Browsing by Author "Gulyuz, Nilay"

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Application of (u-th)/He Hematite Geochronology To the Çaldag Lateritic Ni-Co Deposit, Western Anatolia: Implications for Multi-Stage Weathering Events During Interglacial Periods/Segments
(Elsevier, 2024) Gulyuz, Nilay; Kuscu, Lkay; Danisik, Martin
Lateritic Ni-Co deposits are supergene deposits that develop due to intense weathering of the underlying ultramafic parent rocks and/or their serpentinized equivalents under tropical to sub-tropical climatic conditions. These deposits provide not only important sources of valuable metals such as iron, aluminium, nickel, and cobalt, but they also provide a proxy for paleoclimatic conditions. In this regard, geochronological studies on these deposits are critical to determine the timing of the paleoclimatic conditions, which is important for a better understanding of the paleoclimate at regional scale and for identification of favourable weathering periods that can be targeted in the exploration of undiscovered lateritic deposits in a region. In this contribution, we report hematite (U-Th)/He geochronology results from a well-preserved & Ccedil;aldag lateritic Ni-Co deposit in Western T & uuml;rkiye. We sampled the different parts of the lateritic profile from the different laterite zones at the & Ccedil;aldag deposit and carried out analyses of polished thin section to determine and identify the phases of hematite formation and primary hematite formed during primary lateritization. Then, we applied scanning electron microscopy (SEM) analysis and TESCAN Integrated Mineral Analyser (TIMA) mineral mapping to identify the suitable areas on primary hematites for subsequent (U-Th)/He dating. Primary hematites are detected at the base of the lateritic profiles (transition between the limonite zone and altered serpentinite) that are only in-situ parts of the laterites exposed in two different pits in the deposit. The obtained (U-Th)/He dates of ca. 502, 206, 178, and 63 ka correspond to the interglacial periods. The three youngest (U-Th)/He dates (206, 178, and 63 ka) from the weathering front of the hematite pit become younger towards the deeper parts of the profile in the direction of weathering. The ages indicate the weathering processes should have lasted until the Quaternary with some interruptions during interglacial periods/segments, despite the fact that the main intensive lateralization period is thought to be during the Middle Eocene. This study presents the first hematite (U-Th)/He dating of lateritic Ni-Co deposits and demonstrates the reliable use of this method after a careful selection of hematite samples. Our results suggest that, in contrast to the short-living lateritization model for lateritic Ni-Co deposits, they may have a multi-stage weathering history throughout their long-lasting development. In addition, the study showed that it has huge potential for the dating of lateritization and weathering processes that are related to paleoclimatic events. Finally, knowledge of the favourable paleoclimatic periods of chemical weathering in a region may help in determining the potential areas for ultramafic exposures for discovering new lateritic deposits.
Application of (u-th)/He Hematite Geochronology To the Caldag Lateritic Ni-Co Deposit, Western Anatolia: Implications for Multi-Stage Weathering Events During Interglacial Periods/Segments (Vol 172, 106203, 2024)
(Elsevier, 2024) Gulyuz, Nilay; Kuscu, Ilkay; Danisik, Martin
Çaldağ-manisa (Batı Anadolu) Lateritik Ni-co Yatağındaki Skandiyum Zenginleşmesinin Ön Çalışması
(2024) Gulyuz, Nilay
Skandiyum, biyomedikal araştırmalardan elektroniğe kadar çeşitli uygulamalarda yüksek talep gören en değerli kritik metallerden biridir. Lateritik Ni-Co yatakları skandiyum (Sc) aramaları için başlıca hedefler olarak kabul edilir çünkü Sc bozuşma sırasında kalıntı ve ikincil zenginleştirme yoluyla konsantre olarak, 100 ppm'e kadar ulaşabilir ve potansiyel bir yan ürün haline gelebilir. Bu çalışmada, Batı Anadolu'daki Çaldağ lateritik Ni-Co yatağının iki farklı ocağındaki bozuşmamış ana kayaçlarda ve çeşitli laterit zonlarında Sc dağılımı incelenmiştir. Hematit ocağında, serpantinit protolit ortalama 10,3 ppm Sc içeriği gösterirken, orta-üst limonit zonunda ~66 ppm'e kadar ulaşan önemli bir zenginleşme görülmektedir. Bu serpantinit protolitine kıyasla altı katlık bir artışı temsil etmesine rağmen, maksimum Sc konsantrasyonları (53,6-65,7 ppm) yan ürün Sc potansiyeline sahip diğer nikel lateritlere (~100 ppm) kıyasla nispeten düşüktür. Bu düşük konsantrasyon, serpantinleşmiş peridotit protolitin başlangıçtaki düşük Sc içeriğine ve lateritleşme sonrası tektonik aktiviteye bağlanmaktadır. Buna karşılık, Güney ocağında protolitte daha yüksek başlangıç Sc içeriği (~13 ppm), ancak limonit zonunda daha düşük ortalama Sc içeriği (~6,4 ppm) sergilenmektedir; bunun olası nedeni Sc barındıran minerallerin yüksek oranda deforme olmuş ocak içindeki alterasyon ve ikincil bozuşma süreçleri tarafından lateritleşme sonrası çözünmesidir. Bulgular, Çaldağ yatağının limonit zonlarında ~66 ppm'e kadar Sc konsantrasyonları sergilemesine rağmen, Ni üretiminin yanı sıra bir yan ürün olarak Sc potansiyelinin sınırlı olduğunu göstermektedir. Çaldağ yatağındaki ve Türkiye'deki diğer lateritik yataklardaki Sc dağılım mekanizmalarının daha iyi anlaşılabilmesi için daha detaylı mineralojik ve jeokimyasal araştırmalar yapılması önerilmektedir.
Geological and Mineralization Characteristics of the Kestanelik Epithermal Au-Ag Deposit in the Tethyan Metallogenic Belt, Nw Turkey
(Geological Society Korea, 2020) Gulyuz, Nilay; Gulyuz, Erhan; Shipton, Zoe K.; Kuscu, Ilkay; Lord, Richard A.
Kestanelik epithermal gold deposit is situated in the Biga Peninsula, which hosts numerous metallic deposits belonging to the Tethyan Metallogenic Belt. In the Biga peninsula the Tethyan Metallogenic Belt is represented by a Neo-Tethyan suture zone. Discovered deposits along the belt are commonly associated with Cenozoic magmatism ranging between 52 and 18 Ma in age, formed due syn- to post-collisional tectonics. In this study, we focus on the deposit-scale geological and mineralization characteristics of Kestanelik in order to determine the formation and evolution of the deposit within the tectono-magmatic history of the Biga Peninsula. We (1) mapped the geology of the deposit area (2) conducted paleostress analyses, (3) observed and examined the macroscopic and petrographical textural, mineralogical and alteration characteristics of the mineralization and (4) interpreted geophysical resistivity survey and geochemical assay data. The stratigraphic age of the Kestanelik deposit, bracketed by cross cutting relations and supported by the geophysical data, is middle Lutetian-early Priabonian which also implies that the deposit has a genetic link with the Cenozoic post-collisional calc-alkaline magmatism. A NE-SW oriented compressional regime determined from the paleostress analyses is consistent with the kinematics of the vein system and is attributed to the collision and further convergence after the closure of the northern branch of the Neo-Tethys Ocean. The fracture system provided structural pathways for the transport of the hydrothermal fluids. The common presence of pseudo-bladed quartz and hydrothermal breccias, and the low total sulphide and base metal contents in the mineralized veins indicate that the Kestanelik is a low sulphidation epithermal-type gold deposit. Boiling, mixing (hypogene oxidation) and supergene enrichment are the likely gold deposition and enrichment processes respectively.
Geomorphological and Geo/Thermo-chronological Responses of Indian Plate's Deformation During Neogene- Quaternary Time Along the Eastern Himalayan Syntaxis: Formation of Manabhum Anticline
(Pergamon-elsevier Science Ltd, 2024) Goswami Chakrabarti, Chandreyee; Gulyuz, Erhan; Gulyuz, Nilay; Narzary, Belligraham; Jaiswal, Manoj K.; Karaoglan, Fatih
India-Eurasia and India-Burma collision systems encircle Eastern Himalayan Syntaxis (EHS) in the north and the southeast. The main active structure responsible for the uplift of the Quaternary and Neogene rocks in the easternmost part of the EHS is the NW-SE trending Mishmi Thrust (MT). The spectacular antiformal Manabhum Hill developed during the Quaternary as a ramp antiform over a splay of Mishmi Thrust in its foreland region. The current work presents the deformation scenario, uplift rate, and landform development along the Mishmi Thrust from the Neogene to the Recent for the first time. The surface deformation and the rock and sediment deformation histories have been interpreted from the geomorphology, structure and petrology of the rocks and sediments. We use new (U + Th + Sm)/He low-temperature thermochronology (LTT) of zircon and apatite and Optically Stimulated Luminescence (OSL) dates to calculate the uplift rate for the Neogene to early Quaternary and late Quaternary time intervals, respectively. The Neogene uplift rate varies between 0.91 and 2.3 mm/yr, whereas the early Quaternary uplift rate is similar to 3.1 mm/yr. The increased uplift rate during the Quaternary period with significant deformation of sediments indicates the non-rigid character of the Indian plate in this sector, which experienced compression and clockwise rotation.
Hydrogeochemical Investigation of an Epithermal Mineralization Bearing Basin Using Multivariate Statistical Techniques and Isotopic Evidence of Groundwater: Kestanelik Sub-Basin, Lapseki, Turkey
(Elsevier Gmbh, 2020) Disli, Erkan; Gulyuz, Nilay
This study investigates hydrogeochemical processes controlling the groundwater quality using 64 groundwater samples in the epithermal mineralization bearing Kestanelik Sub Basin, NW Turkey. The groundwater dominantly exhibits a mixed-ion hydrochemical facies characterized by Ca-Mg-HCO3, Mg-Ca-HCO3, Ca-Mg-HCO3-SO4 and Ca-Mg-Na-HCO3 reflecting weakly mineralized waters circulating within calcareous sandstone and colluvium. The molar ratios of (Ca2++Mg2+)/(SO42-+HCO3-) and Na+/Cl(-)ratios and the linear plot between (Na++K+)-Cl- and (Ca2++Mg2+)-(HCO3-+SO42-) indicate that of dissolution of carbonates and silicate weathering, ion and reverse ion exchange processes influence the hydrogeochemistry of groundwater sources. Three and four factors account with 84.48 and 75.27 % of the total variance for spring and well waters, respectively. FC1 in the groundwater samples is described by strong loadings of TH, Ca2+, Mg2+, HCO3-, Ba, TDS, Cl-, EC and SO42-, and moderate loading of Na+, Mn, K+, TDS, pH. FC2 in the samples has strong positive loadings on Al, Fe, Zn, Na+, SO42-, Cl- and moderate positive loadings on B, TDS and K+. FC3 shows strong positive loading on Cu, Al, DO and moderate factor loadings for Fe in the well water samples. FC4 exhibits high positive loadings for As, Zn, and moderate positive loading for EC. Geochemical variables of FC 1, 2, 3 and 4 for the groundwater indicates mixed geogenic source of groundwater contamination through water-rock interaction processes dominantly from (i) the calcareous sandstone, serpentinite and colluvium lithologies and (ii) quartz, illite, pyrite and iron oxide minerals sourced from epithermal mineralization in the area. pH and As values exceed the desirable limits of WHO and TSE 266 guidelines for drinking purpose. The tritium levels show that some well waters have experienced longer water-rock interaction and residence time and are thus recharged from older groundwater sources compared to other well and spring waters.
Low Temperature Thermochronology Reveals Tilting of Crystalline Bodies, Halilaga Porphyry Cu-Au Deposit, Nw Anatolia: Implications for Exploration of Porphyry Copper Deposits and Interpretation of Low-Temperature Thermochronology Data for Regional Tectonics
(Elsevier, 2024) Gulyuz, Nilay; Gulyuz, Erhan; Karaoglan, Fatih; Kuscu, Ilkay
Because most crystalline bodies lack intrinsic paleo-horizontal information, their tilting cannot be measured directly. Their vertical movement, however, may be tracked by low-T thermochronology (LTT) tools. Because tilting is caused by differential vertical movements, it can be understood if the rate of differential movements is determined. In this regard, here we apply a new LTT-based approach to calculate the orientation of a tilted crystalline body, the Halilaga Cu-Au deposit, in NW Anatolia. Orientation is consistent with the one calculated from a drillhole-based 3D model of the deposit. This reveals the significance of tilting calculations for the exploration of porphyry Cu deposits. On the other hand, and more importantly, it emphasizes the importance of tilting calculations for geological applications such as LTT-based exhumation histories of samples taken from vertical profiles, and paleomagnetic studies. AHe data from the Halilaga deposit reveals the earliest response to the Aegean back-arc extension at similar to 24 Ma in the north of Western Anatolia. Lastly, thermal models, the new complementary datasets for the tectonic evolution of the region, show that the Halilaga deposit was exhumed to the surface by the coupling effects of Aegean extension and westward propagation of the North Anatolian Fault, which occurred not earlier than 2 Ma.
Multiphase Deformation, Flluid Fllow and Mineralization in Epithermal Systems: Inferences From Structures, Vein Textures and Breccias of the Kestanelik Epithermal Au-Ag Deposit, Nw Turkey
(Tubitak Scientific & Technological Research Council Turkey, 2023) Gulyuz, Nilay; Shipton, Zoe Kai; Kuscu, Ilkay
We investigate the multiphase deformation, fluid flow, and mineralization processes in epithermal systems by presenting a detailed study of vein textures and breccias of the Kestanelik epithermal Au-Ag deposit, NW Turkey. The mineralization in the deposit is associated with several quartz veins. Fault-hosted veins and mode I veins share many textural and breccia characteristics owing to (i) overprinting of tectonic breccias formed during coseismic rupturing by subsequent coseismic hydrothermal brecciation and (ii) reworking of earlier vein breccia phases by repeated rupturing and hydraulic fracturing events. The spatial distribution of breccias at fault-hosted veins proposes that power of coseismic hydrothermal brecciation is controlled by the distance to the level of boiling within a vein. The brecciation affects the entire vein proximal to the level of boiling; however, it is limited to the footwall contact of the vein more distally at the upper levels of a vein. Varying number of mineralization events for the veins suggests that any individual earthquake event reopened only one or more sealed vein, but not all at once. Fewer mineralization events in fault-hosted veins compared to the mode I veins is either linked to (i) focusing of high fluid flux into the conduits of mode I veins that accommodate more dilation or (ii) reopening of mode I veins owing to the driven of extensional failure under low differential stress. Although fault-hosted veins record fewer mineralization events, they have higher average Au grade (4.106 g/t) compared to that of mode I veins (2.736 g/t). On the other hand, fewer mineralization events in wall rock structures compared to the adjacent faults is attributed to (i) absence or poor development of the damage zone structures in earlier seismic events or (ii) deactivation of them after clogging due to the rotation of the optimum stress field or (iii) their formation as hydraulic extension fractures. This study emphasizes the importance of detailed studies of vein infill for understanding the internal structural evolution of the veins in epithermal deposits that is interest to the geologists within both industry and academic fields.
Repeated Reactivation of Clogged Permeable Pathways in Epithermal Gold Deposits: Kestanelik Epithermal Vein System, Nw Turkey
(Geological Soc Publ House, 2018) Gulyuz, Nilay; Shipton, Zoe K.; Kuscu, Ilkay; Lord, Richard A.; Kaymakci, Nuretdin; Gulyuz, Erhan; Gladwell, David R.
This study presents a detailed study of the dimensions, geometry, textures and breccias of a well-exposed epithermal vein system, the Kestanelik gold deposit in the Biga Peninsula, NW Turkey, and investigates the permeability enhancement mechanisms in epithermal gold deposits. Here mineralization is associated with quartz veins up to 13.6 m thick. Vein textures and breccia components indicate repeated sealing and subsequent brecciation of wall rock and pre-existing vein infill. Field and petrographic analyses characterize east-west-trending veins as left lateral faults, whereas NE-SW-trending veins are extensional (Mode I) fractures. Cataclasite and tectonic breccia of wall rocks and early quartz, hydrothermal crackle breccias, and matrix-supported chaotic breccias of pre-existing vein infill, all of which are cemented by late iron-oxide-bearing quartz, indicate that co-seismic rupturing and hydraulic fracturing are two major permeability enhancement mechanisms. In addition, transient variations in local stress direction, caused by syn-mineralization dyke intrusion, may have enhanced permeability on misoriented surfaces and at locations where the dip changes. This study emphasizes the importance of understanding structural geology and kinematics as controls on the location of boiling and mineralization mechanisms in epithermal gold deposits.
Thermal-Tectonic History of The.ispir-Ulutas Porphyry Cu-Mo Deposit, Eastern Pontides: Implications for Regional Tectonics and Exploration of Porphyry Systems
(Elsevier, 2025) Gulyuz, Nilay
This study employs multiple low-temperature thermochronology techniques-Apatite Fission Track (AFT), Apatite (U-Th)/He (AHe), and Zircon (U-Th)/He (ZHe)-to reveal the cooling, exhumation, and preservation history of the.Ispir-Ulutas porphyry Cu-Mo deposit, the oldest known porphyry deposit in the Eastern Pontides (similar to 131 Ma), and to investigate the relative scarcity of the porphyry systems in the Eastern Pontides. The inverse thermal history model reveals a complex multi-stage cooling/exhumation history of the.IspirUlutas deposit. The ZHe data and thermal model indicate that the deposit was emplaced at a paleodepth of over 5 km at similar to 131 Ma. The deposit experienced two major exhumation stages. The first, occurring during the Middle Eocene (similar to 43-38 Ma), was triggered by anomalous regional compressional forces likely due to the subduction of a mid-ocean ridge along the Bitlis-Zagros suture zone. During this phase, the porphyry system was exhumed to near-surface levels, but only its uppermost parts were eroded. Shortly after, post-collisional volcanic and sedimentary sequences buried the deposit, temporarily protecting it from further erosion. The second major exhumation phase, recorded by AHe data, began around 18 Ma and continues to the present, resulting in approximately 2.5 km of erosion. This phase aligns with the timing of the Arabia-Eurasia collision, which caused gradual uplift and exhumation across the region. In summary, the deep emplacement of the.Ispir-Ulutas deposit (>5 km), combined with the postmineralization burial by Eocene sequences, extended slow exhumation, and drier/continental climatic conditions, played key roles in the preservation of the porphyry system. Lastly, the study proposes that areas in the southern Eastern Pontides, particularly those covered by Eocene sequences, may offer promising exploration targets for new porphyry deposits.