Süphan stratovolkanı'nın volkanostratigrafisi ve jeokimyasal evrimi

TÜBİTAK MAG01.09.2009Doğu Anadolu Bölgesinde yer alan çarpışma kökenli volkanizma kuzeydoğuda Erzurum-Kars Platosundan güneyde Karacadağ’a kadar uzanan geniş bir alanda yüzeylenmektedir. Bölgenin yaklaşık olarak 2/3 sini kaplayan volkanizma irili ufaklı çıkış merkezleri ile büyük hacimlere sahip kalkan ve stratovolkanlar ile karakterize edilir. Van Gölü’nün kuzeyinde yer alan Süphan Stratovolkanı 4050 m yüksekliği ile Doğu Anadolu’da yer alan Kuvaterner yaşlı volkanların en önemli üyelerinden biridir. Neojen-Kuvaterner yaşlı sedimanter birimler üzerine yerleşen Süphan volkanizmasının ilk ürünleri debris avalanche, I. evre piroklastik ürünler ve riyolitik obsidiyen lavlarıdır. Bu birimlerin üzerine ise bazalttan riyolite kadar uzanan lav akışları, riyolitik/dasitik domlar, piroklastik birimler gelmektedir. Volkanizmanın en son ürünleri ise Aygır Maarı’na ait piroklastik birimlerdir. Mineralojik-Petrografik çalışmalar ve lavların major-iz element karakteristikleri volkanizmanın gelişiminde plajiyoklaz + olivin + klinopiroksen + ortopiroksen + amfibol + biyotit + K-felsdpat fraksiyonel kristalleşmesinin etkin olduğunu göstermektedir. Süphan volkanikleri genel olarak subalkali ve alkali karakterler arasında geçiş göstermektedir. İz element içerikleri ele alındığında HFS elemetler LIL elementlere oranla, LRE elementler HRE elementlere oranla zenginleşme göstermiştir. Volkanikler içerisinde yeralan anklavların jeokimyasal özellikleri Süphan volkanizmasının genel karakteri ile uyum göstermektedir. Th/Y-Nb/Y ve izotop korelasyon diyagramları (87Sr/86Sr -143Nd/144Nd, 87Sr/86Sr – Pb206/Pb204, Pb207/204-Pb206/204) volkanizmanın kaynağının dalma-batma bileşeni ile zenginleşmiş bir manto kaynağı olduğunu işaret etmektedir. Bununla birlikte Ba/Nb - Ce/ Nb diyagramı üzerindeki karışım eğrisi de Süphan volkaniklerinin zenginleşmiş bir manto kaynağı ile dalma-batma bileşeni içeren bir kaynağın karışımından oluştuğunu göstermektedir. Doğu Anadolu Bölgesi’nde kabuk kalınlığı ile ilgili jeofizik tabanlı çalışmalar da göz önüne alındığında bu manto kaynağının, dalan levhanın krılması (slab breakoff) yoluyla yitim bileşeni kazanmış astenosferik bir kaynak olabileceği öngörülmüştür. Volkanikler üzerinde gerçekleştirilen Ar-Ar yaş analizleri trakitik lavlar için 0.55±0.34 ile 0.037±0.020 my arasında riyolitik lavlar için ise 0.040±0.022 my yaş vermiştir.Collision-related volcanics in Eastern Anatolia are exposed in a broad zone from the Erzurum-Kars Plateau in the northeast to Karacadağ in the south. Volcanic rocks covered two thirds of the plateau and are characterized by secondary eruption centers and huge shield and stratovolcanoes. Süphan Stratovolcano, located to the north of the Lake Van is one of the most important Quaternary volcanos in Eastern Anatolia with its 4050 m high elevation. Initial products of the Süphan stratovolcano which overly the Neogene-Quaternary sedimentary rocks are the debris avalanche, Ist cycle pyroclastic rocks and rhyolitic obsidian flows. These units are overlain by lava flows with compositions ranging from basalt to rhyolite, rhyolit-dasidic domes and pyroclastic rocks. Aygır maar deposits are the last products of the volcano. Mineralogical-petrographical and major-trace element compositions of the volcanic products point to the effects of plagioclase + olivine + clinopyroxene + ortopyroxene + amphibole + biotite + K-feldspar fractionation in the evolution of the volcanics. Süphan volcanics are transitional between subalkaline and alkaline character. LIL and LRE elements are enriched over HFS and HRE elements respectively. Most of the Süphan enclaves show similar geochemical properties with the Süphan volcanics. Th/Y-Nb/Y and isotope correlation (87Sr/86Sr -143Nd/144Nd, 87Sr/86Sr – Pb206/Pb204, Pb207/204-Pb206/204) diagrams point out a subduction modified enriched mantle source for the source of the volcanics. Mixing curves on Ba/Nb - Ce/ Nb diagrams further suggest that the Süphan volcanics are formed by mixing of an enriched mantle and a source bearing effects of subduction. In the light of geochemical constraints and recent geophysical data regarding lithospheric structure of eastern Anatolia, the source of the Suphan volcanics is interpreted as an astenospheric mantle bearing the effects of previous subduction events via slab breakoff. Ar-Ar ages of the trachytes and rhyolites range between 55±0.34 - 0.037±0.020, 0.040±0.022 ma respectively

Municipal solid waste landfill site selection for the city of Sanliurfa-Turkey: an example using MCDA integrated with GIS

A municipal solid waste (MSW) management system needs solid waste management (SWM) techniques where the presence of a sanitary landfill is vital. One of the most important issues of sanitary landfilling is to locate the facility to an optimal location. Despite the versatility and case-dependent nature of conventional expert-based site selection procedures, the number of sites to be chosen increases with increased population forcing a number of constraints. Consequently, constraints and environmental regulations mechanically mask unsuitable areas, leaving very little areas to be assessed. This turns the situation into a challenging issue for a geographical information system (GIS) used with multi-criteria decision analysis (MCDA), to select optimal site

Identification of possible source areas of stone raw materials combining remote sensing and petrography

Understanding the location and distribution of raw materials used in the production of prehistoric artefacts is a significant part of archaeological research that aims to understand the interregional interaction patterns in the past. The aim of this study is to explore the regional locations of the source rock utilized in the production of stone bowls, which were unearthed at the Neolithic (approximately 6500–5500 BC) site of Domuztepe (Kahramanmaraş-Turkey), via a combination of remote-sensing methods, petrographic and chemical analyses. To accomplish this task, the stone bowls were identified mineralogically, geochemically and spectrally, and then mapped with Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) sensors. According to the defined mineralogical composition, which is iron-rich chlorite, the target areas were selected among geologically potential areas that would bear similar source rocks in near vicinity and the target spectral signature was searched within these target areas. In order to overcome the problem of spectral similarity of chlorite group to some other minerals such as carbonate or epidote group minerals, band ratioing (BR) and feature-oriented principal component analysis (FOPCA) were used with an integrated approach and then their results were filtered according to the outcomes of the relative absorption band-depth (RBD) images. The areas with highest potentials were vectorized and then field checked. Mineralogical investigations on the collected field samples reveal that there is a mineralogical match between the source and target material. One group of stone bowls samples have similar geochemical signatures as the field samples having ultramafic origins. However, there is another group of stone bowls samples which are geochemically dissimilar to the first group of field and bowls samples. The data regarding the geochemical signatures of these two groups indicate a genetic relation between the sample sets. Therefore, it is concluded that the source rock of a major portion of the stone bowls unearthed at Domuztepe most probably originated from the near vicinity of the site