Demet Kiran Yildirim

Bu çalışmanın temel amacı, Türkiye'nin kuzeybatısındaki Kocaseyit bölgesindeki (Balkesir-Havran ilçesi) polimetalik Cu-As-Ni-Pb damar tipi mineralizasyonunun kökenini daha iyi anlamaktır. Bu, mineralizasyonun ve ilişkili olduğu hidrotermal alterasyon türlerinin mineralojik, petrolojik ve jeokimyasal özelliklerinin incelenmesiyle gerçekleştirilmiştir. Kocaseyit bölgesi, Üst Paleozoik yaşlı Kalabak Formasyonu, Jura yaşlı Bayırköy ve Bilecik Formasyonları ile Oligosen-Miyosen yaşlı Düztarla granitoyitleri tarafından kesilen Paleosen-Eosen yaşlı Bağburun Formasyonundan oluşmaktadır. Düztarla granitoyitleri ile dokanaktaki Balya Formasyonu'ndaki (arkozik kumtaşları) KD-GB fay zonu boyunca lokalize olan polimetalik Cu-As-Ni-Pb damar tipi cevherleşme göstermektedir. Cevherleşme ile ilişkili olarak az miktarda karbonatlaşma ve kloritleşme ile birlikte yoğun serisitleşme, kaolinleşme ve piritleşme, çalışma alanında gözlenen baskın alterasyon tipleridir. Çalışma alanında üç cevherleşme fazı belirlenmiştir.Magmatik-hidrotermal fazda, pentlandit, pirit ve bazı arsenopirit minerallerinin oluştuğu gözlenmektedir. Hidrotermal fazda, pirit, arsenopirit, kalkopirit ve sfalerit mineralleri oluşmuştur. Süpergen faz döneminde ise kalkopirit ve piritten sonra sırasıyla malakit, kovellit ve götit oluşumları belirlenmiştir. Granitoyid kayaçlar, kalk-alkali metaalumina I-tipi granitlere özgü özellikler sergilemektedir. Granodiyorit örnekleri granodiyorit, monzonit ve kuvars-monzonit, granit örnekleri ise granit olarak sınıflandırılmış, manyetit serileri ile uyumlu ve geç orojenik ortamda oluşmuşlardır. Alterasyona uğramış kayaçların jeokimyasal özellikleri, bunların Mn-karbonat-serisit-klorit alterasyonu ile birlikte serisit-pirit-klorit alterasyonundan güçlü bir şekilde etkilendiklerini ortaya koymuştur. Alterasyon indeksi ve K2O indeksinin Hafif nadir toprak elementleri (HNTE) ve Ağır nadir toprak elementleri (ANTE) ile korelasyonlarına göre ya HNTE'lerin hidrotermal çözeltilerden kayalara taşınabildiğini ya da HNTE'lerinin kayalarda zenginleştiğini göstermektedir. MgO indeksinin HNTE ve ANTE arasındaki ilişkiye göre, serisitleşme (K bakımından zengin) oluşumunun kloritleşme oluşumundan daha yaygın ve yoğun bir şekilde meydana geldiğini göstermektedir.

This study contributes to our understanding of the evolution of Halılar Cu-Pb (±Zn) mineralization (NW Turkey) based on mineralogical and geochemical results and sulfur isotope data. The study area represents local Cu-Pb with some Zn brecciated-stockwork vein type mineralization along the NE–SW fault gouge zone at the lower boundary of the Sakarkaya and Düztarla granitoid rocks. Two main zones, consisting of sericite–quartz–chlorite ± kaolinite ± pyrite (i.e., zone-1) and calcite–epidote–albite ± chlorite ± sericite (i.e., zone-2), were observed within the central ore mineral zone at the mining site. Different mineralization assemblages were recorded; the main ore mineral contains chalcopyrite, galena, pyrite, and sphalerite within alteration zone-1, and the oxidation/supergene mineralization includes covellite and goethite. The mass balance calculations show that the samples of zone-1 show an increase in SiO₂, Fe₂O₃, K₂O, and LOI along with Ag, As, Cu, Mo, Pb, S, Sb, and Zn, reflecting high pyritization with sericitization and silicification. On the other hand, the samples from zone-2 are rich in CaO; Na₂O; P₂O₅; TiO₂; LOI; and carbon-reflecting calcite, epidote, and albite alterations. A uniform magmatic sulfur source of Halılar sulfides is suggested by their mean δ³⁴S value of −1.62‰. Furthermore, the primary metal source is metasediments and intrusive Düztarla granitoid magmatism. These observations suggest that the Halılar metasediment-hosted Cu-Pb (±Zn) mineralization was formed by epigenetic hydrothermal processes after sedimentation/diagenesis and metamorphism.

Essexites of Kestanbol pluton have significant amount of iron (Fe), titanium (Ti), Rare Earth Elements (REE) and thorium (Th) and considered as the source of Geyikli Heavy Mineral Sands (HMS). Geyikli HMS were enriched by the minerals of magnetite, rutile, monazite and apatite. In Geyikli HMS, REE contents (up to 0,25%) were rised by 4-5 times during placer deposition, mainly caused by the enriching of weathering resistant REE bearing dense phosphate minerals and zircon. On the other hand, Fe (up to 11%) and Ti (up to 2,5%) enrichments are heavily dependent on the magnetite, titanomagnetite and rutile minerals. By using the basic physical mineral processing techniques such sieving, shaking tables, multi gravity seperators, magnetic seperation, it is possible to reach higher grades for both REE and Fe-Ti and to have better initial values for electrochemical mineral processing techniques.

A new fossil pine species from eastern Turkey is described and its botanical affinities are discussed. The sample was collected from the city of Kemaliye, Erzincan province, Turkey, and derives from the early-middle Miocene Divriği formation. Transverse, tangential and radial sections were taken from the petrified wood, and its palaeoxylotomical features were investigated. Based on its anatomical features including idioblastic cells in rays a new fossil-species of the genus Lesbosoxylon Süss & Velitzelos was identified as Lesbosoxylon kemaliyensis Akkemik & Mantzouka, sp. nov. Diagnostic features of the new species are: Transition from earlywood to latewood mostly gradual; axial and radial resin canals with thin-walled epithelial cells present; latewood tracheids thin to thick walled; bordered pits on radial walls of tracheids 1-2(-3) seriate; crassulae common; rays heterocellular, uniseriate, partly biseriate; uniseriate rays up to 27 cells high; fusiform rays up to 30 cells high; axial parenchyma occasionally present; ray tracheids 2-3 rows; cell walls of ray tracheids smooth; cross-field pitting pinoid, 1-2(-6) pits per cross-field. Detailed investigation of the botanical affinities of the new fossil wood suggested that the most closely related modern species is Pinus canariensis C. Sm in Buch, a relict species from the Canary Islands.

Geochemical and mineralogical characteristics of beach sand sediments in southwestern Black Sea: An approach to heavy mineral placers    Hatice Nur Bayram (1*), Aslı Nur Uslu (1), Ali Erdem Bakkalbaşı (1), Demet Kiran Yildirim (1), Zeynep Doner (1), Ali Tugcan Unluer (1)  (1) Istanbul Technical University, Faculty of Mines, Department of Geological Engineering, Istanbul, Turkey (*hnnurbayram@gmail.com)   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 km2 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. 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. Fe2O3 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. Key words: Beach sand sediments; REE-Th-U; heavy minerals; southwestern of Black Sea; Turkey

The major and trace element component of 48 recent sediment samples in three distinct intervals (0–10, 10–20, and 20–30 cm) from Lake Acıgöl is described to present the current contamination levels and grift structure of detrital and evaporate mineral patterns of these sediments in this extreme saline environment. The spatial and vertical concentrations of major oxides were not uniform in the each subsurface interval. However, similar spatial distribution patterns were observed for some major element couples, due mainly to the detrital and evaporate origin of these elements. A sequential extraction procedure including five distinct steps was also performed to determine the different bonds of trace elements in the < 60-μ particulate size of recent sediments. Eleven trace elements (Ni, Fe, Cd, Pb, Cu, Zn, As, Co, Cr, Al and Mn) in nine surface and subsurface sediment samples were analyzed with chemical partitioning procedures to determine the trace element percentage loads in these different sequential extraction phases. The obtained accuracy values via comparison of the bulk trace metal loads with the total loads of five extraction steps were satisfying for the Ni, Fe, Cd, Zn, and Co. While, bulk analysis results of the Cu, Ni, and V elements have good correlation with total organic matter, organic fraction of sequential extraction characterized by Cu, As, Cd, and Pb. Shallow Lake Acıgöl sediment is characteristic with two different redox layer a) oxic upper level sediments, where trace metals are mobilized, b) reduced subsurface level, where the trace metals are precipitated.