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- MakaleYalnız künye2018Scopus SJRQ2Tracing provenance and chemical weathering changes in Ankara Stream sediments, central Turkey: Geochemical and Sr–Nd–Pb–O isotopic evidence
Saydam Eker, Çiğdem; Sipahi, Ferkan; Gümüş, Mustafa Kemal; Özkan, Özay
This study aims to analyze the changes in sediment provenance through the geochemical and Sr–Nd–Pb–O isotopic composition of the Ankara Stream bed and overbank sediments (ASBS and ASOS) and to examine the weathering and sediment transport processes in response to step climate variability. Major, trace, and rare earth elements, as well as Sr–Nd–Pb–O isotopic composition, exhibit generally similar variations for the investigated samples. These sediments have relatively high εNd(0) values and low 87Sr/86Sr ratios. Similar Pb isotopic ratios also characterize these sediments but have slightly different δ18O isotope values with relatively higher δ18O isotope values in the ASBS and lower δ18O isotope values in the ASOS samples. Chemical indices indicate low–moderate chemical weathering in the step-dominated climate. The low average Zr/Sc and Zr/Nb ratios indicate that such geochemical change was dominated by the composition of the source rocks but not sedimentary recycling with zircon enrichment, reflecting first-cycle deposit. Low radiogenic 87Sr/86Sr ratios and negative εNd(0) values indicate that the investigated sediments are relatively derived from young magmatic provinces, which are intermediate sources. Finally, the findings show that the geochemical compositions of the ASBS and ASOS were dominated by the composition of the source materials that originate from Galatia province and Late Cretaceous- Early Tertiary volcanic rocks in central Anatolia. Reasonable semiarid to arid climatic conditions are observed in the region. Active tectonism, increased erosion, and the investigated sediments are also transported rapidly to the stream channel without chemical alteration, and the sediments are the first-cycle products.
AtıfScopus9WoS7OpenAlex10
İncele - MakaleYalnız künye2008Scopus SJRQ1The use of cation packing index for characterizing the weathering degree of granitic rocks
Ceryan, S.; Zorlu, K.; Gokceoglu, C.; Temel, A.
The weathering state and weatherability of rocks are highly important for engineering geology projects and the use of rocks as building stones. The weathering state of rocks can be described by various chemical and petrographical weathering indices. To determine weathering state of a rock, considerable amount of chemical analyses is required. Weatherability of rocks depends on not only their mineral composition but also the number of cation replaceable with hydrogen in a mineral. In this study, the use of the k-value (cation packing index is defined as the number of cation in a mole) for characterizing the degree of weathering of granitic rocks is investigated. For the purpose of the study, the Kurtun granitic rocks are selected as the material of the study. The study contains three main stages and these are field investigations, laboratory studies and regression analyses. During the field studies, in-situ weathering descriptions and sampling are carried out. The samples are subjected to chemical and petrographic analyses and physical and mechanical tests. At the final stage of the study, a series of regression analyses between the cation packing index and other properties of the samples are performed. The results show that the k-value can be used as a weathering indicator. When compared with the other chemical weathering indices, the k-value can be used as a weathering index without chemical analyses, because it can be determined by mineralogical analyses. (C) 2008 Elsevier B.V. All rights reserved.
AtıfWoS43OpenAlex47İncele - MakaleYalnız künye2008A new quantitative weathering classification for igneous rocks
Ceryan, Sener; Tudes, S.; Ceryan, N.
The description and classification of the rocks provide important information for geotechnical modeling in order to predict their engineering behaviors. One of the most imperative parameters influencing the engineering behaviors of the rocks is the degree of weathering. Therefore, it is evident that a realistic weathering classification is necessary mostly for establishing the geotechnical models in the engineering geology studies. For this reason, development of a qualitative weathering classification is the main purpose of the present study. The Weathering State Parameter has been first created by describing the chemical and physical changes separately owing to weathering by employing the ultrasonic wave velocity in the rock material. Then a quantitative weathering index was introduced by combining the weathering condition and the slake-durability known as the indicator of the rock/soil ratio in the rock material. Finally, this index obtained was applied on the prediction of the engineering properties of the Harsit granitic rocks (Giresun, NE Turkey). As a consequence of this study, it has been determined that the engineering properties of the samples and the numerical index proposed could be predicted. In addition, the use and the limitations of the index introduced herein were discussed.
AtıfScopus80OpenAlex75İncele - MakaleYalnız künye2008Scopus SJRQ1Influence of weathering on the engineering properties of Harsit granitic rocks (NE Turkey)
Ceryan, Sener; Tudes, Sule; Ceryan, Nurcihan
Weathering and hydrothermal alteration of the granitic rocks in the Eastern Black Sea Region (NE Turkey) are important phenomena affecting the engineering projects in the region. The study investigated the probable paths of rock-forming mineral transformations due to weathering in the Harsit granitoid rocks, the changes of the major oxides as a consequence of weathering and the effects of weathering on the engineering properties. To identify the changes in the major oxides, the volume concentrations were considered in relation to the dry density. Chemical leaching during weathering was shown to be significant in changing the minerals. It was concluded that the engineering properties of the weathered granitic rocks can be most reliably predicted by P-wave velocity.
AtıfScopus68WoS63OpenAlex77İncele - MakaleYalnız künye2008Scopus SJRQ1New chemical weathering indices for estimating the mechanical properties of rocks: A case study from the Kürtün Granodiorite, NE Turkey
Ceryan, Şener
The chemical weathering of rock proceeds by water-rock interaction. During weathering geochemically mobile elements, alkali and alkali-earth elements are easily leached from rocks, leaving the residual elements to combine with components from the atmosphere to form new minerals. No single, weathering index given in the literature fits the model of the process involved in chemical weathering outlined above. This study deals with the derivation of three new chemical weathering indices oy taking both chemical processes such as leaching and new mineral formation into account. The new indices are chemical leaching index (CLI), chemical weathering product index (CWPI) and total chemical weathering index (TCWI). These indices are applied to selected weathering profiles in the Kürtün granodiorite, NE Turkey, in order to estimate the effects of chemical weathering on the physico-mechanical properties of rock materials. The relative variation of the mechanical properties and TCWI display a statistically significant correlation. Besides, it is shown that TCWI and weatherability index, originally defined by Hodder (1984) can be used together to evaluate the effect of chemical weathering on the mechanical behaviour of rocks.
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