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Keywords = Himalayan orogen

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21 pages, 18066 KB  
Article
Timing and Tectonic Setting of the Zhaguopu Pegmatite-Type Li-Be-Nb-Ta Deposit, Western Himalaya: Implications for Post-Collisional Rare-Metal Metallogeny
by Gen Chen, Haiquan Li, Hao Chen and Xingkai Huang
Minerals 2026, 16(2), 208; https://doi.org/10.3390/min16020208 - 19 Feb 2026
Viewed by 493
Abstract
The Himalayan metallogenic belt is a globally significant province for leucogranites and pegmatites. Recent exploration has yielded major breakthroughs in the exploration of pegmatite-type Li-Be-Nb-Ta rare-metal deposits within its eastern segment. Discoveries such as the Qiongjiagang and Lhozhag deposits underscore the region’s substantial [...] Read more.
The Himalayan metallogenic belt is a globally significant province for leucogranites and pegmatites. Recent exploration has yielded major breakthroughs in the exploration of pegmatite-type Li-Be-Nb-Ta rare-metal deposits within its eastern segment. Discoveries such as the Qiongjiagang and Lhozhag deposits underscore the region’s substantial mineralization potential. In contrast, the western Himalayan segment remains comparatively underexplored. This study presents the geology and geochronology of the newly identified Zhaguopu Li-Be-Nb-Ta deposit in the Gyirong area, providing critical new insights. The deposit is centered on the Gyirong granite dome, which features a core of tourmaline-bearing leucogranite surrounded by a peripheral zone of beryl-bearing pegmatites and vein- to lens-shaped spodumene pegmatites, all hosted within metamorphosed sandstone, slate, and marble. The largest individual spodumene pegmatite vein exceeds 400 m in length, with thicknesses ranging from 0.5 to 4 m and a cumulative thickness surpassing 50 m. Principal ore minerals include spodumene, beryl, and columbite-group minerals. U-Pb geochronology of zircon, monazite, and columbite-group minerals from the leucogranite and pegmatite units constrains the rare-metal mineralization to a tight interval of 25–23 Ma, contemporaneous with the Qiongjiagang and Lhozhag deposits. Whole-rock geochemical data define a coherent fractional crystallization sequence from tourmaline granite through beryl pegmatite to spodumene pegmatite, characterized by increasing SiO2 and peraluminosity, and extreme depletion in Ba, Sr, Eu and Nb/Ta ratios. This geochemical trend underscores the critical role of extreme magmatic differentiation in rare-metal enrichment. Field relationships and these coeval ages strongly support a genetic model in which the mineralized pegmatites originated from the extreme fractional crystallization of a common, cogenetic magmatic suite. The timing of this mineralization event correlates precisely with the post-collisional extension of the Himalayan orogen and the activity of the Southern Tibet Detachment System. We conclude that the interplay between this large-scale tectonism and magmatic differentiation is the fundamental driver for rare-metal enrichment. The discovery of the Zhaguopu deposit highlights the significant and previously underestimated potential for major pegmatite-type rare-metal deposits in the western Himalayan belt. Full article
(This article belongs to the Section Mineral Deposits)
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22 pages, 11470 KB  
Article
Geochronology and Geochemistry of Late Cretaceous Plutonic Rocks in Southeastern Anatolian Orogenic Belt, Eastern Türkiye: Implications for Petrogenesis and Tectonic Evolution
by Abdullah Sar and Mustafa Eren Rizeli
Minerals 2026, 16(2), 173; https://doi.org/10.3390/min16020173 - 5 Feb 2026
Viewed by 689
Abstract
Late Cretaceous plutonic rocks are commonly observed along the Southeastern Anatolian Orogenic Belt (SAOB), which constitutes a significant part of the Alpine–Himalayan Orogenic Belt. Here, we present new whole-rock geochemical analyses, zircon U–Pb ages, and zircon trace element data of plutonic rocks located [...] Read more.
Late Cretaceous plutonic rocks are commonly observed along the Southeastern Anatolian Orogenic Belt (SAOB), which constitutes a significant part of the Alpine–Himalayan Orogenic Belt. Here, we present new whole-rock geochemical analyses, zircon U–Pb ages, and zircon trace element data of plutonic rocks located in the SAOB (eastern Türkiye). This study aims to determine the petrogenesis of the studied plutonic rocks in light of new data and to contribute to the tectonic evolution of the SAOB. Geochemical data demonstrate that the studied granodiorites, diorites, and gabbros are tholeiitic–calc–alkaline in composition, metaluminous, and I-type granite. Zircon U-Pb ages yielded crystallisation ages of 73.52 ± 0.24 Ma for the studied granodiorites and 78.86 ± 0.39 Ma for the diorites. These age data indicate that the studied plutonic rocks represent the youngest granodiorite and diorite formations observed around the study area. High Th/U ratios (granodiorite: 0.15–0.29; diorite: 0.31–0.96) and positive Ce/Ce* (granodiorite: 8.11 to 609.86; diorite: 58.07 to 564.31) and negative Eu/Eu* (granodiorite: 0.49 to 0.62; diorite: 0.59–0.97) values obtained in zircon grains suggest that they are of magmatic origin. Geochemical data indicate that the studied diorites and gabbros originate from a spinel-bearing source representing shallow depths. In light of all the data, the studied plutonic rocks are products of arc magmatism resulting from the subduction of the NeoTethys Oceanic lithosphere along the SAOB. Full article
(This article belongs to the Section Mineral Geochemistry and Geochronology)
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20 pages, 23508 KB  
Article
Petrogenesis of Himalayan Leucogranites: A Perspective from Zircon Trace Elements
by Weirui Lu, Zeming Zhang, Jia Yuan, Yang Zhang, Qiang Li, Yu An and Di Zhan
Minerals 2025, 15(12), 1306; https://doi.org/10.3390/min15121306 - 15 Dec 2025
Viewed by 716
Abstract
Magmatic zircon trace element compositions and their variation trends provide valuable insights into the nature and evolutionary processes of magmatic rocks. The Himalayan orogen contains widespread leucogranites. Despite extensive studies on these granites, the features and petrogenetic implications of trace element composition of [...] Read more.
Magmatic zircon trace element compositions and their variation trends provide valuable insights into the nature and evolutionary processes of magmatic rocks. The Himalayan orogen contains widespread leucogranites. Despite extensive studies on these granites, the features and petrogenetic implications of trace element composition of zircons from the leucogranites remain poorly constrained. In this study, we present a comprehensive dataset comprising new cathodoluminescence (CL) images, U-Pb ages, and trace element compositions of zircons from the Himalayan leucogranites, and compare them to the previously reported trace element data of zircon from I-type granites. Our results show that zircons from the Himalayan leucogranites have high Hf, U, Y, P, Th, Sc, and heavy rare earth element contents (HREE), and low Nb, Ta, Ti, and light rare earth element contents (LREE), and can be divided into two types. Type I (low-U) zircons exhibit well-developed oscillatory zoning, and the U concentrations are mostly <5000 ppm. Type II (high-U) zircons display mottled or spongy textures and possess elevated U contents that are mostly >5000 ppm. Zircons from the Himalayan leucogranites have higher contents of U, Hf, Nb, Ta, and elevated U/Yb ratios, but lower Th/U, Eu/Eu*, Ce/Ce*, LREE/HREE, and Ce/U values than those from I-type granitic zircons. Furthermore, zircons in the Himalayan leucogranites have gradually decreasing Th, Ti, Th/U, Eu/Eu*, and Ce/Ce*, and increasing U, Nb, Ta, and (Yb/Gd)N with increasing Hf. These geochemical features suggest the magmas involved in the genesis of leucogranites originated from the partial melting of metasedimentary sources under relatively reduced conditions, and underwent a high degree of magmatic fractionation. Full article
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25 pages, 17911 KB  
Article
Cenozoic Multiphasic Activity and Mesozoic Basin-Control Role of the Dingri–Gangba Fault, Southern Tibet: An Integrated Study of Structural Analysis, Stratigraphic Correlation, and ESR Geochronology
by Chongyang Xin, Songtao Yan, Hu Li, Xuejian Dai, Tao Liu and Jie Wang
Geosciences 2025, 15(11), 440; https://doi.org/10.3390/geosciences15110440 - 19 Nov 2025
Viewed by 647
Abstract
The Dingri–Gangba fault, a major structure within the Himalayan Orogenic Belt, records significant geological events, including the tectonic evolution of the northern margin of the Indian plate and the uplift of the Tibetan Plateau. However, its geometry, kinematics, and tectonic characteristics remain debated. [...] Read more.
The Dingri–Gangba fault, a major structure within the Himalayan Orogenic Belt, records significant geological events, including the tectonic evolution of the northern margin of the Indian plate and the uplift of the Tibetan Plateau. However, its geometry, kinematics, and tectonic characteristics remain debated. To constrain the tectonic evolution of the Dingri–Gangba fault, this study integrates detailed field investigations and structural analysis with Electron Spin Resonance (ESR) dating to characterize its three-dimensional architecture and quantify the timing of its deformation phases. The results show that the fault trends nearly E–W and exhibits multi-phase structural superimposition, including thrusting (60–40 Ma), normal faulting (35–11 Ma), and strike-slip shear (18–6.8 Ma). These phases reflect a multi-stage tectonic evolution following the India–Eurasia collision. Stratigraphic comparisons reveal that during the Mesozoic, the Dingri–Gangba fault played a significant basin-controlling role, marked by variations in sedimentary thickness, soft-sediment deformation, and volcanic activity. The sedimentary evolution alternated between periods of “differentiation” and “uniformity”. A comprehensive analysis suggests that the tectonic evolution of the Dingri–Gangba fault is closely linked to the dynamic transition of the Tethys Himalaya from a passive continental margin to a collision orogeny, also reflecting changes in the tectonic stress field following the India–Eurasia collision. These findings provide valuable insights into the tectono–sedimentary–magmatic coupling along the southern margin of the Tibetan Plateau. Full article
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20 pages, 31550 KB  
Article
Report of CA. 760 Ma Mafic Rocks in the Eastern Himalayan Orogen: Petrogenesis and Geodynamic Implications
by Yi Yang, Zhi Zhang, Guotao Ma and Suiliang Dong
Minerals 2025, 15(10), 1090; https://doi.org/10.3390/min15101090 - 20 Oct 2025
Viewed by 685
Abstract
Constraints on the Neoproterozoic evolution of the Himalayan terrane remain poorly understood due to the scarcity of Neoproterozoic magmatic rocks. In this study, we report for the first time Middle Neoproterozoic mafic rocks from the eastern Himalayan orogen. Zircon U–Pb dating indicates that [...] Read more.
Constraints on the Neoproterozoic evolution of the Himalayan terrane remain poorly understood due to the scarcity of Neoproterozoic magmatic rocks. In this study, we report for the first time Middle Neoproterozoic mafic rocks from the eastern Himalayan orogen. Zircon U–Pb dating indicates that these rocks crystallized at approximately 760 Ma and can be divided into two distinct groups. Group 1 mafic rocks have E-MORB-like compositions and are enriched in incompatible elements and exhibit relatively higher initial (87Sr/86Sr)i ratios (0.7053–0.7063), lower positive whole-rock εNd(t) values (3.0 to 3.4), and zircon εHf(t) values ranging from 4.9 to 10.4. They also show low Nb/Th ratios and high Th/Yb, Nb/Yb, and (La/Sm)N ratios, suggesting a lithospheric mantle source. In contrast, Group 2 mafic rocks have N-MORB-like compositions and are characterized by light rare earth element (LREE)-depleted patterns, lower initial (87Sr/86Sr)i ratios (0.7033–0.7040), and higher positive whole-rock εNd(t) (4.8 to 6.0) and zircon εHf(t) values (4.6 to 10.9). Their high Nb/Th ratios and low Th/Yb, Nb/Yb, and (La/Sm)N ratios indicate an origin involving interaction between the lithospheric mantle and depleted asthenospheric mantle. The absence of coeval volcanic and sedimentary records, combined with high La/Y and Ti/V ratios, suggests that these mafic rocks differ from typical arc or back-arc basin suites but are consistent with an intraplate setting. Integrating previous studies on multistage Neoproterozoic magmatism in India and the Himalayas, we propose that the ca. 760 Ma mafic rocks in the eastern Himalaya were likely formed within an intraplate continental rift system. Full article
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36 pages, 7458 KB  
Article
Mineral Prospectivity Mapping for Exploration Targeting of Porphyry Cu-Polymetallic Deposits Based on Machine Learning Algorithms, Remote Sensing and Multi-Source Geo-Information
by Jialiang Tang, Hongwei Zhang, Ru Bai, Jingwei Zhang and Tao Sun
Minerals 2025, 15(10), 1050; https://doi.org/10.3390/min15101050 - 3 Oct 2025
Cited by 2 | Viewed by 2704
Abstract
Machine learning (ML) algorithms have promoted the development of predictive modeling of mineral prospectivity, enabling data-driven decision-making processes by integrating multi-source geological information, leading to efficient and accurate prediction of mineral exploration targets. However, it is challenging to conduct ML-based mineral prospectivity mapping [...] Read more.
Machine learning (ML) algorithms have promoted the development of predictive modeling of mineral prospectivity, enabling data-driven decision-making processes by integrating multi-source geological information, leading to efficient and accurate prediction of mineral exploration targets. However, it is challenging to conduct ML-based mineral prospectivity mapping (MPM) in under-explored areas where scarce data are available. In this study, the Narigongma district of the Qiangtang block in the Himalayan–Tibetan orogen was chosen as a case study. Five typical alterations related to porphyry mineralization in the study area, namely pyritization, sericitization, silicification, chloritization and propylitization, were extracted by remote sensing interpretation to enrich the data source for MPM. The extracted alteration evidences, combined with geological, geophysical and geochemical multi-source information, were employed to train the ML models. Four machine learning models, including artificial neural network (ANN), random forest (RF), support vector machine and logistic regression, were employed to map the Cu-polymetallic prospectivity in the study area. The predictive performances of the models were evaluated through confusion matrix-based indices and success-rate curves. The results show that the classification accuracy of the four models all exceed 85%, among which the ANN model achieves the highest accuracy of 96.43% and a leading Kappa value of 92.86%. In terms of predictive efficiency, the RF model outperforms the other models, which captures 75% of the mineralization sites within only 3.5% of the predicted area. A total of eight exploration targets were delineated upon a comprehensive assessment of all ML models, and these targets were further ranked based on the verification of high-resolution geochemical anomalies and evaluation of the transportation condition. The interpretability analyses emphasize the key roles of spatial proxies of porphyry intrusions and geochemical exploration in model prediction as well as significant influences everted by pyritization and chloritization, which accords well with the established knowledge about porphyry mineral systems in the study area. The findings of this study provide a robust ML-based framework for the exploration targeting in greenfield areas with good outcrops but low exploration extent, where fusion of a remote sensing technique and multi-source geo-information serve as an effective exploration strategy. Full article
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24 pages, 3436 KB  
Article
Peculiarities of 222Radon and 238Uranium Behavior in Mineral Waters of Highland Terrains
by George Chelnokov, Vasilii Lavrushin, Natalya Kharitonova, Andrey Pavlov and Farid Salikhov
Water 2025, 17(15), 2211; https://doi.org/10.3390/w17152211 - 24 Jul 2025
Cited by 3 | Viewed by 1011
Abstract
Mineral waters from two tectonically active mountain systems within the Alpine-Himalayan orogenic belt, the Pamir and the Greater Caucasus (Elbrus region), were analyzed for 222Rn activity and 238U concentrations to establish correlations with geological conditions, physicochemical characteristics of water, and to [...] Read more.
Mineral waters from two tectonically active mountain systems within the Alpine-Himalayan orogenic belt, the Pamir and the Greater Caucasus (Elbrus region), were analyzed for 222Rn activity and 238U concentrations to establish correlations with geological conditions, physicochemical characteristics of water, and to assess the potential health risk associated with 238U and 222Rn. It was found that in mineral waters of the Pamir, the concentrations of 238U (0.004–13.3 µg/L) and activity of 222Rn (8–130 Bq/L) are higher than in the Elbrus area: 0.04–3.74 µg/L and 6–33 Bq/L, respectively. Results indicate that uranium mobility in water is strongly influenced by T, pH, and Eh, but is less affected by the age of host rocks or springs′ elevation, whereas radon activity in waters depends on the age of rocks, spring elevation, 238U content, and values of δ18O and δ2H in water. This study reveals fundamental geological distinctions governing uranium and radon sources in the mineral waters of these regions. Isotopic evidence (222Rn and 3He/4He) demonstrates crustal radon sources prevail in Pamir, whereas the Elbrus system suggests mantle-derived components. The U concentrations do not exceed 30 µg/L, and most water samples (94%) showed 222Rn activities below 100 Bq/L, complying with the drinking water exposure limits recommended by the World Health Organization and European Union Directive. However, in intermountain depressions of the Pamirs, at low absolute elevations (~2300 m), radon concentrations in water can increase significantly, which requires special attention and study. Full article
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20 pages, 22036 KB  
Article
Petrogenesis and Tectonic Significance of Miocene Volcanic Rocks in the Ahlatlı–İspir–Erzurum Region, Türkiye
by Mehmet Ali Ertürk and Cihan Yalçın
Minerals 2025, 15(5), 485; https://doi.org/10.3390/min15050485 - 6 May 2025
Viewed by 1461
Abstract
The İspir–Ahlatlı region in northeastern Türkiye, situated within the Eastern Pontides, hosts significant Miocene trachy-andesite volcanic rock exposures. This work seeks to elucidate their petrographic, geochemical, and isotopic compositions to enhance comprehension of their genesis and tectonic significance. Geochemistry reveals a transitional affinity, [...] Read more.
The İspir–Ahlatlı region in northeastern Türkiye, situated within the Eastern Pontides, hosts significant Miocene trachy-andesite volcanic rock exposures. This work seeks to elucidate their petrographic, geochemical, and isotopic compositions to enhance comprehension of their genesis and tectonic significance. Geochemistry reveals a transitional affinity, an enrichment in large-ion lithophile elements (LILEs), and a decrease in high-field-strength elements (HFSEs), suggesting a subduction-modified mantle source. Geochemical variations and fractional crystallisation trends indicate that the parental magma underwent significant differentiation, likely involving the fractionation of amphibole, clinopyroxene, and plagioclase. As supported by recent thermal modelling studies, the presence of intermediate volcanic rocks without associated bimodal suites in the study area may reflect elevated geothermal gradients and lithospheric delamination during post-collisional extension. The signatures indicated that the trachy-andesites originated in a post-collisional extensional environment after the closing of the Neo-Tethys Ocean and the ensuing tectonic reconfiguration of the Eastern Pontides. The reported geochemical traits correspond with post-collisional volcanic phases documented in various sectors of the Alpine–Himalayan orogenic system, such as the Eastern Pontides, the Iranian Plateau, and the Himalayan Belt, reinforcing the notion of a subduction-influenced mantle source. These findings increase the comprehension of magma formation in post-collisional settings and offer novel insights into the geodynamic context of the area. This research improves the understanding of post-collisional volcanic systems, their petrogenetic evolution, and their role in regional tectonic processes. Full article
(This article belongs to the Section Mineral Geochemistry and Geochronology)
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50 pages, 16665 KB  
Review
Geology, Mineralization and Development Potential of Rare and Uncommon Earth Ore Deposits in Southwest China
by Nan Ju, Gao Yang, Dongfang Zhao, Yue Wu, Bo Liu, Pengge Zhang, Xin Liu, Lu Shi, Yuhui Feng, Zhonghai Zhao, Yunsheng Ren, Hui Wang, Qun Yang, Zhenming Sun and Suiliang Dong
Minerals 2025, 15(5), 459; https://doi.org/10.3390/min15050459 - 28 Apr 2025
Cited by 2 | Viewed by 3531
Abstract
The southwestern region of China is tectonically situated within the Tethyan tectonic domain, with the eastern part comprising the Upper Yangtze Block, while the western orogenic belt forms the main part of the Tibetan Plateau. This belt was formed by the subduction of [...] Read more.
The southwestern region of China is tectonically situated within the Tethyan tectonic domain, with the eastern part comprising the Upper Yangtze Block, while the western orogenic belt forms the main part of the Tibetan Plateau. This belt was formed by the subduction of the Paleo-Tethys Ocean and subsequent arc-continent collision, and was later further modified by the India-Asia collision, resulting in complex geological structures such as the Hengduan Mountains. The lithostratigraphy in this region can be divided into six independent units. In terms of mineralization, the area encompasses two first-order metallogenic domains: the Tethyan-Himalayan and the Circum-Pacific. This study synthesizes extensive previous research to systematically investigate representative rare earth element (REE) deposits (e.g., Muchuan and Maoniuping in Sichuan; the Xinhua deposit in Guizhou; the Lincang deposit in Yunnan). Through comparative analysis of regional tectonic-metallogenic settings, we demonstrate that REE distribution in Southwest China is fundamentally controlled by Tethyan tectonic evolution: sedimentary-weathered types dominate in the east, while orogenic magmatism-related types prevail in the west. These findings reveal critical metallogenic patterns, establishing a foundation for cross-regional resource assessment and exploration targeting. The region hosts 32 identified REE occurrences, predominantly light REE (LREE)-enriched, genetically classified as endogenic, exogenic, and metamorphic deposit types. Metallogenic epochs include Precambrian, Paleozoic, and Mesozoic-Cenozoic periods, with the latter being most REE-relevant. Six prospective exploration areas are delineated: Mianning-Dechang, Weining-Zhijin, Long’an, Simao Adebo, Shuiqiao, and the eastern Yunnan-western Guizhou sedimentary-type district. Notably, the discovery of paleo-weathering crust-sedimentary-clay type REE deposits in eastern Yunnan-western Guizhou significantly expands regional exploration potential, opening new avenues for future resource development. Full article
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15 pages, 5625 KB  
Article
Pan-African and Early Paleozoic Orogenic Events in Southern Tibet: Evidence from Geochronology and Geochemistry of the Kangbuzhenri Gneissic Granite in the Zhegu Area
by Ming Cheng, Xuming Hu, Yao Tang, Zhao Deng, Yingzi Min, Shiyi Chen, Saijun Sun and Huanzhan Zhou
Minerals 2024, 14(8), 845; https://doi.org/10.3390/min14080845 - 22 Aug 2024
Cited by 5 | Viewed by 1766
Abstract
The Zhegu area in southern Tibet is situated in the central and eastern part of the Tethys Himalayan tectonic belt, with the Kangbuzhenri area being abundant in gneissic granites. This study examines the petrology, chronology, and geochemistry of the Kangbuzhenri gneissic granite, providing [...] Read more.
The Zhegu area in southern Tibet is situated in the central and eastern part of the Tethys Himalayan tectonic belt, with the Kangbuzhenri area being abundant in gneissic granites. This study examines the petrology, chronology, and geochemistry of the Kangbuzhenri gneissic granite, providing insights into its Pan-African and Early Paleozoic geological evolution. The zircon U-Pb chronology indicates an upper intercept age of ~539 Ma, reflecting Pan-African orogenic events in the eastern part of the Tethys Himalayan tectonic belt, and a lower intercept age of ~144 Ma, representing a late tectonic–thermal event. Geochemically, the gneissic granites are calc-alkaline peraluminous rocks with high SiO2 and Al2O3 contents and low TiO2, P2O5, MgO, and FeOT contents. The gneissic granites are enriched in LREE and LILEs (Rb, Pb, Th, U, etc.), but relatively depleted in HREE and HFSEs (Nb, Ti, P, etc.). Most of them show a weak negative δEu anomaly, except for two samples which show a significant negative δEu anomaly due to the crystallization of plagioclase. Based on the above study, most of the gneissic granites exhibited the characteristics of an I-type granite, while two of the samples were a highly differentiated I-type granite with S-type affinities. All the above characteristics indicate that the gneissic granite likely originated from the partial melting of crustal materials and sediments with a minor involvement of mantle-derived materials. Combined with the previous chronological studies, the Kangbuzhenri gneissic granites were formed in an extensional tectonic environment during post-collision orogeny and then they were influenced by the Kerguelen mantle plume tectonic–thermal event around ~144 Ma and the subsequent Southern Tibet Detachment System (STDS). Full article
(This article belongs to the Section Mineral Geochemistry and Geochronology)
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22 pages, 8347 KB  
Article
Geochronology, Geochemistry, and In Situ Sr-Nd-Hf Isotopic Compositions of a Tourmaline-Bearing Leucogranite in Eastern Tethyan Himalaya: Implications for Tectonic Setting and Rare Metal Mineralization
by Yangchen Drolma, Kaijun Li, Yubin Li, Jinshu Zhang, Chengye Yang, Gen Zhang, Ruoming Li and Duo Liu
Minerals 2024, 14(8), 755; https://doi.org/10.3390/min14080755 - 26 Jul 2024
Cited by 1 | Viewed by 2086
Abstract
Himalayan leucogranite is an excellent target for understanding the orogenic process of the India–Asia collision, but its origin and tectonic significance are still under debate. An integrated study of geochronology, geochemistry, and in situ Sr-Nd-Hf isotopes was conducted for a tourmaline-bearing leucogranite in [...] Read more.
Himalayan leucogranite is an excellent target for understanding the orogenic process of the India–Asia collision, but its origin and tectonic significance are still under debate. An integrated study of geochronology, geochemistry, and in situ Sr-Nd-Hf isotopes was conducted for a tourmaline-bearing leucogranite in the eastern Tethyan Himalaya using LA-ICP-MS, X-ray fluorescence spectroscopy, and ICP-MS and LA-MC-ICP-MS, respectively. LA-ICP-MS U-Pb dating of zircon and monazite showed that it was emplaced at ~19 Ma. The leucogranite had high SiO2 and Al2O3 contents ranging from 73.16 to 73.99 wt.% and 15.05 to 15.24 wt.%, respectively. It was characterized by a high aluminum saturation index (1.14–1.19) and Rb/Sr ratio (3.58–6.35), which is characteristic of S-type granite. The leucogranite was enriched in light rare-earth elements (LREEs; e.g., La and Ce) and large ion lithophile elements (LILEs; e.g., Rb, K, and Pb) and depleted in heavy rare-earth elements (e.g., Tm, Yb, and Lu) and high field strength elements (HFSEs; e.g., Nb, Zr, and Ti). It was characterized by high I Sr (t) (0.7268–0.7281) and low ε Nd (t) (−14.6 to −13.2) and ε Hf (t) (−12.6 to −9.47), which was consistent with the isotopic characteristics of the Higher Himalayan Sequence. Petrogenetically, the origin of the leucogranite is best explained by the decompression-induced muscovite dehydration melting of an ancient metapelitic source within the Higher Himalayan Sequence during regional extension due to the movement of the South Tibetan Detachment System (STDS). The significantly high lithium and beryllium contents of the leucogranite and associated pegmatite suggest that Himalayan leucogranites possess huge potential for lithium and beryllium exploration. Full article
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14 pages, 12256 KB  
Article
Genesis of Gypsum/Anhydrite in the World-Class Jinding Zn-Pb Deposit, SW China: Constraints from Field Mapping, Petrography, and S-O-Sr Isotope Geochemistry
by Gang Huang, Yu-Cai Song, Liang-Liang Zhuang, Chuan-Dong Xue, Li-Dan Tian and Wei Wu
Minerals 2024, 14(6), 564; https://doi.org/10.3390/min14060564 - 29 May 2024
Cited by 2 | Viewed by 2337
Abstract
The world-class Jinding deposit in SW China has ~15 Mt of Zn and Pb metals combined, in an evaporite dome containing amounts of gypsum/anhydrite. These gypsum and anhydrite are mainly located in limestone breccias (Member I), gypsum-bearing complexes (Member III), and red mélange, [...] Read more.
The world-class Jinding deposit in SW China has ~15 Mt of Zn and Pb metals combined, in an evaporite dome containing amounts of gypsum/anhydrite. These gypsum and anhydrite are mainly located in limestone breccias (Member I), gypsum-bearing complexes (Member III), and red mélange, with some occurring as veins in clast-free sandstone (Member IV) and as fractures/vugs of host rock. The gypsum/anhydrite and dome genesis remain equivocal. The gypsum in limestone breccias and in red mélange with flow texture contains numerous Late Triassic Sanhedong limestone fragments. The δ34S (14.1%–17%), δ18O (9.7%–14.6%), and 87Sr/86Sr ratios (0.706913–0.708711) of these gypsum are close to the S-O-Sr isotopes of the Upper Triassic Sanhedong Formation anhydrite in the Lanping Basin (δ34S = 15.2%–15.9%, δ18O = 10.9%–13.1%, 87Sr/86Sr = 0.707541–0.707967), and are inconsistent with the Paleocene Yunlong Formation gypsum in the Lanping Basin (87Sr/86Sr = 0.709406–0.709845), indicating that these gypsum were derived from the Upper Triassic Sanhedong Formation evaporite but not from the Paleocene Yunlong Formation, and formed as a result of evaporite diapirism. The δ34S (14.3%–14.5%), δ18O (10.1%–10.3%), and 87Sr/86Sr ratios (0.709503–0.709725) of gypsum as gypsum–sand mixtures in gypsum-bearing complexes are similar to the 87Sr/86Sr ratios of gypsum in the Yunlong Formation of the Lanping Basin and Cenozoic basins in the northern part of the Himalayan–Tibetan orogen, suggesting that the material source of this gypsum was derived from the Yunlong Formation, and formed as a result of gypsum–sand diapirism. The gypsum veins in clast-free pillow-shaped mineralized sandstone and the gypsum in host rock fractures and vugs formed after the supergene minerals such as smithsonite. The δ34S (−16.3%~−12.7%) and δ18O (−9.8%~−4.7%) of this gypsum indicate that the gypsum is of supergene origin with sulfate derived from the reoxidation of reduced sulfur. We confirmed that the Jinding dome is genetically related to diapir of the Late-Triassic Sanhedong Formation evaporite. Clast-free sandstone and gypsum-bearing complexes in the dome were produced by diapir of the Paleocene Yunlong Formation unconsolidated gypsum–sand mixtures. Full article
(This article belongs to the Special Issue Ag-Pb-Zn Deposits: Geology and Geochemistry)
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20 pages, 16060 KB  
Article
Distribution of Active Faults and Lithospheric Discontinuities in the Himalayan-Tibetan Orogenic Zone Identified by Multiscale Gravity Analysis
by Xiaolong Wu, Jifeng Wu, Yang Xiang and Muhammad Sohail Khan
Appl. Sci. 2023, 13(18), 10101; https://doi.org/10.3390/app131810101 - 7 Sep 2023
Viewed by 1818
Abstract
The lithospheric structure of the Tibetan Plateau and its adjacent area is a hot topic in geodynamic research. It is important to reveal the mechanism of crustal deformation and tectonic evolution of the study area. In this study, the techniques of wavelet multiscale [...] Read more.
The lithospheric structure of the Tibetan Plateau and its adjacent area is a hot topic in geodynamic research. It is important to reveal the mechanism of crustal deformation and tectonic evolution of the study area. In this study, the techniques of wavelet multiscale decomposition and field edge detection were used to study the discontinuities of the lithosphere revealed by multilevel Bouguer gravity anomalies. Specifically, we evaluated the depth characteristics of the major active faults in the study area and identified 15 deep major faults that cut through the lithosphere. They are Chaman fault, Shyok suture zone, Altyn-Tagh fault, Karakash fault, Karakoram fault, Talas-Fergana fault, Kashgarr-Yeshgar transfer system, Rushan-Pshart suture zone, Sangri-Nacuo fault, Main Frontal thrust, Burmese fold belt, Yadong-Gulu fault, Gaoligong fault, Sagaing fault and Nujiang fault. We have also elucidated the tectonic mechanisms of two famous geodynamic phenomena in the Pamir Plateau. The first is the intense intermediate depth seismicity beneath Pamir-Hindukush. It cannot simply be described as the rupture of a subducted residual plate, which could be divided into two distinct tectonic units. One belongs to the Indian plate, the other to the Eurasian plate. Secondly, the mechanism of intense seismicity confined to the western upper crust of the Pamir Plateau could be explained as significant fragmentation of crustal material. Finally, and most importantly, we summarized the coupling mechanism between deep geodynamics and horizontal deformation as observed by modern geodetic techniques. In the upper mantle, the leading edge of the subducting Indian plate reached the SW boundary of Tarim basin and forms a closed structure in western Himalaya. Then, the Tibetan Plateau underwent a tectonic escape towards the east under the continuous compression between the Indian and Eurasian plates. During the process of tectonic escape, the role of the N–S direction normal faults in the Himalayan tectonic zone is limited. Full article
(This article belongs to the Section Civil Engineering)
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20 pages, 10829 KB  
Article
Hydrochemistry of the Geothermal in Gonghe Basin, Northeastern Tibetan Plateau: Implications for Hydro-Circulation and the Geothermal System
by Shasha Liu, Xianchun Tang, Xiaomeng Han, Dailei Zhang and Guiling Wang
Water 2023, 15(11), 1971; https://doi.org/10.3390/w15111971 - 23 May 2023
Cited by 7 | Viewed by 2567
Abstract
The existence of high-temperature geothermal anomalies in the Gonghe Basin on the northeastern margin of the Tibetan Plateau has highlighted a new perspective on the geothermal system of the Himalayan-Tibetan Plateau orogen. In this study, we collected 32 groups of liquid and gas [...] Read more.
The existence of high-temperature geothermal anomalies in the Gonghe Basin on the northeastern margin of the Tibetan Plateau has highlighted a new perspective on the geothermal system of the Himalayan-Tibetan Plateau orogen. In this study, we collected 32 groups of liquid and gas samples from geothermal water, rivers, and boreholes in the Gonghe basin to analyze hydrochemistry, stable isotopes, and geochronology, which allow us to further reveal the geothermal fluid circulations of geothermal reservoirs. The ion contents of liquids identify two distinguished types of water, namely the Na-SO4-Cl type primarily from geothermal water and the Na-SO4-HCO3 and Na-Ca-CO3-SO4 types primarily from cold water. The compositions of the hydrogen and oxygen isotopes of the samples indicate geothermal waters were recharged by atmospheric precipitation and 3000–4600 m high snow mountain meltwater, which may have experienced circulation of 16,300–17,300 years and mixtures of submodern and recent recharge water sources evidenced by isotopes of 3H, 13C, and 14C data. The 3He/4He ratios of these geothermal waters varying from 0.03 to 0.84 Ra further highlighted a crustal-dominated heat source in the region. The deep thermal reservoir temperature in the Gonghe Basin at 160 ± 10 °C and the depth of circulation of geothermal water is 2200–2500 m. Based on this evidence, we have established a geothermal fluid circulation model and refined the exchange processes of fluids and geothermal heat, further enriching the details of the geothermal system in Gonghe Basin. Full article
(This article belongs to the Special Issue Hydrochemical Characteristics of Geothermal Water)
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24 pages, 7566 KB  
Article
Petrogenesis of Early Cenozoic Sarıcakaya–Nallıhan Volcanism in NW Turkey: Implications for the Geodynamic Setting and Source Characterization of the Balkanatolia Magmatic Realm
by Gönenç Göçmengil, Fatma Gülmez, Zekiye Karacik and Namık Aysal
Minerals 2022, 12(12), 1572; https://doi.org/10.3390/min12121572 - 7 Dec 2022
Cited by 4 | Viewed by 2406
Abstract
Sarıcakaya–Nallıhan Volcanism was generated within the Balkanatolia Magmatic Realm between 48 and 44 Ma (by 40Ar–39Ar age determination) and is represented by three different volcanic units all displaying subduction-related geochemical signatures, such as depletion in HFSE and enrichment in LREE [...] Read more.
Sarıcakaya–Nallıhan Volcanism was generated within the Balkanatolia Magmatic Realm between 48 and 44 Ma (by 40Ar–39Ar age determination) and is represented by three different volcanic units all displaying subduction-related geochemical signatures, such as depletion in HFSE and enrichment in LREE and LILE. The first unit (V1) consists of nepheline-normative, olivine basalts with OIB-like affinity. The second (V2) and third (V3) units are represented by more evolved compositions such as basaltic-andesitic, andesitic, and dacitic-rhyolitic lavas. Even the most basic lavas have elevated Mg# values (62–69), and they are far from representing the true mantle melts. Source characterization of Sarıcakaya–Nallıhan Volcanism reveals that there might be two possible mantle sources for the primary melts of the lavas: (i) metasomatized peridotitic mantle fluxed by sedimentary melts, or (ii) accreted mélange. The direct melting of the mélange-like lithologies is a more favorable mechanism for the Middle Eocene (44–40 Ma) magmatism in Balkanatolia since the Hf–Nd trace element, Nd isotopic systematics and petrological modelling efforts supported the latter. Overall, Early Cenozoic magmatism within this realm was characterized, first (58–44 Ma) by contractional and later (44–40 Ma) by extensional tectonics and the late-stage magmatic phase in the area was possibly controlled by melting of accreted mélange-like lithologies. The presented data indicate that mélange melting might be much more common than envisaged for the magmatism in the Alpine–Himalayan orogenic belt. Full article
(This article belongs to the Section Mineral Geochemistry and Geochronology)
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