Dünyada enerji kaynaklarının rastgele dağılmış olması, yükselen enerji fiyatları, küresel ısınma ve iklim değişikliği gibi çevresel sorunlar, yakın gelecekte fosil yakıtların tükenecek olması, bu enerji kaynaklarının çevre ve insan sağlığı üzerindeki etkileri, yabancı kaynaklara ve az sayıda enerji zengini ülkeye bağımlılık sebebiyle ülkeler farklı enerji kaynaklarına yönelmiştir. Uranyumu yakıt olarak kullanan nükleer enerji üretimi Türkiye için alternatif bir kaynak olarak ele alınmaktadır. Türkiye’nin kanıtlanmış uranyum rezervi 32.4 kiloton olup, halen uranyum içerebilecek havzaların araştırılması devam etmektedir. Bu kapsamda, Pliyo-Miyosen genişlemeli rejim sonucu gelişen Dinar (Afyonkarahisar, Batı Anadolu) kömür oluşumları ekonomik açıdan önem arz edebilecek uranyum içerikleri bakımından ilgi çekebilmektedir. Çeşitli derinliklerden ve 5 sondaj kuyusundan toplam 17 adet kömür numunesi alınmıştır. Bu numunelerin uranyum içeriklerinin 1065 μg/g mertebelerine kadar çıktığı görülmüştür. Havzada mevcut olan uranyumun, kömürleşme süreci ve kömür tabakalarının üzerinin volkanoklastik sedimanlar tarafından örtülmesinden sonra, hidrotermal akışkanlar ile karışan yeraltı sularının etkisiyle katmanlı epijenetik köken modeline uygun şekilde oluştuğu düşünülmektedir. Ayrıca, yüksek uranyum içeriğinin, linyit damarlarının üst katmanlarında yoğunlaşması sebebiyle havza diğer epijenetik linyit oluşumları ile benzerlik göstermektedir.

Toros orojenik kuşağı boyunca karbonatlı kayaçlar ile ilişkili birçok Zn-Pb yatağı bulunmaktadır. Farklı tektonik birliklerin bir arada gözlendiği Çayarası (Alanya-Antalya) kuzeydoğusunda (Orta Toroslar) Aladağ Birliğine ait Alt-Orta Triyas yaşlı karbonatlı kayaçlar ile ilişkili baritli Zn-Pb cevherleşmeleri bulunmaktadır. Epijenetik oluşumlu, stratabound karakterli cevherleşmede galenit ve sfalerit cevher mineralini, barit ve kalsit ise gang mineralini oluşturmaktadır. Kırık ve çatlaklarda gözlenen cevher damarları damar tipi hidrotermal cevherleşmeyi krakterize etmektedir. Cevher zonlarından derlenen örneklerin jeokimyasal analizleri sonucunda PbO maksimum % 57,10 ve ZnO ise maksimum % 33,74 oranına ulaşmaktadır. Tektonik yapılar açısından zengin olan bölgede Kuzeybatı-Güneydoğu uzanımlı fay takımlarının cevherleşmede etkili olduğu düşünülmektedir.

<p>The Ozvatan carbonatite complex is located on the Eastern Part of the Central Anatolia, Turkey and host considerable Light Rare Earth Elements (LREE) mineralizations. The carbonatites in Ozvatan complex are mostly coarse grained calcio-carbonatites (sövites) with fluorites and minor opaque minerals. The carbonatites were intruded into silica undersaturated nepheline syenites and caused an intense fenitization process. The calcio-carbonatites of the study are were predominantly enriched in terms of La (up to 995 ppm), Ce (up to 1386 ppm) and Nd (up to 211 ppm). Also some of the LILE’s are enriched including Sr (up to 2%) and Ba (up to 0.75) as expected.  The stable δ<sup>13</sup>C<sub>V-PDB  </sub>and δ<sup>18</sup>O<sub>V-SMOW </sub>values of the Ozvatan carbonatites represent fractional crystallization and hydrothermal alteration trends. The δ<sup>13</sup>C values (-6.0 – 4.1 ‰) are generally in tune with worldwide carbonatite range. However, it cannot be concluded as a primary ignous carbonatitic melt due to relatively high δ<sup>13</sup>C<sub>V-PDB </sub>values.<sub> </sub> The  δ<sup>18</sup>O values (13.3 – 49.3 ‰)  are  also high  mostly cauesed by the high intensity hydrothermal activities (fenitization) or the contamination of meta-carbonate basement rocks. Overall, it can be stated that the, carbonatites of the Ozvatan are products of fractionation of a carbonated silicate melt, low temprature metasomatism and crustal contamination.</p> <p> </p> <p>Keywords: Alkaline Magmatism, Carbonatite, Stable isotopes</p>

<p><strong>Geochemical and mineralogical characteristics of beach sand sediments in southwestern Black Sea: An approach to heavy mineral placers  </strong></p><p><strong> </strong><strong>Hatice Nur Bayram (1*), Aslı Nur Uslu (1), Ali Erdem Bakkalbaşı (1), Demet Kiran Yildirim (1), </strong><strong>Zeynep Doner (1), Ali Tugcan Unluer (1)</strong></p><p><strong> </strong>(1) Istanbul Technical University, Faculty of Mines, Department of Geological Engineering, Istanbul, Turkey (*hnnurbayram@gmail.com)</p><p><strong>Abstract: </strong><strong> </strong></p><p>Coastal or beach placer deposits are enrichments of heavy minerals with significant metal content that have been mechanically formed. This work studies the geochemical and mineralogical characteristics of beach sand sediments of southwestern Black Sea, Turkey which cover approximately 20 km<sup>2</sup> area. The study area has 4 main geological units: Upper Cretaceous moderately-K kalkalkaline Istanbul volcanics, Oligocene Danismen Formation which is dominated by flood plain, marshy and lake environments, Upper Miocene-Pliocene Belgrad Formation which is dominated by terrestrial deposits, mostly gravel, sand and clay dominated and Quaternary formations which include sandy beaches, sand dunes and river alluvials.</p><p>A total of 8 beach sand samples were analyzed by X-ray Diffraction (XRD) and X-ray Fluorecance (XRF). Mineralogical compositions are mainly dominated by quartz, siderite, albite, calcite and minor amount of magnetite. Siderite-rich beach sands are observed in western part of the study area and mostly derived from Danismen Formation. Fe<sub>2</sub>O<sub>3</sub> contents of this area are determined up to 40%.  On the other hand, in eastern part of the study area REE-Th-U content of beach sands are relatively higher than source rocks which is defined as a high-Al moderately-K kalkalkaline felsic rocks. The highest HFSE concentration were determined in -250+125µm fraction which consists of 16.5% of eastern beach sand. In this fraction LREE-Zr-U content rise drastically. It can be considered that REE-LREE contents is related with monazite minerals and U contents is related with zircon minerals, considering the monazite and zircon minerals are resistant to weathering and likely to occur in the orthomagmatic phase in the source volcanics.</p><p><strong>Key words</strong>: Beach sand sediments; REE-Th-U; heavy minerals; southwestern of Black Sea; Turkey</p>

<p>Mediterranean type karstic bauxite deposits are considered as the primary source for aluminum (Al) production in Europe. During the Al production, Gallium (Ga) is extracted from the so called Bayer-liquor during the processing of bauxite to alumina. Ga, a rare metal, is widely used in modern chemistry and electronic industry. During the past decades, the worldwide demand for Ga has been continuously increasing. In Turkey, karstic bauxite deposits are generally found with shallow marine carbonate rocks which were deposited during Mesozoic period and located in Tauride Carbonate platform. Most of these karstic bauxite deposits can be hosted considerable Ga enrichments, with other immobile elements such as rare earth elements (REE), titanium (Ti), lithium (Li), and iron (Fe). This work focuses on the revealing of the potential Ga enrichments in bauxides from different deposits of Turkey (Mortaş-Doğankuzu, Konya; Küçükkoraş, Karaman; Acıelma-Yoğunoluk, Kahramanmaraş bauxite deposits). Geochemical data of major and trace elements of studied bauxite deposits show that these deposits have significant Ga enrichments (up to 72.6 ppm), as well as the REE (up to 580 ppm), Ti (up to 1.8%), and Li (up to 428 ppm) enrichments. In addition, the Ga enrichments show strong positive correlation with heavy rare earth elements (HREE) and moderate positive correlation with Al, Fe, Ti, Li and Sn elements. In this context, it can be concluded that the most probable source for Ga is rock forming aluminosilicates of the source rock due to the substitution with Al<sup>3+</sup> and Fe<sup>3+</sup>. During weathering process Ga exhibiting immobile behavior much like Al and Fe. Gallium is than incorporated into Al-bearing phases and thus enriched in the bauxite. Presence of Li content can be also interpreted as a contribution from micaceous source such as meta-carbonate rocks of Tauride platform. Moreover, geochemical association between Ga, Ti, Li, tin (Sn) and HREE can be explained by the redox and pH conditions causing other ions seperated from shallow environments.</p>