Geosciences

2023

Jump to: 2022, 2021

19 pages, 4283 KiB

Open AccessArticle

Fluid Redox Fingerprint of the CaCO₃+Antigorite Dehydration Reaction in Subducted Metacarbonate Sediments

by Andrea Maffeis, Simona Ferrando, James Alexander Denis Connolly, Maria Luce Frezzotti and Daniele Castelli

Geosciences 2023, 13(5), 130; https://doi.org/10.3390/geosciences13050130 - 30 Apr 2023

Cited by 2 | Viewed by 1890

Abstract

Antigorite dehydration is a process able to release, in comparison with other minerals, the highest amount of H₂O from a subducting slab. The released fluid delivers critical elements (e.g., S, Cu, and REE) to the overlying subarc mantle, modifying the mantle [...] Read more.

Antigorite dehydration is a process able to release, in comparison with other minerals, the highest amount of H₂O from a subducting slab. The released fluid delivers critical elements (e.g., S, Cu, and REE) to the overlying subarc mantle, modifying the mantle source of arc magmas and related ore deposits. Whether antigorite breakdown produces oxidising or reducing fluids is debated. Whereas previous studies have investigated antigorite dehydration in serpentinites (i.e., in a (C)AMFS-H₂O system), this contribution is devoted to the CMFS-COHS carbonate system, which is representative of the metacarbonate sediments (or carbonate-dominated ophicarbonate rocks) that sit atop the slab. Thermodynamic modelling is used to investigate the redox effect of the carbonate-buffered antigorite dehydration reactions (i.e., brucite breakdown and antigorite breakdown) on electrolytic fluid geochemistry as a function of P-T-fO₂. The influence of P-T-fO₂ conditions on the solubility of C and S, solute-bound H₂ and O₂, fluid pH, the average valence states of dissolved C and S, and the fluid redox budget indicates that, in metacarbonate sediments, the CaCO₃+antigorite reaction tends to produce reducing fluids. However, the redox state of such fluids is buffered not only by the redox state of the system but also, most importantly, by concomitantly dissolving redox-sensitive minerals (i.e., carbonates, graphite, pyrite, and anhydrite). A qualitative correlation between the redox state of the system and the possible depth of fluid release into the mantle wedge is also derived. Full article

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2022

Jump to: 2023, 2021

26 pages, 5339 KiB

Open AccessArticle

Surface Water and Groundwater Suitability for Irrigation Based on Hydrochemical Analysis in the Lower Mayurakshi River Basin, India

by Susmita Ghosh, Biplab Sarkar, Aznarul Islam, Pravat Kumar Shit, Adolfo Quesada-Román and Harun Al Rasid Gazi

Geosciences 2022, 12(11), 415; https://doi.org/10.3390/geosciences12110415 - 10 Nov 2022

Cited by 9 | Viewed by 2882

Abstract

The present work investigates the hydrochemical properties of the surface and groundwater of the Mayurakshi River Basin (India) for assessing their irrigation suitability with respect to irrigation hazards. The study involves 72 water samples classified as 48 surface water samples (pre-monsoon: 24; post-monsoon: [...] Read more.

The present work investigates the hydrochemical properties of the surface and groundwater of the Mayurakshi River Basin (India) for assessing their irrigation suitability with respect to irrigation hazards. The study involves 72 water samples classified as 48 surface water samples (pre-monsoon: 24; post-monsoon: 24) and 24 groundwater samples (pre-monsoon:12; post-monsoon: 12). Regarding the specific irrigation hazard, percent of sodium and soluble sodium percentage have demonstrated the groundwater vulnerability to sodium while the surface water is observed to be free from this kind of hazard. Similar findings have also been retained for magnesium hazard and the potential salinity hazard. Moreover, regarding the seasonality of the hazards, the post-monsoon season has depicted a higher level of irrigation hazards compared to the pre-monsoon season. The study found that the general evolution of groundwater hydrochemistry and the suitability of water for irrigation are principally governed by carbonate weathering, sand mining, stone crushing, and the development of brick kiln industries. Our methodology can be a good example for similar contexts, especially in developing and tropical countries. Full article

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17 pages, 3798 KiB

Open AccessArticle

Revised Rainfall Threshold in the Indonesian Landslide Early Warning System

by Ragil Andika Yuniawan, Ahmad Rifa’i, Fikri Faris, Andy Subiyantoro, Ratna Satyaningsih, Alidina Nurul Hidayah, Rokhmat Hidayat, Akhyar Mushthofa, Banata Wachid Ridwan, Eka Priangga, Agus Setyo Muntohar, Victor G. Jetten, Cees J. van Westen, Bastian V. den Bout and Samuel J. Sutanto

Geosciences 2022, 12(3), 129; https://doi.org/10.3390/geosciences12030129 - 11 Mar 2022

Cited by 16 | Viewed by 4514

Abstract

Landslides are one of the most disastrous natural hazards that frequently occur in Indonesia. In 2017, Balai Sabo developed an Indonesia Landslide Early Warning System (ILEWS) by utilizing a single rainfall threshold for an entire nation, leading to inaccuracy in landslide predictions. The [...] Read more.

Landslides are one of the most disastrous natural hazards that frequently occur in Indonesia. In 2017, Balai Sabo developed an Indonesia Landslide Early Warning System (ILEWS) by utilizing a single rainfall threshold for an entire nation, leading to inaccuracy in landslide predictions. The study aimed to improve the accuracy of the system by updating the rainfall threshold. We analyzed 420 landslide events in Java with the 1-day and 3-day effective antecedent rainfall for each landslide event. Rainfall data were obtained from the Global Precipitation Measurement (GPM), which is also used in the ILEWS. We propose four methods to derive the thresholds: the first is the existing threshold applied in the Balai Sabo ILEWS, the second and third use the average and minimum values of rainfall that trigger landslides, respectively, and the fourth uses the minimum value of rainfall that induces major landslides. We used receiver operating characteristic (ROC) analysis to evaluate the predictability of the rainfall thresholds. The fourth method showed the best results compared with the others, and this method provided a good prediction of landslide events with a low error value. The chosen threshold was then applied in the Balai Sabo-ILEWS. Full article

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18 pages, 5781 KiB

Open AccessCommunication

OpenForecast: An Assessment of the Operational Run in 2020–2021

by Georgy Ayzel and Dmitriy Abramov

Geosciences 2022, 12(2), 67; https://doi.org/10.3390/geosciences12020067 - 1 Feb 2022

Cited by 2 | Viewed by 2339

Abstract

OpenForecast is the first openly available national-scale operational runoff forecasting system in Russia. Launched in March 2020, it routinely provides 7-day ahead predictions for 834 gauges across the country. Here, we provide an assessment of the OpenForecast performance on the long-term evaluation period [...] Read more.

OpenForecast is the first openly available national-scale operational runoff forecasting system in Russia. Launched in March 2020, it routinely provides 7-day ahead predictions for 834 gauges across the country. Here, we provide an assessment of the OpenForecast performance on the long-term evaluation period from 14 March 2020 to 31 October 2021 (597 days) for 252 gauges for which operational data are available and quality-controlled. Results show that OpenForecast is a robust system based on reliable data and solid computational routines that secures efficient runoff forecasts for a diverse set of gauges. Full article

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31 pages, 11621 KiB

Open AccessArticle

Geochemistry of Sub-Depositional Environments in Estuarine Sediments: Development of an Approach to Predict Palaeo-Environments from Holocene Cores

by Dahiru D. Muhammed, Naboth Simon, James E. P. Utley, Iris T. E. Verhagen, Robert A. Duller, Joshua Griffiths, Luke J. Wooldridge and Richard H. Worden

Geosciences 2022, 12(1), 23; https://doi.org/10.3390/geosciences12010023 - 5 Jan 2022

Cited by 4 | Viewed by 2932

Abstract

In the quest to use modern analogues to understand clay mineral distribution patterns to better predict clay mineral occurrence in ancient and deeply buried sandstones, it has been necessary to define palaeo sub-environments from cores through modern sediment successions. Holocene cores from Ravenglass [...] Read more.

In the quest to use modern analogues to understand clay mineral distribution patterns to better predict clay mineral occurrence in ancient and deeply buried sandstones, it has been necessary to define palaeo sub-environments from cores through modern sediment successions. Holocene cores from Ravenglass in the NW of England, United Kingdom, contained metre-thick successions of massive sand that could not be unequivocally interpreted in terms of palaeo sub-environments using conventional descriptive logging facies analysis. We have therefore explored the use of geochemical data from portable X-ray fluorescence analyses, from whole-sediment samples, to develop a tool to uniquely define the palaeo sub-environment based on geochemical data. This work was carried out through mapping and defining sub-depositional environments in the Ravenglass Estuary and collecting 497 surface samples for analysis. Using R statistical software, we produced a classification tree based on surface geochemical data from Ravenglass that can take compositional data for any sediment sample from the core or the surface and define the sub-depositional environment. The classification tree allowed us to geochemically define ten out of eleven of the sub-depositional environments from the Ravenglass Estuary surface sediments. We applied the classification tree to a core drilled through the Holocene succession at Ravenglass, which allowed us to identify the dominant paleo sub-depositional environments. A texturally featureless (massive) metre-thick succession, that had defied interpretation based on core description, was successfully related to a palaeo sub-depositional environment using the geochemical classification approach. Calibrated geochemical classification models may prove to be widely applicable to the interpretation of sub-depositional environments from other marginal marine environments and even from ancient and deeply buried estuarine sandstones. Full article

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2021

Jump to: 2023, 2022

29 pages, 7410 KiB

Open AccessArticle

Petrology of Mafic Dykes from the Njimom Area (West-Cameroon): A Contribution to the Characterization of Late Paleozoic and Mesozoic Magmatism in the Southern Continental Part of the Cameroon Volcanic Line

by Noël-Aimée Kouamo Keutchafo, Nicole Armelle Wambo Simeni, Brillant Kandzi Nforba, Agathe Arrissa Noucoucouk, Josiane Demlabin Sonmo, Depesquidoux Tchato Tchaptchet, Jean Pierre Tchouankoue and Ciro Cucciniello

Geosciences 2022, 12(1), 12; https://doi.org/10.3390/geosciences12010012 - 28 Dec 2021

Cited by 3 | Viewed by 2440

Abstract

In the western Cameroon, crop out several dyke swarms of Paleozoic–Mesozoic age. These dykes intrude the Precambrian basement in the southern continental part of the Cretaceous Cameroon Volcanic Line. In the Njimom area, two groups of mafic dykes that crosscut the Neoproterozoic basement [...] Read more.

In the western Cameroon, crop out several dyke swarms of Paleozoic–Mesozoic age. These dykes intrude the Precambrian basement in the southern continental part of the Cretaceous Cameroon Volcanic Line. In the Njimom area, two groups of mafic dykes that crosscut the Neoproterozoic basement rocks have been observed. A first group intrudes the mylonites whereas the second group intrudes the granites. The dykes are alkaline basalts and hawaiites. The mineralogical assemblage of both groups of dykes consists of plagioclase, clinopyroxene, altered olivine, and opaque oxides. The dykes that cross-cut the Precambrian mylonitic gneisses show moderate TiO₂ (1.7–2.0 wt.%), low MgO (4.4–7.1 wt.%), and compatible trace element concentrations (e.g., Cr = 70–180 ppm; Ni = 30–110 ppm). The dykes that intrude the granites have TiO₂ contents between 2.3 and 2.5 wt.% and moderate compatible trace element concentrations (e.g., Cr = 260–280 ppm; Ni = 170–230 ppm). MgO varies from 5.9 to 9.2 wt.%. All mafic dykes are enriched in light lanthanide element and show moderate Zr/Nb and high Zr/Y, Nb/Yb, and Ti/V ratios similar to those of average ocean island basalt (OIB)-type magmas. Some dykes that intrude the mylonites show evidence of contamination by continental crust. The composition of the clinopyroxenes of the dykes that intrude the mylonites clearly indicate different and unrelated parental magmas from dykes that intrude the granites. Contents and fractionation of the least and the most incompatible elements suggest low degrees of partial melting (3–5%) of heterogeneous source slightly enriched in incompatible elements in the spinel stability field. The geochemical features of Njimom dykes (in particular the dykes that intrude the granites) are similar to those of Paleozoic and Mesozoic dykes recorded in the southern continental part of the Cameroon Volcanic Line, suggesting multiple reactivations of pre-existing fractures that resulted in the fragmentation of western Gondwana and the opening of the South Atlantic Ocean. Full article

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20 pages, 4352 KiB

Open AccessArticle

Soil Moisture Profiles of Unsaturated Colluvial Slopes Susceptible to Rainfall-Induced Landslides

by Paolo Paronuzzi, Marco Del Fabbro and Alberto Bolla

Geosciences 2022, 12(1), 6; https://doi.org/10.3390/geosciences12010006 - 24 Dec 2021

Cited by 5 | Viewed by 3229

Abstract

In this work, we describe soil moisture profiles related to typical colluvial slopes that were involved in rainfall-induced shallow failures occurring in alpine and pre-alpine areas of the Friuli Venezia Giulia Region (NE Italy). The trend of the volumetric water content (θ [...] Read more.

In this work, we describe soil moisture profiles related to typical colluvial slopes that were involved in rainfall-induced shallow failures occurring in alpine and pre-alpine areas of the Friuli Venezia Giulia Region (NE Italy). The trend of the volumetric water content (θ_w) showed a general increase from the ground surface to the bottom soil layer, with two or three marked moisture peaks. The saturation degree (S) varied from 65–70% (topsoil horizon) to nearly saturated basal colluvium (S = 95–100%). Soil moisture data demonstrates that, for a very humid climate, colluvial covers are often close to the saturation condition for most of the year. The calculated suction profiles indicated that maximum values ranging from 40 to 55 kPa often occur in the slope surficial soil (depth < 0.2–0.5 m). This negative pore-water pressure greatly decreases after a heavy rainfall event because of the infiltration process. Complete saturation of colluvial cover in the alpine and pre-alpine regions generally requires rainfall exceeding 150–200 mm for a 24-h storm duration. This results in a recurrence time of Tr ≅ 5–10 years for critical rainfall episodes involving colluvial slopes in the Friuli Venezia Giulia Region. The case histories analyzed demonstrate the importance of performing a detailed lithostratigraphic analysis of the colluvial deposit in order to properly define the suction measurement points, which there should be more of than the three-point determinations usually reported in the literature (for example, z = 0.5, 1.0 and 1.5 m). Full article

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21 pages, 8448 KiB

Open AccessArticle

The Specific Length of an Underground Tunnel and the Effects of Rock Block Characteristics on the Inflow Rate

by Alireza Shahbazi, Ali Saeidi, Romain Chesnaux and Alain Rouleau

Geosciences 2021, 11(12), 517; https://doi.org/10.3390/geosciences11120517 - 16 Dec 2021

Cited by 3 | Viewed by 2751

Abstract

The specific length of a tunnel (STL) and a new analytical model for calculating the block surface area of the rock mass are introduced. First, a method for determining the appropriate length of a tunnel for a numerical simulation is described. The length [...] Read more.

The specific length of a tunnel (STL) and a new analytical model for calculating the block surface area of the rock mass are introduced. First, a method for determining the appropriate length of a tunnel for a numerical simulation is described. The length is then used to examine the correlation between the inflow rate to the tunnel and the block volume, the block surface area, and the fracture intensity (P₃₂) through analytical and numerical modeling. The results indicate that the length of the tunnel should at least be equal to the least common multiple (LCM) of the apparent spacings of the joint sets at the wall of the tunnel to obtain the more reliable and immediate results for the inflow rate to a tunnel that is excavated in a fractured rock mass. A new analytical model was developed to calculate the block surface area and determine the essential joint set parameters, which include the dip, dip direction, and spacing. The determination of the rock block characteristics through numerical modeling requires considering the intact block for calculations. The results indicated that the inflow rate to the tunnel increased with an increase in fracture intensity and a decrease in block volume and surface area. The STL and the analytical model used for calculating the block surface area are validated through numerical simulations with 3DEC software version 7.0. Full article

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16 pages, 1937 KiB

Open AccessArticle

Effective Continuum Approximations for Permeability in Brown-Coal and Other Large-Scale Fractured Media

by Roger Hu and Stuart D. C. Walsh

Geosciences 2021, 11(12), 511; https://doi.org/10.3390/geosciences11120511 - 14 Dec 2021

Cited by 3 | Viewed by 2304

Abstract

The stability of open-pit brown-coal mines is affected by the manner in which water is transmitted or retained within their slopes. This in turn is a function of the in-situ fracture network at those mines. Fracture networks in real mines exhibit significant degrees [...] Read more.

The stability of open-pit brown-coal mines is affected by the manner in which water is transmitted or retained within their slopes. This in turn is a function of the in-situ fracture network at those mines. Fracture networks in real mines exhibit significant degrees of heterogeneity; encompassing a wide range of apertures, inter-fracture separations, and orientations. While each of these factors plays a role in determining fluid movement, over the scale of a mine it is often impractical to precisely measure, let alone simulate, the behaviour of each fracture. Accordingly, effective continuum models capable of representing the bulk effects of the fracture network are needed to understand the movement of fluid within these slopes. This article presents an analysis of the fracture distribution within the slopes of a brown coal mine and outlines a model to capture the effects on the bulk permeability. A stress-dependent effective-fracture-permeability model is introduced that captures the effects of the fracture apertures, spacing, and orientation. We discuss how this model captures the fracture heterogeneity and the effects of changing stress conditions on fluid flow. The fracture network data and the results from the effective permeability model demonstrate that in many cases slope permeability is dominated by highly permeable but low-probability fractures. These results highlight the need for models capable of capturing the effects of heterogeneity and uncertainty on the slope behaviour. Full article

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12 pages, 3206 KiB

Open AccessArticle

Laboratory Measurements to Image Endobenthos and Bioturbation with a High-Frequency 3D Seismic Lander

by Inken Schulze, Dennis Wilken, Michael L. Zettler, Mayya Gogina, Mischa Schönke and Peter Feldens

Geosciences 2021, 11(12), 508; https://doi.org/10.3390/geosciences11120508 - 10 Dec 2021

Cited by 5 | Viewed by 2709

Abstract

The presented 3D seismic system operates three transducers (130 kHz) from a stationary lander and allows non-destructive imaging of small-scale objects within the top decimeters of silty sediments, covering a surface area of 0.2 m². In laboratory experiments, samples such as [...] Read more.

The presented 3D seismic system operates three transducers (130 kHz) from a stationary lander and allows non-destructive imaging of small-scale objects within the top decimeters of silty sediments, covering a surface area of 0.2 m². In laboratory experiments, samples such as shells, stones, and gummy worms of varied sizes (down to approx. 1 cm diameter) could be located in the 3D seismic cube to a depth of more than 20 cm and differentiated by a reflected amplitude intensity and spatial orientation. In addition, simulated bioturbation structures could be imaged. In a practical application, the system allows to determine the abundance of endobenthos and its dynamic in muddy deposits in-situ and thus identify the intensity of local bioturbation. Full article

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23 pages, 6960 KiB

Open AccessArticle

From Lithological Modelling to Groundwater Modelling: A Case Study in the Tiber River Alluvial Valley

by Cristina Di Salvo, Marco Mancini, Massimiliano Moscatelli, Maurizio Simionato, Gian Paolo Cavinato, Michele Dimasi and Francesco Stigliano

Geosciences 2021, 11(12), 507; https://doi.org/10.3390/geosciences11120507 - 10 Dec 2021

Cited by 1 | Viewed by 3076

Abstract

This study presents the results of a research project financed by the Lazio Regional Government. The research focused on defining an integrated model of recent alluvial deposits in the Tiber River. To achieve this objective, geological boreholes were made to monitor the aquifer [...] Read more.

This study presents the results of a research project financed by the Lazio Regional Government. The research focused on defining an integrated model of recent alluvial deposits in the Tiber River. To achieve this objective, geological boreholes were made to monitor the aquifer and in situ and laboratory tests were carried out. The data obtained were used to detail stratigraphic aspects and improve the comprehension of water circulation beneath the recent alluvial deposits of the Tiber River in the urban area of Rome, between the Ponte Milvio bridge and the Tiber Island. The stratigraphic intervals recognised in the boreholes were parameterised based on their litho-technical characteristics. The new data acquired, and integrated with existing data in the database of Institute of Environmental Geology and Geoengineering of the Italian National Research Council, made it possible to produce a three-dimensional model of the lithologies in the study area. The model of the subsoil, simplified for applied reasons, was described in hydrostratigraphic terms: three different lithotypes were subjected to piezometric levels monitoring. Finally, the research generated a numerical hydrological model in a steady state. In general, this study demonstrates how a numerical hydrogeological model calibrated by piezometric monitoring data can support the construction of a geological model, discarding or confirming certain hypotheses and suggesting other means of reconstructing sedimentary bodies. Full article

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26 pages, 5808 KiB

Open AccessArticle

Garnet Chemical Zoning Based Thermobarometry: Method Evaluation and Applications in the Menderes Massif, Western Turkey

by Thomas M. Etzel and Elizabeth J. Catlos

Geosciences 2021, 11(12), 505; https://doi.org/10.3390/geosciences11120505 - 10 Dec 2021

Cited by 1 | Viewed by 3134

Abstract

The garnet chemical zoning method (GZM) is a reliable thermodynamic approach for forward modeling pressure-temperature (P-T) paths using observed garnet and bulk rock compositions. However, intracrystalline diffusion is known to compromise the integrity of GZM modeled garnet-growth P-T paths. For this reason, extracting [...] Read more.

The garnet chemical zoning method (GZM) is a reliable thermodynamic approach for forward modeling pressure-temperature (P-T) paths using observed garnet and bulk rock compositions. However, intracrystalline diffusion is known to compromise the integrity of GZM modeled garnet-growth P-T paths. For this reason, extracting reliable metamorphic estimates from garnet-bearing schists in the Central Menderes Massif (CMM), western Turkey, has been difficult. To evaluate the impact of diffusion on GZM, we simulate garnet growth and diffusion for an average metapelite using the program Theria_G. Modeled garnet compositions from four simulations are used to estimate P-T conditions and paths by GZM, which are compared against Theria_G specified P-T-t trajectories. Factors influencing results are heating/cooling rate, grain size, and peak T. At a maximum T of 610 °C, both undiffused and diffused garnet compositions returned estimates comparable to prescribed conditions regardless of heating/cooling rate. Diffused profiles from simulations reaching a maximum T of 670 °C also reproduced prescribed P-T paths if tectonism occurred at high heating/cooling rates (50 °C/my). From these insights and additional Theria_G simulation-derived observations for CMM garnets, we deduce that metamorphism in the region exceeded 650 °C and achieved a maximum burial P between 8–10 kbar prior to Cenozoic exhumation. Full article

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21 pages, 25790 KiB

Open AccessArticle

Investigating the Potential Role of Geological Context on Groundwater Quality: A Case Study of the Grenville and St. Lawrence Platform Geological Provinces in Quebec, Canada

by Roxane Tremblay, Julien Walter, Romain Chesnaux and Lamine Boumaiza

Geosciences 2021, 11(12), 503; https://doi.org/10.3390/geosciences11120503 - 9 Dec 2021

Cited by 6 | Viewed by 3270

Abstract

The hydrogeochemical study of the Lanaudière and Eastern Mauricie regions (Canada) demonstrates that trace elements appear to be better tracers of geological influence on groundwater chemistry than major elements. Isotopic ratios and the similar chemical composition of groundwater suggest that the physicochemical parameters [...] Read more.

The hydrogeochemical study of the Lanaudière and Eastern Mauricie regions (Canada) demonstrates that trace elements appear to be better tracers of geological influence on groundwater chemistry than major elements. Isotopic ratios and the similar chemical composition of groundwater suggest that the physicochemical parameters of groundwater have a greater effect on hydrogeochemical mechanisms than the immediate geological environment The results allow us to propose a conceptual model of groundwater geochemical evolution with the aim to guide the protection and sustainable management of regional groundwater resources in the Lanaudière and Eastern Mauricie regions. These regions were selected because of their location at the boundary of the Grenville and St. Lawrence Platform geological provinces, representing two distinct geological contexts (Precambrian crystalline rocks and Paleozoic sedimentary rocks). Regional-scale hydrogeochemical and isotopic groundwater characterization was carried out to identify the role of the differences in regional geology on groundwater quality. Our analyses included major and trace elements, stable isotopes, and multivariate statistics. Similar processes are at the origin of dissolved major chemical elements and suggest that soluble minerals common to both geological provinces control groundwater chemistry. If differences exist, they are due to the hydrogeological conditions of the samples, such as residence time or groundwater entrapment at the time of the postglacial marine incursion of the Champlain Sea, rather than the geological context. Some differences, sometimes significant, were observed for some minor elements (F⁻, Mn²⁺, H₂S), which implies a more comprehensive knowledge of the chemistry of the stratigraphic units within the Lanaudière and Eastern Mauricie aquifers. Full article

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28 pages, 8416 KiB

Open AccessArticle

Assessing Thermal Maturity through a Multi-Proxy Approach: A Case Study from the Permian Faraghan Formation (Zagros Basin, Southwest Iran)

by Amalia Spina, Simonetta Cirilli, Andrea Sorci, Andrea Schito, Geoff Clayton, Sveva Corrado, Paulo Fernandes, Francesca Galasso, Giovanni Montesi, Zelia Pereira, Mehrab Rashidi and Roberto Rettori

Geosciences 2021, 11(12), 484; https://doi.org/10.3390/geosciences11120484 - 23 Nov 2021

Cited by 17 | Viewed by 4261

Abstract

This study focuses on the thermal maturity of Permian deposits from the Zagros Basin, Southwest Iran, employing both optical methods (Thermal Alteration Index, Palynomorph Darkness Index, Vitrinite Reflectance, UV Fluorescence) and geochemical analyses of organic matter (Rock Eval Pyrolysis and MicroRaman spectroscopy) applied [...] Read more.

This study focuses on the thermal maturity of Permian deposits from the Zagros Basin, Southwest Iran, employing both optical methods (Thermal Alteration Index, Palynomorph Darkness Index, Vitrinite Reflectance, UV Fluorescence) and geochemical analyses of organic matter (Rock Eval Pyrolysis and MicroRaman spectroscopy) applied to the Faraghan Formation along two investigated Darreh Yas and Kuh e Faraghan surface sections. Furthermore, an integrated palynofacies and lithofacies analysis was carried out in order to integrate the few studies on the depositional environment. The Faraghan Formation, which is widely distributed in the Zagros area, generally consists of shale intercalated with sandstones and pebble conglomerates in the lower part, followed by a succession of sandstone, siltstone and shaly intercalations and with carbonate levels at the top. The integrated palynofacies and lithofacies data confirm a coastal depositional setting evolving upwards to a shallow marine carbonate environment upwards. Rock Eval Pyrolysis and Vitrinite Reflectance analysis showed that the organic matter from samples of the Darreh Yas and Kuh e Faraghan sections fall in the mature to postmature range with respect to the oil to gas generation window, restricting the thermal maturity range proposed by previous authors. Similar results were obtained with MicroRaman spectroscopy and optical analysis such as Thermal Alteration Index and UV Fluorescence. Palynomorph Darkness Index values were compared with Rock Eval Pyrolysis and vitrinite reflectance values and discussed for the first time in the late stage of oil generation. Full article

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26 pages, 18122 KiB

Open AccessArticle

When Enough Is Really Enough? On the Minimum Number of Landslides to Build Reliable Susceptibility Models

by Giacomo Titti, Cees van Westen, Lisa Borgatti, Alessandro Pasuto and Luigi Lombardo

Geosciences 2021, 11(11), 469; https://doi.org/10.3390/geosciences11110469 - 14 Nov 2021

Cited by 27 | Viewed by 2801

Abstract

Mapping existing landslides is a fundamental prerequisite to build any reliable susceptibility model. From a series of landslide presence/absence conditions and associated landscape characteristics, a binary classifier learns how to distinguish potentially stable and unstable slopes. In data rich areas where landslide inventories [...] Read more.

Mapping existing landslides is a fundamental prerequisite to build any reliable susceptibility model. From a series of landslide presence/absence conditions and associated landscape characteristics, a binary classifier learns how to distinguish potentially stable and unstable slopes. In data rich areas where landslide inventories are available, addressing the collection of these can already be a challenging task. However, in data scarce contexts, where geoscientists do not get access to pre-existing inventories, the only solution is to map landslides from scratch. This operation can be extremely time-consuming if manually performed or prone to type I errors if done automatically. This is even more exacerbated if done over large geographic regions. In this manuscript we examine the issue of mapping requirements for west Tajikistan where no complete landslide inventory is available. The key question is: How many landslides should be required to develop reliable landslide susceptibility models based on statistical modeling? In fact, for such a wide and extremely complex territory, the collection of an inventory that is sufficiently detailed requires a large investment in time and human resources. However, at which point of the mapping procedure, would the resulting susceptibility model produce significantly better results as compared to a model built with less information? We addressed this question by implementing a binomial Generalized Additive Model trained and validated with different landslide proportions and measured the induced variability in the resulting susceptibility model. The results of this study are very site-specific but we proposed a very functional protocol to investigate a problem which is underestimated in the literature. Full article

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24 pages, 7496 KiB

Open AccessArticle

Metamodel-Based Slope Reliability Analysis—Case of Spatially Variable Soils Considering a Rotated Anisotropy

by Tingting Zhang, Xiangfeng Guo, Julien Baroth and Daniel Dias

Geosciences 2021, 11(11), 465; https://doi.org/10.3390/geosciences11110465 - 9 Nov 2021

Cited by 6 | Viewed by 2205

Abstract

A rotation of the anisotropic soil fabric pattern is commonly observed in natural slopes with a tilted stratification. This study investigates the rotated anisotropy effects on slope reliability considering spatially varied soils. Karhunen–Loève expansion is used to generate the random fields of the [...] Read more.

A rotation of the anisotropic soil fabric pattern is commonly observed in natural slopes with a tilted stratification. This study investigates the rotated anisotropy effects on slope reliability considering spatially varied soils. Karhunen–Loève expansion is used to generate the random fields of the soil shear strength properties (i.e., cohesion and friction angle). The presented probabilistic analyses are based on a meta-model combining Sparse Polynomial Chaos Expansion (SPCE) and Global Sensitivity Analysis (GSA). This method allows the number of involved random variables to be reduced and then the computational efficiency to be improved. Two kinds of deterministic models, namely a discretization kinematic approach and a finite element limit analysis, are considered. A variety of valuable results (i.e., failure probability, probability density function, statistical moments of model response, and sensitivity indices of input variables) can be effectively provided. Moreover, the influences of the rotated anisotropy, autocorrelation length, coefficient of variation and cross-correlation between the cohesion and friction angle on the probabilistic analysis results are discussed. The rotation of the anisotropic soil stratification has a significant effect on the slope stability, particularly for the cases with large values of autocorrelation length, coefficient of variation, and cross-correlation coefficient. Full article

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32 pages, 15440 KiB

Open AccessArticle

Evaluation of Nine Operational Models in Forecasting Different Types of Synoptic Dust Events in the Middle East

by Sara Karami, Dimitris G. Kaskaoutis, Saviz Sehat Kashani, Mehdi Rahnama and Alireza Rashki

Geosciences 2021, 11(11), 458; https://doi.org/10.3390/geosciences11110458 - 7 Nov 2021

Cited by 18 | Viewed by 2909

Abstract

This study investigates four types of synoptic dust events in the Middle East region, including cyclonic, pre-frontal, post-frontal and Shamal dust storms. For each of these types, three intense and pervasive dust events are analyzed from a synoptic meteorological and numerical simulation perspective. [...] Read more.

This study investigates four types of synoptic dust events in the Middle East region, including cyclonic, pre-frontal, post-frontal and Shamal dust storms. For each of these types, three intense and pervasive dust events are analyzed from a synoptic meteorological and numerical simulation perspective. The performance of 9 operational dust models in forecasting these dust events in the Middle East is qualitatively and quantitatively evaluated against Terra-MODIS observations and AERONET measurements during the dust events. The comparison of model AOD outputs with Terra-MODIS retrievals reveals that despite the significant discrepancies, all models have a relatively acceptable performance in forecasting the AOD patterns in the Middle East. The models enable to represent the high AODs along the dust plumes, although they underestimate them, especially for cyclonic dust storms. In general, the outputs of the NASA-GEOS and DREAM8-MACC models present greater similarity with the satellite and AERONET observations in most of the cases, also exhibiting the highest correlation coefficient, although it is difficult to introduce a single model as the best for all cases. Model AOD predictions over the AERONET stations showed that DREAM8-MACC exhibited the highest R² of 0.78, followed by NASA_GEOS model (R² = 0.74), which both initially use MODIS data assimilation. Although the outputs of all models correspond to valid time more than 24 h after the initial time, the effect of data assimilation on increasing the accuracy is important. The different dust emission schemes, soil and vegetation mapping, initial and boundary meteorological conditions and spatial resolution between the models, are the main factors influencing the differences in forecasting the dust AODs in the Middle East. Full article

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38 pages, 13596 KiB

Open AccessArticle

Reservoir Quality of Upper Jurassic Corallian Sandstones, Weald Basin, UK

by Dinfa Vincent Barshep and Richard Henry Worden

Geosciences 2021, 11(11), 446; https://doi.org/10.3390/geosciences11110446 - 29 Oct 2021

Cited by 12 | Viewed by 3695

Abstract

The Upper Jurassic, shallow marine Corallian sandstones of the Weald Basin, UK, are significant onshore reservoirs due to their future potential for carbon capture and storage (CCS) and hydrogen storage. These reservoir rocks, buried to no deeper than 1700 m before uplift to [...] Read more.

The Upper Jurassic, shallow marine Corallian sandstones of the Weald Basin, UK, are significant onshore reservoirs due to their future potential for carbon capture and storage (CCS) and hydrogen storage. These reservoir rocks, buried to no deeper than 1700 m before uplift to 850 to 900 m at the present time, also provide an opportunity to study the pivotal role of shallow marine sandstone eodiagenesis. With little evidence of compaction, these rocks show low to moderate porosity for their relatively shallow burial depths. Their porosity ranges from 0.8 to 30% with an average of 12.6% and permeability range from 0.01 to 887 mD with an average of 31 mD. The Corallian sandstones of the Weald Basin are relatively poorly studied; consequently, there is a paucity of data on their reservoir quality which limits any ability to predict porosity and permeability away from wells. This study presents a potential first in the examination of diagenetic controls of reservoir quality of the Corallian sandstones, of the Weald Basin’s Palmers Wood and Bletchingley oil fields, using a combination of core analysis, sedimentary core logs, petrography, wireline analysis, SEM-EDS analysis and geochemical analysis to understand the extent of diagenetic evolution of the sandstones and its effects on reservoir quality. The analyses show a dominant quartz arenite lithology with minor feldspars, bioclasts, Fe-ooids and extra-basinal lithic grains. We conclude that little compactional porosity-loss occurred with cementation being the main process that caused porosity-loss. Early calcite cement, from neomorphism of contemporaneously deposited bioclasts, represents the majority of the early cement, which subsequently prevented mechanical compaction. Calcite cement is also interpreted to have formed during burial from decarboxylation-derived CO₂ during source rock maturation. Other cements include the Fe-clay berthierine, apatite, pyrite, dolomite, siderite, quartz, illite and kaolinite. Reservoir quality in the Corallian sandstones show no significant depositional textural controls; it was reduced by dominant calcite cementation, locally preserved by berthierine grain coats that inhibited quartz cement and enhanced by detrital grain dissolution as well as cement dissolution. Reservoir quality in the Corallian sandstones can therefore be predicted by considering abundance of calcite cement from bioclasts, organically derived CO₂ and Fe-clay coats. Full article

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16 pages, 3876 KiB

Open AccessArticle

Evaluating Spatial Regression-Informed Cokriging of Metals in Soils near Abandoned Mines in Bumpus Cove, Tennessee, USA

by Melissa Magno, Ingrid Luffman and Arpita Nandi

Geosciences 2021, 11(11), 434; https://doi.org/10.3390/geosciences11110434 - 20 Oct 2021

Cited by 3 | Viewed by 2631

Abstract

Inorganic contaminants, including potentially toxic metals (PTMs), originating from un-reclaimed abandoned mine areas may accumulate in soils and present significant distress to environmental and public health. The ability to generate realistic spatial distribution models of such contamination is important for risk assessment and [...] Read more.

Inorganic contaminants, including potentially toxic metals (PTMs), originating from un-reclaimed abandoned mine areas may accumulate in soils and present significant distress to environmental and public health. The ability to generate realistic spatial distribution models of such contamination is important for risk assessment and remedial planning of sites where this has occurred. This study evaluated the prediction accuracy of optimized ordinary kriging compared to spatial regression-informed cokriging for PTMs (Zn, Mn, Cu, Pb, and Cd) in soils near abandoned mines in Bumpus Cove, Tennessee, USA. Cokriging variables and neighborhood sizes were systematically selected from prior statistical analyses based on the association with PTM transport and soil physico-chemical properties (soil texture, moisture content, bulk density, pH, cation exchange capacity (CEC), and total organic carbon (TOC)). A log transform was applied to fit the frequency histograms to a normal distribution. Superior models were chosen based on six diagnostics (ME, RMS, MES, RMSS, ASE, and ASE-RMS), which produced mixed results. Cokriging models were preferred for Mn, Zn, Cu, and Cd, whereas ordinary kriging yielded better model results for Pb. This study determined that the preliminary process of developing spatial regression models, thus enabling the selection of contributing soil properties, can improve the interpolation accuracy of PTMs in abandoned mine sites. Full article

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19 pages, 3699 KiB

Open AccessArticle

Two-Scale Investigation of the Retention Behavior of a Well-Graded Mixed Soil

by Osvaldo Bottiglieri, Francesco Cafaro and Federica Cotecchia

Geosciences 2021, 11(10), 431; https://doi.org/10.3390/geosciences11100431 - 18 Oct 2021

Cited by 1 | Viewed by 1879

Abstract

The hydraulic characterization of mixed compacted soils is helpful for the design of earthworks subjected to drying–wetting cycles. When the mixed soil is well-graded and made of both coarse and fine fractions, its matric suction may also be due to the short-range adsorption [...] Read more.

The hydraulic characterization of mixed compacted soils is helpful for the design of earthworks subjected to drying–wetting cycles. When the mixed soil is well-graded and made of both coarse and fine fractions, its matric suction may also be due to the short-range adsorption phenomena, as for the soil investigated in this research work. A silty–clayey sand was created by a mixing procedure and experimentally investigated at two different scales. Physical modeling of an infiltration process was performed, allowing an inverse numerical analysis to infer the water retention and the hydraulic conductivity functions of the soil, whereas element testing on soil specimens allowed direct determination of the same equations. In the article, problems related to the employed suction measurement techniques have been pointed out and discussed. By this two-scale combined strategy, features of the soil hydraulic behavior, such as the wetting collapse, the shrinkage during drying, and the loop of hysteresis, were also determined. Full article

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21 pages, 6066 KiB

Open AccessArticle

Tidal Flood Risk on Salt Farming: Evaluation of Post Events in the Northern Part of Java Using a Parametric Approach

by Anang Widhi Nirwansyah and Boris Braun

Geosciences 2021, 11(10), 420; https://doi.org/10.3390/geosciences11100420 - 9 Oct 2021

Cited by 4 | Viewed by 2731

Abstract

Tidal flood risk threatens coastal urban areas and their agriculture and aquaculture, including salt farming. There is, therefore, an urgency to map and portray risk to reduce casualties and loss. In the floodplain of Cirebon, West Java, where salt farming dominates the landscape, [...] Read more.

Tidal flood risk threatens coastal urban areas and their agriculture and aquaculture, including salt farming. There is, therefore, an urgency to map and portray risk to reduce casualties and loss. In the floodplain of Cirebon, West Java, where salt farming dominates the landscape, this type of flooding has frequently occurred and disrupted the local economy. Based on two recorded events in 2016 and 2018 as benchmarks, this paper formulates an innovative approach to analyze tidal flood risk in salt farming areas. Our study considers the fundamental concepts of hazard and vulnerability, then uses selective parameters for evaluation in an Analytical Hierarchical Process (AHP)-based Geographic Information System. The analytical process includes weighting criteria judged by experts and uses the resulting values to define the spatial characteristics of each salt parcel. Our high-resolution simulations show that the two flood events in 2016 and 2018 affected almost all salt production areas, particularly in the eastern, middle, and western parts of the Cirebon floodplain, although to very different degrees. The study also uses a physical-based approach to validate these results. The damage estimates show a strong positive correlation for economic loss (r = 0.81, r = 0.84). Finally, the study suggests that our multi-methods approach to assessing tidal flood risk should be considered in disaster mitigation planning and integrated coastal zone management in salt farming areas. Full article

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15 pages, 15849 KiB

Open AccessArticle

Rock Glacier Dynamics by a Thermo-Elastic-Viscoplastic Constitutive Relationship

by Stefano Alberti and Luca Flessati

Geosciences 2021, 11(10), 417; https://doi.org/10.3390/geosciences11100417 - 7 Oct 2021

Viewed by 2539

Abstract

As a result of mountain permafrost creep, rock glaciers are common features in high-altitude periglacial areas. From a practical point of view, beyond their localization and inventorying, both the monitoring and prediction of their evolution due to climate changes are crucial. One of [...] Read more.

As a result of mountain permafrost creep, rock glaciers are common features in high-altitude periglacial areas. From a practical point of view, beyond their localization and inventorying, both the monitoring and prediction of their evolution due to climate changes are crucial. One of the effects of climate change is the thickening of the basal shear zone (the portion of the rock glacier where most deformations are localized), eventually leading to the development of unexpected and unprecedented (in terms of location, magnitude, frequency, and timing) instability phenomena. These phenomena bear consequences for the understanding of landscape evolution, natural hazards, and the safe and sustainable operation of high-mountain infrastructures. Most of the studies about active rock glaciers are focused on the analysis of monitoring data, while just a few studies are focused on modeling their behavior to understand their possible further evolution. The active rock glacier response is characterized by a viscous (rate-dependent) behavior, influenced by seasonal temperature oscillations, and characterized by a seasonal transition from slow to fast. In this work, a new thermo-mechanical model based on the delayed plasticity theory and calibrated on experimental results is proposed. The model is employed to evaluate the influence of geometry and forcing (air temperature) on a real rock glacier (Murtèl-Corvatsch rock glacier) creep behavior. Full article

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19 pages, 4406 KiB

Open AccessArticle

Enhanced Steady-State Solution of the Infinite Moving Line Source Model for the Thermal Design of Grouted Borehole Heat Exchangers with Groundwater Advection

by Adinda Van de Ven, Roland Koenigsdorff and Peter Bayer

Geosciences 2021, 11(10), 410; https://doi.org/10.3390/geosciences11100410 - 29 Sep 2021

Cited by 6 | Viewed by 2630

Abstract

The objective of this study is to assess the suitability of the analytical infinite moving line source (MLS) model in determining the temperature of vertical grouted borehole heat exchangers (BHEs) for steady-state conditions when horizontal groundwater advection is present. Therefore, a numerical model [...] Read more.

The objective of this study is to assess the suitability of the analytical infinite moving line source (MLS) model in determining the temperature of vertical grouted borehole heat exchangers (BHEs) for steady-state conditions when horizontal groundwater advection is present. Therefore, a numerical model of a grouted borehole is used as a virtual reality for further analysis. As a result of the first analysis, it has been discovered that established analytical methods to determine the borehole thermal resistance as a mean value over the borehole radius can also be applied to BHEs with groundwater advection. Furthermore, the deviation between a finite MLS and the infinite MLS is found to be only less than 5% for BHEs of a depth of 30 m or more, and Péclet numbers greater than 0.05. Finally, the accuracy of the temperature change calculated with the infinite MLS model at the radius of the borehole wall compared to the temperature change at a numerically simulated grouted borehole is addressed. A discrepancy of the g-functions resulting in a poor dimensioning of BHEs by the infinite MLS model is revealed, which is ascribed to the impermeable grouting material of the numerical model. A correction function has been developed and applied to the infinite MLS model for steady-state conditions to overcome this discrepancy and to avoid poor dimensioning of BHEs. Full article

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22 pages, 11835 KiB

Open AccessArticle

Tracing δ¹⁸O and δ²H in Source Waters and Recharge Pathways of a Fractured-Basalt and Interbedded-Sediment Aquifer, Columbia River Flood Basalt Province

by David Behrens, Jeff B. Langman, Erin S. Brooks, Jan Boll, Kristopher Waynant, James G. Moberly, Jennifer K. Dodd and John W. Dodd

Geosciences 2021, 11(10), 400; https://doi.org/10.3390/geosciences11100400 - 23 Sep 2021

Cited by 8 | Viewed by 2861

Abstract

The heterogeneity and anisotropy of fractured-rock aquifers, such as those in the Columbia River Basalt Province, present challenges for determining groundwater recharge. The entrance of recharge to the fractured-basalt and interbedded-sediment aquifer in the Palouse region of north-central Idaho is not well understood [...] Read more.

The heterogeneity and anisotropy of fractured-rock aquifers, such as those in the Columbia River Basalt Province, present challenges for determining groundwater recharge. The entrance of recharge to the fractured-basalt and interbedded-sediment aquifer in the Palouse region of north-central Idaho is not well understood because of successive basalt flows that act as restrictive barriers. It was hypothesized that a primary recharge zone exists along the basin’s eastern margin at a mountain-front interface where eroded sediments form a more conductive zone for recharge. Potential source waters and groundwater were analyzed for δ¹⁸O and δ²H to discriminate recharge sources and pathways. Snowpack values ranged from −22 to −12‰ for δ¹⁸O and from −160 to −90‰ for δ²H and produced spring-time snowmelt ranging from −16.5 to −12‰ for δ¹⁸O and from −120 to −90‰ for δ²H. With the transition of snowmelt to spring-time ephemeral creeks, the isotope values compressed to −16 and −14‰ for δ¹⁸O and −110 and −105‰ for δ²H. A greater range of values was present for a perennial creek (−18 to −13.5‰ for δ¹⁸O and −125 to −98‰ for δ²H) and groundwater (−17.5 to −13‰ for δ¹⁸O and −132 to −105‰ for δ²H), which reflect a mixing of seasonal signals and the varying influence of vapor sources and sublimation/evaporation. Inverse modeling and the evaluation of matrix characteristics indicate conductive pathways associated with paleochannels and deeper pathways along the mountain-front interface. Depleted isotope signals indicate quicker infiltration and recharge pathways that were separate from, or had limited mixing with, more evaporated water that infiltrated after greater time/travel at the surface. Full article

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17 pages, 5371 KiB

Open AccessArticle

Rain, Snow and Frozen Soil: Open Questions from a Porescale Perspective with Implications for Geohazards

by Ivo Baselt and Thomas Heinze

Geosciences 2021, 11(9), 375; https://doi.org/10.3390/geosciences11090375 - 6 Sep 2021

Cited by 6 | Viewed by 3434

Abstract

Climate change is already affecting high mountain regions, such as the European Alps. Those regions will be confronted with a significant rise of temperatures above the global average, and more and heavier rain events, also during wintertime. The system response to the coincidence [...] Read more.

Climate change is already affecting high mountain regions, such as the European Alps. Those regions will be confronted with a significant rise of temperatures above the global average, and more and heavier rain events, also during wintertime. The system response to the coincidence of rain, snow, and possibly frozen soil depends on the almost infinite number of possible combinations of thermo-hydraulic states of the involved phases. Landslides, snow avalanches, debris flows, or extensive surface runoff are just a few of the possible hazardous outcomes. With rising temperatures and increased precipitation, those hazardous outcomes are expected to occur even more frequently in the future, requiring a better understanding of those coupled processes for hazard mitigation strategies. The macroscopic phenomena are controlled by porescale processes, such as water freezing and ice grains blocking pores, which are only barely understood. The strong coupling between thermal state and hydraulic parameters, the possible phase change, and material heterogeneity pose great challenges for investigation. This work provides an overview of documented hazard events regarding rain, snow, and possibly frozen soil. The current state in theoretical and experimental research is presented before several knowledge gaps are derived and possible techniques to address those gaps are discussed. Full article

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