedimentary successions of these basins are made up of mudstone, carbonate (limestone and dolomite) and detrital rocks, and also of crystal or vitric tuffs about 135 to 200 m thick. The Degirmenli (Bigadic), Emirler (Bigadic) Kopenez (Emet) and Karaoren (Kirka) tuffs constituting the zeolite deposits are situated beneath four borate deposits (colemanite, ulexite, borax). The most abundant diagenetic silicate minerals are K- and Ca-clinoptilolites in the zeolite deposits, and Li-rich trioctahedral smectites (stevensite, saponite and hectorite) and K-feldspar in the borate deposits. In the Degirmenli, Emirler. Kopenez and Karaoren deposits, the following diagenetic facies were developed from rhyolitic glasses rich in K and poor in Na: (glass + smectite), (K-clinoptilolite + opal-CT), (Caclinoptilolite + K-feldspar ± analcime ± quartz) and (K-feldspar+analcime+quartz). K-feldspar which is also rarely associated with phillipsite (Karaoren) and heulandite (Degirmenli and Karaoren), succeeds clinoptilolite and precedes analcime in these diagenetic facies where dioctahedral smectites, opal-CT and quartz are the latest minerals. No diagenetic transformations exist between clinoptilolite, K-feldspar and analcime that were formed directly from glass. The lateral facies distributions resulted from the differences in salinity and pH of pore water trapped during deposition of the tuffs, but vertical distributions in vitric tuffs seem to have been controlled by the glass/liquid ratio of the reacting system and the permeability or diffusion rate of alkali elements. The Bigadic, Emet and Kirka zeolite deposits which were formed in saline basins rich in Ca and Mg ions, show similar chemical changes, i.e. loss of alkalis and gain in alkaline-earth elements that have taken place during the diagenetic transformation of rhyolitic glasses to dioctahedral smectites or clinoptilolite. The absence of sodic zeolites such as mordenite, erionite, chabazite and silica-rich phillipsite is mainly due to the very high K/Na ratio of the starting materials rather than initial alkaline conditions or high Na content in lake waters.

Geological, mineralogical and geochemical characteristics of zeolite deposits associated with borates in the Bigadiç, Emet and Kirka Neogene lacustrine basins, western Turkey

Oil decolorization properties of the Emirler clinoptilolite and its acid-activated forms were studied using neutralized cottonseed oil. Although the oil decolorization capacity of natural clinoptilolite is low, it can be improved by a factor of 1.8 after HCl activation under the optimized conditions (1M HCl, solid/liquid ratio = 1/20, T = 25°C, t = 1 hour). Acid activation increases the total specific surface area from 40 to 70 m2/g which is mostly realized with a pore diameter range smaller than 15 nm. The bleaching capacity of acid-activated clinoptilolite is comparable to that of natural bentonitic clays but it is 1.6 times lower than the capacity of activated bleaching earths such as Tonsil and others. However, the amount of oil absorbed by clinoptilolite during the bleaching process is almost half that compared with the commonly used natural and acid-activated clays.

M. N. Gündoğdu

Papers

Petrology and geochemistry of potassic rocks in the Gölcük area (Isparta, SW Turkey): genesis of enriched alkaline magmas

Zeolite occurrences and the erionite-mesothelioma relationship in Cappadocia, central Anatolia, Turkey

Geological, mineralogical and geochemical characteristics of zeolite deposits associated with borates in the Bigadiç, Emet and Kirka Neogene lacustrine basins, western Turkey

Oil decolorization properties of the Emirler clinoptilolite (Bigadiç, Turkey)

An in-depth study on post-harvest storage conditions depending on putrescine treatments of kiwifruit