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- MakaleYalnız künye2025Scopus SJRQ2Concentrations, distribution, and source appointment of heavy metal/loids in non-clastic sedimentary rocks: a case study of early jurassic chert, northeastern türkiye
Saydam Eker, Çiğdem; Kaygusuz, Abdullah; Arı, Uğur Volkan
The Current study used geochemical indicators such as the geo-accumulation index (Igeo), the Enrichment Factor (EF), and the contamination factor (CF) to evaluate the regional distributions and accumulations of various heavy metal/loids (HM; Co, Mo, Pb, Zn, Cu, Ni, As, Cd) in early Jurassic cherts in the Gümüşhane (NE Türkiye). Five stratigraphic section measurement (MS) areas (Tedaş, Alemdar, Akçakale, Tekke, and Pirahmet) and one borehole (Eskibağlar well) were selected for sampling. Major and trace element compositions of the selected 25 samples were measured by inductively coupled plasma optical emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS). Calculated geochemical indexes indicated that Alemdar, Tekke MS, and Eskibağlar well samples were polluted with Pb, Zn, Cu, As, and Cd, Tedaş, Akçakale, and Pirahmet MS samples were polluted with Cd. Pearson's correlation coefficient (PCC) and principal component analysis (PCA) suggested that Zn, Pb, and Cu contaminating the Alemdar, Tekke MS, and Eskibağlar well samples were of ore mineralization origin, As was of terrigenous input, and Cd was probably of diatom origin. PCC and PCA showed that the Cd contaminating the Tedaş, Akçakale, and Pirahmet MS samples was probably of diatom origin, and the other metals found at normal levels in the samples were due to terrigenous input. The Early Jurassic period, which was a rift environment in the Gümüşhane region, is thought to have produced the cherts of the Alemdar, Tekke MS, and Eskibağlar well samples in a graben environment, while the cherts of the Tedaş, Akçakale, and Pirahmet MS were deposited in a horst environment. δU values, Ni/Co, and Vi/(V + Ni) ratios indicated that oxic-anoxic conditions were generally prevalent in the depositional environment, but redox conditions did not affect the abundance and distribution of HMs. These findings provide critical information for assessing heavy metal/loid enrichment and contamination potential not only in clastic sedimentary rocks, river sediments, and soils but also in non-clastic sedimentary rocks.
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İncele - MakaleAçık Erişim2024Scopus SJRQ1Evaluation of Cherts in Gumushane Province in Terms of Alkali Silica Reaction
Demir Şahin, Demet
Alkali–silica reaction (ASR) occurs when alkali oxides coming from the cement composition in concrete come together with reactive silica and moisture coming from the aggregate. Additional maintenance and repair costs caused by the development of ASR in concrete cause the cost to increase. However, thanks to the measures taken against ASR in the early period, it contributes to the creation of sustainable and durable concrete structures. The article investigated the usability of cherts with eight different chemical compositions as aggregates in ready-mixed concrete plants in Gümüşhane. Cherts have been investigated for alkaline reactivity and are intended to be used largely as a source for concrete plants. ASR length changes of the samples prepared according to ASTM C1260 standard were determined after 3, 7, 14, and 28 days of the curing period. Microstructural examination, ultrasonic P-wave velocity, and bending and compressive strength experiments supporting ASR were carried out. The obtained test results were compared between the reference (limestone) sample and each other, as well as with the values specified in the standards. The compressive and bending strength values of the samples increase depending on their ASR. It was observed that the crack structures and types increased depending on the increase in the crack values.
AtıfScopus2WoS2OpenAlex5İncele - MakaleYalnız künye2012Scopus SJRQ2Trace and rare earth elements as indicators of provenance and depositional environments of Lias cherts in Gumushane, NE Turkey
Eker, Cigdem Saydam; Sipahi, Ferkan; Kaygusuz, Abdullah
Trace elements and rare earth elements (REEs) of Lias-aged cherts in the Gumushane area were studied in order to understand their origin and depositional environment. Twenty three chert samples from five stratigraphic sections were analysed by inductively coupled plasma-mass spectrometry, X-ray diffraction, and mineralogical investigation. Lias cherts in the study area are microcrystalline, cryptocrystalline quartz, and megaquartz depending on mineralogical content. Trace elements of the cherts were compared with PAAS, Co, Y, and Th had stronger depletions in the five sections, whereas V, Ni, Zr, Nb, and Hf had smaller depletions. The distribution of Zr, Hf, and Ta yields Zr/Hf, Zr/Ta and Hf/Ta ratios (25/645, 37/665, and 0.18/3, respectively) that differ from those of chondrites and average upper continental crust, suggesting that these elements are likely non-detrital but are sourced from seawater. Th/U ratios range from 0.04 to 0.45 and are lower than those of the upper continental crust (average: 3.9). Lias-aged cherts have low total REE abundances and stronger depletions in five sections of the PAAS and chondrite-normalised plots. The cherts are characterised by a positive Eu anomaly (average: 4.9) and LREE-enrichment (LaN/YbN=average: 3.5). In addition, about one-half of the cherts exhibit positive Ce anomaly (range: 0.25-2.58), chondritic Y/Ho values (range: 3.3-60), and low (La/Ce)N values (average: 1.8). REE and trace element abundance in Lias cherts indicate that these elements were likely derived from hydrothermal solutions, terrigenous sources, and seawater. The REE patterns of the cherts show that they were probably deposited close to a continental margin.
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