Geosciences

14 pages, 9836 KiB

Open AccessArticle

Cenozoic Reactivation of the Penacova-Régua-Verin and Manteigas-Vilariça-Bragança Fault Systems (Iberian Peninsula): Implication in Their Seismogenic Potential

by Sandra González Muñoz and Fidel Martín González

Geosciences 2024, 14(9), 243; https://doi.org/10.3390/geosciences14090243 - 10 Sep 2024

Viewed by 144

Abstract

The Penacova-Régua-Verin (PRV) and the Manteigas-Vilariça-Bragança (MVB) are two of the longest faults of the Iberian Peninsula. These faults striking NNE–SSW, over lengths of >200 km, were developed during late-Variscan Orogeny and reactivated in response to the Alpine Cycle tectonics. Their tectonic evolution [...] Read more.

The Penacova-Régua-Verin (PRV) and the Manteigas-Vilariça-Bragança (MVB) are two of the longest faults of the Iberian Peninsula. These faults striking NNE–SSW, over lengths of >200 km, were developed during late-Variscan Orogeny and reactivated in response to the Alpine Cycle tectonics. Their tectonic evolution during Alpine compression (Cenozoic) and their implication in the active tectonic activity of Iberia are under discussion. Their recent tectonic activity is recorded in the vertical offset of geomorphological surfaces, in the associated pull-apart basins, and in M > 7 paleoseismic events. Based on the vertical surface offset of Pliocene surfaces (140–300 m for the MVB fault and 150–200 m for the PRV), together with the horizontal offset (1300–1600 m for MVBF fault and 600–1400 m for PRVF), we can conclude that they were reactivated as left-lateral strike-slip faults with a reverse component during the Pliocene (3.6 Ma)–present. These results indicate that these faults are not related to the strain transmission during the collision with Eurasia (Eocene–Oligocene). However, they are related to the intraplate strain of the southern collision with the African plate during the Upper Neogene. The estimated slip-rate is 0.2–0.5 mm/a for both faults. These slip-rates evidence important implications for the seismic hazard of this intraplate region. Full article

(This article belongs to the Section Structural Geology and Tectonics)

► Show Figures

Figure 1

17 pages, 15568 KiB

Open AccessArticle

Pleistocene Glacial Transport of Nephrite Jade from British Columbia, Canada, to Coastal Washington State, USA

by George E. Mustoe

Geosciences 2024, 14(9), 242; https://doi.org/10.3390/geosciences14090242 - 9 Sep 2024

Viewed by 238

Abstract

Since prehistoric times, indigenous residents of southwest British Columbia, Canada, collected water-worn nephrite specimens from the gravel bars along the Fraser River, using the stone for the manufacture of tools that were widely traded with other tribes. Allochthonous nephrite occurs in another geologic [...] Read more.

Since prehistoric times, indigenous residents of southwest British Columbia, Canada, collected water-worn nephrite specimens from the gravel bars along the Fraser River, using the stone for the manufacture of tools that were widely traded with other tribes. Allochthonous nephrite occurs in another geologic setting. Late Pleistocene continental glaciers transported nephrite and many other rock types from western Canada to northwest Washington State, producing extensive sediment deposits that border the Salish Sea coast in Whatcom and Island Counties, Washington. This material was little utilized by indigenous residents, but “black jade” specimens are prized by modern collectors. The depositional history and mineralogy of this material has received little attention. X-ray diffraction and SEM/EDS analyses indicate that the Salish Sea “black jade” is a form of impure nephrite that probably originated from metamorphism of a mafic igneous parent material (metabasite). The texture consists of prismatic amphibole crystals (ferro-actinolite) set in a matrix rich in plagioclase feldspar. Pyrite inclusions are locally present. A second material, sometimes erroneously labelled “muttonfat jade” by amateur collectors, consists of an intermixture of quartz and sillimanite. Full article

(This article belongs to the Section Cryosphere)

► Show Figures

Figure 1

19 pages, 7689 KiB

Open AccessArticle

Development of High-Silica Adakitic Intrusions in the Northern Appalachians of New Brunswick (Canada), and Their Correlation with Slab Break-Off: Insights into the Formation of Fertile Cu-Au-Mo Porphyry Systems

by Fazilat Yousefi, David R. Lentz, James A. Walker and Kathleen G. Thorne

Geosciences 2024, 14(9), 241; https://doi.org/10.3390/geosciences14090241 - 7 Sep 2024

Viewed by 430

Abstract

High-silica adakites exhibit specific compositions, as follows: SiO₂ ≥ 56 wt.%, Al₂O₃ ≥ 15 wt.%, Y ≤ 18 ppm, Yb ≤ 1.9 ppm, K₂O/Na₂O ≥ 1, MgO < 3 wt.%, high Sr/Y (≥10), and La/Yb [...] Read more.

High-silica adakites exhibit specific compositions, as follows: SiO₂ ≥ 56 wt.%, Al₂O₃ ≥ 15 wt.%, Y ≤ 18 ppm, Yb ≤ 1.9 ppm, K₂O/Na₂O ≥ 1, MgO < 3 wt.%, high Sr/Y (≥10), and La/Yb (>10). Devonian I-type adakitic granitoids in the northern Appalachians of New Brunswick (NB, Canada) share geochemical signatures of adakites elsewhere, i.e., SiO₂ ≥ 66.46 wt.%, Al₂O₃ > 15.47 wt.%, Y ≤ 22 ppm, Yb ≤ 2 ppm, K₂O/Na₂O > 1, MgO < 3 wt.%, Sr/Y ≥ 33 to 50, and La/Yb > 10. Remarkably, adakitic intrusions in NB, including the Blue Mountain Granodiorite Suite, Nicholas Denys, Sugar Loaf, Squaw Cap, North Dungarvan River, Magaguadavic Granite, Hampstead Granite, Tower Hill, Watson Brook Granodiorite, Rivière-Verte Porphyry, Eagle Lake Granite, Evandale Granodiorite, North Pole Stream Suite, and the McKenzie Gulch porphyry dykes all have associated Cu mineralization, similar to the Middle Devonian Cu porphyry intrusions in Mines Gaspé, Québec. Trace element data support the connection between adakite formation and slab break-off, a mechanism influencing fertility and generation of porphyry Cu systems. These adakitic rocks in NB are oxidized, and are relatively enriched in large ion lithophile elements, like Cs, Rb, Ba, and Pb, and depleted in some high field strength elements, like Y, Nb, Ta, P, and Ti; they also have Sr/Y ≥ 33 to 50, Nb/Y > 0.4, Ta/Yb > 0.3, La/Yb > 10, Ta/Yb > 0.3, Sm/Yb > 2.5, Gd/Yb > 2.0, Nb + Y < 60 ppm, and Ta + Yb < 6 ppm. These geochemical indicators point to failure of a subducting oceanic slab (slab rollback to slab break-off) in the terminal stages of subduction, as the generator of post-collisional granitoid magmatism. The break-off and separation of a dense subducted oceanic plate segment leads to upwelling asthenosphere, heat advection, and selective partial melting of the descending oceanic slab (adakite) and (or) suprasubduction zone lithospheric mantle. The resulting silica-rich adakitic magmas ascend through thickened mantle lithosphere, with minimal affect from the asthenosphere. The critical roles of transpression and transtension are highlighted in facilitating the ascent and emplacement of these fertile adakitic magmas in postsubduction zone settings. Full article

(This article belongs to the Special Issue Zircon U-Pb Geochronology Applied to Tectonics and Ore Deposits)

► Show Figures

Figure 1

24 pages, 7824 KiB

Open AccessArticle

Biogenic Origin of Fe-Mn Crusts from Hydrothermal Fields of the Mid-Atlantic Ridge, Puy de Folles Volcano Region

by Elena S. Sergienko, Elena R. Tarakhovskaya, Oleg V. Rodinkov, Svetlana Yu. Yanson, Dmitrii V. Pankin, Valery S. Kozlov, Kamil G. Gareev, Alexander N. Bugrov and Petr V. Kharitonskii

Geosciences 2024, 14(9), 240; https://doi.org/10.3390/geosciences14090240 - 6 Sep 2024

Viewed by 397

Abstract

Ferromanganese formations are widespread in the Earth’s aquatic environment. Of all the mechanisms of their formation, the biogenic one is the most debatable. Here, we studied the Fe-Mn crusts of hydrothermal fields near the underwater volcano Puy de Folles (rift valley of the [...] Read more.

Ferromanganese formations are widespread in the Earth’s aquatic environment. Of all the mechanisms of their formation, the biogenic one is the most debatable. Here, we studied the Fe-Mn crusts of hydrothermal fields near the underwater volcano Puy de Folles (rift valley of the Mid-Atlantic Ridge). The chemical and mineralogical composition (optical and electron microscopy with EDX, X-ray powder diffraction, X-ray fluorescence analysis, Raman and FTIR spectroscopy, gas chromatography—mass spectrometry (GC-MS)) and the magnetic properties (static and resonance methods, including at cryogenic temperatures) of the samples of Fe-Mn crusts were investigated. In the IR absorption spectra, based on hydrogen bond stretching vibrations, it was concluded that there were compounds with aliphatic (alkane) groups as well as compounds with double bonds (possibly with a benzene ring). The GC-MS analysis showed the presence of alkanes, alkenes, hopanes, and steranes. Magnetically, the material is highly coercive; the blocking temperatures are 3 and 13 K. The main carriers of magnetism are ultrafine particles and X-ray amorphous matter. The analysis of experimental data allows us to conclude that the studied ferromanganese crusts, namely in their ferruginous phase, were formed as a result of induced biomineralization with the participation of iron-oxidizing and iron-reducing bacteria. Full article

(This article belongs to the Special Issue Geochemistry in the Development of Geothermal Resources)

► Show Figures

Figure 1

8 pages, 1793 KiB

Open AccessArticle

The Youngest European Record of the Chelonian Family Trionychidae (Calabrian, Central Italy) Offers New Clues on the Quaternary Extirpation History of the Softshell Turtles

by Alberto Collareta, Simone Casati, Edoardo Terranova, Francesco Nobile, Giulia Bosio, Andrea Di Cencio and Giovanni Coletti

Geosciences 2024, 14(9), 239; https://doi.org/10.3390/geosciences14090239 - 3 Sep 2024

Viewed by 367

Abstract

We report on the geologically youngest occurrence of the softshell turtle family Trionychidae in Europe, from middle Calabrian (Emilian) strata cropping out at Montalto, Pisa Province (Tuscany, central Italy). This record indicates that the softshell turtles survived well past the glacial pulse at [...] Read more.

We report on the geologically youngest occurrence of the softshell turtle family Trionychidae in Europe, from middle Calabrian (Emilian) strata cropping out at Montalto, Pisa Province (Tuscany, central Italy). This record indicates that the softshell turtles survived well past the glacial pulse at ca. 1.8 Ma. That the most recent finds of Trionychidae all over Europe come from mainland Italy further evokes the role of the Apennine peninsula as a refugium for humid-dwelling herpetofaunas through most of the Plio-Pleistocene. Reduced humidity associated with the intensified cool stages at the beginning of the Early–Middle Pleistocene Transition may have been behind the demise of the last European softshell turtles. Full article

(This article belongs to the Section Sedimentology, Stratigraphy and Palaeontology)

► Show Figures

Figure 1

22 pages, 4832 KiB

Open AccessArticle

Cenozoic Carbon Dioxide: The 66 Ma Solution

by Patrick Frank

Geosciences 2024, 14(9), 238; https://doi.org/10.3390/geosciences14090238 - 3 Sep 2024

Viewed by 1372

Abstract

The trend in partial pressure of atmospheric CO₂, P(CO₂), across the 66 MYr of the Cenozoic requires elucidation and explanation. The Null Hypothesis sets sea surface temperature (SST) as the baseline driver for Cenozoic P(CO₂). The crystallization [...] Read more.

The trend in partial pressure of atmospheric CO₂, P(CO₂), across the 66 MYr of the Cenozoic requires elucidation and explanation. The Null Hypothesis sets sea surface temperature (SST) as the baseline driver for Cenozoic P(CO₂). The crystallization and cooling of flood basalt magmas is proposed to have heated the ocean, producing the Paleocene–Eocene Thermal Maximum (PETM). Heat of fusion and heat capacity were used to calculate flood basalt magmatic Joule heating of the ocean. Each 1 million km³ of oceanic flood basaltic magma liberates ~5.4 × 10²⁴ J, able to heat the global ocean by ~0.97 °C. Henry’s Law for CO₂ plus seawater (H_S) was calculated using δ¹⁸O proxy-estimated Cenozoic SSTs. H_S closely parallels Cenozoic SST and predicts the gas solute partition across the sea surface. The fractional change of Henry’s Law constants,

\frac{H_{n} - H_{i}}{H_{n} - H_{0}}

is proportional to ΔP(CO₂)_i, and

\frac{H_{n} - H_{i}}{H_{n} - H_{0}} \times ∆ P (C O_{2}) + P (C O_{2})_{m i n}

, where ΔP(CO₂) = P(CO₂)_max − P(CO₂)_min, closely reconstructs the proxy estimate of Cenozoic P(CO₂) and is most consistent with a 35 °C PETM ocean. Disparities are assigned to carbonate drawdown and organic carbon sedimentation. The Null Hypothesis recovers the glacial/interglacial P(CO₂) over the VOSTOK 420 ka ice core record, including the rise to the Holocene. The success of the Null Hypothesis implies that P(CO₂) has been a molecular spectator of the Cenozoic climate. A generalizing conclusion is that the notion of atmospheric CO₂ as the predominant driver of Cenozoic global surface temperature should be set aside. Full article

(This article belongs to the Section Sedimentology, Stratigraphy and Palaeontology)

► Show Figures

Figure 1

21 pages, 30921 KiB

Open AccessArticle

New Porphyry Copper–Molybdenum Ore Occurrence in Arganaty Granites of the Eastern Balkhash (Kazakhstan): Geology, Geochemistry, and Mineralogy

by Adilkhan Baibatsha, Ilya Vikentyev, Daulet Muratkhanov and Kanat Bulegenov

Geosciences 2024, 14(9), 237; https://doi.org/10.3390/geosciences14090237 - 2 Sep 2024

Viewed by 307

Abstract

In the Balkhash region of Kazakhstan, there are numerous copper and copper–molybdenum deposits, including superlarge Aktogay, Aidarly, Kounrad, and large Sayak deposits. Despite the proximity to these ore districts, the Arganaty district of the Eastern Balkhash region has not attracted significant interest in [...] Read more.

In the Balkhash region of Kazakhstan, there are numerous copper and copper–molybdenum deposits, including superlarge Aktogay, Aidarly, Kounrad, and large Sayak deposits. Despite the proximity to these ore districts, the Arganaty district of the Eastern Balkhash region has not attracted significant interest in terms of exploration for many years. Our recent work has identified previously undetected copper–molybdenum mineralization in the granites of the Arganaty massif and has provided a new perspective on the economic potential of this area. In this study, based on the geology, mineralogy, and geochemistry of the Arganaty granites using data from XRF and ICP-MS methods, we reassessed the geological structure and prospectivity of this area. Our investigations have found that the intrusive rocks of the Arganaty massif belong to I-type granites and were formed in a subduction setting rather than a collision setting, as was previously believed. This also indicates the high prospects of the territory in the context of the possible discovery of large Cu or Cu–Mo deposits. Full article

► Show Figures

Figure 1

24 pages, 13123 KiB

Open AccessArticle

Geological and Structural Framework, Inventory, and Quantitative Assessment of Geodiversity: The Case Study of the Lake Faro and Lake Ganzirri Global Geosites (Italy)

by Roberta Somma, Sebastiano Ettore Spoto and Salvatore Giacobbe

Geosciences 2024, 14(9), 236; https://doi.org/10.3390/geosciences14090236 - 1 Sep 2024

Viewed by 456

Abstract

The geoconservation policies assumed by the Sicilian Region (Italy) induced to classify as geosites all the geodiversity preserved in the Sicilian natural reserves. In particular, two of these geosites present in the oriented natural reserve of the coastal lagoon of Cape Peloro (Messina, [...] Read more.

The geoconservation policies assumed by the Sicilian Region (Italy) induced to classify as geosites all the geodiversity preserved in the Sicilian natural reserves. In particular, two of these geosites present in the oriented natural reserve of the coastal lagoon of Cape Peloro (Messina, NE Sicily, Italy), denoted “Morpho–tectonic system of Cape Peloro–Lake Faro” and “Morpho–tectonic system of Cape Peloro–Lake Ganzirri”, were considered Global areal geosites on the base of their tectonic origin. Lacking an official scientific report of these sites, the present research was aimed to investigate the lagoon, in order to provide the (i) geological and structural framework, (ii) inventory, and (iii) quantitative assessment of geodiversity. The study geosites resulted to be originated during the post–Wurmian sea–level rise and the strong extensional tectonics affecting the Calabria–Peloritani Arc still active. Indeed, the lagoon depression hosting the Lakes Faro and Ganzirri, developed on low-relief coasts because of different systems of capable faults, NW–SE oriented in the Lake Faro and ENE–WSW oriented in the Lake Ganzirri. The quantitative assessment of geodiversity indicated high scores for the scientific value and the potential educational and touristic uses. On the basis of these results, it was possible to confirm the attribution of Lake Faro’s and Lake Ganzirri’s geodiversity to Global areal geosites, being the study morpho-structures key localities, providing indicators of representativeness, geological diversity, and rarity that ought to be protected as clear and unequivocal examples of the Earth’s geological history and evolution of the Quaternary tectonic coastal lagoons. Actual criticisms that could irreversibly affect the environmental equilibria have been evidenced. Possible actions for the redevelopment of the oriented natural reserve of the coastal lagoon of Cape Peloro and the extension of the geosites were also described. Full article

(This article belongs to the Special Issue Editorial Board Members' Collection Series: "Trends and Prospects in Geoheritage, Geoparks, and Geotourism")

► Show Figures

Figure 1

15 pages, 7578 KiB

Open AccessArticle

Virtual Mineralogical Museums and Mineral Websites as Learning Agents: Analysis of How Minerals Are Represented

by Guiomar Calvo and Pedro Lucha

Geosciences 2024, 14(9), 235; https://doi.org/10.3390/geosciences14090235 - 1 Sep 2024

Viewed by 516

Abstract

Virtual mineralogical museums can help visitors construct and enhance their personal scientific mineral models through the information they incorporate. For this to be possible, they must contain a series of key aspects related to minerals’ properties (chemical and physical), use and origin, and [...] Read more.

Virtual mineralogical museums can help visitors construct and enhance their personal scientific mineral models through the information they incorporate. For this to be possible, they must contain a series of key aspects related to minerals’ properties (chemical and physical), use and origin, and the relationships between them. In this study, 38 sites are analyzed, their main characteristics identified, and their educational value assessed, to verify whether all the key aspects considered for the construction of an appropriate and complete mineral model are present. Photographs and mineral files predominate over 3D models and 3D tours. In many of the sites aimed at university students or geoscience experts, there are abundant data about mineral properties, but not in those aimed at a broad public audience. Data about the uses and relationship between uses, extraction, and mineral properties are seldom included. Even if connectivity is very high in all the sites, there are no elements that can be used to test if there has been a knowledge gain after visiting them. The results show that there is still a lot of information missing for this type of resources to be truly helpful for the general population and, specifically, for educational uses. Full article

(This article belongs to the Collection Education in Geosciences)

► Show Figures

Figure 1

18 pages, 9959 KiB

Open AccessArticle

Seismic Response of Pile Foundations in Clayey Soil Deposits Considering Soil Suction Changes Caused by Soil–Atmospheric Interactions

by Ali Shojaeian, Tommy Bounds, Kanthasamy K. Muraleetharan and Gerald Miller

Geosciences 2024, 14(9), 234; https://doi.org/10.3390/geosciences14090234 - 29 Aug 2024

Viewed by 353

Abstract

Extreme variations in weather patterns have become increasingly common across the Southern Great Plains of the United States. The soil layer in the active zone above the groundwater table is often subjected to moisture variations due to seasonal weather changes that will influence [...] Read more.

Extreme variations in weather patterns have become increasingly common across the Southern Great Plains of the United States. The soil layer in the active zone above the groundwater table is often subjected to moisture variations due to seasonal weather changes that will influence the behavior of soils, including their strength and stiffness parameters. Designing a pile foundation in seismic-prone areas without considering the moisture changes in soil interacting with piles may adversely impact the seismic performance of the piles. The main aim of this study is to investigate the role of soil moisture conditions and suction caused by soil–atmospheric interactions on the dynamic behavior of the pile foundations interacting with clayey soils. This study uses a stand-alone finite element computer code called DYPAC (Dynamic Piles Analysis Code) developed using the Beams on Nonlinear Winkler Foundation (BNWF) approach. The influence of soil suction is incorporated into the p-y curves and free-field soil displacements using site response analyses by employing the concept of apparent cohesion. To perform nonlinear site response analyses, DEEPSOIL software V6.1 is utilized. The variation in soil suction with depth along the pile is considered using unsaturated seepage analysis performed by employing the commercial software PLAXIS LE Groundwater for three different clayey soils with plasticity ranging from low to medium to high. The analyses were performed using actual past daily recorded weather data for a testbed that experienced significant back-to-back flash droughts in 2022. This study found that extreme weather events like flash droughts can significantly affect the soil suction and seismic performance of the piles interacting with the unsaturated clayey soils. Full article

(This article belongs to the Special Issue Advances in Thermo-Hydro-Mechanical Characterization and Modelling of Unsaturated Soils)

► Show Figures

Figure 1

19 pages, 5887 KiB

Open AccessArticle

Evaluating the Effectiveness of Seepage Countermeasures and Retrofitting Strategies for Mitigating Nappe Flow-Induced Reverse Flow and Erosion for Overtopping Flow from a Levee

by Liaqat Ali, Kento Sekine and Norio Tanaka

Geosciences 2024, 14(9), 233; https://doi.org/10.3390/geosciences14090233 - 29 Aug 2024

Viewed by 319

Abstract

Levee failure due to nappe flow and subsequent erosion presents a significant challenge to flood protection infrastructure. This study evaluates the effectiveness of horizontal drainage layers, a common seepage control method, in mitigating these risks. While many traditional solutions to mitigate overtopping are [...] Read more.

Levee failure due to nappe flow and subsequent erosion presents a significant challenge to flood protection infrastructure. This study evaluates the effectiveness of horizontal drainage layers, a common seepage control method, in mitigating these risks. While many traditional solutions to mitigate overtopping are costly and complex, horizontal drainage layers offer a promising and cost-effective alternative. These layers not only address seepage control but also manage nappe flow-induced erosion, potentially reducing construction and maintenance costs. Despite extensive research on their role in seepage control, a gap remains in understanding their effectiveness against overtopping-induced erosion, particularly in managing reverse flow. Existing studies often address seepage control or nappe flow erosion separately, overlooking the integrated impact of these layers. This study aims to address this gap by evaluating the performance of horizontal drainage layers under simulated overtopping conditions. The research involves two series of experiments, Series I: Focuses on newly built levees equipped with full (HD15L50 and HD25L50, where the thicknesses are 15 and 25 cm, respectively, with a horizontal drainage layer length of 50 cm and a crest length of 40 cm), partial length (HD15L40 and HD25L40), and short/reduced length (HD15L30 and HD25L30). The results showed that full-length layers reduce erosion inside the levee body and foundation by almost 100% and enhance levee stability due to their superior ability to dissipate hydraulic energy. Series II: Investigates practical solutions for retrofitting existing levees using shorter drainage layers with extended crests and gauzed sheets (HD15L15L30C60GH and HD25L30C60GH, where the thicknesses are 15 and 25 cm, the drainage length is 30 cm, and the crest is extended to 60 cm with gauzed sheets). Although shorter layers were less effective than full-length ones, extending the levee crest significantly improved their performance, achieving protection levels comparable to full-length layers, providing a valuable solution for upgrading existing levees. Overall, this study offers valuable insights by systematically evaluating and optimizing seepage control techniques. These findings can be directly applied to guide levee design, maintenance, and risk reduction strategies. This research contributes significantly to improving the resilience of levee systems against water pressure and ensuring their long-term stability. Full article

► Show Figures

Figure 1

20 pages, 7597 KiB

Open AccessArticle

Steady-State Shear Rheology of Aqueous Noncolloidal Carbonate Suspensions

by William Apau Marfo, Kristofer Gunnar Paso and Maarten Felix

Geosciences 2024, 14(9), 232; https://doi.org/10.3390/geosciences14090232 - 29 Aug 2024

Viewed by 448

Abstract

Carbonate muds are essential sedimentary components in geological carbon cycles. Model carbonate muds are prepared from crushed, sieved carbonate rock. The carbonate rock particles are primarily smaller than 62.5 µm. Steady-state shear viscosity was measured for model carbonate muds prepared from three types [...] Read more.

Carbonate muds are essential sedimentary components in geological carbon cycles. Model carbonate muds are prepared from crushed, sieved carbonate rock. The carbonate rock particles are primarily smaller than 62.5 µm. Steady-state shear viscosity was measured for model carbonate muds prepared from three types of carbonate rock: limestone Grey, limestone Marl, and limestone Castleton. Model carbonate muds were prepared using fresh water or 3.5 g/L NaCl solution. The carbonate particle concentrations were 1.81 volume percent and 26.95 volume percent, representing semi-dilute and concentrated particle regimes, respectively. Carbonate mud viscosity was measured at temperatures ranging from 8 °C to 35 °C. Shear rates ranged from 60 s⁻¹ to 2500 s⁻¹. Pseudoplasticity occurs at low shear rates and is caused by the release of occluded water during shear-driven breakup and dispersal of particle aggregates. Shear thickening occurs at high shear rates and is caused by transient particle clusters, called hydroclusters, that are reinforced by lubrication forces or frictional particle contacts. Carbonate mud viscosity decreases at increasing temperatures. The presence of 3.5 g/L NaCl in the aqueous phase slightly increased the mud viscosity in the semi-dilute particle concentration regime because of a weak viscosifying effect of NaCl on the aqueous phase. In the concentrated particle regime, electrolytes screened electroviscous effects, reducing the viscosity of muds containing particles with electrically charged surfaces. In aqueous solution, limestone Marl had a comparatively high concentration of charged particles on its surface. Limestone Castleton had a comparatively low concentration of charged particles on its surface. Surface charges were not rheologically evident on limestone Grey. Full article

(This article belongs to the Section Sedimentology, Stratigraphy and Palaeontology)

► Show Figures

Figure 1

20 pages, 3235 KiB

Open AccessArticle

Assessment of Groundwater Age in the Upper Chao Phraya River Basin Using Tritium and Carbon-14 Isotope Analysis

by Jeerapong Laonamsai, Kiattipong Kamdee, Monthon Youngprawat, Chalermpong Polee, Chakrit Saengkorakot, Patchareeya Chanruang, Nichtima Uapoonphol, Peerapat Charoonchat and Phongthorn Julphunthong

Geosciences 2024, 14(9), 231; https://doi.org/10.3390/geosciences14090231 - 28 Aug 2024

Viewed by 599

Abstract

Groundwater is a critical resource in the Upper Chao Phraya basin, providing consistent water supplies for agricultural, domestic, and industrial activities, especially during the dry season. This study utilized tritium and carbon-14 dating techniques to investigate groundwater age, analyzing 273 samples collected in [...] Read more.

Groundwater is a critical resource in the Upper Chao Phraya basin, providing consistent water supplies for agricultural, domestic, and industrial activities, especially during the dry season. This study utilized tritium and carbon-14 dating techniques to investigate groundwater age, analyzing 273 samples collected in 2021 from various wells and depths across the basin. Tritium and carbon-14 were measured using liquid scintillation counting (LSC). The results revealed a wide range of groundwater ages, including recently recharged water with tritium concentrations up to 2.4 TU, corresponding to groundwater ages ranging from a few months to 44.17 years BP (Before Present), with an average of 18.26 years BP. Older groundwater was identified with carbon-14 concentrations as low as 3.22 pMC, indicating ages of up to 22,899 years, with a mean age of 6687 years BP. Correlation analysis showed a positive relationship between tritium and carbon-14 concentrations (r = 0.52). Spatial distribution patterns indicated that tritium concentrations were higher in northern and mountainous areas, identifying these as critical recharge zones. In contrast, lower carbon-14 concentrations in the central and southern areas suggested the presence of older groundwater, emphasizing the need for careful management of these ancient water reserves. The spatial variation in tritium and carbon-14 concentrations highlights differences in groundwater circulation and recharge patterns, enabling the identification of key recharge zones in the northern and highland regions. This highlights the importance of conserving these areas from pollution and over-extraction. The presence of old groundwater in the central and southern areas further emphasizes the need for ongoing monitoring to sustainably manage these long-term water resources. This study enhances the understanding of groundwater dynamics in the Upper Chao Phraya basin and provides valuable insights for improving water resource management strategies. Full article

► Show Figures

Figure 1

15 pages, 12548 KiB

Open AccessArticle

The Implications of Seeping Hydrocarbon Gases in the Gunsan Basin, Central Yellow Sea, off the Southwest of Korea

by Jin-Hyung Cho, Seung-Yong Lee, Seok Jang, Nam-Do Jang, Cheol-Ku Lee, Seung-Hun Lee, Byung-Cheol Kum, Bo-Ram Lee and Seom-Kyu Jung

Geosciences 2024, 14(9), 230; https://doi.org/10.3390/geosciences14090230 - 27 Aug 2024

Viewed by 539

Abstract

A detailed analysis of high-resolution (3.5 kHz) chirp seismic profiles acquired in the Gunsan Basin of the central Yellow Sea revealed that hydrocarbon gases are actively seeping via the formation of many plumes. The uppermost sedimentary layer was acoustically confirmed to be fully [...] Read more.

A detailed analysis of high-resolution (3.5 kHz) chirp seismic profiles acquired in the Gunsan Basin of the central Yellow Sea revealed that hydrocarbon gases are actively seeping via the formation of many plumes. The uppermost sedimentary layer was acoustically confirmed to be fully or partially charged with gases. Somewhat favored by the low-tide period, episodic gas seepage is mainly associated with the underlying fault systems of Cretaceous-Cenozoic sedimentary strata in the southwestern part of the basin. Catastrophic gas expulsion seems to have formed a crater at the sidewall of a sedimentary ridge and two diapirs. Here, methane is poorly concentrated but rich in the heavy carbon isotope (δ¹³C, −52.6‰ to −44.7‰ The Vienna Peedee Belemnite [VPDB]), indicating that methane formed mainly through biodegradation of heavy oils at depth remains in the shallow sediments following its expulsion. Episodic rapid upward advection of porewater is also manifest by unmixed heavy methane trapped in the upper part of the primary biogenic methane (δ¹³C, about −90‰ VPDB)-filled sediment core. These findings imply that the Gunsan Basin fulfills the requirements for possible generation and preservation of oil and gas, like the petroliferous basins of eastern China and the Yellow Sea. Full article

(This article belongs to the Section Geochemistry)

► Show Figures

Figure 1

27 pages, 6676 KiB

Open AccessArticle

Thermal State and Thickness of the Lithospheric Mantle Beneath the Northern East-European Platform: Evidence from Clinopyroxene Xenocrysts in Kimberlite Pipes from the Arkhangelsk Region (NW Russia) and Its Applications in Diamond Exploration

by Elena Agasheva, Alyona Gudimova, Elena Malygina, Alexey Agashev, Alexey Ragozin, Elena Murav’eva and Anna Dymshits

Geosciences 2024, 14(9), 229; https://doi.org/10.3390/geosciences14090229 - 26 Aug 2024

Viewed by 366

Abstract

This paper presents the reconstruction of the architecture of the lithospheric mantle, including its thermal state and thickness, as well as the scale and efficiency of its sampling by four kimberlites from the Arkhangelsk diamondiferous province: Arkhangelskaya, Lomonosovskaya, V. Grib, and TSNIGRI-Arkhangelskaya. These [...] Read more.

This paper presents the reconstruction of the architecture of the lithospheric mantle, including its thermal state and thickness, as well as the scale and efficiency of its sampling by four kimberlites from the Arkhangelsk diamondiferous province: Arkhangelskaya, Lomonosovskaya, V. Grib, and TSNIGRI-Arkhangelskaya. These kimberlites differ in terms of their composition, diamond content, and location. Data presented include the major-element composition of clinopyroxene xenocrysts (>2000 grains), P–T calculations from compositionally filtered Cr-diopside grains, and the reconstruction of local paleogeotherms. Additionally, we used available data on Ni content in peridotitic garnet xenocrysts to calculate their T values and project them onto local Cr-diopside-derived geotherms to reconstruct the vertical distribution of mantle xenocrysts and assess the efficiency of lithospheric mantle sampling by different kimberlites. We identified the presence of a >200 km-thick lithospheric mantle beneath the region at the time of kimberlite emplacement. We also found that the diamond content of the studied pipes was, to some extent, dependent on the following set of factors: (1) the thermal state of the lithospheric mantle; (2) the width of the real “diamond window” marked by mantle xenocrysts, especially by diamond-associated garnets; and (3) the efficiency of lithospheric mantle sampling by kimberlite. The results of this study can be used to inform diamond exploration programs within the region. Full article

(This article belongs to the Section Geochemistry)

► Show Figures

Figure 1

17 pages, 18820 KiB

Open AccessArticle

A Multidisciplinary Geophysical Approach to Characterize a Fracture Zone: The Southern Limit of the Mining District of Linares-La Carolina, Spain

by Javier Rey, Rosendo Mendoza, José Vilchez, M. Carmen Hidalgo, Isla Fernández and Sara Berman

Geosciences 2024, 14(9), 228; https://doi.org/10.3390/geosciences14090228 - 25 Aug 2024

Viewed by 401

Abstract

In many cases, the lateral extension of economically valuable mineral deposits is linked to fractures. Knowing the characteristics of these tectonic structures is crucial for determining the continuity of mineralization in the subsoil and, consequently, for planning their exploitation. To address this challenge, [...] Read more.

In many cases, the lateral extension of economically valuable mineral deposits is linked to fractures. Knowing the characteristics of these tectonic structures is crucial for determining the continuity of mineralization in the subsoil and, consequently, for planning their exploitation. To address this challenge, a multidisciplinary study was carried out using various geophysical techniques and direct field observations to analyze the effectiveness of each technique in the investigation of fractures. For this purpose, the mining district of Linares-La Carolina in southeastern Spain, known for hosting Philonian deposits of galena (PbS), was chosen. At the southern boundary of this mining district, the seams stopped being exploited when they lost their continuity due to the presence of a regional normal fault. This fault zone was responsible for hiding the seams under a thick sedimentary cover. Detailed geological mapping allowed us to deduce the presence of two fracture systems. The geophysical techniques of electrical resistivity tomography and the time domain electromagnetic method were used, allowing us to identify the positions and the vertical displacement of these faults. Furthermore, using magnetometry, the presence of a third system of fractures was deduced. The results showed that this multidisciplinary analysis provides information of interest concerning the complex structure that configures the limits of this mining district. Full article

(This article belongs to the Section Geophysics)

► Show Figures

Figure 1

18 pages, 5530 KiB

Open AccessArticle

Stress-Based Model for Interpreting Shear Wave Velocity from Seismic Cone Penetration Tests in Unsaturated Soil

by Tareq Abuawad, Gerald A. Miller and Kanthasamy K. Muraleetharan

Geosciences 2024, 14(9), 227; https://doi.org/10.3390/geosciences14090227 - 24 Aug 2024

Viewed by 315

Abstract

Shear wave velocity is an important parameter for estimating soil properties used in analyzing the dynamic response of soil to seismic loading. This paper focuses on developing a model for predicting shear wave velocity in unsaturated soils. The model was developed primarily for [...] Read more.

Shear wave velocity is an important parameter for estimating soil properties used in analyzing the dynamic response of soil to seismic loading. This paper focuses on developing a model for predicting shear wave velocity in unsaturated soils. The model was developed primarily for the interpretation of seismic cone penetration tests (SCPTs) in unsaturated soil to account for seasonal variations in moisture conditions. In practice, SCPTs typically occur over a period of days without the option of choosing a wet or dry period. The question becomes, if tests are conducted during a dry period, how can shear wave velocity corresponding to a wetter period be predicted, or vice versa? Answering this question was the primary motivation of this work. The work involved field testing with the seismic cone penetrometer during wet and dry periods and a focused study at three sites involving comparison between field and laboratory testing for shear wave velocity. The model presented in this paper is built upon the significant work of many other researchers with reference to new experimental data obtained by the authors. It is demonstrated that a stress-based model incorporating matric suction can provide reasonable predictions of shear wave velocity and provides a method to interpret the impact of changing moisture content on shear wave velocities determined with SCPTs. Full article

(This article belongs to the Special Issue Advances in Thermo-Hydro-Mechanical Characterization and Modelling of Unsaturated Soils)

► Show Figures

Figure 1

16 pages, 4734 KiB

Open AccessTechnical Note

Experimental Analysis of Rock Boulder Impacts on Brick Walls to Support Numerical Modelling of Building Damage

by Olga Mavrouli, Xuanmei Fan, Zhou Li, Dongpo Wang and Qiang Xu

Geosciences 2024, 14(9), 226; https://doi.org/10.3390/geosciences14090226 - 23 Aug 2024

Viewed by 358

Abstract

To estimate the expected damage due to rockfalls and debris flows for buildings and people, it is essential to assess the response of brick walls to boulder impacts. There are scarce physical tests of the impact of boulders on brick walls, which are [...] Read more.

To estimate the expected damage due to rockfalls and debris flows for buildings and people, it is essential to assess the response of brick walls to boulder impacts. There are scarce physical tests of the impact of boulders on brick walls, which are typical of residential buildings. A simple and low-cost experimental setup for investigating the damage of unreinforced brick walls that are subjected to a boulder’s impact is presented. The setup consists of a ramp that is adjusted with a light steel structure. Seven pilot tests for five single-leaf brick walls of a 1000 × 1000 mm² area, hit by a 72.925 kg granite boulder, and from five release heights (0.25 m, 0.50, 1.00 m, 2.50 m, and 3.00 m) are performed. The observed damage indicates that wall breakthrough occurs for translational kinetic energies as low as 500 J. The prevalent failure mechanism is local shear damage. Additionally, a numerical model to simulate the physical tests was developed using the FEM. Using the same properties as in the physical testing, the numerical model is found to realistically reproduce the displacement of a node at the centre of the impact, as well as the translational impact velocity and energy, for the same five boulder release heights. Full article

(This article belongs to the Section Natural Hazards)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Geosciences, Volume 14, Issue 9 (September 2024) – 18 articles

Further Information

Guidelines

MDPI Initiatives

Follow MDPI