The Biga Peninsula of NW Turkey is host to many kaolin and halloysite deposits with mineralization occurring at the intersections of fault zones in contact with Late Eocene-Miocene calc-alkaline volcanic rocks. Distinguishing between the relative overprinting of hypogene by supergene processes in these deposits is a challenge and important because they affect the physical-chemical properties of minerals and their potential for industrial applications. This study examines the Sarıbeyli-Sığırlı and Bodurlar kaolin deposits in NW Turkey, which were formed from similar volcanics as evidenced by 40Ar/39Ar. Late Eocene (34.2 ± 0.20 Ma) to Early Oligocene (32.7 ± 0.17 Ma) ages for both primary volcanic rocks and alunites are consistent with surrounding rocks in the Çanakkale region. Criteria used to distinguish hypogene alteration from supergene alteration processes come from X-ray diffraction (XRD), Fourier-transform infrared (FTIR) and Raman spectroscopies, thermal gravimetric analysis (TGA), scanning and transmission electron microscopy (SEM, TEM), and elemental analyses. Isotopic δ18O depletion and δD enrichment of the Sarıbeyli-Sığırlı deposit suggests that it was more influenced by magmatic waters than was the Bodurlar deposit. The Bodurlar deposit contains a paucity of dickite compared to the Sarıbeyli-Sığırlı deposit, which is evidenced by lower TGA endotherms, higher ratios of XRD intensities for reflections at 1.316 Å and 1.307 Å, distinctive FTIR absorbance bands at 3620 cm− 1 and 3652 cm−1, and relative Raman intensities of the γ1 and γ5 vibrational modes.A genetic model is proposed whereby these deposits are mainly formed through an acid-sulfate hydrothermal alteration, in what appears to be a volcanic-hydrothermal system. The extent of hydrothermal alteration was controlled by fault density and the initial texture of the volcanic rocks. These steam-heated environments included sulfide-enriched vapors and groundwater mixed to varying degrees in the vadose zone. The Sarıbeyli-Sığrlı and Bodurlar deposits, respectively, contain mineral assemblages that reflect both hypogene (kaolinite, alunite, dickite) and supergene (kaolinite, halloysite, jarosite) processes. These observations offer a basis for comparing and discriminating the relative influence of these two important alteration processes responsible for the formation of kaolin deposits in NW Turkey and around the world.

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Dacitic andesitic calc-alkaline lavas and their pyroclastic rocks of Upper Cretaceous age are widespread in the Ordu area, eastern Black Sea Coast of Turkey. Ca-bentonite and Ca/Nabentonite deposits with significant economic potential formed in the broader region. The mineralogy and geochemistry of these deposits were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and chemical analyses. The parent rocks (PR) and bentonite samples were analysed for the major and trace element contents, including rare-earth elements, to understand the effect of differential alterations on element mobility. The bentonites contain mainly di-octahedral Ca-montmorillonite with minor amounts of illite, quartz, calcite, dolomite and feldspar. Primary K-feldspar and plagioclase phenocrysts were altered in the bentonite horizons, and were completely leached at greater depth. For this reason, the higher quality bentonites are found at deeper zones. Bentonite horizons are characterized by relatively high loss on ignition (LOI: 9.8–20.8%) and MgO content (3–5%) and low K2O (<0.5%) and Na2O (<2%) contents compared with the least altered parent rocks. Silicon, Ca, Mg, Mn and P are markedly enriched whereas Fe, Na, K and Ti are depleted in the bentonite samples. The chondrite-normalized rare earth element (REE) patterns show identical trends characterized by strong light rare earth element (LREE) enrichment in both the PR and bentonite samples. The LREE contents are higher than those of their heavy counterparts (HREE) in the samples. Alteration of the PR to bentonite is associated with intense chemical leaching and subsequent removal of K and Na in open-system conditions.

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Çağımızda iklim ve ekoloji krizleri ile mücadele etmek için karbon emisyonlarının azaltılması adına yenilikçi çözümlere ihtiyaç duyulmaktadır. Son 30 yıllık dönemde gerçekleştirilen öncü teorik çalışmalar, atmosfer-litosfer etkileşim süreçlerinin doğal bir sonucu olarak oluşan karbonat minerallerinin, atmosferik karbondioksitin kalıcı bertarafı bakımından büyük potansiyel taşıdığını göstermiştir. Bununla birlikte, atmosferik karbondioksitin jeolojik bertarafını hedefleyen yerel uygulamaların başarıyla gerçekleştirilmesi için, başta karbonatlaşmanın hangi kaya türlerinde ve hangi koşullarda en etkili biçimde gerçekleştirilebileceğine dair yaklaşımlarda bulunmak adına literatürdeki pek çok eksiliğin giderilmesine ihtiyaç vardır. Alp-Himalaya orojenik kuşağında yer alan Türkiye, Tetis okyasnusun kalıntılarını temsil eden ofiyolit ve ofiyolitik yığışım karmaşaları bakımından oldukça zengin bir coğrafyadır. Kuzeybatı Anadolu’da Bursa-Orhaneli civarında geniş alanlarda gözlenen Orhaneli ofiyoliti tipik bir ofiyolit istifinin bazik-ultrabazik litolojilerini oluşturan dünit, harzburjit, klinopiroksenit, gabro ve serpantinlerin yanısıra, değişik boyutlarda kireçtaşı ve şist blokları ile radyolarit ve tüflerden meydana gelir. Mostra ölçeğinde çeşitli ayrışma profilleri ve alterasyon dereceleri sergileyen dünit başlıca olivin + ortopiroksen, magnetit, serpantin, talk, spinel ve kil minerallerinden oluşmaktadır. Bu çalışma kapsamında, Orhaneli ofiyoliti dünitlerinden derlenen numuneler üzerinde kesikli reaktör düzeneğinde, CO2 tutma pontasiyellerinin belirlenmesi amacıyla reaksiyon deneylerine tâbi tutulmuşlardır. Kırıntılı ve blok olarak hazırlanan dünit örneklerinde farklı pH2-pH4 ‘ya sahip asit çözeltileri ilave edilerek bu çözeltilerden karbondioksit gazı geçirilmiştir. Deney örnekleriden yapılan mineralojik, petrografik, mikromorfolojik ve kimyasal analizler, numune yüzeyleri ile mikro süreksizlikler boyunca şiddetli alterasyon zonlarının gelişimi ve bu zonlarda manyezit ve siderit gibi Mg- ve Fe- karbonat minerallerinin kristallendiğini ortaya koymuştur. Elde edilen bulgular, Orhaneli ofiyolitinin mostra ölçeğinde CO2 saklama potansiyelinin olabileceği ortaya koymaktadır.

&lt;p&gt;The multi-disciplinary studies yield a more complicated picture on seismic cycles, especially with the increasing evidence on creeping, slow slip events, tremors and repeating earthquakes. Recent observations support triggering of large earthquakes even by small or slow earthquakes and creeping of different portions of the fault. The Palu-Hazar Lake section of the East Anatolian Fault (EAF) is an example place of such kind of behaviour, where the 24 January Mw 6.8 Sivrice Earthquake was nucleated along the neighbouring segments. This sinistral strike-slip fault forms the eastern boundary of the Anatolian &lt;em&gt;Scholle&lt;/em&gt; between Karl&amp;#305;ova (Bing&amp;#246;l) in the northeast and T&amp;#252;rko&amp;#287;lu (Kahramanmara&amp;#351;) in the southwest within the complex tectonic frame of the Eastern Mediterranean.&lt;/p&gt; &lt;p&gt;In this study, we aim to correlate any potential influence of bedrock lithology on this creeping section of the EAF. First, we revised the active fault and geological maps by using the multi spectral satellite images (e.g., Landsat 8 OLI) and high-resolution digital surface models (~0.65 m ground pixel resolution). Then, we determined potential exposures along the EAF and made systematic sampling both from cohesive and incohesive fault rock exposures within our study region. Collected samples are prepared for X-ray diffraction (XRD) measurements, especially for the determination of the fault clay types. Fault rock samples from ophiolitic (mafic and ultramafic) rocks and accretionary complexes (shale, sandstone, volcanics, ophiolite fragments) are mostly made of vermiculite and include minor amounts of smectite and chlorite according to our XRD measurements. Although the low shear strength of vermiculate may trigger aseismic slip at shallow depths with change in pore water pressure, it is possible that there may be no correlation between bedrock lithology and creeping, considering the poorly known seismic history of the EAF.&lt;/p&gt; &lt;p&gt;This study is supported by T&amp;#220;B&amp;#304;TAK Project no. 118Y435.&lt;/p&gt; &lt;p&gt;Keywords: earthquake, East Anatolian Fault, creep, fault rocks&lt;/p&gt;