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In the recent past, several weathering indicators have been developed to describe its state of weathering. The state of rock weathering is a useful indicator to estimate the integrity of tropically weathered rock material and mass which weatherability plays an important role in a tropical region. Through a ground assessment tool, the strength and durability of the rock mass could be estimated and complex or adopted to simplify the early prediction of the complex engineering parameter. This paper presents several models of the Weathering Index (WI) using selected significant parameters using statistical analysis. For this purpose, several sites have been chosen to represent granitic rock mass. Forty (40) numbers of samples were collected and tested comprising from four (4) sites in Malaysia. Several laboratory tests have been conducted such as Point Load Index (Is(50)), dry density, Slake Durability 1 (SD1), Slake Durability 2 (SD2) and moisture content. The field and laboratory data sets are used to determine the WI by using simple regression and MLR analysis Significant parameters found to be useful in determining the WI are selected namely SD1, dry density, Is(50), and block volume. These parameters were selected based on stepwise analysis using Statistical Package for the Social Sciences (SPSS). Following the models' implementation, the models were evaluated and the best prediction model was selected after considering statistical coefficients, such as coefficient of determination (R2), variance account for (VAF), and root mean squared error (RMSE), as well as utilizing a straightforward ranking approach. The findings of this study could contribute to the more accurate prediction of WI using a more simplistic field and laboratory parameters. Therefore, the WI is useful during the initial stages and planning of rock excavation work and provides a good description of weathering grade and rock mass properties, which will affect excavatability in granitic areas. [ABSTRACT FROM AUTHOR]

In this study, rock samples from various tectonic domains of North Pakistan are assessed in terms of their physical, mechanical, and petrographic characteristics. A comprehensive petrographic investigation unveiled a range of vital textural characteristics within the samples, encompassing modal mineralogical composition, mineral alterations, micro-fracture occurrences, and mineral grain sizes. A comprehensive suite of both destructive and non-destructive tests, coupled with thorough aggregate testing across all rock types, has been diligently conducted. These tests included Compressive Strength (UCS), Tensile Strength (UTS), Point Load Test (PLT), Schmidt Hammer test (SHT), Ultrasonic Pulse Velocity (UPV), Specific Gravity, Water Absorption, and Porosity assessments. The integration of field observations, petrographic insights, and physico-mechanical data has facilitated the assignment of weathering grades to the samples. This rigorous analysis has culminated in the classification of granite into three distinct strength classes: high-strength properties (Grade-I) comprising four out of eight samples, intermediate-quality (Grade-II) granites represented by two out of eight samples, and low-quality (Grade-III) granites constituting the remaining two samples. Remarkably, all samples surpass the minimum strength thresholds recommended for versatile building stone applications. Furthermore, the physico-mechanical assessment demonstrates that the granitic rock aggregates align comfortably with the stipulated limits of respective standards, thereby validating their suitability as viable aggregate sources. Through regression analysis, it becomes evident that the empirical correlation linking UCS with SHT and UPV offers heightened reliability compared to the UTS and PLT correlations. Consequently, the compelling geotechnical and petrographic outcomes strongly advocate for the feasibility of employing granitic rocks as a pragmatic choice for construction material aggregates. Ultimately, the research not only contributes to the scientific understanding of granitic rocks but also provides actionable knowledge for optimizing construction practices in the specific geological context of North Pakistan. [ABSTRACT FROM AUTHOR]

In this paper, we evaluate chemical weathering and its climatic significance in different periods (pre- and post-industrialization) in a basin impacted by 500 years of mining activities. We consider the geochemical and mineralogical composition of stream sediments and overbank deposits from the Guanajuato River Basin (GRB) in central Mexico. This research provides information about the weathering modifications caused by anthropogenic impacts before and after mining activities. The elemental concentrations of major elements were determined using X-ray fluorescence spectrometry, and the clay mineralogy was determined using X-ray diffraction (XRD). The chemical weathering intensity was estimated using the chemical index of alteration (CIA), the plagioclase index of alteration (PIA), and the weathering index of Parker (WIP) indices. The clay minerals in overbank sediments are kaolinite > smectite > chlorite > and vermiculite influenced by climatically driven weathering. In-stream sediments, the clay minerals are chlorite > vermiculite > kaolinite > smectite, influenced by the origin of the sediments and showing that physical weathering has been dominant in recent times because of changes in the vegetation cover and accelerated erosion in the stream sediments of the GRB. The weathering indices show that chemical weathering was greater in the preindustrial epoch (overbank sediments) compared with the present day (stream sediments) in the GRB. According to the CIA, clay content, and chemical composition, we identified four paleoclimatic conditions from 2450 ± 40 yr BP to 9410 ± 40 BP. There is a wet period at the base of the column (9410 ± 40 BP), followed by an early cold period and a wet period surrounding 2450 ± 40 yr BP. The combination of weathering indices and the clay content proved to be a useful tool; it was used to determine the weathering evolution of the basin and the anthropogenic impacts in a basin where there are historical references to mining activity over the last 500 years. [ABSTRACT FROM AUTHOR]

The cavernous features are considered one of the geological hazards that are dominant in the carbonate rocks as a results of dissolution effect of groundwater. The dissolution process extends for many years at the subsurface layers and causes catastrophic collapse if migrated to the surface layers. The problem become crucial in the urbanization areas where there are wide varieties of construction activities. Beside the natural weathering process, the human interventions, representing in the wastewater, can accelerate the weathering process of the prevailing cracks. Al Kharj governorate is one of the promising areas close to Riyadh, the capital of Saudi Arabia, that attracts wide aspects of urbanization, agriculture and industrial activities. The study area is located inside an urban neighborhood at the western part of Al Kharj city. The site is surrounded by buildings extensions from three sides and the fourth side was excluded from urbanization activities due to existence of surface cracks along the area especially at the northern direction. Excavations and boring tests reveal that the exposed cracks are extended downward and may be connected to subsurface karstic features in the limestone rocks. Two surface geophysical measurements have been planned to provide clear information about the locations, horizontal and vertical extensions of the cavernous features along the study site. The Time Domain Electromagnetic (TEM) and Electrical Resistivity Tomography (ERT) methods were applied for investigating the subsurface characteristics up to 40m depth with different resolutions. The data have been acquired along profiles path across most of the surface fractured features. In spite of the inverted TEM data representing the subsurface resistivity variations in 1D mode, the dense TEM stations and the direct comparing the results with the available borehole lithology, enabled to trace the subsurface cavernous features laterally and vertically with reasonable resolution. Moreover, the 2D ERT processed data have been compared with the TEM results along some localities for guiding the data interpretation to locate the subsurface cavernous features. The two methods are analyzing the subsurface in two different resolutions, the TEM can explore the deeper parts and the layer successions, whereas the ERT methods can provide the lateral extension tracing of cavernous features. Based on the results 3D fence diagrams, most of the cavernous features that are located along the northern part of the study area related to fractured limestone zones extend vertically to more than 20m in some localities. Data interpretation has been flowed by excavation process for confirming the interpreted anomalies and resulted in discovery of huge cavity system extended laterally and vertically at deeper massive limestone layer. [ABSTRACT FROM AUTHOR]

Pyrite (FeS2) is one of the most abundant sulfides on Earth and has already been studied in numerous ways for decades because of its rapid oxidation and the associated environmental impacts. This study proposes a new experimental physico-chemical approach (air, tridistilled water and water drip exposure) to determine the oxidation rate of pyrite using surface and depth data via XPS (X-ray Photoelectron Spectroscopy) analyses. Our experimental study of almost pure pyrite reveals a maximum oxidation rate of 11.7 ± 1.8 nm day−1 for drip exposure with precipitation of sulfates or Fe-oxides depending on the experimental condition. The oxidation rates obtained under various experimental conditions may be extrapolated to weathering rates of different zones of supergene profiles/ores (leached zone, saprolite and cementation zone). The extrapolation suggests a maximum rate of 4.3 ± 0.6 m Ma−1, which is consistent with data obtained by isotope dating of weathering profiles. Under geological conditions however, the oxidation rate of pyrite may be influenced by additional parameters, such as the nature of the host rock, its porosity/permeability, the climate, the influence of an oxidizing environment, and the mineralization of secondary minerals. [ABSTRACT FROM AUTHOR]

Salt weathering recognized as an important reason for the weathering of cultural relics. To research the salt weathering of the Banyueshan Giant Buddha in Ziyang, Sichuan, China, the sandstones of the Banyueshan Giant Buddha were taken samples. Through field investigation and laboratory test, the weathering damage types and weathering mechanism of sandstones were defined and analyzed. The research showed that the main weathering damage types of sandstones include exfoliation, soiling, chapping, hollowing and encrustation. The lithotype of the sandstones is confirmed to be yellowish-gray medium-fine grained lithic feldspar sandstone by microscopy. Conventional XRD analysis showed that the clay minerals content and calcite increased in weathered sandstone samples compared with core samples. The results all showed that the soluble salts content of weathered sandstone samples is higher than that of core samples by XRF, XRD of sedimentation separation and soluble salt ion detection. The possibility of damage for soluble salts in sandstone is discussed by considering the local climate conditions, the conversion conditions of various soluble salts and the accompanying crystallization pressure. Finally, it is found that the crystallization expansion of soluble salts under temperature change and dry–wet cycles is the internal reason of promoting weathering. The research results have a good referential value for the protection of culture relics in similar geological environments. [ABSTRACT FROM AUTHOR]

The significant role in high-tech and green technologies, recent outstripping demand, and constrained global supply of rare earth elements (REEs) have led to the exploration of phosphate deposits worldwide as a sustainable source for the recovery of REEs as by-products. In this context, the Eppawala Phosphate Deposit (EPD) in Sri Lanka can be considered a potential source for recovering REEs as a by-product. The REE geochemistry and mineralogy of sixty representative samples from the weathered regolith (primary apatite crystals and secondary phosphate matrix) and the carbonatite source rock at the EPD were analyzed. The average total REE content (∑REE) in the weathered regolith ranged from 2500 to 6092 ppm, with higher enrichment of light REEs than heavy REEs. The weathered regolith was highly enriched in REEs compared to the parent carbonatite due to residual enrichment of apatite with calcite and dolomite dissolution. Furthermore, REE immobilization during matrix formation results from the retention of REEs in fluorapatite and hydroxylapatite. Mineralogical analyses revealed that the major REE ore minerals in the EPD are apatite group minerals. Despite the relatively low REE grade (~ 0.48% total rare earth oxide) compared to the other phosphate deposits in the world, this deposit is significantly enriched in critical and highly demanded REEs, such as Nd (54,468 tonnes), Pr (17,994 tonnes), and Tb (2,897 tonnes). Therefore, with upgraded extraction techniques, the EPD could become a potential source of REEs that could contribute to maintaining a sustainable REE supply chain in the future. [ABSTRACT FROM AUTHOR]

As a building material, limestone is affected salt and acid solutions resulting from intense weather conditions over time. In the present study, variations in capillary water absorption, porosity, physical changes, and internal rock decomposition mechanisms caused by salt crystallization and air pollutants (SOx and NOx) in sedimentary limestone from the Antalya region were explored. The mineralogical–petrographical and geochemical properties of the limestones were determined using polarizing light microscopy, scanning electron microscopy (SEM), and X-ray fluorescence methods. The variations in the capillary water absorption coefficient, weight, and pore distribution and size were also determined by mercury porosimetry (MIP). An increase in weight was observed in the salt and SA (150 ± 10 mL deionized water and 500 ± 10 mL H2SO3 acid) weathering tests, but a reduction in weight was found under the action of NA (150 ± 10 mL deionized water and 500 ± 10 mL HNO3 acid). The reaction of SA with the limestones influenced the presence of calcium sulphite hemihydrate and gypsum on the rock surface, which affected weight gain. A decrease was observed in the weights of the limestones under the action of NA, and the porous structure seen in the microscale examination from SEM analysis supported a loss of material. The values for capillary water absorption increased in the limestones exposed to salt, SA, and NA. According to MIP analysis, the pore size distribution curves became multimodal, and the pore sizes varied in the studied limestones exposed to salt, SA, and NA. The findings of our study serve as an important guide for the use of limestone as a natural stone in regions with severe weather conditions. [ABSTRACT FROM AUTHOR]

Clay mineralogy of Plio-Quaternary sediments of SE slopes of Medvednica Mt. was compared to that of the overlying weathering horizons. Three locations of Plio-Quaternary sediments, representing past weathering products, were sampled along with the overlying material, representing more recent weathering cycles. Particle size distribution, pH and cation exchange capacity (CEC) of the samples were analyzed. Bulk mineralogy was determined using X-ray diffraction (XRD). Clay mineralogy was determined, after carbonate cement, organic matter and free Fe oxides removal, on fractions < 2 and < 0.2 μm using XRD and Fourier-transform infrared spectroscopy (FTIR). Average layer charge of the expandable layers was determined using the O-D method. Major elements content was determined using inductively coupled plasma optical emission spectroscopy (ICP-OES). Bulk mineralogy comprises quartz, feldspars, mica, clay minerals and occasional Al and Fe (oxy)hydroxides. Clay mineralogy differs subtly between samples; dioctahedral expandable clay minerals dominate with illite and kaolinite present. Hydroxyl interlayering of expandables is noted in the surface samples, corresponding to lower CEC values. Average absolute layer charge of the expandable layers is higher in the surface samples and decreases with depth on two of the investigated locations. Overall, clay mineralogy of the Plio-Quaternary sediments reflects a more intensive weathering regime, confirmed by the presence of Al (oxy)hydroxides and lower absolute charge of the expandable layers. The weathered material and soil overlying these sediments shows heterogeneity in genesis, but corresponds to less intense weathering regime, confirmed by the formation of hydroxy-interlayered minerals and higher absolute charge of the expandable layers. [ABSTRACT FROM AUTHOR]

Coastal areas are extremely sensitive to variations in environmental conditions. The interaction of marine and continental processes causes a high degree of dynamism, generating depositional formations of great value for palaeoenvironmental reconstruction. This paper focuses on two pedostratigraphic deposits located under the current beach, in close proximity to archaeological tumuli located on Areoso Island (Ría de Arousa, NW Iberian Peninsula). Employing a geoarchaeological approach, sea-level rise, environmental conditions and human occupation over a 6000-year period are interpreted. The results of granulometric and mineralogical data, elemental composition and stratigraphic features, help to identify three successive environments: continental (rock weathering, soil formation and erosion); a transition to a coastal environment; and the establishment of full coastal conditions. The geomorphological evolution of the last 6.0 kyr BP has been controlled by climate, sea-level rise and human activity. The continental facies shows evidence of low sea-level up to 4.8 kyr BP and the first evidence of coastal processes after 3.2 kyr BP. These pedostratigraphic deposits located in an open coastal system improve the Holocene sea-level rise curve in the NW Iberian Peninsula and help to understand the context in which the most important archaeological structures on the island (the tumuli) began to be eroded. [ABSTRACT FROM AUTHOR]

Changbai Mountain area is an important mineral water storage and development area in China. The hydrochemical composition of mineral water is the decisive factor for mineral–water quality. Based on the hydrochemical data of 74 mineral water samples collected from 2018 to 2020, the characteristics and formation mechanism of the hydrochemical components of the mineral water were analyzed. The results show that the formation of single-type mineral springs (metasilicate mineral water) is controlled by rock weathering; compound mineral springs (metasilicate mineral water with high CO2 content) are the product of CO2-rich, weakly acidic, confined hot groundwater with high salinity, which are mixed with shallow groundwater as rising along the fracture. The volcanic geological process greatly influences the formation of the hydrochemical components of mineral springs on the North slope of Changbai Mountain. The mineral springs on the Longgang Mountain are greatly affected by human activities. The results of cluster analysis only consider that hydrochemical components are consistent with the classification of the areas which concentrated distributions of mineral as determined by hydrogeological and geomorphological studies. The results of this study are useful for understanding the distribution, hydrochemical characteristics, and formation mechanism of mineral springs in the Changbai Mountain area of China and provide the theoretical basis for the protection and development of mineral spring. [ABSTRACT FROM AUTHOR]

The geochemical characteristics of stream/slopewash sediments, modal composition and petrography of the clastic units from the Siwalik Group has been investigated to determine the provenance and tectonic setting of these rocks, as well as to appraise the influence of the weathering and recycling processes upon source rock signatures. The higher CIA index indicates that the source area underwent moderate to intense chemical weathering processes, possibly due to climatic and/or tectonic variations. Alternatively, modal analyses show that the source area of the Siwalik rocks may have been composed of recycled sedimentary materials. The La/Th ratios and Hf discriminant plot show that they originally come from a differentiated silicic source. This has been further supported by Hiscott Diagram (Cr/V vs. Y/Ni) and Th–Hf–Co discrimination diagram which supports a primitive silicic source for these rocks indicating a higher proportion of felsic material in their primitive source area. The Eu/Eu* versus (Gd/Yb)N diagram for the samples of the Siwalik sediments indicates that the source rocks are mainly influenced by post-Archean felsic rocks. [ABSTRACT FROM AUTHOR]

Many cultural heritage sites in Mexico have been built with volcanic tuff rocks from the earliest Central American civilizations to the time of the Spanish conquest and up to the present. Throughout this long period of time, the stones have been subjected to progressive weathering as evidenced by different types of damage phenomenon such as scaling, sanding, crumbling, sugaring and salt efflorescence. This study utilizes a collection of 53 tuffs from different regions in Mexico that show a diverse range of colors, rock compositions and mineralogy, and heterogeneous rock fabrics indicative of their volcanic origin. Comprehensive investigations have been done that include detailed petrographic analyses, cathodoluminescence, clay mineral analyses, and the determination of a wide range of petrophysical properties (e.g., porosity, capillary water uptake, water absorption, sorption, hydric and thermal expansion, and mechanical properties). All analyzed data combined are used for derivation of some general trends concerning the suitability/durability of tuffs applied as natural building stones. [ABSTRACT FROM AUTHOR]

Rock weathering fractures in nature are complex and fracture healing is an effective strategy for rock weathering mitigation. This study is a first attempt to apply microbially induced calcium carbonate precipitation (MICP) technology in the healing of nature-weathering-like rough fractures (NWLRF). Sandstone was studied as an example due to its wide distribution as construction, sculpture and monument materials all over the world. To achieve a high healing efficiency, a repeated mixture injection strategy was proposed. Based on a series of laboratory MICP injection experiments on four types of NWLRF, we systematically explored the fundamental micro-healing mechanism and the influence factors including fracture aperture, characteristics of branch fractures, and cementation solution concentration. Experimental results demonstrated that MICP healing with the repeated mixture injection strategy had the ability to efficiently heal the penetrated NWLRF well with length in centimeter scale and aperture in millimeter scale, but cannot heal the non-penetrated branch fractures under low injection pressure. The repeated mixture injection strategy furtherly achieved a high apparent fracture healing ratio and a significant reduction of transmissivity. The apparent fracture healing ratios of all main fractures were higher than 80% and the maximum was 96.3%. Fracture transmissivity was reduced by at least three orders of magnitude from about 1 × 10–4 m2/s to less than 1 × 10–7 m2/s, and the highest reduction reached to four orders of magnitude. For the aspect of the effects, larger cementation solution concentration, finer aperture and penetrated branch fracture were beneficial to improve the healing effect. Moreover, the MICP healing mechanism with high fracture healing ratio and significant reduction of transmissivity on sandstone NWLRF was also analyzed. The research results have important theoretical significance and technical guidance value for the disaster prevention and mitigation of rock weathering. [ABSTRACT FROM AUTHOR]

Small historical churches in rural villages are mainly functional buildings, lacking spectacular architectural or ornamental features. This is also true for the St. Johannis Chapel Lütgenrode near Göttingen (Lower Saxony, Germany), which dates back to the 13th century. The use of ca. 10 different natural building stones (Triassic sandstone and limestone, Holocene fresh water carbonate), scattered roof tiles and bricks result in a highly heterogeneous character of the chapel's ascending walls. In addition, various repairs over the last centuries, using inadequate materials, amplified damages and produced critical stability problems, in particular at the southern wall. Here, the suitability of the dimensional stones are evaluated for construction and replacement purposes. A semi-quantitative distribution of lithotypes was performed, and weathering forms were mapped in detail. On-site analyses (micro-drilling resistance, the Schmidt hammer rebound test, capillary water absorption) provide data on the deterioration state of the main lithologies. The petrophysical data show that stratigraphically comparable building stones exhibit different technical characteristics and weathering behavior. All data serve to characterize the state of weathering and provide the data set to plan for future restoration work. The amount needed for restoration work has been estimated to be approximately 435,000–550,000 EUR. Because the local church authorities evaluate the significance of a church based on the frequency of its use, a secular use would be able to save the Lütgenrode chapel, but then the church political leaders would have to act quickly. [ABSTRACT FROM AUTHOR]

The presence of uranium (U) in potable groundwater must be treated with extreme care because of its health concerns. The study area consists of complex lithology and various land use activities including natural and anthropogenic processes. The present study aims to assess the seasonal distribution, probable sources and factors responsible for U mobilization in groundwater and provides a holistic picture of geochemical processes in the study area. To achieve these objectives, a total of 680 groundwater samples were collected during four different seasons (pre-monsoon, southwest monsoon, monsoon and post-monsoon). The samples were collected with lithological differences to determine the effects of natural geochemical processes in addition to the anthropogenic impacts. The trend of anions reflected the following order during PRM and NEM: Cl > HCO3− > NO3 > SO4 > PO4, and cations Na > Ca > Mg > K during PRM and SWM. The U concentration in the samples ranged from 10 to 70 ppb, being higher during the NEM season. The samples were classified into three groups based on U concentration (< 10 ppb, 10–15 ppb and > 15 ppb) and studied using various geochemical diagrams, statistical application, thermodynamic study and saturation states for different minerals. The maximum concentration of U in groundwater during different seasons reflects that NEM > POM > SWM > PRM. The higher U values were observed in the hornblende–biotite–gneiss irrespective of the season. U in groundwater migrates away from the source due to its high solubility, where it tends to form complexes, especially in the presence of phosphates or carbonates. Analysis of the data shows that the majority of the samples in the monsoon season reflect dilution and recharge processes. In contrast, during SWM and PRM, ion exchange and anthropogenic influences predominate the processes. The PCA study shows that secondary salt leaching, weathering, anthropogenic influences and ion exchange play a significant role in determining the groundwater chemistry in this region. [ABSTRACT FROM AUTHOR]

Sandy-marly siltstones, sandy-silty marlstones, silicified marlstones and marly silicites are the characteristic cyclically deposited sediments in large areas of the Bohemian–Saxonian and Münsterland Cretaceous Basins. In the German-speaking area, these typical sedimentary rocks are called Pläner. In the Czech Republic they are called opuka, in Poland/Lithuania opoka and in France/Wallonia gaize. They can be easily quarried as managable dimensional stones, which can be formatted with little effort and were therefore the preferred material for use as a masonry stone. In the Middle Ages, Pläner was therefore the dominant stone used for exterior architecture. Harder Pläner was used as floor slabs and for paving. In Prague, a local Pläner is exposed with beds reaching a thickness of 1.3 m. This local variety is called the Golden Pläner/zlatá opuka, where it was also used for high-quality sculptural work. The Golden Pläner is therefore a stone with a wide variety of uses. Prague also owes its title as the "Golden City" to this rock. The Golden Pläner is well studied. Its mineral composition, important petrophysical characteristics and weathering behavior have been published in several geoscientific papers. Publications dealing with the other Pläner stones of the Czech Republic, those in Saxony or exposed in the Münsterland are still lacking. The aim of this paper is to illustrate the similarities and differences of the Pläner stones used as a building material from the Cretaceous basins considered here. Four different types of Pläners can be classified based on their primary facies and early diagenetic characteristics, but also the limestones that are called Pläners, which occur within the Pläner sequences and the residuals of these Pläners are considered. The high proportion of very fine-grained constituents requires the combination of several analytical and observational methods such as optical microscopy, microanalysis, powder X-ray diffraction and textural analysis of pore space by mercury porosimetry. To be able to classify the weathering resistance, and thus the possibility of using Pläners as a natural stone, the structural parameters of compressive strength, porosity, water absorption, freeze–thaw resistance and hygric dilatation were also determined. [ABSTRACT FROM AUTHOR]

Various geological processes (mineral composition, structure, tectonics, weathering, etc.) affect the physical–mechanical properties of rock. Petrological and engineering geological characteristics of paleoweathered rock (PWR) from the K1/J2 contact zone are described in detail via field investigation and experimental testing. This PWR exhibits mainly sandy grains and mud structures, layered and massive strata, and calcareous and argillaceous cements; fissures are developed and often filled with argillaceous and detrital materials; nine minerals and seven oxides are present, and quartz is present in each sample. Long-term weathering results in a consistent bulk density and high total porosity due to the transformation of primary minerals into secondary clay minerals, forming PWR that undergoes argillization in water. The axial point load strength (PLS) is the largest among the tested PLSs, followed by the diametral PLS, and the irregular PLS. The uniaxial compressive strength (UCS) varies widely, but the results are reliable. The mineralogical, physical and mechanical properties of the PWR are compared to predict one parameter from another and study their mutual influence. The PLS and UCS of the PWR are negatively correlated with the elastic mineral group (EMG) content, weathering alteration indexes, water content, and total porosity and positively correlated with the quartz content, brittle mineral group (BMG) content, bulk density, real density, and longitudinal wave velocity. The UCS and the PLS, axial (diametral) PLS and irregular PLS are positively correlated. These results provide a theoretical basis for physical and mechanical property prediction of PWR masses and rapid estimation of UCS in engineering. [ABSTRACT FROM AUTHOR]

Understanding the long- and short-term weathering features according to rock type is very important for maintaining the original form of stone heritages. In this study, the material characteristics of a deteriorated five-story stone pagoda were compared with those of fresh rocks from its quarrying site at nearby Geumgolsan Mountain, Korea, to diagnose the degree of damage and develop a comprehensive interpretation of the weathering mechanism. The stone pagoda was built from lithic tuff comprising pumice and phenocrysts such as quartz, K-feldspar, plagioclase, and mica based on plagioclase substrates; the mineralogical and geochemical characteristics are similar to those of the fresh rocks. The lithic tuff of the stone pagoda demonstrated a low ultrasonic velocity of 2863 m/s and a high water absorption rate and porosity of 9.5% and 19.2%, respectively, which are poorer than the physical properties of the fresh rocks (i.e., ultrasonic velocity of 3336 m/s, water absorption rate of 8.65%, and porosity of 17.83%). The lithological characteristics and physical properties demonstrated a considerable influence on the weathering and stability of the stone pagoda. In particular, fragments of relatively weak pumice detached from the original rock to form cavities of various sizes. These cavities introduced moisture within the rock, which produced oxides and hydroxides of iron and manganese. In addition, contaminants such as dust, salt crystals, clay minerals, and microorganisms adhering to the surface of the stone pagoda accelerated its physical, chemical, and biological weathering. The results of this study will be important for realizing the stable and long-term conservation of the five-story stone pagoda at Geumgolsan Mountain. [ABSTRACT FROM AUTHOR]

Hydrochemical assessment of the Cauvery River Basin (CRB), an east flowing Western Ghats (WG) river, is carried out to understand the dissolved load sources and controlling mechanisms with quantification of source-wise input to the dissolved load. Silicate weathering rates (SWR) and associated CO2 consumption rates (CCR) are evaluated on account of silicate basement of CRB comprising of granulites and supracrustal rocks. The source-wise solute load contributions estimated using the chemical mass balance model signify that 68% of total load is from chemical weathering followed by anthropogenic (18.5%) and atmospheric (13.5%) inputs respectively, indicating that chemical weathering is the major solute load controlling mechanism for CRB. The intensity of silicate chemical weathering occurring in the CRB is measured by degree of weathering index (Re). It is found to be higher (> 3), suggesting an incomplete weathering of drainage rocks (primary minerals) resulting in formation of soils comprising of secondary minerals including oxides, alumino-silicates and clay minerals (kaolinite, montmorillonite and smectite). Detailed understanding of the mechanism of chemical weathering is carried out using Ca/Na and Mg/Na elemental ratios of different end-members including primary minerals from rocks and secondary minerals from soils. The Na-normalized mixing diagram reveals that chemical weathering of secondary minerals is dominating and the solute load contribution to the total dissolved load is significantly higher (35.5%) from secondary minerals than primary minerals (23.5%). The SWR and associated CCR are estimated to be 13 t km−2 year−1 and 3.3 × 105 mol km−2 year−1, respectively, at outlet (Musiri) of the CRB. Results additionally signify that SWR of the east flowing WG river, Cauvery, are several times (~ 4) lower than the average SWR of west flowing WG rivers even though the associated CCR are comparable for both river systems. [ABSTRACT FROM AUTHOR]

The effect of alteration on the geochemistry and mechanical properties of granite from Pingjiang, Hunan Province, China was investigated. Six weathered and 14 hydrothermally altered samples in 3 adits were collected for mechanical strength tests, mineralogical and geochemical analysis. The types of alteration observed within the samples were chloritization and argillization. Samples taken from a silicified fracture zone were enriched in quartz. Weathering was observed to significantly weaken the granite whereas the effects of hydrothermal alteration on strength were more complex. The porosity increased with the enrichment of the altered minerals, indicating that the formation of altered minerals degrades the strength of physical bonds between minerals within the granite. The granite Na2O, CaO, K2O, MgO and SiO2 contents decreased while Fe2O3T increased due to weathering. Variations of major elements within the hydrothermally altered granite were distinguished from those observed in weathered samples—notably Mg was removed whilst Si and Fe were generally stable during the hydrothermal alteration. Whereas the quartz-enriched samples gained Si with slight depletions in Mg and Fe. Trace and rare earth elements were both removed in hydrothermal alteration. The variable behavior of major element was quantified by the mobility index which indicated that the different geochemical changes were attributed tochloritization and argillization. Furthermore, the mobility index of Mg was used to identify the dominated alteration in granite and evaluate the effects of chloritization and argillization. Generally, chloritization was found to be more dominant than argillization in weakening the granite. [ABSTRACT FROM AUTHOR]

The Baumberger Sandstone, a sandy limestone, is used since the Middle Ages as a building material not only in the surrounding Münster region of North Rhine-Westphalia (Germany), where it is quarried since to date. To prevent the ingress of water and reduce weathering processes conservation methods, mostly in form of organosilicon compounds, were used. This study deals with the performance of applied hydrophobing agents on Baumberger Sandstone samples and their influence on the weathering processes during long-term exposure. The samples were exposed at several locations in Germany to different climatic conditions for up to 24 years. Afterwards, investigations concerning the water absorption behaviour and the degree of superficial damages were carried out. With an evaluation method on basis of NMR measurements, a very low and uneven distributed effective hydrophobic zone could be detected. This caused an ingress of water in the uppermost part and a progressive weathering of investigated natural stones. Thus the hydrophobic surface treatment did not lead to a significant decrease of weathering or damaging processes. Based on these results a hydrophobic surface treatment of Baumberger Sandstone seems not to be suitable. [ABSTRACT FROM AUTHOR]

The Meymand world heritage site (Kerman Province, Iran) is a rock-hewn village carved within a pyroclastic rock mass, Meymand Tuff. This site, having an ancient local population with an age of 2000 years, is hosted by a weak rock exposed to deterioration and weathering processes. However, our understanding of the characteristics of the Meymand Tuff is limited to some previous general studies. Therefore, in the present study, the stratigraphy and intrinsic characteristics of the Meymand tuff are investigated to determine its weathering behavior and durability. For this purpose, comprehensive field and laboratory investigations were carried out. The stratigraphy of the valley and the pyroclastic flows that had deposited the Meymand tuff were identified and outlined based on field investigations and many surveyed sections along the Meymand valley. Next, the mineralogical composition, texture, structure, physical and mechanical properties, water absorption rate, slake durability, wetting–drying durability, shrinkage potential of the fine portion, and collapse potential of the Meymand tuff were assessed through laboratory investigations. The results revealed that two pyroclastic flows had deposited the host tuff rocks of the Meymand site. These rocks have a heterogeneous texture comprising very coarse-grained clasts to the fine-grained matrix. Rock characteristics including heterogeneous texture, high porous and open structure, clay-rich mineralogical composition, high water absorption capacity, and swelling and shrinkage potential of the fine portion of the matrix have resulted in adverse behaviors in Meymand tuff. These behaviors are pertained to the strength softening, weight loss, and deterioration at wetting drying cycles. [ABSTRACT FROM AUTHOR]

Volcanic tuffs naturally show a strong heterogeneity in their petrography and petrophysical properties. The arrangement of the components in tuffs can create a very wide spectrum of porosities and fabrics, which in turn can lead to a highly differential weathering behavior. Considerable amounts of clay minerals and zeolites are common and can contribute to a high sensitivity to expansional processes and salt crystallization. Understanding the influence of the rock properties on material behavior and durability can help to make predictions on future material behavior and evaluate the suitability of the material for construction purposes. This study presents the petrographic and petrophysical data of 15 selected tuffs and 513 tuffs from the literature used as building stones. Regression analysis show if parameters are comparable and if key parameters can be identified. Key parameters can potentially be used for the estimation of the material behavior, without the use of expensive analytics or weathering simulations. [ABSTRACT FROM AUTHOR]

The presence of salts during cyclic wet and dry conditions can cause weathering of rock and is the main cause of damage to ancient and modern buildings. Accordingly, salt weathering, especially of granite, has aroused great interest. Determining the relationship between wet–dry cycling and the physical properties of rock is of great significance to geotechnical engineering. In this paper, granite samples were processed into two shapes (round and semicircular) and subject to 0, 10, 20, 30, 40 and 50 wet–dry cycles, with the wetting achieved with 0%, 5%, 10% or 20% concentrations of Na2SO4 solution. The mass loss, roughness and indentation hardness of granite samples all changed to some extent with cycle number, with greater changes occurring at higher salt concentrations. Rock shape also affects the extent of weathering damage, as surface area and features such as corners facilitate the ingress of salt solution. [ABSTRACT FROM AUTHOR]

Bacterial weathering plays a significant role in rock weathering, yet only a limited number of studies were conducted on this topic. The recent rapid developments in geomicrobiology are expected to increase the pace of research in this area. The extent and duration of the biological weathering processes on mineral and rock samples and minerals preferred by bacteria are still not fully understood due to the wide variety of both bacterial species and rock types. Biological weathering of rock types found in Turkey has also not been studied before. Here, we investigated the effects of two species of bacteria actively contributing to rock weathering on three rock types commonly used as building stone materials in Turkey. Granite, andesite, and limestone samples could interact with Bacillus species (B. subtilis and B. pumilus) in closed system reactors. Samples obtained from these reactors were analysed via scanning electron microscopy (SEM) monitoring to identify morphological features and chemical composition changes. Chemical elements consumed most by bacteria were identified. Changes in the colour index were determined via RGB measurements. The effects of experimental conditions on bacterial growth were monitored via daily optical density measurements. The effects of bacteria on the physical properties of rock samples were also evaluated. B. subtilis and B. pumilus were found to be more aggressive on limestone/andesite and granite, respectively. [ABSTRACT FROM AUTHOR]

The soil position in the landscape reveals its formation history. Landscapes combine surface features and subsurface components (parent material) of the earth, at which the soil inserts as a three-dimensional and dynamic natural body. The present research aimed to study the soil–landscape relationship in a sandstone-gneiss topolithosequence and the factors determining soil diversification in the State of Amazonas, Brazil. The study extended along a transect of 9253 m, covering the distance between the first and the last profile, for a total of five profiles opened. Profile selection considered landscape topography, from the highest to the lowest relief of the terrain. Soil profiles characterization and classification were based on morphological, chemical, and physical properties and the mineralogy of the clay fraction by X-ray diffraction (XRD). Lithological contrasts and landscape variations determined the different soil types along the topolithosequence. Morphological, physical, chemical, and mineralogical attributes also varied along the landscape. The relief and the parent material, sandstone-gneiss, were the main factors influencing the pedogenesis. Goethite (5–40 g kg–1) was the predominant Fe oxide in all the soils, reflecting the low total iron content (Fet ≤ 68 g kg–1) of the soils and parent materials. The predominance of the sand fraction in all the studied profiles reflected the alluvial nature of the parent material, with the highest values (total sand > 800 g kg–1) occurring in the convex creep slope. Knowing the geomorphic surfaces and the parent material was effective for understanding the variation of the soil attributes along the landscape. [ABSTRACT FROM AUTHOR]

Aeolian sediments and other surface deposits are widespread along the broad valleys across the Yarlung Tsangpo (YT) catchment on the southern Tibetan Plateau (TP) and are considered important sources of global dust. However, geochemical differentiation in different reaches, sedimentary circulation, and dust transmission processes in the YT valleys are poorly understood. In this study, 47 samples of different types of sediments were collected from different YT valleys, and the major and trace-element (excluding rare-earth elements, REEs) compositions of 42 bulk samples and the trace elements (including REEs) compositions for the fine (< 75 μm) fractions of 21 samples were determined. The results show that the different sediments are predominantly sourced from local felsic bedrocks, originating mainly from the Lhasa terrane through the tributary systems, which are primarily controlled by the physical weathering, and only incipient chemical weathering. The geochemical characteristics of the various sediment types exhibited spatial differentiation because of the complex structure and topography, intense surface circulation, and mixing processes of the detritus from both banks. Owing to the complexity of regional surface processes, conventional non-isotopic geochemical methods might not be the most effective tool for sediment provenance tracing on a large spatial scale. Nevertheless, aeolian deposits in the broad valleys across YT mainly have a near-source clastic supply of local origins, belonging to a regional self-cycling process, which might not be transported by wind across different reaches because of high topographic obstacles. [ABSTRACT FROM AUTHOR]

The drainage microbasin of the Bule stream drains an important part of the Quadrilátero Ferrífero, known as one of the main metallogenetic provinces on the planet and of great importance for Brazilian mineral production. The surface water chemistry was analyzed to quantify the chemical weathering rates and the CO2 consumption associated with the weathering processes. Bicarbonate, calcium, magnesium, and silica are the main ions dissolved in the basin, reflecting the local lithotype composed of dolomites, phyllites, and quartzites. The main source of dissolved elements for the basin is carbonate rocks, followed by rainfall. The sulfide oxidation process appeared as the main source of sulfate for the river (approximately 90%). The total weathering rate was 1.5 × 105 mol km−2 year−1 and the total CO2 consumption was 7.3 × 104 mol km−2 year−1, where carbonate rocks are mainly responsible for these flows (> 90%). The highest values were found at high flow, where for the carbonate phases, the weathering rate was 5.38 × 102 mol km−2 day−1, and for CO2 consumption, it was 2.92 × 102 mol km−2 day−1. Despite being a microbasin, the results are relevant when compared to large basins, showing the importance of small-scale studies of rivers that drain basins with a predominance of the lithological type. [ABSTRACT FROM AUTHOR]

The Lesser Himalayan belt, being the most complex litho-tectonic units of Himalaya, is in frequent danger of slope destabilisation. The present study intends to assess geotechnical characteristics of identified perilous slide zones for their detailed slope stability analysis in one of the highly complex structural entities of Lesser Himalaya, named as Purola schuppen zone. It involves imbricate thrusting and embraces a number of slide zones in weathered quartzite, phyllite, schist and shales. On the basis of discontinuity characteristics, viz. their orientations and interrelationship with slope, structural attributes and debris materials, slide zones are showing planar, wedge or circular failure patterns. Kinematic analysis is attempted to identify the possible mode of structurally controlled failure in rock mass. As per their failure types, these slide zones are analysed for stability using geotechnical parameters evaluated in lab. For circular failure zones, angle of internal friction and cohesion, are attained quantitatively by direct shear test and varying from 30.8° to 36.8° and from 0.04 to 0.41 kg/cm2, respectively. In case of planar and wedge failures, modified slope mass rating technique is used that assigns class V status for Kothgaon slide zone indicating very bad rock mass and unstable to completely unstable slope conditions with probability of failure as high as 0.9 while Taluka slide is partially stable with normal rock mass falling in class IV. Factor of safety, estimated by circular failure charts using slope, soil and strength characteristics, is varying from 0.75 to 1.50 in dry conditions, signifying critical stable state while it reduces less than unity in wet conditions as saturation upsurges due to nearby percolation of rainwater through discontinuities and cracks. Imbricate thrust zone, substantial weathering and jointing in rock masses, steep slopes and nearby vicinity to stream channels are major contributory reasons of instability in the area, while road widening and rainfall are acting as catalysts prompting the failure. [ABSTRACT FROM AUTHOR]

In recent years, several soft computing models have been proposed to estimate the elastic modulus of magmatic rocks. However, there are lacks in models that consider the different weathering degrees in determining the elastic modulus of rocks. In the literature, mechanical properties are widely used as inputs in predictive models for weathered rocks; however, there are only a few models that use index properties representing the effect of weathering on magmatic rocks. In this study, support vector regression (SVR) Gaussian process regression (GPR), and artificial neural network (ANN) models were developed to predict the elastic modulus of magmatic rocks with different degrees of weathering. The inputs selected by the best subset regression approach were porosity, P-wave velocity, and slake durability index. Key performance indicators (KPIs) were computed to validate the accuracy of the developed models. In addition to KPIs, Taylor diagrams and regression error characteristic (REC) curves were used to assess the performance of the developed prediction models. In this study, considering the difficulties of expressing the error using only RMSE and MAE, a new performance index (PI), PIMAE, was proposed using normalized MAE instead of normalized RMSE. It was also indicated that PIRMSE and PIMAE should be used together in performance analysis. When considering the Taylor diagram, PIRMSE, and PIMAE, the GPR models performed best, and the SVR model performed the worst in both the training and test periods. Similarly, according to the REC curve in both periods, the performance of the SVR was the worst, while the performance of the ANN model was the best. The PIRMSE and PIMAE values of the GPR model for the test data were 1.3779 and 1.4142, respectively, and they were 1.2567 and 1.4139, respectively, for the ANN model. According to the computed response surfaces, an increase in the P-wave velocity, and a decrease in the porosity increased the elastic modulus. However, changes in slake durability index only had a minor effect on the elastic modulus. [ABSTRACT FROM AUTHOR]

The Jinsha River Bridge (Baiyu, China) site has obvious weathering characteristics, which affects the construction of the project. To establish the correlation between the chemical weathering coefficient and the rocks mechanical characteristic, the analysis of the chemical composition of surface water and rocks (metasandstone, slate and phyllite) in the study area was conducted, and the long-term strength of the rock by the creep test was obtained. It is determined that the main driver of the hydrochemical composition is the chemical weathering of silicate and carbonate rocks. By investigating the mobility of elements in water and rocks, seven major elements, namely, SiO2, TiO2, Al2O3, Fe2O3, MgO, K2O, and Na2O were used to obtain the rock chemical weathering discriminant based on the calculations performed with SPSS.22. Then the correlation between weathering coefficient and long-term strength was analyzed by regression analysis, and the results indicate that the higher the rock chemical weathering coefficient is, the higher the long-term strength it has. Moreover, a confining pressure of 20 MPa is observed to be the point at which rock chemical weathering affects the rock mass engineering characteristics, and this finding has a certain significance in terms of engineering guidance. In summary, this fitted discriminant coefficient is suitable for assessing rock chemical weathering of weakly to moderately weathered metamorphic rock in the study area and can effectively characterize and predict the rock weathering degree and mechanical properties in the study area, providing support to engineering design and construction. [ABSTRACT FROM AUTHOR]

Geochemical and isotopic investigations were carried out in the Tapi Valley geothermal area in India to determine the principal factors that are responsible for the geochemical evolution of the thermal and non-thermal waters in the study area. The impact of thermal water discharges on the surrounding potable water resources had also been assessed. It was found that thermal water did not contain any toxic elements (mercury, antimony, arsenic) which are detrimental to human consumption. Thermal waters were found to be less mineralized compared to the non-thermal ground waters. The water types of the thermal and non-thermal waters were found to be mostly Na–Cl–HCO3 and Ca–Mg–HCO3, respectively. Silicate weathering and ion-exchange processes were found to be main factors that determined the dissolved solute concentration in the study area. Stable isotopic (δ18O, δ2H) analysis unequivocally established the meteoric origin of the thermal waters. Thermal waters in Unapdeo, Anekdev, Kundwa and Ratanpura were found to have distinct isotopic compositions signifying that separate reservoirs were feeding these hot springs. The application of chemical geothermometers showed a wide variation in the estimation of reservoir temperature. The quartz geothermometer produced the most reliable reservoir temperature estimate of 110 ± 12 °C. Multicomponent geothermometry was found to better constrain the reservoir temperature. This modelling result indicated that the thermal water in this region had attained simultaneous equilibrium with respect to quartz, aragonite, stilbite, calcite, enstatite, heulandite, diopside minerals in the temperature range of 120 ± 5 °C which could be taken as the subsurface reservoir temperature. [ABSTRACT FROM AUTHOR]

Several studies have addressed the elaboration of petrographic indices, applicability, and their execution in the characterization of weathering grades. Petrographic indices directly depend on a visual criterion used to distinguish fresh mineral from weathered mineral, which is usually not shown. As investigated, this causes a lack of coherence among petrographic indices data for mechanical properties estimation aiming at engineering geology applications. This paper involved a readjustment of technique for the calculation of weathering indices and the establishment of criteria to gather the minerals under weathering into the petrographic index's formula based on a standardized classification of textural and micromorphological modifications. The results have shown that varying the criteria influence indices values for the same physical–mechanical properties, resulting in different types of best-fit lines, but with reasonable coefficients of determination along the weathering grades. This in part explains the variability of literature correlations. The use of a standardized classification of rock-forming minerals contributed to finding closely related mechanical degradation tendencies among literature data. [ABSTRACT FROM AUTHOR]

A study of two typical red soil profiles, Gumu (GM-limestone) and Sanjiacun (SJC-dolomite) was conducted at Yunnan–Guizhou Plateau, China. The study employed mineralogy, geochemical and elemental ratios to assess the mobilisation and distribution of elements during weathering and pedogenesis. The mineralogy results revealed similarity in distribution of secondary minerals in both profiles, with exception at the ferricrete layer. The results revealed inheritance relationship between red soils and their underlying bedrocks indicating that clay minerals were likely derived from in situ weathering products or metasomatic process rather than detrital process. During weathering and pedogenesis process, alkaline elements such as K and Rb behave similarly and were closely related. All lanthanide elements except for Ce shared similar transport trend with Y and Be; however, Be exhibited significant enrichment at ferricrete layer of the dolomite profile. Transitional elements such as Co and Mn behave similarly; while, the High Field Strength Elements (HFSE) were stable, except for Th and Sc which indicate depletion in upper soil layer of the dolomite profile. Our findings further revealed that both profiles have experienced intense chemical weathering with high Chemical Index of Alteration values (CIA: 83–93) and a constant Ba/Sr ratio > 2. Overall, both profiles experienced similar elemental behaviour with the accumulation of major elements, the leaching of alkaline earth elements and the fluctuation of trace elements including Rare earth elements (REEs). The elemental behaviour was primarily controlled by redox reaction, pH, water availability, ionic radii and the stability of secondary oxides/hydroxides. Our study further highlights the use of newly proposed geochemical proxy Fe/Na ratio, which revealed high correlation (R2 ≈ 0.90) with U, Ba, Zn, Cu, Mo, Ni, Sb and REEs of power functions. These findings indicate that Fe/Na ratio may be used to investigate the behaviour of trace elements including REEs in highly weathered soils. [ABSTRACT FROM AUTHOR]

Rock's surface micro-topography and geotechnical properties' limits are expected to be altered on weathering progress to a new form(s) and limits, respectively. The quantification of weathering damage for a given rock is of value e.g. to compute weathering rate, weathering intensity and rock's durability to weathering processes and to take a decision regarding restoration urgency. The current study aims to examine the variation/constancy of micro-topography and geotechnical properties' limits of the Triassic sandstone constituting well-aged wall, at Aachen city, on weathering progress over short duration (12 years of investigation from 2007 to 2019). The Equotip hardness tester and micro-erosion meter are tools used for micro-topographic and rock's surface hardness investigations on one hand, and the mercury intrusion porosimetry has been used for measuring rock's pore size distribution and salt susceptibility on the other hand. These tools are accurate, numerical, comprehensive, easily applicable and preferable particularly for ancient buildings and archaeological sites where sampling is not recommended or prohibited. The wall side under consideration has been selected as its constructional blocks present a wide spectrum of weathering forms as well as rock's surface micro-topography (over 12 years of investigation) through increasing the weathering forms' dimensions and/or creation of new weathering forms. The net result of the current study indicated a noticeable variation in stone's micro-topography on weathering progress, the rock's stone surface hardness highly controls rock's weathering susceptibility and no clear relation can be noted between stone's surface roughness and its susceptibility. The pore size distribution is the most controlling parameter for rock's weathering susceptibility. [ABSTRACT FROM AUTHOR]

The water quality of the rainwater is obviously different from that of the groundwater after it reaches the surface and passes through the vadose zone. This study aims to further evaluate and analyze how soil CO2 changes under natural conditions, to provide a theoretical background for the establishment of CO2 geological storage, and to provide a basis for the detection of CO2 leakage in order to provide insights for expanding CO2 research. The changes in soil CO2 concentration under different conditions were simulated and analyzed by laboratory experiments, and the effects of CO2 on water chemical composition were also analyzed. In this study, two experimental groups (vegetation group (V) and high-temperature sterilization group (R)) and one blank group (B) were established. The results showed that the CO2 concentration in column R was the lowest, while that in column V was the highest. With rainfall infiltration, soil CO2 concentration gradually increased. When the rainwater infiltrated to 215 cm, the CO2 concentrations in the columns V, B, and R were 5100 mg·m−3, 4450 mg·m−3, and 32,000 mg·m−3, respectively. At infiltration depths from 5 to 215 cm, the Na+, Ca2+, Mg2+, SO42−, and HCO3− concentrations in columns V and B decreased, whereas they increased in soil column R. The simulation revealed that the CO2 concentration ranged from 560 mg·m−3 to 50,000 mg·m−3; pH value decreased; NO3− and Cl− remained stable; SO42− decreased; and fCO2, HCO3−, Ca2+ and Mg2+ increased. [ABSTRACT FROM AUTHOR]

This study aimed to determine the current geological and engineering features of granite blocks used as riprap material in the construction of Gelingüllü Dam which is in use for nearly 20 years. The riprap layer is divided into four zones (A, B, C and D) from the lowest lake water level to dam crest by noting the durations underwater. Samples taken from the zones were investigated for petrographic, physical, chemical and mechanical characteristics. Schmidt hardness hammer experiments were completed on site for blocks in the zones. The shape features of the blocks were determined with the fractal dimension method. Physical weathering developed on sections close to the surface of blocks in zones A, B and C which were in contact with water. Compared to blocks in zone D, blocks in zones A, B and C had higher porosity, water absorption and Los Angeles abrasion loss values, with lower density, uniaxial compressive strength, Schmidt hardness rebound values and Vp values. The increased porosity of blocks from zones A, B and C was caused by greater effects of physical factors like wetting–drying and freeze–thaw affecting the blocks in these zones in contact with lake water. This increased the speed of fragmentation and weakening of the blocks. According to the results obtained in the study, it is understood that over nearly twenty years, the weathering processes affecting the riprap layer have caused changes to the physical and mechanical features of the rock blocks. [ABSTRACT FROM AUTHOR]

Chilika lake, the largest brackish water lagoon in Asia, has a unique setting, where the north-eastern part receives freshwater from the terrestrial runoff, and the south-eastern part receives seawater from the Bay of Bengal. The seasonal variability in the quantity of inflowing water and their mixing in the lake controls the mobilization and precipitation of various elements. Seasonal sediment samples were collected from both the river and seawater influenced regions of the lake to understand the spatio-seasonal distributions of various elements along the salinity gradient. The major elements present in the sediments are mostly derived from the parent rock weathering in the source region and subsequently transported into the lake by the rivers. Seasonal variations in trace element concentrations are more prominent in the north-eastern part of the lake (i.e., low salinity region), and their higher concentrations have been observed during the post-rainy period. The affinity of the elements (Al, Fe, Mn, Li, V, Co, Cr, Cu, Th, and Zn) towards fine-grain sediments suggests that the size distribution pattern controls their accumulation, retention, and remobilization. The concentrations of Cr, Cu, and Pb exceeded the effects range low, and effects range median benchmarks indicating the potential biological risk in the low salinity region as compared to the high salinity region. The statistical analysis indicated that the concentrations of elements in the region proximal to the sea mouth are controlled by grain size and physicochemical condition of the lake water. In contrast, the element concentrations in the interior region are associated with anthropogenic activities and weathering processes. Continuous monitoring and assessment of element concentrations of the lake sediments can help to protect the lake ecology from the harmful element contaminations. [ABSTRACT FROM AUTHOR]

Lacustrine sediments of the Big Lachman Lake (James Ross Island, Antarctica) are dominated by clay- and silt-sized particles of varied petrographic composition. These are of volcanic origin and are derived predominantly from the Mendel Formation. The intensity of chemical weathering of volcanic rock particles in the sediments was expressed by the Chemical Index of Alteration (CIA), which reflects alteration of feldspars and formation of clay minerals. The observed mineral assemblage of montmorillonite, illite, and kaolinite probably originated from alteration of volcanic glass and from alteration of feldspars to clay minerals. CIA weathering rates from the lacustrine sediments are similar to those of Early Jurrasic high-Ti volcanic rocks of the Mount Poster Formation and Middle Jurrasic high-Ti volcanic rocks of the Mapple Formation from the Antarctic Peninsula. However, the sediments show a good fit in OIB-normalized incompatible trace-element patterns only with the high-Ti volcanic rocks from the Middle Jurassic rhyolites of the Mapple Formation, while the fit with Cenozoic basalts of the James Ross Island Volcanic Group is poorer. Rocks from the Antarctic Peninsula were probably transported through the Prince Gustav channel by small glaciers during the Neogene and Quaternary. [ABSTRACT FROM AUTHOR]

A hydrogeochemical study was conducted in the outcropped part of the coal-bearing Upper Carboniferous formations in the Ruhr area to investigate the characteristics of regional mine water and understand the hydrogeochemical conditions. Twenty-eight mine water samples from the adits of different abandoned coal mines were collected and analyzed for major ions, iron (Fe2+, Fetotal) and sulfide (H2S). The water samples had a pH of 6.39–7.65. Total dissolved solids (TDS) ranged from 157 to 1806 mg L−1. Mine water samples were dominated by HCO3− > Ca2+ > SO42− > Mg2+ > Na+ > Cl− > K+ > NO3− > (F−, Li+). Several water samples had elevated SO42−, Fetotal, and H2S concentrations up to 354 mg L−1, 4.2 mg L−1, and 10 µg L−1, respectively. The water types (Ca–Mg–HCO3–SO4, Na–Ca–HCO3–SO4, Ca–Mg–Na–HCO3–SO4, and Na–Ca–Mg–HCO3–SO4) were the dominant hydrogeochemical facies. Gypsum and halite were always undersaturated, while calcite and dolomite were undersaturated in about 82% of water samples. The chemical weathering processes of pyrite, calcite, dolomite, gypsum, and halite, as well as ion exchange, appear to be the dominant hydrogeochemical processes controlling adit mine water chemistry. In general, there was an increasing trend of TDS and major ion concentrations from south to northeast in the study area. This study may aid in the improvement of water management in the Ruhr area since the adits discharge into the river Ruhr which is strongly used for the drinking water supply of a large metropolitan region in western Germany. [ABSTRACT FROM AUTHOR]

Groundwater in crystalline basement is highly mineralized. The chemistry of bedrocks in crystalline basement of Ogbomosho in relation to chemical composition of groundwater in the area was, therefore, investigated employing a combined approach involving hydrogeological, geological mapping and geochemical method. A total of seventy five (75) water samples collected from wells; shallow and deep, bore within rock exposures (6) and other locations within the study area were analyzed for elemental composition using Inductive Coupled Plasma-Mass Spectrometry (ICP-MS). Physico-chemical parameters, temperature, electrical conductivity (EC), total dissolved solids (TDS) and acidity (pH), were measured in situ using HANNA HI9813-6 hand-held meter. Six rock samples representative of the main geological units of the study area were also collected and analyzed for major oxides and rare earth elements (REE) concentrations using ICP-MS. Thin sections of the rock samples were prepared and observed under petrological microscope for mineralogical compositions of the rocks. Acidity ions/TDS model of groundwater in the area was also established to determine the reactivity of the rock minerals and groundwater evolution pattern. The results of in-situ physico-chemical tests of the water samples indicate the temperature, EC, TDS and pH ranged within 26.6–31.7 °C, 72–1491 mS/cm, 36–747 ppm and 6.15–9.3, respectively. The petrographical analysis revealed biotite, quartz, potassic feldspar (microcline), perthite, albite, hornblende, plagioclase, myrmekite, topaz and muscovite. The major oxides, SiO2, Al2O3, Fe2O3, MgO, CaO, Na2O, K2O, TiO2, P2O5 and MnO, varied with median values of 72.21%, 14.99%, 1.17%, 0.375%, 2.245%, 4.215%, 3.46%, 0.16%, 0.045% and 0.015%. These indicate dorminance of SiO2 and Al2O3 suggesting acidic and metamorphic/acidic igneous rocks, respectively. The median percentage oxide compositions of the cations in rocks were, therefore, of the order: Na2O > K2O > CaO > MgO. The dissolved cations consequent upon weathering of the minerals were also of the order Na+ (26.9 mg/l) > K+ (4.69 mg/l) > Mg2+ (4.57 mg/l) > Ca2+ (4.23 mg/l) in groundwater based on their median values. These indicate solute concentration in groundwater is proportional to the reactivity of the bedrock minerals. The major anions, HCO3−, Cl− and NO3−, varied within 5.0–455 mg/l, 14.18–184.34 mg/l and 0.02–0.21 mg/l, respectively, in groundwater. The cross-plots of TDS against Ca2+, Na+, Cl− and HCO3− indicate the groundwater in the area is moderately to highly mineralized. The ionic reactivity based on pH ions/TDS plots indicated six-type models. The ionic concentration at low pH within 6.4–7.2 increases with pH for Type-1 (Ca2+), Type-5 (NO3−) and Type-6 (HCO3−,TDS), decreases for Type-2 (Mg2+, K+) but constant as pH increases for Type-4 (Cl−). At high pH, greater than 7.2 but less than 9, ionic concentration increases with pH for Type-1, Type-2 and Type-4, decreases with pH for Type-6 and constant for Type-5. However, the ionic concentration of Na+ (Type-3) momentarily increased, decreased and subsequently increased through low to high pH. These indicate varied degree of reactivity of the bedrock minerals and groundwater evolution pattern. Thus, the composition of dissolved ions in groundwater is controlled by weathering of Ca-feldspar (plagioclase), K-feldspar (orthoclase), Na-feldspar (albite) and biotite found in host rocks. The similarity in trend of cations in groundwater and their oxides in rock samples suggests the influences of local rock chemistry on the groundwater chemistry and hence, groundwater–rock interaction in the study area. The groundwater evolution pattern in the area depends on pH and reactivity of the ions produced from the weathering of the minerals. The chemical compositions of natural waters are, therefore, a direct indication of the geology of their catchment. [ABSTRACT FROM AUTHOR]

The chemical composition of river sediments reflects bedrock geochemistry in the area of erosion and characterizes trend of weathering in the catchment area. The article presents data about chemical composition of Zeya River sediments. This river is one of the largest watercourses in the Amur River basin. The chemical composition of river sediments was analyzed by X-ray fluorescence spectrometry. Compared with the upper continental crust, the river sediments are depleted in almost all analyzed major elements. According to the analysis of major element the ratio, degree of weathering of river sediments in Middle Reach of the Zeya increases down the river. The chemical composition of studied river sediments is close to those in the rivers of northeastern China. [ABSTRACT FROM AUTHOR]

In this paper, the landslide mechanism in highly weathered volcanic rocks is analyzed in Niushoushan Hill in Nanjing; this hill is mainly composed of volcanic tuff rocks. The gradually weathered rocks reduce the hillslope stability and cause landslides during continuous rainfall. The kaolin and montmorillonite clay minerals were tested using an X-ray diffractometer. The subsequent swelling, disintegration, and permeable tests indicated the location of soft zones and the poor hydraulic conductivity of the highly weathered tuff (HWT). The overflow from boreholes and joints exposes a confined aquifer that is caused by rainfall infiltration in the lower moderately weathered tuff (MWT), which crops out on the top of the hill and is bounded on the interface of the HWT and MWT. The electrical resistivity tomography method was carried out for the considered slope to define the boundaries of the discontinuities as a supplement to drilling. The displacements of the slope surface and the deep rocks were monitored, and the results indicated that sliding had not stopped after a long period of continuous rainfall. Slope stability analysis, considering a water head rise due to rainfall infiltration, was carried out using the Slide v6.0 computer package. The simulation included steady-state flow, transient seepage associated with rainfall and slope stability variation caused by different infiltration conditions. The results indicate that the HWT with low permeability can confine the activity of the lower aquifer and result in a rapid rise of pore pressure in response to rainfall, which can lead to slope failure. [ABSTRACT FROM AUTHOR]

Many ancient city walls have stability problems such as internal damage, surface weathering and erosion, and even degradation of bearing capacity. The protection of ancient city wall has thus become a serious problem to be solved, and this study was carried out to provide specific protection recommendations. We identified and classified the failure modes of a number of ancient city walls and give specific protection recommendations for different kinds of failure modes. Based on numerical simulation, the analysis of the failure mechanism of an ancient city wall in Beijing has put forward. We found that the main failure mode of ancient city wall is rainstorms and that the rainfall degree, the duration of rainfall, and the presence of permeable channels in the wall all have a significant impact on the deformation of the wall, and there may have a bulging phenomenon in the lower part of the surface of the wall; in addition, the temperature has little effect on the deformation of the wall. Our classification method can be applied to identify the failure modes of similar ancient buildings and can provide suggestions for protective measures. [ABSTRACT FROM AUTHOR]

Groundwater trace element geochemistry was evaluated in the Narji Limestone which possesses a range of substituted trace elements in the mineral matrix. The data indicate three interrelated processes control water-rock interactions and elemental concentrations in this aquifer. Dissolution influenced by pH-Eh, recharge processes and residence time controls Ca, Mg, Mn, Al, Cd, Ba, Sr, Co, Li, Rb, V, Fe, Pb, As, Si and Cu concentrations, while the weathering of quartzites and shales releases minute quantities of Na, K, Cl, Si and F into groundwater. A significant amount of Na, K, Cl, NO , SO , Al, Fe, Cd, As, Pb, Ni, Zn, Mn, Sr, Cl, Br, Sb, Ag, Mo, Co and Cu has leached into groundwater from the use of fertilizers/manures and decayed organic matter in cultivated areas. High evapotranspiration has concentrated the chemicals by about 84%. Urbanization, land-use changes, mining and local industries have significantly increased Cd, Se, Ni, Zn, V, Fe, Cd, Sb, Ag and Cr concentrations in groundwater. The composition of groundwater is also affected by sewage, waste disposal and industrial and commercial activities. The chemical properties of about 18% of groundwater samples suggest the role of dissolution/weathering, 46% of samples have been influenced by the effects of evaporation and agricultural activities while 29% of the samples have been affected by natural hydrogeochemical processes and the effects of agricultural and industrial contamination. The quality of groundwater in the area generally conforms to the WHO recommended limits for drinking. Increasing anthropogenic interactions are likely to degrade the groundwater as karst is highly prone to contamination. This demands further investigations to ensure that the groundwater remains suitable for its intended uses in the future. [ABSTRACT FROM AUTHOR]

This paper presents the results of a comprehensive study on the morphology of weathering profiles developed on metamorphic and sedimentary rocks under subtropical climate, focusing on its influence on geotechnical parameters of weathering materials. Several cut and natural slopes were selected for more detailed descriptions of their physical, mineralogic, geologic, structural and geotechnical parameters, focusing on weathered rock materials, including characteristics of matrix (e.g., fabric, mineralogy and degree of weathering) and rock mass (e.g., rock:soil ratio, discontinuity characteristics, JRC-joint roughness coefficient, and JCS-joint compressive strength). Samples from the upper portions of the profiles and down into the transition zone between rock and soil were collected to determine their physical and geotechnical parameters, to prepare and describe thin sections and to perform X-ray diffraction (XRD) analyses and point load tests. Results indicate that weathering profiles are thin, contacts between material layers are sharp and there is a strong structural control on weathering, mainly by stress-relief joints. Soil-like material is present only in portions of the rock mass near the ground surface or along structural discontinuities (foliation and fractures). Thin-section description can provide important indexes and information that can be related to chemical and physical weathering of those rocks and so be used to differentiate materials present along profiles. Also, physical parameters have proved to be useful for the distinction of different weathered materials. Finally, XRD and thin-section description have allowed the identification of important mineralogical changes due to weathering. [ABSTRACT FROM AUTHOR]

In order to research hydro-geochemistry characteristic and environmental significance of river and spring water, 68 samples were collected in different ablation periods (initial ablation period; ablation period; end ablation period) in Hulugou river basin. The results showed that the chemical type of the river and spring in different ablation period was SO -Ca-Mg type in Hulugou River Basin. Compared with water samples in different ablation, the order of the total ionic concentration was the initial ablation period > the end ablation period > ablation period, with the mean was 238.29, 237.19 and 178.19 mg/L, respectively. From the analysis of ionic sources, which indicated the chemical composition of river and spring water was controlled by crustal materials during the different ablation period in the Hulugou River Basin. And the dominant processes were water-rock intersection, especially the weathering and dissolution of dolomite. Meanwhile, the results of enrichment factor also confirmed that most of the ions influenced by local soil source in study area. But the ratios of NO , SO and Cl to Na also confirmed that anthropogenic also influenced the water chemistry in study area. The results are also helpful for further understanding the hydro-geochemistry characteristic in different ablation period in the alpine regions of western China and providing scientific basis for further study on hydro-geochemistry. [ABSTRACT FROM AUTHOR]

This study focused on analyzing and calculating the correction factor between direct and indirect methods for the ultrasonic testing of stone monuments using a customized transducer and couplant. To achieve this goal, the P-wave velocity in 11 rock specimens, including two artificially weathered samples, was measured in a laboratory by applying both direct and indirect methods using an ultrasonic tester. Statistical interpretation of the results revealed that the indirect P-wave velocities were always lower than the direct velocities, with the correction factors between them differing by rock type. The average correction factors produced by the indirect method were 1.50 in the medium- to coarse-grained granite sample, 1.37 in fine-grained granite, 1.58 in fine-grained diorite, 1.38 in medium-grained diorite, 1.59 in sandstone, and 1.71 in marble. In addition, the regression equation and coefficient of determination, R were acceptably high, suggesting a sufficient relationship between the two variables for use in engineering. This study will significantly contribute to improving the reliability of ultrasonic testing for weathering evaluation of a stone monument. [ABSTRACT FROM AUTHOR]

Engineering properties of building stones can vary because of degradation by weathering agents. Thermal fluctuation is one of the most important agents on deteriorations such as sugaring, bowing, cracking and spalling of marble. As a result, physical and mechanical properties of marble used in the construction of old and/or modern structures are adversely affected by time. On the other hand, some properties of building stones are always required for decision of rehabilitation works. Several kinds of conventional tests have been suggested for characterization of stones, to measure their properties or to evaluate conservation or repair works. However, in most cases, sampling from historical buildings is not possible. Therefore, nondestructive testing methods are often suggested for the prediction of weathering grade of building stones. One of the most practical methods for similar purposes is ultrasonic pulse velocity measurement, which can be performed easily. The main goal of this study is attainment of sound empirical correlations between the ultrasonic pulse velocity and engineering properties of previously deteriorated marble. Experimental works were conducted on seven different specimen categories of a coarse-grained marble having different micro-crack frequencies induced by both cyclical heating-cooling and freeze-thaw actions. The experimental results indicated that physical and mechanical properties of Muğla marble can be reliably estimated for different environmental cases by ultrasonic pulse velocities. P-wave velocities in dry and saturated cases are two sound indicators of both the apparent porosity and the coefficient of capillary absorption, and whereby the sugaring type of deterioration for coarse-grained marbles. [ABSTRACT FROM AUTHOR]