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19 pages, 12075 KiB  
Article
Integrating Gravimetry and Spatial Analysis for Structural and Hydrogeological Characterization of the Northeast Tadla Plain Aquifer Complex, Morocco
by Salahddine Didi, Said El Boute, Soufiane Hajaj, Abdessamad Hilali, Amroumoussa Benmoussa, Said Bouhachm, Salah Lamine, Abdessamad Najine, Amina Wafik and Halima Soussi
Geographies 2025, 5(3), 35; https://doi.org/10.3390/geographies5030035 - 16 Jul 2025
Viewed by 345
Abstract
This study was conducted in the northeast of the Tadla plain, within the Beni Mellal-Khenifra region of Morocco. The primary objective is to elucidate the geometric and hydrogeological characteristics of this aquifer by analyzing and interpreting data from deep boreholes as well as [...] Read more.
This study was conducted in the northeast of the Tadla plain, within the Beni Mellal-Khenifra region of Morocco. The primary objective is to elucidate the geometric and hydrogeological characteristics of this aquifer by analyzing and interpreting data from deep boreholes as well as gravimetric and electrical measurements using GIS analysis. First, the regional gradient was established. Then, the initial data were extracted. Subsequently, based on the extracted data, a gravity map was created. The investigation of the Bouguer anomaly’s gravity map exposes the presence of a regional gradient, with values varying from −100 mGal in the South to −30 mGal in the North of the area. These Bouguer anomalies often correlate with exposed basement rock areas and variations in the thickness of sedimentary layers across the study area. The analysis of existing electrical survey and deep drilling data confirms the results of the gravimetry survey after applying different techniques such as horizontal gradient and upward extension on the gravimetric map. The findings enabled us to create a structural map highlighting the fault systems responsible for shaping the study area’s structure. The elaborated structural map serves as an indispensable geotectonic reference, facilitating the delineation of subsurface heterogeneities and providing a robust foundation for further hydrogeological assessments in the Tadla Plain. Full article
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19 pages, 3874 KiB  
Article
The Formation Age and Geological Setting of the Huoqiu Group in the Southern Margin of North China Craton: Implication for BIF-Type Iron Prospecting Potentiality
by Lizhi Xue, Rongzhen Tang, Xinkai Chen, Jiashuo Cao and Yanjing Chen
Minerals 2025, 15(7), 695; https://doi.org/10.3390/min15070695 - 29 Jun 2025
Viewed by 318
Abstract
The Huoqiu Group is located in the southern margin of the North China Craton and is considered an Archean geologic body. Its supracrustal rocks are divided into the Huayuan, Wuji, and Zhouji formations in ascending order. The Wuji and Zhouji formations contain large [...] Read more.
The Huoqiu Group is located in the southern margin of the North China Craton and is considered an Archean geologic body. Its supracrustal rocks are divided into the Huayuan, Wuji, and Zhouji formations in ascending order. The Wuji and Zhouji formations contain large BIF-type iron deposits. The BIFs show geological and geochemical features of Paleoproterozoic Lake Superior-type rather than Archean Algoma-type. The study of the formation ages and evolutionary history of the Huoqiu Terrane will provide significant guidance for the mineralization and exploration of the Huoqiu iron deposits. In this paper, we collected all available isotopic ages and Hf isotopic compositions obtained from the Huoqiu Terrane and reassessed their accuracy and geological meanings. We conclude that the Wuji and Zhouji formations were not older than 2343 Ma. Therefore, the BIFs hosted in the Wuji and Zhouji formations must be of Paleoproterozoic age. The magmatic zircons from the TTG gneisses and granite yield U-Pb ages of Neoarchean Era, indicating that the Wuji and Zhouji formations of the Huoqiu Group were deposited on an Archean granitic basement that mainly comprises the trondhjemite-tonalite-granodiorite (TTG) gneisses and granites of the “Huayuan Formation”. The Early Precambrian crystalline basement in the Huoqiu area can be divided into the Huayuan Gneiss Complex and the Huoqiu Group, comprising the Wuji and Zhouji formations. The tectonic scenario of granitic complexes overlain by supracrustal rocks in the Huoqiu Terrane has been recognized in the Songshan, Zhongtiao, Xiaoshan, and Lushan Early Precambrian terranes in the southern margin of the North China Craton. As indicated by the zircon U-Pb ages and εHf(t) data, the crustal growth of the Huoqiu Terrane occurred mainly at ~2.9 Ga and ~2.7 Ga. Based on the sedimentary age, environment, and rhythm, the BIFs in the Huoqiu region are considered to be of Lake Superior type and of great potential for Fe ore exploration. Full article
(This article belongs to the Section Mineral Geochemistry and Geochronology)
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31 pages, 34129 KiB  
Article
Prediction of Buried Cobalt-Bearing Arsenides Using Ionic Leach Geochemistry in the Bou Azzer-El Graara Inlier (Central Anti-Atlas, Morocco): Implications for Mineral Exploration
by Yassine Lmahfoudi, Houssa Ouali, Said Ilmen, Zaineb Hajjar, Ali El-Masoudy, Russell Birrell, Laurent Sapor, Mohamed Zouhair and Lhou Maacha
Minerals 2025, 15(7), 676; https://doi.org/10.3390/min15070676 - 24 Jun 2025
Viewed by 739
Abstract
The Aghbar-Bou Azzer East mining district (ABED) is located between the Bou Azzer East and Aghbar deposits. It is an area of approximately 7 km long towards ENE–WSW and 2 km wide towards N–S. In this barren area, volcano-sedimentary rocks are attributed to [...] Read more.
The Aghbar-Bou Azzer East mining district (ABED) is located between the Bou Azzer East and Aghbar deposits. It is an area of approximately 7 km long towards ENE–WSW and 2 km wide towards N–S. In this barren area, volcano-sedimentary rocks are attributed to the Ouarzazate group outcrop (Ediacarian age): they are composed of volcanic rocks (ignimbrite, andesite, rhyolite, dacite, etc.) covered by the Adoudou detritic formation in angular unconformity. Given the absence of serpentinite outcrops, exploration investigation in this area has been very limited. This paper aims to use ionic leach geochemistry (on samples of soil) to detect the presence of Co-bearing arsenides above hidden ore deposits in this unexplored area of the Bou Azzer inlier. In addition, a detailed structural analysis allowed the identification of four families of faults and fractures with or without filling. Three directional major fault systems of several kilometers in length and variable orientation in both the Cryogenian basement and the Ediacaran cover have been identified: (i) ENE–WSW, (ii) NE–SW, and (iii) NW–SE. Several geochemical anomalies for Co, As, Ni, Ag, and Cu are aligned along three main directions, including NE–SW, NW–SE, and ENE–WSW. They are particularly well-defined in the western zone but are only minor in the central and eastern zones. Some of these anomalies correlate with the primary structural features observed in the studied area. These trends are consistent with those known under mining exploitation in nearby ore deposits, supporting the potential for similar mineralization in the ABED. Based on structural analysis and ionic leach geochemistry, drilling programs were conducted in the study area, confirming the continuity of serpentinites at depth beneath the Ediacaran cover and the presence of Co–Fe-bearing arsenide ores. This validates the ionic geochemistry technique as a reliable method for exploring buried ore deposits. Full article
(This article belongs to the Special Issue Novel Methods and Applications for Mineral Exploration, Volume III)
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23 pages, 15341 KiB  
Article
Petrogenesis of Middle Jurassic Syenite-Granite Suites and Early Cretaceous Granites with Associated Enclaves in Southwestern Zhejiang, SE China: Implications for Subduction-Related Tectonic Evolution Beneath Northeastern Cathaysia Block
by Yu Wang, Haoyuan Lan, Chong Jin and Yuhuang Zhang
Minerals 2025, 15(5), 474; https://doi.org/10.3390/min15050474 - 30 Apr 2025
Viewed by 465
Abstract
Late Mesozoic magmatism in Southeast China extensively reworked the Cathaysia Block’s crust, linked to the Paleo-Pacific Plate subduction beneath East Asia. The northeastern Cathaysia Block, largely covered by Cretaceous volcanic-sedimentary basins, has limited Jurassic exposure to Early Cretaceous intrusions, which provides critical insights [...] Read more.
Late Mesozoic magmatism in Southeast China extensively reworked the Cathaysia Block’s crust, linked to the Paleo-Pacific Plate subduction beneath East Asia. The northeastern Cathaysia Block, largely covered by Cretaceous volcanic-sedimentary basins, has limited Jurassic exposure to Early Cretaceous intrusions, which provides critical insights into deep crust-mantle processes. In this study, we present zircon U-Pb geochronology and Hf isotope, whole-rock geochemistry, and Sr-Nd isotopes of the Middle Jurassic syenite-granite suites and Early Cretaceous granites with enclaves in the Qingyuan area (SW Zhejiang Province) to constrain their petrogenesis and tectonic significance. Middle Jurassic syenites and alkali-feldspar granites (169–167 Ma) exhibit calc-alkaline to shoshonitic affinities and weakly peraluminous compositions. Early Cretaceous granites (134 Ma) and their enclaves (136 Ma) are high-K calc-alkaline and weakly peraluminous to metaluminous. All samples show LILE and LREE enrichment, HFSE depletion, and negative Eu and Sr anomalies, with only syenites displaying negative Ce anomalies. We suggest that the Middle Jurassic syenites originated from the partial melting of an enriched lithospheric mantle influenced by subduction-related metasomatism. Alkali-feldspar granites derived from partial melting of the basement of the Cathaysia Block. Early Cretaceous granites formed by partial melting of lower crustal mafic rocks, with enclaves representing earlier crystallization products, which were then mechanically mixed with granites. We propose the NE Cathaysia Block underwent significant reworking from the Middle Jurassic to the Early Cretaceous. Middle Jurassic syenites formed in a compressional setting linked to Paleo-Pacific Plate subduction, while Early Cretaceous magmatism reflects lithospheric extension and crust-mantle interaction triggered by slab rollback. Full article
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33 pages, 44898 KiB  
Article
The Supra-Salt Sedimentary Sequence of the North Caspian Depression: Stratigraphy and Sedimentary History
by Aitbek Akhmetzhanov, Saule Uvakova, Kenzhebek Ibrashev, Gauhar Akhmetzhanova and Vyacheslav Zhemchuzhnikov
Geosciences 2025, 15(4), 143; https://doi.org/10.3390/geosciences15040143 - 9 Apr 2025
Viewed by 611
Abstract
The North Caspian Basin, known for its oil and gas potential, was formed because of the evolution of the ancient Tethys Ocean and is also a result of the collision of the East European, Kazakhstania, and Siberian paleocontinents. At the beginning of the [...] Read more.
The North Caspian Basin, known for its oil and gas potential, was formed because of the evolution of the ancient Tethys Ocean and is also a result of the collision of the East European, Kazakhstania, and Siberian paleocontinents. At the beginning of the Mesozoic Era, it was a part of the northern continental margin of the Neo-Tethys, which formed Eurasia. In the Late Triassic and Early Jurassic, a major restructuring of the North Caspian sedimentary basin occurred, characterized by angular unconformity and the erosion of underlying sediments in the coastal zones of the basin. The sedimentary succession of the depression accumulating in the Mesozoic Era consisted of alternating siliciclastic and carbonate rocks. It began to form due to the destruction of the uplifts formed north and west of the East European craton and Urals, which resulted in coastal clastic material in the Triassic and Jurassic, but by the end of the Jurassic and Cretaceous, when all uplifts existing in the north of Tethys were leveled, it was mostly marine environments that contributed to the accumulation of siliciclastic and carbonate strata. The appearance of a large amount of sedimentary material towards the center of the depression, causing stress, as well as the deflection of the basement, contributed to fault tectonics and the resumption and manifestation of salt tectonics. As a result of the continuous diapirism of salt bodies during the Late Mesozoic, mini basins were formed, in which different sedimentogenesis was manifested. These processes contributed to the redistribution of hydrocarbons from the underlying pre-salt formations to the intermediate depth interval post-salt succession with Permian–Triassic and also near-surface Jurassic–Cretaceous formations. Full article
(This article belongs to the Section Sedimentology, Stratigraphy and Palaeontology)
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28 pages, 2517 KiB  
Article
Petrography and Geochemistry of Lower Jurassic Sandstones in the Eastern Junggar Basin: Implications for Provenance and Tectonic Setting
by Furong Li, Zhi Zhang, Can Zhao, Jinqi Han, Jiaye Liu, Yaoyun Guo, Xinyu Tang, Chang Su, Xu Chang and Tong Wu
Minerals 2025, 15(3), 279; https://doi.org/10.3390/min15030279 - 9 Mar 2025
Viewed by 1145
Abstract
The Junggar Basin basement comprises microcontinental blocks amalgamated through successive paleo-oceanic accretion events. Stratigraphic and provenance studies within the basin are crucial for reconstructing its evolution and understanding the closure of paleo-oceanic systems. This study presents an integrated petrographic and geochemical analysis of [...] Read more.
The Junggar Basin basement comprises microcontinental blocks amalgamated through successive paleo-oceanic accretion events. Stratigraphic and provenance studies within the basin are crucial for reconstructing its evolution and understanding the closure of paleo-oceanic systems. This study presents an integrated petrographic and geochemical analysis of the Lower Jurassic Badaowan Formation sandstones in the Dongdaohaizi Depression, located in the eastern Junggar Basin. The results reveal a progressive decrease in lithic fragment content and an increase in quartz content from older to younger strata within the Badaowan Formation, indicating an increase in compositional maturity. Provenance analysis indicates that the sandstones are predominantly derived from tuffaceous rocks, granites, basalts, and minor metamorphic rocks. Heavy mineral assemblages, including zircon, chromian spinel, tourmaline, and garnet, suggest parent rocks consisting primarily of intermediate to acidic igneous rocks, mafic igneous rocks, and metamorphic rocks. Integrated petrographic and geochemical data from the surrounding areas of the Dongdaohaizi Depression confirm that the Badaowan Formation sandstones are primarily sourced from the eastern Kelameili Mountain. The continued uplift and migration of the Kelameili Mountain during the Early Jurassic played a dominant role in shaping the sedimentary provenance. LA-ICP-MS analyses reveal that the rare earth element (REE) concentrations in the Lower Jurassic sandstones are slightly lower than the average REE content of the upper continental crust. The sandstones exhibit weak differentiation between light and heavy REEs, reflecting a depositional environment characterized by anoxic reducing conditions. Geochemical results indicate a tectonic setting dominated by a passive continental margin and continental island arc in the source area. Synthesizing these findings with related studies, we propose that the Kelameili Ocean, as part of the Paleo-Asian Ocean, underwent a complex evolution involving multiple oceanic basins and microcontinental subduction–collision systems. From the Middle Ordovician to Late Silurian, the Kelameili region evolved as a passive continental margin. With the onset of subduction during the Middle Devonian to Early Carboniferous, the eastern Junggar Basin transitioned into a continental island arc system. This tectonic transition was likely driven by episodic or bidirectional subduction of the Kelameili Ocean. Full article
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20 pages, 13571 KiB  
Article
Geochemistry and U–Pb Chronology of the Triassic Yanchang Formation in the Southern Ordos Basin, China: Implications for Provenance and Geological Setting
by Fenhong Luo, Hujun Gong, Hang Liu, Bin Lv and Dali Xue
Minerals 2025, 15(3), 233; https://doi.org/10.3390/min15030233 - 26 Feb 2025
Viewed by 544
Abstract
During the deposition of the Middle–Upper Triassic Yanchang Formation, the southern margin of the Ordos Basin (OB) serves as a critical area for investigating the tectonic interactions between the North China Block (NCB) and Qinling Orogenic Belt (QOB). The provenance record of this [...] Read more.
During the deposition of the Middle–Upper Triassic Yanchang Formation, the southern margin of the Ordos Basin (OB) serves as a critical area for investigating the tectonic interactions between the North China Block (NCB) and Qinling Orogenic Belt (QOB). The provenance record of this sedimentary succession can be utilized to trace basin–mountain interactions using petrological, geochemical, and zircon age geochronological studies. We analyzed lithic fragments, geochemistry, and detrital zircon U–Pb ages of samples from the Xunyi Sanshuihe field profile, Weibei Uplift. Discrimination diagrams of major and trace elements revealed provenances and tectonic-sedimentary settings. Middle–Upper Triassic sandstones comprise quartz, feldspar, and lithic fragments. Their compositions are plotted within recycled orogenic and magmatic arc provenance fields. Multiple element diagrams reveal a felsic igneous rock provenance. Detrital zircon age spectra display four prominent age groups, which are ca. 240–270, 410–450, 1800–2200, and 2400–2600 Ma, and one minor age group, that is, 870–1197 Ma in the Late Triassic sample. We conclude that the provenance of the Yanchang Formation changed significantly during the Middle–Late Triassic. The Late Triassic sediments were mainly QOB-derived, and the basement was from the NCB. The pre-Triassic strata and Longmen pluton in the southwest of OB were the provenance of Middle Triassic sediments. The QOB suffered rapid uplift and denudation, resulting in rapid deposition and deep-water deposition in the southern OB, which provides excellent conditions for the high-quality oil shale of Ch 7. Full article
(This article belongs to the Section Mineral Geochemistry and Geochronology)
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25 pages, 5469 KiB  
Article
Natural Hydrogen in Uruguay: Catalog of H2-Generating Rocks, Prospective Exploration Areas, and Potential Systems
by Marcos Sequeira, Ethel Morales, Isabelle Moretti, Gerardo Veroslavsky, Facundo Plenc, Roberto d’Avila and Hector de Santa Ana
Geosciences 2025, 15(2), 54; https://doi.org/10.3390/geosciences15020054 - 5 Feb 2025
Cited by 2 | Viewed by 2344
Abstract
The increasing demand for carbon-free energy in recent years has positioned hydrogen as a viable option. However, its current production remains largely dependent on carbon-emitting sources. In this context, natural hydrogen, generated through geological processes in the Earth’s subsurface, has emerged as a [...] Read more.
The increasing demand for carbon-free energy in recent years has positioned hydrogen as a viable option. However, its current production remains largely dependent on carbon-emitting sources. In this context, natural hydrogen, generated through geological processes in the Earth’s subsurface, has emerged as a promising alternative. The present study provides the first national-scale assessment of natural dihydrogen (H2) potential in Uruguay by developing a catalog of potential H2-generating rocks, identifying prospective exploration areas, and proposing H2 systems there. The analysis includes a review of geological and geophysical data from basement rocks and onshore sedimentary basins. Uruguay stands out as a promising region for natural H2 exploration due to the significant presence of potential H2-generating rocks in its basement, such as large iron formations (BIFs), radioactive rocks, and basic and ultrabasic rocks. Additionally, the Norte Basin exhibits potential efficient cap rocks, including basalts and dolerites, with geological analogies to the Mali field. Indirect evidence of H2 in a free gas phase has been observed in the western Norte Basin. This suggests the presence of a potential H2 system in this area, linked to the Arapey Formation basalts (seal) and Mesozoic sandstones (reservoir). Furthermore, the proposed H2 system could expand exploration opportunities in northeastern Argentina and southern Brazil, given the potential presence of similar play/tramp. Full article
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40 pages, 14218 KiB  
Article
Geochemistry and Petrogenesis of Permo–Triassic Silicic Volcanic Rocks from the Circum-Rhodope Belt in the Vardar/Axios Zone, Northern Greece: An Example of a Post-Collision Extensional Tectonic Setting in the Tethyan Realm
by Argyro Asvesta
Geosciences 2025, 15(2), 48; https://doi.org/10.3390/geosciences15020048 - 2 Feb 2025
Viewed by 994
Abstract
The western side of the Vertiskos Unit crystalline basement in northern Greece is fringed by a Permo–Triassic low-grade metamorphic volcano-sedimentary complex that belongs to the Circum-Rhodope Belt (CRB), which is an important part of the Vardar/ Axios oceanic suture zone. The silicic volcanic [...] Read more.
The western side of the Vertiskos Unit crystalline basement in northern Greece is fringed by a Permo–Triassic low-grade metamorphic volcano-sedimentary complex that belongs to the Circum-Rhodope Belt (CRB), which is an important part of the Vardar/ Axios oceanic suture zone. The silicic volcanic rocks from the CRB are mainly rhyolitic to rhyodacitic lavas with aphyric and porphyritic textures as well as pyroclastic deposits. In this study, geochemical data obtained with X-ray fluorescence (XRF) for the CRB silicic volcanic rocks are reported and discussed to constrain their petrogenesis and tectonic setting. The rocks are peraluminous and show enrichment in K, Rb, Th, Zr, Y, and Pb while being depleted in Ba, Sr, Nb, P, and Ti, and they have Zr + Nb + Y + Ce > 350 ppm, which are characteristic features of anorogenic A-type granites. They have a Y/Nb ratio > 1.2 and belong to A2-subtype granitoids, implying crust-derived magma in a post-collisional tectonic setting. The high Rb/Sr ratio (3.45–39.14), the low molar CaO/(MgO + FeOt) ratio, and the CaO/Na2O ratio (<0.5), which they display, indicate that metapelites are the magma sources. Their low Al2O3/TiO2 ratio (<100), consistent with their high zircon saturation temperatures (average TZr = 886 °C), and their low Pb/Ba ratio (average 0.06) reveal that they were generated by biotite dehydration melting. The increased Rb/Sr ratio relative to that of presumable parental metapelites of the Vertiskos Unit, coupled with their low Sr/Y ratio (0.12–1.08), reflects plagioclase and little or no garnet in the source residue, indicating magma derivation at low pressures of 0.4–0.8 GPa that correspond to a depth of ~15–30 km. The nearby tholeiitic basalts and dolerites, interstratified with the Triassic pelagic sediments, indicate bimodal volcanism in the region. They also support a model involving an upwelling asthenosphere that underplated the Vertiskos Unit basement, supplying the heat required for crustal melting at low pressures. The Permo–Triassic magmatism marks the transition from an orogenic to an anorogenic environment during the initial stage of continental breakup of the Variscan basement in a post-collision extensional tectonic framework, leading to the formation of the nascent Mesozoic Neo-Tethyan Maliac–Vardar Ocean. This apparently reveals that the Variscan continental collision between the Gondwana-derived Vertiskos and Pelagonian terranes must have been completed by at least the earliest Late Permian. Full article
(This article belongs to the Section Geochemistry)
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16 pages, 8675 KiB  
Article
Investigating the Structural Framework Beneath Riyadh Region for Potential Geothermal Exploration Utilizing Geological and Geophysical Data
by Abdulrhman H. Alghamdi, Faisal A. Alonaizi and Majed A. Almalki
Sustainability 2024, 16(24), 11286; https://doi.org/10.3390/su162411286 - 23 Dec 2024
Viewed by 1595
Abstract
With growing electricity demand and an increasing focus on renewable energy, geothermal energy exploration is gaining prominence in Saudi Arabia. This study investigates the geothermal potential of the Riyadh region by integrating various geophysical data with geological information, providing a detailed image of [...] Read more.
With growing electricity demand and an increasing focus on renewable energy, geothermal energy exploration is gaining prominence in Saudi Arabia. This study investigates the geothermal potential of the Riyadh region by integrating various geophysical data with geological information, providing a detailed image of the structural framework and thermal distribution. We generated a 2D density and susceptibility model using gravity and aeromagnetic data, constrained by well-logs information for sedimentary rocks. Distinct salt layers with low densities (2.15 g/cm3) were introduced in the model overlying the basement rocks, as well as unexposed faults, which may play a crucial role in the thermal regime in the study area. We produced a comprehensive thermal model extracted from the density and susceptibility model, along with temperature measurements from the Minjur Aquifer. The presence of the salt layer not only affects the geothermal gradient, but also suggests the potential for enhanced surface heat flow in specific areas. The results highlight the presence of a promising geothermal reservoir, the Minjur Formation, which exhibits significant potential for geothermal energy extraction due to its porosity, permeability, and sufficient thermal gradient ranging from 80 °C to 120 °C at depths of 2 to 3 km. These findings offer significant implications for Saudi Arabia’s transition to cleaner energy sources and support the future development of geothermal infrastructure in urban areas like Riyadh. Full article
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26 pages, 8922 KiB  
Article
Comparative Study of Sulfides from Porphyry, Skarn, and Carbonate-Replacement Mineralization at the Recsk Porphyry-Mineralized Complex, Hungary
by Máté Biró, Johann G. Raith, Monika Feichter, Máté Hencz, Gabriella B. Kiss, Attila Virág and Ferenc Molnár
Minerals 2024, 14(9), 956; https://doi.org/10.3390/min14090956 - 21 Sep 2024
Cited by 1 | Viewed by 1425
Abstract
A calc–alkaline dioritic–andesitic–dacitic intrusive–volcanic complex of Early Oligocene (30 Ma) age and its Mesozoic sedimentary basement at Recsk host a well-preserved porphyry–skarn–polymetallic carbonate-replacement–epithermal mineral system. The unique occurrence offers an exceptional possibility to study these related mineralization types at a single locality. This [...] Read more.
A calc–alkaline dioritic–andesitic–dacitic intrusive–volcanic complex of Early Oligocene (30 Ma) age and its Mesozoic sedimentary basement at Recsk host a well-preserved porphyry–skarn–polymetallic carbonate-replacement–epithermal mineral system. The unique occurrence offers an exceptional possibility to study these related mineralization types at a single locality. This study presents the textural–paragenetic, compositional characteristics, and systematics of sulfide mineral assemblages for the porphyry, skarn, and carbonate-replacement ore types, which are currently situated at a depth of 500–1200 m below the present surface. Detailed petrography combined with EPMA analyses of molybdenite, galena, sphalerite, tetrahedrite-group minerals and Bi-bearing sulfosalts allows for the establishment of characteristic mineral and chemical fingerprints for each mineralization type. Rhenium concentration in molybdenite, occurring as rare disseminations and quartz–carbonate veinlets in altered host rocks in all three mineralization types, shows a decreasing trend towards the more distal mineralization types. High Re contents (x¯ = 1.04 wt.%, max. up to 4.47 wt%) are typical for molybdenite from the porphyry mineralization, but Re is not homogeneously distributed, neither within individual molybdenite crystals nor on a mineralization scale. Copper and Se show opposite behavior in molybdenite, both becoming enriched in the more distal mineralization types. Silver, Bi, and Se concentrations increase in galena and tetrahedrite-group minerals, both towards the country rocks, making them the best candidates for vectoring within the whole hydrothermal system. For tetrahedrite-group minerals, Ag, Bi, Se, together with Sb and Zn, are the suitable elements for fingerprinting; all these are significantly enriched in the distal carbonate-replacement mineralization compared to the other, more proximal ore types. Additionally, further trends can be traced within the composition of sulfosalts. Lead-bearing Bi sulfosalts preferentially occur in the polymetallic carbonate-replacement veins, while being under-represented in the skarn and porphyry mineralization. Porphyry mineralization hosts Cu-bearing Bi sulfosalts dominantly, while skarn is characterized by Bi-dominated sulfosalts. Sphalerite, although present in all mineralization types, cannot be used for fingerprinting, vectoring, or thermobarometry based on EPMA measurements only. Trace element contents of sphalerite are low, often below the detection limits of the analyses. This is further complicated by the intense “chalcopyrite disease” occurring throughout the distal mineralization types. All the above-listed major, minor, and trace element ore mineral characteristics enable the characterization of the Recsk ores by mineral geochemical fingerprints, providing a possible vectoring tool in porphyry Cu–(Mo)–Au-mineralized systems. Full article
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32 pages, 415681 KiB  
Article
Geoheritage of the Iconic EN280 Leba Road (Huila Plateau, Southwestern Angola): Inventory, Geological Characterization and Quantitative Assessment for Outdoor Educational Activities
by Fernando Carlos Lopes, Anabela Martins Ramos, Pedro Miguel Callapez, Pedro Santarém Andrade and Luís Vítor Duarte
Land 2024, 13(8), 1293; https://doi.org/10.3390/land13081293 - 15 Aug 2024
Cited by 1 | Viewed by 2007
Abstract
The EN280 Leba Road is a mountain road that runs along the western slope of Serra da Leba (Humpata Plateau) and its outstanding escarpments, connecting the hinterland areas of the Province of Huila to the coastal Atlantic Province of Namibe, in Southwest Angola. [...] Read more.
The EN280 Leba Road is a mountain road that runs along the western slope of Serra da Leba (Humpata Plateau) and its outstanding escarpments, connecting the hinterland areas of the Province of Huila to the coastal Atlantic Province of Namibe, in Southwest Angola. In the Serra da Leba ranges, as in Humpata Plateau, a volcano-sedimentary succession of Paleo-Mesoproterozoic age known as the Chela Group outcrops extensively. This main unit records a pile of sediments with a thickness over 600 m, overlying a cratonic basement with Eburnean and pre-Eburnean granitoids. This sequence is overlain in unconformity by the Leba Formation, which consists of weakly deformed cherty dolostones rich in stromatolites. Along the EN280 Leba Road, in the downward direction, were inventoried and characterized eight sites that, by their exceptional geological content and the singularity of their geoforms, are worth being defined and formalized as geosites: (1) traditional mining clay pit in the Humpata Plateau (post-Eburnean Paleo-Mesoproterozoic claystones); (2) old lime oven of Leba (post-Eburnean Meso-Neoproterozoic cherty dolostones with stromatolites); (3) viewpoint of the Serra da Leba (post-Eburnean Paleo-Mesoproterozoic volcano-sedimentary formations and Eburnean Paleoproterozoic granitoids); (4) vertical beds at the beginning of the descent (post-Eburnean Paleo-Mesoproterozoic volcano-sedimentary formations); (5) slope of the fault propagation fold (post-eburnean Paleo-Mesoproterozoic volcano-sedimentary formations); (6) reverse fault in granitoid rocks (Eburnean Paleoproterozoic granitoids); (7) Dolerite Curve (Eburnean Paleoproterozoic granitoids and dolerites); (8) ductile simple shear zone (Eburnean Paleoproterozoic granitoids and mylonites). These sites were primarily selected using the results of fieldwork (observations, measurements, reproduction of representations, and creation of models), interpretation of remote sensing data, and data from previously published bibliographies and cartography. A quantitative assessment of the selected sites to be preserved through their classification as geosites (integration in a geoconservation strategy) was proposed. The first position in the numerical assessment is occupied by the landscape dimension geosite “Viewpoint of the Serra da Leba”. This position is conferred, mainly, by its high geological, use, and Management values, being therefore considered the place with the highest geoheritage value in the studied area. Based on the previous characterization and evaluation, several field activities were proposed to be included in a guidebook, highlighting aspects such as landscapes, outcrops, rocks, structures, fossils, and georesources. The high scientific, didactic, and aesthetic values of these geological contexts and their high degree of geodiversity justify their integration into a geoeducational transect, contributing to the appreciation and awareness of the geological heritage of Serra da Leba, as well as to its promotion and scientific and educational dissemination. Full article
(This article belongs to the Special Issue Urban Resilience and Heritage Management)
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23 pages, 19232 KiB  
Article
Application of Geophysical Methods in the Identification of Mineralized Structures and Ranking of Areas for Drilling as Exemplified by Alto Guaporé Orogenic Gold Province
by Jorge Echague, Marcelo Leão-Santos, Rodrigo Melo, Thiago Mendes and Welitom Borges
Minerals 2024, 14(8), 788; https://doi.org/10.3390/min14080788 - 31 Jul 2024
Viewed by 2196
Abstract
Mineral exploration works conducted in the Alto Guaporé Gold Province (AGGP), situated in the southwest region of the Amazon Craton in Brazil, faces the challenges of many gold provinces around the world, i.e., declines in the discoveries of new economic deposits and increases [...] Read more.
Mineral exploration works conducted in the Alto Guaporé Gold Province (AGGP), situated in the southwest region of the Amazon Craton in Brazil, faces the challenges of many gold provinces around the world, i.e., declines in the discoveries of new economic deposits and increases in exploration costs. Ground geophysical methods, combined with structural analyses and geological mapping, are valuable tools that have potential to improve accuracy in selecting exploration targets and in determining drilling locations. AGGP deposits are primarily associated with regional N20°–W50° inverse faulting and sheared geologic contacts between Meso-Neoproterozoic siliciclastic metasedimentary rocks and Mesoproterozoic basement (granite and volcano–sedimentary sequences). Mining currently occurring in the central portion of the province drives exploration works towards the many existing targets at the area. Among them, the ABP target is one of the most promising for being located few kilometers north of the Pau-a-Pique mine. At the ABP target, gold is associated with hydrothermal alteration located in the sheared contacts and in the hinge zone of folded metasedimentary sequence. Hydrothermal phases include Fe-oxides, sulfide (py), muscovite and quartz veins. In this study, we use magnetic and geoelectric (induced polarization) surveys coupled with structural and geological mapping to identify potential footprints within the ABP target. The results from induced polarization (IP) profiles successfully mapped the shape and orientation of the main structures down to approximately 350 m at the ABP target, indicating potential locations for hydrothermal alteration hosting gold. Additionally, 3D magnetic data inversions illustrated the distribution of magnetic susceptibilities and magnetization vectors associated with shear zone structures and isolated magnetic bodies. Magnetic data highlighted fault zones along the contacts between metamorphic rocks and granites, while IP data identified areas with high chargeability, correlating with sulfidation zones mineralized with gold. These findings suggest a metallogenic model where gold deposits are transported through deep structures connected to regional faults, implying significant tectonic and structural control over gold deposition. The results underscore the potential of multiparameter geophysics in identifying and characterizing deposits in both deep and strike, thereby advancing our understanding of mineral occurrences in the region and enhancing the search for new mineralized zones. Full article
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24 pages, 26872 KiB  
Article
Opening and Post-Rift Evolution of Alpine Tethys Passive Margins: Insights from 1D Numerical Modeling of the Jurassic Mikulov Formation in the Vienna Basin Region, Austria
by Darko Spahić, Eun Young Lee, Aleksandra Šajnović and Rastimir Stepić
Geosciences 2024, 14(8), 202; https://doi.org/10.3390/geosciences14080202 - 30 Jul 2024
Cited by 1 | Viewed by 1928
Abstract
This study employed 1D numerical pseudo models to examine the Upper Jurassic carbonate succession, focusing on the Mikulov Formation in the Vienna Basin region. It addresses the protracted and complex history of the Jurassic source rock play, revealing a transition from rapid syn-rift [...] Read more.
This study employed 1D numerical pseudo models to examine the Upper Jurassic carbonate succession, focusing on the Mikulov Formation in the Vienna Basin region. It addresses the protracted and complex history of the Jurassic source rock play, revealing a transition from rapid syn-rift (>200 m/Ma) to slower post-rift sedimentation/subsidence of the overlying layers during extensional deformation (up to 120 m/Ma with a thickness of 1300 m). This provides valuable insights into the rift-to-drift stage of the central Alpine Tethys margin. The Mikulov marls exhibit characteristics of a post-rift passive margin with slow sedimentation rates. However, a crustal stretching analysis using syn-rift heat flow sensitivity suggested that thermal extension of the basement alone cannot fully explain the mid-Jurassic syn-rift stage in this segment of the Alpine Tethys. The sensitivity analysis showed that the mid-late Jurassic differential syn-rift sequences were exposed to slightly cooler temperatures than the crustal stretching model predicted. Heat flow values below 120 mW/m2 aligned with measurements from deeply settled Mesozoic successions, suggesting cold but short gravity-driven subsidence. This may account for the relatively low thermal maturation of the primary source rock interval identified by the time-chart analysis, despite the complex tectonic history and considerable sedimentary burial. The post-Mesozoic changes in the compaction trend are possibly linked to the compressional thrusting of the Alpine foreland and postdating listric faulting across the Vienna Basin. Full article
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31 pages, 8433 KiB  
Article
Groundwater Dynamics in African Endorheic Basins in Arid to Semi-Arid Transition Zones: The Batha Aquifer System, NE Chad
by Abakar Bourma Arrakhais, Abderamane Hamit, Claude Fontaine, Fatima Abdelfadel, Moustapha Dinar and Moumtaz Razack
Water 2024, 16(14), 2067; https://doi.org/10.3390/w16142067 - 22 Jul 2024
Cited by 2 | Viewed by 2025
Abstract
This study investigates the Batha endorheic basin in Chad, situated east of the Lake Chad basin in the arid to semi-arid Sahelian zone. This region has not yet undergone comprehensive geological and hydrogeological studies. More broadly, the transition zone between semi-arid and arid [...] Read more.
This study investigates the Batha endorheic basin in Chad, situated east of the Lake Chad basin in the arid to semi-arid Sahelian zone. This region has not yet undergone comprehensive geological and hydrogeological studies. More broadly, the transition zone between semi-arid and arid climates has been minimally explored. This research aims to evaluate the resources and dynamics of this multi-layered system using a combined geology-hydrogeology-hydrochemistry-isotopes approach. The multilayer system includes sedimentary layers (Quaternary, Pliocene, and Eocene) over a crystalline basement. A piezometric investigation of the system shows a general SE–NW groundwater, indicating an interconnection between all layers. Hydrochemical analyses identifies four main facies (calcium-bicarbonate, sodium-bicarbonate, sulphate-sodium, and mixed), primarily controlled by water–rock interaction with secondary influences from base-exchange and evaporation. Saturation indices indicate that these waters are close to equilibrium with the calcite-Mg phases, gaylussite and gypsum. Stable isotopes (oxygen-18 and deuterium) categorize groundwater into three groups: ancient water, recent and older meteoric water mixtures affected by evaporation, and mixtures more heavily impacted by evaporation. Tritium contents reveal three groups: current rainwater, modern water, and sub-modern water. These results indicate that ionic and isotopic differentiations cannot be strictly linked to specific layers, confirming the interconnected nature of the Batha system. The observed heterogeneity is mainly influenced by lithological and climatic variations. This study, though still limited, enhances significantly the understanding of the basin’s functioning and supports the rational exploitation of its vital resources for the Batha area’s development. Future investigations to complete the present study are highlighted. Full article
(This article belongs to the Special Issue Water, Geohazards, and Artificial Intelligence, 2nd Edition)
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