This study presents the first comprehensive soil gas survey across southern Uruguay’s H<sub>2</sub> prospective terranes. A pre-field trip selection was done on the basement rock nature, as well as vegetation anomalies in subcircular depressions and fault presence. The Neoproterozoic terrane, north of Punta del Este, and the Archean Rio de la Plata Craton, north of Montevideo, as well as along the suture zones between the two, were targeted. Our findings reveal substantial H<sub>2</sub> concentrations, significantly outperforming many established basins worldwide. The suture zones act as critical migration conduits for H<sub>2</sub> coming from a deeper structural level. Slightly abnormal helium signatures confirm an active, deep-sourced fluid system, particularly within the Sierra Ballena and Cordillera shear zones. The Archean Rio de la Plata Craton appears promising but has only been partially sampled and warrants further investigation. These results underscore the high potential of Uruguay as a new frontier for natural hydrogen exploration.
Vassilis Amiridis, Stelios Kazadzis, Antonis Gkikas
et al.
The Mediterranean, and particularly its Eastern basin, is a crossroad of air masses advected from Europe, Asia and Africa. Anthropogenic emissions from its megacities meet over the Eastern Mediterranean, with natural emissions from the Saharan and Middle East deserts, smoke from frequent forest fires, background marine and pollen particles emitted from ocean and vegetation, respectively. This mixture of natural aerosols and gaseous precursors (Short-Lived Climate Forcers—SLCFs in IPCC has short atmospheric residence times but strongly affects radiation and cloud formation, contributing the largest uncertainty to estimates and interpretations of the changing cloud and precipitation patterns across the basin. The SLCFs’ global forcing is comparable in magnitude to that of the long-lived greenhouse gases; however, the local forcing by SLCFs can far exceed those of the long-lived gases, according to the Intergovernmental Panel on Climate Change (IPCC). Monitoring the spatiotemporal distribution of SLCFs using remote sensing techniques is important for understanding their properties along with aging processes and impacts on radiation, clouds, weather and climate. This article reviews the current state of scientific know-how on the properties and trends of SLCFs in the Eastern Mediterranean along with their regional interactions and impacts, depicted by ground- and space-based remote sensing techniques.
Understanding how the lithosphere accommodates deformation along oblique convergent plate boundaries is an important issue for unveiling orogenic belt exhumation. The Variscan belt exposed in Sardinia represents an area where it is possible to investigate the inner part of this orogen and a km-scale transpressive shear zone, i.e. the Posada-Asinara shear zone, that drove the exhumation of the metamorphic core of the belt. Even though the Asinara island offers very good exposure of main tectonic units building up the Variscan belt of Sardinia, a detailed geological map of the island is still lacking, due to a former limitation of access that lasted for many years. In this contribution, we compile a new 1:25.000 geological-structural map of the entire Asinara island useful to better understand this key sector of the Variscan belt in Sardinia.
Abstract Three-dimensional (3D) geological modeling based on borehole data usually requires many manual operations, and the modeling process remains very complicated and time consuming. This paper presents an automatic implicit 3D geological modeling and visualization method that can be applied to urban geotechnical drilling data. First, by analyzing the general characteristics of these types of data, the implicit Hermite radial basis function (HRBF) surface is used to simulate geological interfaces according to lithological layers/units in boreholes. Second, the marching tetrahedra (MT) visualization method is optimized with new data structures and split operations to extract explicit mesh models from implicit geological surfaces. Then, the optimized tetrahedron used in the field of 3D urban drilling modeling is described in detail. Finally, the local geotechnical engineering data of two Chinese cities are used to verify the modeling algorithm, and several kinds of spatial analyses are carried out, including visualization, data querying, accuracy assessment and multiple cutting methods. The results show that the proposed urban subsurface 3D geological modeling method is effective in visualizing the structural shape, topological relationship and formation properties of strata that can be used to predict underground conditions and reduce construction risks during urban geotechnical engineering projects.
Accurate measurements and predictions of near-surface soil drying and evaporation following heavy rainfall events are often needed for research in agriculture and hydrology. However, such measurements and predictions at mine waste pile and tailing settings are limited. The prediction of evaporation at mine waste piles is essential for many problems in geotechnical engineering, including the design of soil cover systems for the long-term closure of hazardous waste sites, and thus mitigates, for example, the generation of acid mine drainage (AMD) and metal leaching. AMD is one of mining’s most serious threats to the environment. This study investigated the short-term (8 days) and medium-term (27 days) drying rates and evaporative fluxes at the surface and near-surface of the Deilmann South waste-rock (DSWR) pile at the Key Lake uranium mine, northern Saskatchewan, using the gravimetric (GV) method and SoilCover (SC) model, respectively, during and following heavy rainfall events for the environment. The SC simulation results showed that during the weather-controlled stage (Stage I) of the first 5-day period of rainfall events, while the surface was wet, the potential evaporation (PE) was equal to the actual evaporation (AE) (i.e., AE/PE = 1). As the surface became drier on Day 6, the cumulative PE began to separate from the cumulative AE and the surface’s drying rate rapidly diverged from those at the deeper depths. This occurrence signaled the onset of the soil profile property-controlled stage (Stage II). As the drying continued, the surface became desiccated and the slow-rate drying stage (Stage III) was established from Day 7 onward. The SC-simulated AE results were compared to those measured using the eddy covariance (EC) method for the same test period at the DSWR pile in a different study. The comparison showed that the two methods yielded similar AE results, with 18% relative errors. The results of this study provided the opportunity to validate the SC model using actual data gathered under field conditions and to ascertain its ability to accurately predict the PE and AE at the surfaces of mine waste piles.
Patinya Pornsopin, Passakorn Pananont, Kevin P. Furlong
et al.
Abstract The Thai Meteorological Department (TMD) seismic network began development in 2008. There are a total of 71 seismic stations consisting of 26 borehole stations and 45 surface stations currently installed. The three-component data from the TMD seismic network have been widely used in previous seismological studies. In a recent analysis, we have found that sensor orientation as reported in the site metadata is sometimes significantly incorrect, especially for borehole stations. In this study, we analyze P-wave polarization data from regional and teleseismic earthquakes recorded in the network to estimate the true instrument orientation relative to geographic north and compare that to station metadata. Of the 45 surface stations, we found that at present, ~ 82% are well oriented (i.e., aligned within 0–15° of true north). However, 8 sites have sensors misoriented by more than 15°, and some stations had a temporal change in sensor orientation during an upgrade to the seismic system with replacement of the sensor. We also evaluated sensor orientations for 26 TMD borehole seismic stations, from 2018 to the 2022. For many of the borehole stations, the actual sensor orientation differs significantly from the TMD metadata, especially at short-period stations. Many of those stations have sensor misorientations approaching 180°, due to errors in the ambient noise analysis calibration techniques used during installation. We have also investigated how this sensor misorientation affects previous seismic studies, such as regional moment tensor inversion of earthquakes sources and receiver function stacking. We have found that the large deviations in sensor orientation can result in erroneous results and/or large measurement errors. A cause of the orientation error for borehole sites could be a combination of strong background surface ambient seismic noise coupled with an incorrect reference instrument response.
Abstract Shale oil refers to oil stored in organic-rich shale. It is an important part of unconventional oil and provides a large amount of resources. Based on the systematic study of the geological characteristics of shale oil in China's major continental basins, the geological connotation of the “sweet area (section)” in shale oil is proposed in this paper, and it refers to areas (sections) that can be preferentially explored and developed in oil-bearing shale formations under current economic and technical conditions. The formation conditions and distribution characteristics of continental shale oil in China are analyzed with a focus on the geological properties of the Triassic Yanchang Formation in the Ordos Basin, the Cretaceous Qingshankou Formation in the Songliao Basin and the Permian Lucaogou Formation of the Jimusar Sag in the Junggar Basin. It is found that the “sweet areas” of shale oil with medium-high maturation are mainly located in thick shales with a Ro greater than 0.9%, and the “sweet sections” are mainly located in the middle and lower parts of the shale formation. The geological resources of continental shale oil in the major continental basins in China are estimated to be approximately 3700 × 108 tons. The in situ conversion process (ICP) may be a key technology for the effective development of medium-to low-mature shale oil. The scale, maximum burial depth and present depth of the organic-rich shale are proposed as the three key parameters for the optimization of pilot sites by taking the Triassic Yanchang Formation in the Ordos Basin as an example. Using ICP, it is expected that the recoverable resources of China's continental shale oil will be approximately (400–500) × 108 tons. The terminology of "man-made reservoir" is proposed in this paper. In an "man-made reservoir", the overall industrial output of the "sweet areas (sections)" is formed by artificial intervention and the construction of an underground fracture network system with "man-made permeability". Continental shale oil may be another revolutionary source of unconventional oil and is expected to be first successfully produced in China.
Abstract Persistence of geological discontinuities is of great importance for many rock-related applications in earth sciences, both in terms of mechanical and hydraulic properties of individual discontinuities and fractured rock masses. Although the importance of persistence has been identified by academics and practitioners over the past decades, quantification of areal persistence remains extremely difficult; in practice, trace length from finite outcrop is still often used as an approximation for persistence. This paper reviews the mechanical behaviour of individual discontinuities that are not fully persistent, and the implications of persistence on the strength and stability of rock masses. Current techniques to quantify discontinuity persistence are then examined. This review will facilitate application of the most applicable methods to measure or predict persistence in rock engineering projects, and recommended approaches for the quantification of discontinuity persistence. Furthermore, it demonstrates that further research should focus on the development of persistence quantification standards to promote our understanding of rock mass behaviours including strength, stability and permeability.
Magí Franquesa, Armando M. Rodriguez-Montellano, Emilio Chuvieco
et al.
Accurate reference data to validate burned area (BA) products are crucial to obtaining reliable accuracy metrics for such products. However, the accuracy of reference data can be affected by numerous factors; hence, we can expect some degree of deviation with respect to real ground conditions. Since reference data are usually produced by semi-automatic methods, where human-based image interpretation is an important part of the process, in this study, we analyze the impact of the interpreter on the accuracy of the reference data. Here, we compare the accuracy metrics of the FireCCI51 BA product obtained from reference datasets that were produced by different analysts over 60 sites located in tropical regions of South America. Additionally, fire severity, tree cover percentage, and canopy height were selected as explanatory sources of discrepancies between interpreters’ reference BA classifications. We found significant differences between the FireCCI51 accuracy metrics obtained with the different reference datasets. The highest accuracies (highest Dice coefficient) were obtained with the reference dataset produced by the most experienced interpreter. The results indicated that fire severity is the main source of discrepancy between interpreters. Disagreement between interpreters was more likely to occur in areas with low fire severity. We conclude that the training and experience of the interpreter play a crucial role in guaranteeing the quality of the reference data.
AbstractHydrothermal quartz veins from the Butte deposit display euhedral and mottled cathodoluminescent (CL) textures that reflect the growth and deformation history of quartz crystals. A CL-euhedral texture consists of oscillatory dark-light zonations that record primary precipitation from an aqueous fluid. The origin of a CL-mottled texture, which consists of irregularly distributed dark and light portions, is less clear. Previous work showed that in some veins, CL-euhedral and CL-mottled crystals coexist, but the processes leading to their formation and coexistence were unknown. We find that CL-mottled crystals occur predominantly along the wall rock fracture surface and in vein centers and that CL-euhedral cockscomb quartz protrudes from the mottled layers along the wall rock. We infer that the mottled crystals formed by strain-induced recrystallization that was preferentially accommodated by the rheologically weaker layers of noncockscomb quartz because cockscomb crystals are in hard glide orientations relative to adjacent noncockscomb layers. During strain, crystals in noncockscomb layers that are not initially susceptible to slip can rotate in their deforming matrix until they deform plastically. Some of the CL-mottled crystals exhibit a relict CL-euhedral texture (“ghost bands”) whereby bright bands have been blurred and deformed owing to Ti redistribution facilitated by grain boundary migration. The edges of some CL-euhedral crystals become CL-mottled by localized grain boundary migration along adjacent crystals that do not align perfectly. Throughout the veins, CL-mottled crystals are randomly oriented, indicating that small deviatoric stresses were sufficient to drive recrystallization and mobilization of trace elements. Ti concentrations in CL-mottled crystals (23-47 ppm Ti; mean of 31 ppm) overlap those of CL-euhedral dark growth bands (16-40 ppm Ti; mean of 25 ppm Ti) in neighboring CL-euhedral crystals. Average Ti concentrations in CL-mottled quartz and CL-euhedral dark growth bands correspond to temperature estimates of 600°C (31 ppm Ti; CL-mottled) and 619°C (25 ppm Ti; dark bands), which are in good agreement with previous quartz precipitation temperature estimates based on independent thermobarometers. We conclude that recrystallization resets CL-mottled Ti concentrations close to the equilibrium value for the conditions of deformation and that CL-dark growth bands record near-equilibrium Ti concentrations. Recognition of widespread quartz recrystallization in porphyry Cu deposits underscores the significant role that strain plays in deposit formation. Individual veins host crystals that preserve conditions of primary growth and other crystals that preserve conditions of deformation and thermal overprint. Textural information is key to accurately interpreting trace element data and identifying different stages of vein formation. Our suggestion that CL-dark bands are the best candidates for near-equilibrium growth will aid the interpretation of trace element zoning in other hydrothermal systems.
Introduction One of the main goals of spatial analysis of precipitation at area is to reach the standard project storm (SPS) for that area, through which can be reached the standard project flood (SPF). This analysis includes the characteristics of rainfall depth at a certain area and for a specific duration. Relation between depth and rainfall area which called depth-area-duration (DAD), is shown usually by set of curves that each shows different duration of rainfall. Using these curves, a reduction factor is determined for specific area and is applied to adjust the average point rainfall related to frequency of this project. The present study carried out under topic of investigation and map of depth- area- duration in Lorestan, in an area over 28559/5 Km2 in west part of country.Materials and Methods Weak coefficient of correlation is shown meaningfulness of the relation between rainfall and altitude in different time base. this is resulted from different reasons such as extension of area, lack of transmittal and number of suitable weather stations and different extension and tension of mountain than rain flaw. Considering above points cause those other methods of drawing precipitation maps include interpolation or geostatistical methods including, spline, IDW, kriging and Co-kriging were used.Results and Discussion Weak coefficient of correlation is shown meaningfulness of the relation between rainfall and altitude in different time base. this is resulted from different reasons such as extension of area, lack of transmittal and number of suitable weather stations and different extension and tension of mountain than rain flaw. Considering above points cause those other methods of drawing precipitation maps include interpolation or geostatistical methods including, spline, IDW, kriging and Co-kriging were used.Conclusion The results show that to preparing precipitation maps of selecting storms, simple co- kriging (SCK) is a suitable method to calculate the amount of rainfall of selecting storms in lorestan province. So the above way is used for preparing precipitation maps. Resulted from investigation of surface reduction factor of rain fall shows that in time duration 12 and 48 hrs with the increase of each 5000 surface reduction factor reduces for 0.1 in 24 hrs duration within 18000 Km2. This coefficient has a slow decreasing trend and then that is similar to 12 and 48 hrs rainfalls. Assessing the daily rainfall statistics of some of rain gauge stations in somewhere of the province by the Meteorological Organization and the Ministry of Energy, shows that sometimes there is a significant difference between the perception rates recorded by these organizations. Therefore, in order to eliminate the existing defects, it is suggested that the stations occupied by these organizations and their monitoring status be periodically evaluated by the experts of the relevant organizations and possible defects be prevented.
River, lake, and water-supply engineering (General), Engineering geology. Rock mechanics. Soil mechanics. Underground construction
Perach Nuriel1*, John Craddock2, Andrew R.C. Kylander-Clark3, I. Tonguç Uysal4, Volkan Karabacak5, Ramazan Kadir Dirik6, Bradley R. Hacker3, and Ram Weinberger1,7 1Geological Survey of Israel, 32 Yeshayahu Leibowitz St. Jerusalem, 9371234, Israel 2Department of Geology, Macalester College, St. Paul, Minnesota 55105, USA 3Department of Earth Science, University of California, Santa Barbara, California 93106, USA 4CSIRO Energy, 26 Dick Perry Avenue, Kensington, Western Australia 6151, Australia 5Department of Geological Engineering, Eskisehir Osmangazi University, Eskisehir 26040, Turkey 6Department of Geological Engineering, Hacettepe University, Ankara 06640, Turkey 7Department of Geological and Environmental Sciences, Ben-Gurion University, Beer-Sheva 84105, Israel
María Luz González-Regalado, Guadalupe Monge, María Isabel Carretero
et al.
The Doñana National Park is a Biosphere Reserve located within the estuary of the Guadalquivir River (SW Spain). It is mainly composed of extensive fluvio-tidal marshes partially protected by an elongated sandy spit. Three phases have been distinguished in the late Holocene evolution of this spit based on textural, geochemical, palaeontological and, chronological data recorded in a long core (31 m). Phase 1 (890 BCE-218 BCE) is characterized by the alternation of lagoonal silty sediments and slightly polluted marsh deposits, the latter with contamination from thousand-year-old mining. Phase 2 (218 BCE-90 CE) is characterized by several historical tsunamis, which caused the erosion of previous dune systems and the deposit of these sandy sediments on the adjacent bottom of the lagoon. Phase 3 (90 CE-Present) includes a regressive sequence (lagoonal bottom-marsh-dune system), with the pollution of lagoonal sediments due to Roman mining activities.
<p>We present a new algorithm for the estimation of the plant area density (PAD) profiles and plant area index (PAI) for forested areas based on data from airborne lidar.</p>
<p>The new element in the algorithm is to scale and average returned lidar intensities for each lidar pulse, whereas other methods do not use the intensity information at all, use only average intensity values, or do not scale the intensity information, which can cause problems for heterogeneous vegetation. We compare the performance of the new algorithm to three previously published algorithms over two contrasting types of forest: a boreal coniferous forest with a relatively open structure and a dense beech forest. For the beech forest site, both summer (full-leaf) and winter (bare-tree) scans are analyzed, thereby testing the algorithm over a wide spectrum of PAIs.</p>
<p>Whereas all tested algorithms give qualitatively similar results, absolute differences are large (up to 400 % for the average PAI at one site). A comparison with ground-based estimates shows that the new algorithm performs well for the tested sites.
Specific weak points regarding the estimation of the PAD from airborne lidar data are addressed including the influence of ground reflections and the effect of small-scale heterogeneity, and we show how the effect of these points is reduced in the new algorithm, by combining benefits of earlier algorithms. We further show that low-resolution gridding of the PAD will lead to a negative bias in the resulting estimate according to Jensen's inequality for convex functions and that the severity of this bias is method dependent. As a result, the PAI magnitude as well as heterogeneity scales should be carefully considered when setting the resolution for the PAD gridding of airborne lidar scans.</p>