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Extraction of meaningful information on the timing of fault activity from clay gouges using radiometric dating methods, such as those based on the K-Ar system, can be challenging. One of the factors complicating interpretation of the radiometric dating results is the presence of multiple K-bearing components in the gouge material. In the current study, an attempt was made to develop a new interpretative method for K-Ar and 40Ar-39Ar dating, capable of handling a three-component mixture. In addition, the mineral composition of clay gouges from the Tatra Mountains (Poland), which has not been investigated before, is reported. The mineral compositions of the bulk clay gouge material and separated size fractions were determined by X-ray diffractometry and Fourier-transform infrared spectroscopy. The gouge samples were composed of quartz, dioctahedral mica (as a discrete phase and as a component of mixed-layered illite-smectite), and chlorite, commonly with plagioclase and more rarely with K-feldspar, dioctahedral smectite, calcite, anatase, or trace kaolinite. One feldspar-free sample containing three mica polytypes (1Md, 1M, and 2M1) was chosen for dating with the 40Ar-39Ar method. The results of 40Ar-39Ar dating were interpreted using three concepts: Illite Age Analysis (IAA), a method based on the MODELAGE software, and a newly developed three-component concept. The age values obtained with IAA were −14 Ma ± 31 Ma and 180 ± 91 Ma for authigenic (1Md) and inherited (1M + 2M1) components, respectively. The MODELAGE-based approach returned –4 ± 40 Ma and 165 ± 62 Ma. The three-component approach returned age values of polytypes as follows: 1Md, 15 ± 37 Ma; 1M, 135 ± 57 Ma; 2M1, 121 ± 56 Ma based on the medians and the interquartile ranges of non-normal distributions of Monte Carlo-simulated age values. The results obtained indicated that the 1Md polytype was probably formed during the most recent stage of fault activity, while 1M and 2M1 polytypes are of equal age, roughly. [ABSTRACT FROM AUTHOR]

Soil is one of the most important constituents of an ecosystem, playing a crucial role in many environmental reactions and processes. Despite the fact that many environmental studies were conducted in the vicinity of Longyearbyen, very little is known about the physical and chemical properties as well as mineralogy of soils occurring in this town. Thus, the main aims of this study were: (1) to determine the texture, chemical properties and mineralogy of the topsoil horizons of urban soils occurring in the Longyearbyen area (Spitsbergen, Norway); and (2) to determine and explain their spatial distribution within the area of Longyearbyen. In general, the topsoils are characterised by loamy texture; acidic reaction; quite high content of total organic carbon (TOC); high content of Si, Al and Fe; and low content of K, Na, Ca, Mg and P. Quartz, K-feldspar, plagioclase, mica and chlorite are the prevailing minerals. Differences in the concentration of TOC, total nitrogen and elements in the topsoils are mainly related to the diversity of texture and mineralogy of the local parent material and the development of vegetation cover. The results indicate that topsoils in Longyearbyen are characterised by the natural properties and are not strongly transformed by human activity. However, pollution of soil with trace elements related to coal mining should be checked. [ABSTRACT FROM AUTHOR]

The online version of the original article can be found at https://doi.org/10.1007/s42860-022-00176-7 Clays and Clay Minerals https://doi.org/10.1007/s42860-022-00176-7 This article was updated to correct errors in Equations 5, 6, 7, 8 and Table 7 that were introduced during the production process. [Extracted from the article]