Hasil untuk "Geology"

A. Chatzipavlis, D. Trogu, A. Ruju et al.

<p>This study presents an Early Warning System (EWS) for coastal flooding that integrates wind, wave, and sea level forecasts which are validated using in situ records. The system employs the SWAN spectral wave model to simulate nearshore hydrodynamics while an empirical approach is used to assess Total Watel Level (TWL) exceedances over a user-defined morphological threshold, deriving from repeated topographic surveys. This approach utilizes widely used empirical methods for wave run-up estimation and makes use of the most effective one after calibration. The performance of the EWS is assessed through seven monitored surge events of varying magnitude and hydrodynamic conditions, demonstrating strong agreement between projected TWL exceedances over predefined morphological thresholds, particularly under high-energy wave conditions. Minor discrepancies are noted during events with marginal TWL exceedances over short durations. Results underline the system's potential as a valuable tool for coastal hazard assessment and risk management, with future improvements focusing on appropriate updates of the beach morphology and the integration of suitable numerical techniques and machine learning algorithms.</p>

Nuria Andrés, José M. Fernández‐Fernández, David Palacios et al.

Gljúfurárjökull, located on the Tröllaskagi Peninsula in northern Iceland, is a small glacier approximately 3.8 km in length. This study analyses the glacier's evolution through a combination of methods including: (i) geomorphological mapping, (ii) Cosmic‐Ray Exposure (CRE) dating, (iii) lichenometry and (iv) palaeoglacier reconstruction (volume, extent and Equilibrium Line Altitude (ELA)) for each identified ice‐marginal position. The mean CRE ages obtained are as follows: Glacial Phase 1: no samples available for CRE dating; Glacial Phase 2: 2.6±0.5 ka (n = 2); Glacial Phase 3: 3.2±1.1 ka (n = 7); Glacial Phase 4: 2.5±0.2 ka (n = 2); Glacial Phase 5: between 2.1 ka and a few hundred years. Lichenometry results for surfaces older than 130 years show inconsistencies both internally and in comparison with CRE ages. However, for the most recent glacier margins, lichenometric dates are coherent and align with historical photographic evidence. Accordingly, the ages proposed for glacier marginal positions 6 and 7 are 1899/1904 CE and 1912/1917 CE, respectively, slightly predating position 8, which is documented in aerial photographs from 1946 CE. The millennial‐ to centennial‐scale evolution of Gljúfurárjökull outlined in this study is consistent with the patterns observed in debris‐free glaciers across Tröllaskagi, as well as in many Icelandic and Arctic glaciers. Notably, the Little Ice Age (LIA) advance at Gljúfurárjökull was less extensive than earlier Neoglacial advances, a trend common in the Sub‐Arctic and Arctic regions. Since the end of the LIA, the glacier has experienced a general retreat, interrupted only by a brief advance during the 1980s–1990s—again mirroring broader Arctic glacial behaviour. Overall, this study underscores the high sensitivity of Gljúfurárjökull to climatic fluctuations during the Late Holocene. The application of CRE dating reveals that the glacier's evolution aligns closely with patterns observed in other Icelandic and Arctic glaciers.

Yong Chang, Nan Mu, Yaoyong Qi et al.

Reliable precipitation inputs are essential for hydrological modeling, yet global precipitation products often exhibit substantial discrepancies that introduce significant uncertainties into streamflow simulations and projections. In this study, we assessed the relative contribution of precipitation dataset uncertainty to discharge simulations and projections, in comparison with uncertainties from model structure, model parameters, and climate projections, in the Liujiang catchment, southwest China. Three widely used satellite-based products (CHIRPS, PERSIANN, and IMERG) and one reanalysis dataset (ERA5) were combined with three hydrological models of varying structural complexity to simulate streamflow. Using an ANOVA-based variance decomposition framework, we quantified the contributions of different uncertainty sources under both historical and future climate conditions. Results showed that precipitation input uncertainty dominates discharge simulations during the calibration period, contributing over 60% of total variance particularly at high flows, while interactions among precipitation, model structure, and parameters govern low-flow simulations. Under future climate scenarios, climate projection uncertainty overwhelmingly dominates discharge predictions with 50–80% of uncertainty contribution, yet precipitation products still contribute significantly across time scales. The compensation of precipitation biases by hydrological models can cause parameter values to deviate from their true physical meaning. This deviation may further amplify the differences in discharge projections driven by different precipitation products under future climate conditions and increase the overall uncertainty of streamflow projections. Overall, this study introduced an integrated approach to simultaneously assess precipitation uncertainty across flow regimes and future climate scenarios. These results emphasized the necessity of using ensemble approaches that incorporate multiple precipitation products in hydrological forecasting and impact studies, particularly in data-scarce regions reliant on global datasets.

P. Duan, H. Li, Z. Ma et al.

<p>The 8.2 ka event has been extensively investigated as a remarkable single event but rarely considered as a part of multi-centennial climatic evolution. Here, we present absolutely dated speleothem multi-proxy records spanning 9.0–7.9 ka from Beijing in North China, near the northern limit of the East Asian summer monsoon (EASM) and thus sensitive to climate change, to provide evidence of the intensified multi-decadal climatic oscillations since 8.52 ka. Three extreme excursions characterized by inter-decadal consecutive <span class="inline-formula"><i>δ</i>¹⁸</span>O excursions exceeding <span class="inline-formula">±1<i>σ</i></span> are identified from 8.52 ka in our speleothem record. The earlier two are characterized by enriched <span class="inline-formula">¹⁸</span>O at <span class="inline-formula">∼8.50</span> and 8.20 ka, respectively, suggesting a prolonged arid event, which is supported by the positive trend in <span class="inline-formula"><i>δ</i>¹³</span>C values, increased trace element ratios, and lower growth rate. Following the 8.2 ka event, an excessive rebound immediately emerges in our <span class="inline-formula"><i>δ</i>¹⁸</span>O and trace element records but moderate in the <span class="inline-formula"><i>δ</i>¹³</span>C, probably suggesting pluvial conditions and nonlinear response of the local ecosystem. Following two similar severe droughts at 8.50 and 8.20 ka, the different behavior of <span class="inline-formula"><i>δ</i>¹³</span>C suggests the recovering degree of resilient ecosystem responding to different rebounded rainfall intensity. A comparison with other high-resolution records suggests that the two droughts–one pluvial pattern between 8.52 and 8.0 ka is of global significance instead of being a regional phenomenon, and is causally linked to the slowdown and acceleration of the Atlantic Meridional Overturning Circulation that was further dominated by the freshwater injections in the North Atlantic.</p>

Kevin L. McCormack, Mark D. Zoback, Andrew W. Frederiksen et al.

We report a study using teleseismic <i>P</i>-wave receiver functions to infer the orientation of the maximum horizontal principal stress from the direction of upper crustal shear-wave velocity anisotropy. We apply an inverse approach using the Neighborhood Algorithm to conduct a nonlinear search, attaining a best-fitting crustal model that includes shear velocity anisotropy. Unlike previous methods reported in the literature, this method is able to distinguish anisotropy in the upper, brittle crust from that in the lower, ductile crust in certain instances. We apply this method to teleseismically recorded earthquakes in the Central Valley of California, the Permian Basin, Texas, northern Oklahoma and sites near the San Andreas Fault in California. Of the forty-one stations to which we apply this method, twenty have a good apparent signal. A misfit calculation is performed by calculating a zero-lag cross-correlation coefficient for each modeled receiver function with the data for a given back azimuth range. While the fast polarization direction in the upper crust of some of these stations aligns with independent indicators of the direction of the maximum horizontal principal stress, the fast direction in the upper crust at other stations does not, apparently indicating that the anisotropy was resulting from a different mechanism.

Daniel Porras, Javier Carrasco, Pedro Carrasco et al.

The objective of this study was to obtain the deep subsurface structure of a saline-evaporitic formation affected by an anticlinal structure, defining the position and thickness for its future exploitation (potassium salts). To improve this knowledge, geophysical methods can be applied to establish detailed information on geological structures at depth. This work analyzes the results of a deep time domain electromagnetic (TDEM) survey acquired over the southern flank of the Barbastro-Balaguer Anticline present in the Ebro Basin in the vicinity of Graus (Huesca, Spain), that controls the geometry of the Barbastro saline-evaporitic formation, of interest from the mining point of view. A deep time domain electromagnetic system (TDEM) is used, providing a penetration capability down to 3.0 km depth. A parametric constrained inversion over a lithological known borehole (Monzón-1) is used to obtain a resistivity model and then applied to the rest of the survey points. The applied methodology contributes to improving the geological knowledge, revealing a new detailed geological structure of the Barbastro saline-evaporitic formation affected by the Barbastro-Balaguer Anticline. The survey shows that the Barbastro saline-evaporitic formation presents a structure with a ramp hanging wall and close to flat footwall, generally dipping to the SW, with a decreasing thickness from 1103 m to 601 m, in concordance with the previous accepted geological structural model. The new geophysical study provides essential data, allowing design and drilling optimization in future mining exploitations.

Rahim Abdollahzadeh kahrizi, Amir Hossein Kokabinezhad Moghaddam, Edris Merufinia

IntroductionThe increase in demand for water resources due to population growth and economic development along with water wastage and a decrease in rainfall, on the other hand, has made it significant to pay attention to water demand and make sound policies. Our country is facing the risk of a water crisis in the coming years, mainly due to its location in a dry and semi-arid climate, as well as the ever-increasing growth of water consumption. To alleviate the water crisis, international trade in agricultural products can play a significant role in redistributing water resources because traded goods contain a large amount of virtual water. Water restriction in Iran is an undeniable fact, for this purpose, trading based on virtual water can be a solution to reduce the effects of water restriction. Due to being located in a dry and semi-arid climate, Iran is facing the risk of a water crisis in the coming years. Therefore, in order to deal with it, it is necessary to be more sensitive to the types of water consumption. Among these uses is virtual water. The water used in the production process of goods is called virtual water, a part of which is kept in the product. Virtual water trade occurs when goods are imported into global markets. Virtual water trading is expected to reduce water consumption at the national and international levels due to more efficient and specialized use of water. Today, the concept of virtual water is one of the most critical issues in water resources management. Today, the problem of water shortage has become a serious concern due to climate changes and uneven distribution of rainfall in most regions and countries, including Iran, and is considered the most important obstacle to the economic development of these countries. Trade as a tool to prevent the unnecessary withdrawal of water resources, focusing on the strategy of virtual water trade, can play an essential role in achieving the economic development of countries. Materials and Methods The study area of the research is the Shiblo-Poldasht plain in the northwest of Iran. This area is located in the east of the Poldasht study area and in the north of the Qara Ziauddin study area. The aim of this research was to investigate the statistical status of the cultivated area, the production performance, and the evaluation of the productivity and virtual water of agricultural crops in the Poldasht plain. The time frame of the research is from 2011 to 2021 in an 11-years period. Accurate calculation and determination of water requirement (m3 ha-1). The amount of water required by a plant for its proper growth, taking into account the loss of evaporation and transpiration of the plant, is called the water requirement of the plant. Therefore, the water requirement of the plant depends on the amount of evaporation and transpiration of the plant. It is worth noting that due to different climates and weather conditions, plant growth conditions and as a result, the amount of water needed by plants are also different. In the present research, the various productivity indicators and virtual water of the crops of Dasht-Poldasht have been examined. Moreover, according to the objectives of the research, the physical and financial indicators of water productivity, including the performance index per unit of water volume (CDP), income per unit of water volume (BPD), and net return per unit of water volume (NBPD) have been calculated. Results and Discussion In this research, the amount of virtual water and the productivity index as well as the net and gross economic value of the major crops grown in Poldasht city in West Azarbaijan province were investigated. In this regard, first, data and information related to crops were collected through relevant organizations and institutions, and NETWAT, CROPWAT, and CLIMWAT programs and Excel programs were used to draw graphs and graphical results. Then the yield of crops was calculated by dividing the amount of crops produced by the area of ​​planting crops and the productivity index and virtual water. The results of this research show that the watermelon crop with a harvesting area of ​​5789 ha and a production rate of 237951000 kg and a production yield of 41103.99 kg ha-1 with a water requirement of 2760 m3 ha-1 has a productivity of 14.89 kg m-3 and has The highest level of productivity is also the results show that the alfalfa product is the lowest level of productivity. It is worth noting that despite the fact that the watermelon product has high production and productivity at a very low harvest level, it is also a very water-loving product that has a relatively high water requirement, and generally experts are looking for an alternative product due to the lack of water resources. Finally, it is suggested that traditional (submerged) irrigation methods should be replaced by modern pressurized irrigation methods so that in addition to increasing efficiency and productivity, we can see a reduction in water consumption and its wastage. It is also suggested that the water requirements of agricultural crops be compared with each other using the data of the Agricultural Jihad Organization and the aforementioned programs, and its effect on the amount of water consumed and its savings, as well as the net and gross values ​​of the production of crops, and the final results It is compared with the national water document to fully verify the amount of water needed. Conclusion Despite the fact that the watermelon product has high production and productivity at a very low harvest level, it is also a very water consuming product possessing a relatively high water requirement, and generally experts are looking for an alternative product, due to the lack of water resources. Finally, it is suggested that traditional flood irrigation methods should be replaced by modern pressurized irrigation methods, so that in addition to increasing efficiency and productivity, we can encounter with a reduction in water consumption and its wastage. It is also suggested that the water requirement of agricultural crops should be compared with each other using the data of the Agricultural Jihad Organization and the aforementioned programs, and its effect on the amount of water consumed and its saving, as well as the net and gross values of crop production, should be evaluated. Finally, the results have been compared with the national water document so that the amount of water needed can be fully verified.

Zhaoxiang Chu, Yiming Wang

Abstract This letter introduces the founding of a new Deep Underground Science and Engineering Laboratory-DUSEL in China, the distinguishing feature of which is focusing on the key scientific issue on the law of fluid matter migration within the Earth’s Critical Zone in geoscience. Various technical, economic, and social challenges were elucidated. The achievements of this facility and thereby ambitious research may provide essential solutions to both energy transition and climate security, and then bolster support for decarbonization of China’s energy sector, finally helping attain its double carbon’ goal. Graphical Abstract

Sthevanie Dhita Sudrazat, Ida Herawati

Batuserpih organik merupakan salah satu reservoar non konvensional yang memiliki heterogenitas dan struktur yang kompleks. Pemodelan fisika batuan pada batu serpih organik penting dilakukan untuk mengetahui karakteristik dari reservoar tersebut. Penelitian ini bertujuan untuk mengetahui pengaruh kerogen dan mineral terhadap properti fisis dan sifat anisotropi dari batuserpih organik. Pemodelan dilakukan dengan menggunakan: teori efektif medium Kuster Toksöz untuk menggabungkan fluida dan solid pada masing-masing matriks, Self-Consistent Approximation (SCA) untuk mengetahui properti fisis dari keseluruhan batuserpih, serta Backus Average untuk menentukan parameter anisotropi dari batuserpih organik. Penelitian ini melakukan perhitungan rasio Vp/Vs, impedansi akustik, dan parameter anisotropi untuk tingkat kematangan immature dengan variasi mineral lempung serta jumlah material organik. Hasil penelitian menunjukkan bahwa rasio Vp/Vs, impedansi akustik dan parameter anisotropi batuserpih sangat sensitif terhadap kandungan material organik dan variasi mineralogi. Kesimpulan dari penelitian ini bahwa peningkatan kandungan material organik menurunkan rasio Vp/Vs dan impedansi akustik batuan, namun meningkatkan sifat anisotropi. Sementara itu, peningkatan kandungan mineral lempung meningkatkan rasio Vp/Vs namun menurunkan impedansi akustik, serta meningkatkan nilai parameter anisotropi.

Maulana Rizki Aditama, Huzaely Latief Sunan, FX Anjar Tri Laksono et al.

The thickness of the liquefable layer can be the factor inducing liquefaction hazard, apart from seismicity. Several studies have been conducted to predict the possibility of the liquefable layer based on the filed sampling. However, a detailed investigation of the subsurface interpretation has not been defined, in particular the thickness estimation of the liquefable layer. This study is carried out in south Cilacap area where potential liquefaction is exists due to the earthquake history data and near surface condition. The aim of this study is to investigate the physical properties and thickness distribution using GGMplus gravity data and resistivity data. This research is conducted by spectrum analysis of gravity model and 2D resistivity model . This study’s main results is by performing the residual gravity anomaly with the associated SRTM/DEM data to define the subsurface physical distribution and structural orientation of the area. Residual gravity anomaly is also separated through the low pass filter in order to have robust interpretation. The residual anomaly indicates that the area has identical structural pattern with geological and SRTM map. The results show a pattern of high gravity index in the northeast area of ​​the study having range of 70 – 115 MGal gravity index, associated with the volcanic breccia, and a low gravity profile with less than 65 in the southwest, associated with the alluvial and water table dominated distribution. The thickness of Alluvial is determined by resistivity model with H1 at a range of 3 meters and H2 at a range of 4 m. This research is included in the potential liquefaction category with the potential for a large earthquake.

Sayedeh Sara Sayedi, Benjamin W Abbott, Brett F Thornton et al.

The continental shelves of the Arctic Ocean and surrounding seas contain large stocks of organic matter (OM) and methane (CH _4 ), representing a potential ecosystem feedback to climate change not included in international climate agreements. We performed a structured expert assessment with 25 permafrost researchers to combine quantitative estimates of the stocks and sensitivity of organic carbon in the subsea permafrost domain (i.e. unglaciated portions of the continental shelves exposed during the last glacial period). Experts estimated that the subsea permafrost domain contains ∼560 gigatons carbon (GtC; 170–740, 90% confidence interval) in OM and 45 GtC (10–110) in CH _4 . Current fluxes of CH _4 and carbon dioxide (CO _2 ) to the water column were estimated at 18 (2–34) and 38 (13–110) megatons C yr ^−1 , respectively. Under Representative Concentration Pathway (RCP) RCP8.5, the subsea permafrost domain could release 43 Gt CO _2 -equivalent (CO _2 e) by 2100 (14–110) and 190 Gt CO _2 e by 2300 (45–590), with ∼30% fewer emissions under RCP2.6. The range of uncertainty demonstrates a serious knowledge gap but provides initial estimates of the magnitude and timing of the subsea permafrost climate feedback.

Jawed Akhtar Ansari, Rashid Umar

The present study has been carried out to assess the factors controlling the hydrogeochemical characteristics and groundwater quality in a part of Unnao district, Uttar Pradesh, India. For this purpose total 68 groundwater samples were collected from pre- and post- monsoon season corresponding to June and November 2013 and analyzed for physico-chemical parameters such as pH, electrical conductivity, total hardness, total dissolved solids and major cations (Ca2+, Mg2+, Na+, K+) and anions (HCO3−, Cl−, SO42−, NO3−, F−). Groundwater of the area is slightly alkaline in nature. Major groundwater facies identified are ‘Ca + Mg-HCO3’ and ‘Na + K-HCO3’ during both sampling seasons. The PHREEQC geochemical modeling program was used to evaluate the saturation state of minerals and its dissolution/precipitation reactions occurring in groundwater. The computed saturation indices demonstrate oversaturated condition with respect to dolomite and calcite and undersaturated condition with gypsum, halite and fluorite. Drinking and agriculture quality of groundwater samples were also assessed. Parameters such as total dissolved solids, Na+, K+, HCO3−, Cl−, SO42−, F− exceed the desirable limits of drinking water standards as prescribed by Bureau of Indian Standards and Word Health Organization in few samples. Agricultural water quality is assessed by using various indices such as sodium adsorption ratio, residual sodium carbonate, and permeability index. Excess value of these indices at some sites restrict its suitability for irrigation purpose. Therefore, groundwater management plan is required to improve the water quality in the area. Keywords: Groundwater, Hydrogeochemical characteristics, Saturation index, Water quality, Unnao, India

J. Fyke, J. T. M. Lenaerts, J. T. M. Lenaerts et al.

Annually averaged precipitation in the form of snow, the dominant term of the Antarctic Ice Sheet surface mass balance, displays large spatial and temporal variability. Here we present an analysis of spatial patterns of regional Antarctic precipitation variability and their impact on integrated Antarctic surface mass balance variability simulated as part of a preindustrial 1800-year global, fully coupled Community Earth System Model simulation. Correlation and composite analyses based on this output allow for a robust exploration of Antarctic precipitation variability. We identify statistically significant relationships between precipitation patterns across Antarctica that are corroborated by climate reanalyses, regional modeling and ice core records. These patterns are driven by variability in large-scale atmospheric moisture transport, which itself is characterized by decadal- to centennial-scale oscillations around the long-term mean. We suggest that this heterogeneity in Antarctic precipitation variability has a dampening effect on overall Antarctic surface mass balance variability, with implications for regulation of Antarctic-sourced sea level variability, detection of an emergent anthropogenic signal in Antarctic mass trends and identification of Antarctic mass loss accelerations.

F. Jørgensen, R. R. Møller, Lars Nebel et al.

I. B. Lambert, P. Wyllie

NIE Yi-miao, NIU Fu-sheng, LIU Shu-xian et al.

Graphite tailing is a secondary resource, and could be be recovered when the mica mineral content in tailing is higher than 10%. Graphite tailings in Heilongjiang Province contain >10% mica minerals that are 500-800 mesh. These minerals are finer than conventional mica minerals making it difficult to identify its mineral species. In order to resolve this problem, X-ray Diffraction (XRD) was used to analysis mineral composition of the graphite tailing, along with chemical analysis, Scanning Electron Microscopy-Energy-Dispersive Spectrometry (SEM-EDS) and Optical Microscopy. XRD analysis shows that mica minerals can be recovered and chemical analysis indicates that these minerals are possibly muscovite or biotite. Morphology studies indicate that mica minerals in graphite tailing and pure sericite minerals are mainly schistic and scaled, whereas pure biotite is mainly schistic. EDS analysis shows that graphite tailing contains 5%-13% SiO2 and 4%-8% Al2O3. Mica mineral in graphite tailing has color similar to that of pure sericite but different from that of pure biotite, indicated by Optical Microscope. It is concluded that the mica mineral in graphite tailing is sericite of muscovite subtype. This research will provide reliable information for the subsequent mineral processing of graphite tailing and identification of sericite with similar fineness.

W. Hobbs

R. Rotberg, Ye Feng

Summer Instruction in Geology, 1875 In order to furnish an opportunity for teachers in natural science and special students in Geology to become acquainted with the methods of practical work in that science, a Summer School of Geology will be established, during the months of July and August, at a camp near Cumberland Gap, in the State of Kentucky. This place has been chosen on account of the eminent advantages it offers for the study of a great section of the American Palæozoic rocks, and of the structure of the Appalachian Mountains, and on account of the co-operation of the Kentucky Geological Survey which is promised in a letter from the Governor of that State to the President of the University. It is also a very healthy region.

E. Antevs

G. Koch, Richard F. Link