Volcanic Rocks Research Articles

Geochemistry of magnetite from Fe-skarn deposits along the central Loei Fold Belt, Thailand

Abstract Fe-deposits in Thailand are mostly located along the Loei Fold Belt in Central Thailand. The study areas, Khao Lek (KL) and Khao Thab Kwai (KTK), have Fe-deposits hosted in contact metamorphized Permian limestone and Permo-Triassic volcanic rocks. Magnetite forms over a wide range of geological conditions and incorporates various trace elements into its cubic spinel structure. The KL and KTK Fe-skarn deposits are mainly composed of massive magnetite. The main discriminator elements for magnetite are characterized by the distribution of Mg, Al, Si, Ca, Ti, V, Cr, Mn, Co, Ni, and Cu. Thus, this study focused on the chemical characteristics of magnetite to identify the origins of the iron ore deposits. This study investigated the trace element chemistry of the magnetite using laser ablation inductively coupled plasma mass spectrometry. The high Ca + Al + Mn and low Ti + V and Ni/Cr + Mn contents of hydrothermal magnetite in the KL and KTK deposits support a typical skarn origin, and the textural and trace element features of the KL and KTK magnetite are analogous to those of typical calcic-Fe skarn deposits worldwide.

Petrogenesis of volcanic rocks from the Quaternary Eifel volcanic fields, Germany: detailed insights from combined trace-element and Sr–Nd–Hf–Pb–Os isotope data

Quaternary rocks from the East and West Eifel volcanic fields in western Germany are a key suite of intraplate volcanic rocks that can provide insights into volcanism of the Central European Volcanic Province (CEVP) and into continental intraplate volcanism in general. We present a comprehensive dataset for Eifel lavas including isotope as well as major and trace element data for 59 samples covering representative compositions of the different volcanic fields. In line with previous studies, the lavas are all SiO2-undersaturated, alkaline-rich and mainly comprise primitive basanites, melilitites, and nephelinites (Mg# ≥ 57). Geochemical compositions of samples from both volcanic subfields display distinct differences in their trace-element as well as radiogenic isotope compositions, largely confirming previous subdivisions. Coupled trace-element and radiogenic Sr–Nd–Hf–Pb–Os isotope compositions can now provide firm evidence for spatially heterogeneous mantle sources and compositionally distinct magmatic pulses. Within the West Eifel Field, Sr–Nd–Pb isotope compositions of the younger (≤80 ka), ONB-suite (olivine-nephelinite-basanite) are similar to FOZO (FOcal ZOne) or the EAR (European Asthenospheric Reservoir) and resemble compositions that have been previously reported from plume-sourced ocean island basalts (OIB). In marked difference, older (700 Ma to 80 ka) volcanic rocks from the F-suite (Foidite) in the West Eifel field and from the entire east Eifel Field tap a more enriched mantle component, as illustrated by more radiogenic Sr isotope (86Sr/87Sr up to 0.705408) and variable Pb isotope compositions (206Pb/204Pb = 18.61–19.70, 207Pb/204Pb = 15.62–15.67 and 208Pb/204Pb = 38.89–39.76). Combined trace-element compositions of ONB-suite samples are in good agreement with results from batch melting models suggesting a hybrid composition of Eifel magmas formed through mixing 10% of a FOZO-like melt with 90% of a DMM-like melt, similar to melts from the Tertiary HEVF. However, radiogenic Sr–Nd–Pb isotope compositions of F-suite and EEVF and some ONB lavas require the admixture of melts from lithospheric mantle sources. Elevated Nb/Ta and Lu/Hf ratios in combination with variable 187Os/188Os ratios can now demonstrate the presence of residual carbonated eclogite components, either in the lithosphere or in the asthenospheric mantle. Finally, by combining geochemical and temporal constraints of Tertiary and Quaternary volcanism it becomes evident that CEVP volcanism in central and western Germany has resulted from compositionally distinct magmatic pulses that tap separate mantle sources. Although the presence of a mantle plume can neither be fully confirmed nor excluded, plume-like melt pulses which partially tap carbonated eclogite domains that interact to variable extents with the lithosphere provide a viable explanation for the temporal and compositional cyclicity of CEVP volcanism.

Fluid‐rock interaction experiments with andesite at 100°C for potential carbon storage in geothermal reservoirs

AbstractGeothermal energy extraction often results in the release of naturally occurring carbon dioxide (CO2) as a byproduct. Research on carbon storage using volcanic rock types other than basalt under both acidic and elevated temperature conditions has been limited so far. Our study uses batch reactor experiments at 100°C to investigate the dissolution of andesite rock samples obtained from an active geothermal reservoir in Sumatra (Indonesia). The samples are subjected to reactions with neutral‐pH fluids and acidic fluids, mimicking the geochemical responses upon reinjection of geothermal fluids, either without or with dissolved acidic gases, respectively. Chemical elemental analysis reveals the release of Ca2+ ions into the fluids through the dissolution of feldspar. The overall dissolution rate of the rock samples is 2.4 × 10–11 mol/(m2 · s) to 4.2 × 10–11 mol/(m2 · s), based on the Si release during the initial 7 h of the experiment. The dissolution rates are about two orders of magnitude lower than those reported for basaltic rocks under similar reaction conditions. This study offers valuable insights into the potential utilization of andesite reservoirs for effective CO2 storage via mineralization.

Evidence of a Low‐Velocity Zone in the Upper Mantle Beneath Cumbre Vieja Volcano (Canary Islands) Through Receiver Functions Analysis

AbstractOceanic volcanic islands have a complex internal structure due to their geological evolution. La Palma is the second youngest in the Canary Islands. Historical eruptions occurred in the Cumbre Vieja (CV) volcanic system, including the last 2021 Tajogaite eruption. The seismicity before, during, and after the Tajogaite eruption provides valuable information for a better understanding of deep volcanic processes. We applied the receiver function technique to image the crustal and upper mantle structures beneath the CV volcanic complex. We investigated the first 50 km of the lithosphere, identifying various seismic discontinuities. After a thin layer of recent volcanic rocks, we found a layer corresponding to the old oceanic crust. Beneath the Moho, we found a significant decrease in the seismic velocities until about 37 km of depth. This low‐velocity layer corresponds to a zone of partial melting with interconnected magmatic chambers that feed the volcanic activity in CV.

Stratigraphic and U-Pb zircon age constraints on the timing of the Yanliao Biota in northern China

The Yanliao Biota from northern China is one of the most famous Mesozoic terrestrial lagerstätten in the world, with well-preserved fossil records in the Jurassic volcanic-sedimentary Ningcheng and Jianchang basins. However, the temporal evolution of the Yanliao Biota remains controversial, mainly due to the confusing stratigraphic framework and the unclear age of fossiliferous deposits in the Ningcheng basin. To address this issue, we carried out detailed field investigations and secondary ion mass spectrometry (SIMS) U-Pb age dating of zircons on fossiliferous and related strata in the southern part of the Ningcheng basin. The Jurassic infill of this area is composed of, in ascending order, fossil-bearing tuffaceous clastic rocks (unit 1), andesite and pyroclastic rocks (unit 2), fossil-bearing clastic rocks interlayered with minor volcanic rocks (unit 3), and andesite and pyroclastic rocks (unit 4). Integration of stratigraphic and geochronological data indicates that the Yanliao Biota in the Ningcheng basin appeared no later than ca. 163 Ma and lasted until ca. 156 Ma. A comparison with other analogous basins in northern China (e.g., the Luanping, Jianchang, and Beipiao basins) leads to the conclusion that the Yanliao Biota evolved in two phases and lasted for more than 11 m.y.: the first phase from ca. 167 Ma to ca. 163 Ma in the middle Bathonian to middle Callovian, followed by the second phase between ca. 161 Ma and ca. 156 Ma in the lower and middle Oxfordian.

Taraxacum sect. Erythrosperma (Asteraceae, Cichorioideae) in Slovakia IV. Distribution of T. erythrospermum and synonymisation of T. slovacum

The group of lesser dandelions (Taraxacum sect. Erythrosperma) is represented by more than 215 species growing in mostly xerothermic habitats throughout Europe. The only known species with sexual reproduction in this section is the diploid T. erythrospermum. It occurs in southern parts of Europe and reaches its northern limit in central Europe. In this study, we aimed at a detailed mapping of the species distribution in Slovakia in order to understand the spatial distribution at its northern range limits. We found that it is the most common xerothermous species in Slovakia, growing on various substrates such as limestone, dolomite, travertine, volcanic rocks and sands, while it is less common on brown soils and ruderal biotopes. It is a characteristic species of the class Festuco-Brometea with an altitudinal range extending from 120 to 650 m above sea level. We delimited the northern distribution and documented its highest occurrence at approximately ca 1500 m a.s.l. Two taxa, T. slovacum and T. punctatum, were described from the territory of Slovakia and we discuss their relationships to T. erythrospermum, with which T. slovacum is synonymised here for the first time. We also present new data on the genome size of T. erythrospermum in Slovakia, which range from 1.529 to 1.604 pg with a mean of 1.554 pg (± 0.024 SD), and provide chorological data on a remarkable morphological variant with grey-coloured achenes.

Eocene mafic alkaline volcanism in north Central Iran; Signatures of development and subsequent melting of a pyroxenite mantle source

Volcanic rocks from the Miami-Davarzan area are basalts to trachyandesites interlayered with fossiliferous beds and bear significant implications on the Eocene geodynamic evolution of northern central Iran. The rocks constitute two distinct groups, a low-Nb and a high-Nb suite. The least evolved low-Nb suite includes clinopyroxene-olivine phyric samples and is characterized by higher CaO and lower Al2O3 as compared to peridotite partial melts. The high-Nb suite includes more evolved plagioclase-clinopyroxene phyric samples. Fractional crystallization modeling using least-squares mass balance calculations for major elements suggests that the high-Nb suite was formed from a low-Nb parental melt by differentiation of a clinopyroxene-dominated mineral assemblage. The Miami-Davarzan volcanic rocks are characterized by significant large ion lithophile elements (LILE) and light rare earth elements (LREE) enrichment and high field strength elements (HFSE) depletion, which are typical signatures of subduction-related settings. Immobile, highly to moderately incompatible elements such as NbTa, LaCe, PrNd are higher in the Miami-Davarzan volcanic rocks as compared to the typical magmatic arcs, which is an indication of slab melt involvement and metasomatism of the mantle source. The Sr-Nd-Pb isotopic data also confirm a common mantle source involving the addition of subducted sediments into a depleted mantle source for both the low-Nb and high-Nb suites. The geochemical characteristics such as high CaO, low Al2O3, and the isotopic data can be best explained by derivation of the low-Nb suite parental melt from a pyroxenite mantle source. The pyroxenite mantle source was probably developed as a result of interaction between shallow depleted mantle and slab plus sediment-derived melts. It is suggested that the extensional phase that dominated the northern central Iran during the Eocene prompted partial melting of a pyroxenite mantle source.

Study on Rock Mechanical Properties of Deep Volcanic Rock Reservoir

Volcanic rocks exhibit complex mechanical properties due to their special diagenetic forms. Laboratory tests were conducted to study the influence of confining pressure changes on the mechanical properties of deep volcanic rocks, and outcrop volcanic rocks single triaxial tests were conducted simultaneously to study the mechanical properties of deep volcanic rocks. The maximum deviatoric stress and elastic modulus are used to study the variation of mechanical properties of volcanic rocks with confining pressure. The maximum deviatoric stress of underground core increases linearly with the increase of confining pressure. The elastic modulus reaches its maximum at 80MPa confining pressure. Although the variation trend of mechanical parameters of underground core with confining pressure is similar to that of outcrop core with confining pressure, the underground core shows a larger maximum deviatoric stress and elastic modulus. It can be seen from the 80MPa confining pressure comparison test that the mechanical properties of underground core under high confining pressure are superior to those of outcrop core. The mechanical properties of outcrop core under high confining pressure are significantly affected by natural fractures, while the mechanical properties of underground core are less affected by natural fractures.The brittleness index of volcanic rocks decreases with the increase of confining pressure, and the decreasing range is relatively low. The brittleness index of outcrop volcanic rocks decreases with the increase of confining pressure, but its sensitivity to confining pressure is much higher than that of underground core.

Quantitative characterization and fracture morphology in reservoirs with various lithologies: An experimental investigation

Accurately quantifying the development of hydraulic fractures is pivotal for further elucidating the relationship between reservoir physical properties and hydraulic fracture propagation. In this research, we centered on reservoirs featuring diverse lithologies, procured downhole full-diameter cores, conducted triaxial hydraulic fracturing experiments, and employed CT scanning and electron microscopy to characterize fracture morphology. The primary findings are summarized as follows: sandstones specimens typically exhibit bi-wing fractures inclined at a certain angle to σH, with internal microfractures predominantly comprised of corrugated shear fractures traversing mineral grains. Conversely, conglomerate specimens display a higher prevalence of branching fractures, with fracture zones forming in areas of gravel densities and weak heterogeneous matrices, along with the development of multiple microfractures. Volcanic rock specimens fractures primarily propagate via deflection following NF activation, showcasing two modes of microfracture propagation: through and alongside the NF. Quantitative parameters of fracture morphology indicate that the fractal dimension ranges from 2.02 to 2.08 for sandstone fractures, 2.19 to 2.22 for conglomerate fractures, and 2.11 to 2.13 for volcanic rock fractures. Notably, the NF filler in volcanic rock undergoes erosion by fracturing fluid, accumulating non-uniformly on the surface of rock crystals, thereby augmenting fracture tortuosity. Additionally, the fracture surface area of conglomerates surpasses that of sandstones and volcanic rocks by 1.3 times, with the stripping rate of conglomerate fracture surfaces exceeding 10%. Furthermore, the average normal width of conglomerate fractures surpasses 2 mm, whereas volcanic rock and sandstone measure 1.6 mm and 1.1 mm, respectively. Notably, sandstone fractures exhibit uniform normal width distribution, while conglomerate fractures, especially those around gravels and eroded by fracturing fluid, manifest larger widths. Moreover, NF influenced volcanic rock fractures also exhibit wider widths. Elucidating the quantitative attributes of fracture morphology in lithologically diverse reservoirs holds significant implications for formulating hydraulic fracturing and targeted optimization strategies aimed at enhancing fracturing efficacy.

The superiority of hydrophilic polyurethane in comammox-dominant ammonia oxidation during low-strength wastewater treatment

Carriers have been extensively employed to enhance nitrification performance during low-strength wastewater treatment by retaining slow-growing ammonia oxidizing microorganisms (AOMs). Still, there is a dearth of systematic understanding of biofilm properties and microbial community structure formed on different carriers. In this study, hydrophilic polyurethane foam (PUF) carriers were prepared and compared with five widely used commercial carriers, namely Kaldness 3, Biochip, activated carbon, volcanic rock, and zeolite. The results indicated that the biofilms formed on carriers enhanced microbial ammonia oxidation activity. Additionally, the biofilm developed on the PUF demonstrated the most superior performance among all selected carriers, not only exhibiting the highest abundant and the most active AOMs, with amoA gene abundance of 1.41 × 1013 copies/m3 and specific ammonia oxidation rate of 9.84 g NH+ 4-N/(m3 × h), but also possessing a compact structure, with 3.41 kg VSS/m3 and 46.83 mg extracellular polymeric substances/g VSS. The high-throughput sequencing analysis revealed that the comammox (CMX) Nitrospira dominated on biofilm due to the intrinsically low apparent half-saturation constant for substrate. A unique ecological community structure was established on PUF, characterized by low species diversity and high homogeneity in alignment with community characteristics of CMX. The biofilms on PUF contributed to the proliferation of CMX Nitrospira dominated by Nitrospira nitrosa, achieving the highest proportion among colonial three AOMs at 86.58 %. The appropriate average pore size, superior hydrophilicity, and large specific surface area of PUF carriers provided a robust foundation for the exceptional ammonia oxidation performance of the formed biofilms.

A Quantitative Provenance Analysis (QPA) Approach to Quantify Controls on Sediment Generation and Sediment Flux in the Upper Reaches of the Magdalena River (Colombia): 2. Lithological Control on Contribution to Silt‐ to Clay‐Sized Fractions

AbstractThe composition of 27 fluvial silt and clay sediments was used in this study to identify and quantify the processes in the upper valley of the Magdalena river in South Colombia. The combination of seismic activity, intense precipitation, and landsliding resulted in limited chemical weathering and a very efficient transfer of weathered products to the transfer zone of both tributary rivers and the main trunk. Inputs from plutonic, high‐grade metamorphic, volcanic, and low‐ to medium‐grade metamorphic lithologies vary in coarse silt‐sized versus fine silt‐ and clay‐sized sediments, reflecting inherited textural parameters and mineralogy. Plutonic and high‐grade metamorphic rocks mostly produce sand‐sized sediments, up to two times more than coase silt and up to 10 times more than fine silt to clay. The prevalence of siltstone in the area enhances the contribution of sedimentary rocks to fine silt and clay (up to 50% higher than to sand). Volcanic rocks mainly produce coarse silt (up to 2.5 times more than sand). Low‐grade metamorphic detritus is enriched in silt and clay (up to 5–7 times). These findings highlight the critical role of lithology in regulating sediment generation. The study's approach can establish or modify factors modeling lithological control on suspended sediment flux, such as in the BQART equation.

Oligocene to Miocene magmatic and hydrothermal evolution in the Maricunga belt (Región de Copiapó, Chile): A new look to a long known metallogenic belt

The Maricunga metallogenic belt, herein defined to encompass the region from 25° S to 28° S along the Cordillera Frontal of northern Chile, is known for hosting a series of gold-copper and lesser copper-molybdenum porphyries and gold-silver epithermal systems that are hosted in a segment of the late Oligocene-Miocene Andean calc-alkaline magmatic arc. Based on an up-to-date geochronological database, four episodes of magmatism and related hydrothermal deposits are proposed to characterize intensity and style of volcanism and hypabyssal intrusive rocks over time. The late Oligocene episode (26-21 Ma) is characterized by stratovolcanoes, dome complexes, pyroclastic sequences, and hypabyssal intrusives of andesitic to dacitic composition that host gold-rich porphyry systems such as Caspiche, Maricunga, and La Pepa. The early Miocene episode (21 to 17 Ma) has similar rock types but is volumetrically reduced, hosting epithermal and porphyry deposits like La Coipa and Caserones, respectively. A reinvigoration of volcanism occurred during the third stage between 17 and 11 Ma, giving rise to large volcanic complexes and intra- to extra-caldera ignimbritic deposits that host several gold-rich porphyry deposits such as Lobo-Marte, Luciano, and Cerro Casale; as well as epithermal deposits such as Fenix. Some of the 17 to 11 Ma and younger igneous rock belong to the high-K calc-alkaline series, showing a higher alkali content compared to previous periods. The last magmatic episode, from 11 to 5 Ma, coincides with the shallowing of the subduction angle and is characterized by an eastward migration of volcanism, and more heterogeneous rocks including trachytic compositions. During this period mineralization was emplaced at the Salares Norte epithermal deposit and El Volcan porphyry Au-Cu deposit.Porphyry and epithermal systems formed throughout the evolution of the Maricunga belt. Overprint of advanced argillic alteration on porphyry style alteration is widespread albeit commonly devoid of significant addition of epithermal Au-Ag mineralization. The Au-rich nature of the majority of the porphyry systems is attributed to the shallow crustal depths of emplacement compared to Cu- and Mo-rich porphyry systems. Conversely, high-sulfidation epithermal Au-Ag deposits such as La Coipa and Nueva Esperanza are not known to be telescoped on coeval porphyry gold deposits.The location of the mineralized centers was favored by crustal weaknesses expressed by intersection of oblique- and parallel-to arc structures, the former inherited from the construction of the continent before to the formation of the Andean range. The arc oblique structures also segment the Maricunga belt into domains with unique magmatic and hydrothermal styles.

Groundwater potential identification using electrical resistivity tomography method in Sendangrejo Village, Minggir District, Sleman Regency, Special Region of Yogyakarta

Groundwater is vital element for living. One of methods to identify groundwater potential is Electricity Resistivity Tomography (ERT). This study aims to identify the groundwater potential occurrence in Sleman, Yogyakarta through non-destructive geoelectrical surveys. Based on the ERT models and geological information, supported by hydrogeological data in the research area, drilling a well at the planned location was deemed necessary to reach a depth of at least 100 to 250 meters in order to tap into the maximum groundwater potential. Groundwater is predicted to flow and accumulate in the pores and fractures of rocks. Well drilling in the northern part of section line 1 was more favourable and recommended due to the lower elevation compared to the area of section line 2, where the drill location was originally planned at a higher elevation uphill. Layers of hard rock, presumably lava and breccia, have already been found at a depth of 5 to 15 meters based on historical open well excavations around the area. Identifying the characteristics of subsurface volcanic rocks during drilling is suggested to evaluate drilling and well planning. Well logging should be conducted to collect lithostratigraphy and rock mass information. Further tests of hydraulic conductivity for each potential layer.

Fluid geochemistry of the Cerro Galán geothermal system (Southern Puna, Argentina): Implications for the geothermal potential of one of the youngest giant calderas in the Andes

The exploration of novel geothermal systems, particularly those promising for electrical power generation, plays a fundamental role in incorporating new renewable sources into the energy matrix. Geothermal systems associated with volcanic calderas are considered ideal targets for exploration. This study focuses on the geochemical features of fluids from the Cerro Galán hydrothermal system, which is hosted within a major resurgent caldera with >3.5 Myr of magmatic evolution situated on the Southern Puna (Central Volcanic Zone of the Andes, NW Argentina). The main aim is constructing the first geochemical conceptual model and provide information on the geothermal potential of this interesting resource. The main hydrothermal reservoir consists of a NaCl aquifer with estimated temperatures up to 187 °C at depth. This reservoir is likely hosted within the fractured pre-caldera basement rocks, mainly including Miocene-Pliocene volcanic rocks and Proterozoic-Cambrian igneous and metamorphic rocks. The confinement of the deep reservoir is attributed to the deposits of the Toconquis Group and Cueva Negra Ignimbrite, along with the basal section of the Cerro Galán Ignimbrite, which exhibit low permeability due to hydrothermal alteration. The presence of a phreatic explosion crater near one of the hot spring-rich areas is likely indicating past over-pressurization of the hydrothermal aquifer, resulting from efficient sealing. Furthermore, the absence of anomalous soil CO2 flux values on the top of the reservoir, except where the thermal spring discharges are located, can be explained by an effective cap-rock layer. Deep circulation of meteoric water, enriched with atmospheric gases, receives inputs of magmatic fluids (~11% of primordial helium), leading to the development of the hydrothermal NaCl aquifer. However, this deep fluid contribution might be underestimated due to significant crustal assimilation (up to 50%) involved in the magma genesis of the Cerro Galán Volcanic Complex, a process which modifies the He isotopic signature of the magmatic endmember. The hot springs, characterized by high flow rate (up to 459 m3/h) are positioned at the intersection between the caldera margins and the NNE-SSW oriented tectonic structures, suggesting favorable permeability conditions. The preliminary geothermal gradient for the Cerro Galán area is estimated at around 98–101 °C/km. Such a high gradient can be attributed to the considerable heat flux generated by the transcrustal plumbing system of the Cerro Galán caldera, which includes the shallow crystal mush reservoir (<4 km depth). The preliminary geothermal potential of this giant caldera was performed using the volumetric method along with Monte Carlo simulations. The results indicate a probable power production capacity of 2.09 MWe and 10.85 MWe at 90 and 50% confidence level, respectively. The results presented in this work constitute a foundational knowledge base to promote a more advanced exploration phase for the geothermal resource. Additionally to the local energy demand, lithium and other metal mining operations, which are operating independently from the National Interconnected System, could potentially be interested in power generation through binary cycles.

Discovery of Middle Jurassic bimodal volcanic rocks in the Xuanhua district on the northern edge of the North China Craton and their geological significances

Discovery of Middle Jurassic bimodal volcanic rocks in the Xuanhua district on the northern edge of the North China Craton and their geological significances

A Quantitative Provenance Analysis (QPA) Approach to Quantify Controls on Sediment Generation and Sediment Flux in the Upper Reaches of the Magdalena River (Colombia): 1. Natural and Anthropic Controls on the Sand Fraction

AbstractThis study investigates the upper Magdalena river basin (Colombia), which is characterized by tectonic activity, tropical climate, heterogeneous lithological assemblages, and anthropic influence. It aims to comprehend factors controlling sediment generation, flux, and composition by incorporating petrographic data from 27 recent fluvial samples along with geochemistry, geomorphological parameters, historical precipitation, land cover, landsliding and suspended sediment load data. The analysis shows mismatches between sand composition and drainage lithology distribution. A new set of endmember mixing models is presented, quantifying the impacts of erodibility, sand generation potential (related to lithology), and sediment connectivity between hillslopes and river outlets (related to geomorphology). Results show enhanced sediment generation from sedimentary rocks (up to 40%) due to high erodibility, and decreased sediment flux from low‐ to medium‐grade metamorphic rocks (up to 60%) due to controlling morphometric parameters. Overrepresentation of plutonic and high‐grade metamorphic rocks and underrepresentation of volcanic rocks (up to 100%) are controlled by mineralogical and textural parameters. Enhanced landsliding activity in areas with volcanic activity occasionally overshadows basin‐wide compositional trends driven by morphological and lithological characteristics, as it controls rare overrepresentation of volcanic and low‐grade metamorphic detritus in the sand fraction. Sediment retention by hydroelectric dams significantly decreases suspended sediment flux by 30%, while deforestation plays a minor role in sediment flux. This study underscores the importance of coupling sediment generation, geomorphology and the distribution of stochastic events related to seismic activity in any sediment production‐focused study and for developing numerical models in Quantitative Provenance Analysis (QPA).

Petrogenesis and tectonic implications of late Permian andesites from Rongzharinian, northern Qiangtang, Tibet

At convergent margins, high-magnesian andesitic rocks (HMAs) can offer vital information about the formation of the continental crust and the interactions between the deep crust and mantle. This study focuses on new identified HMAs from the Rongzharinian area, northern Qiangtang Terrane (NQT). We report the major, trace elemental, Sr-Nd-Hf isotopic data, and zircon U-Pb age of volcanic rocks with the aim of understanding their petrogenesis and tectonic setting. A concordant age of 257.7 ± 1.5 Ma for the Rongzharinian high-Mg andesites is determined by zircon U-Pb dating using LA-ICP-MS techniques. The Rongzharinian HMAs have high MgO contents (5.88–7.39 wt%), Mg# values (63–68), and Cr (143–185 ppm) and Ni (48–66 ppm) concentrations, close to primitive HMAs. They underwent variable degrees of fractionation of amphibole and minor clinopyroxene and negligible crustal contamination during magma evolution. REE modeling results show that the Rongzharinian HMAs can be generated by 4 %–7% melting of hydrous spinel lherzolite at relatively shallow depths. Geochemical data indicate that the Rongzharinian HMAs were dominantly derived from the mixed mantle wedge source composed of N-MORB-like and E-MORB-like components. Based on the regional tectonic evolution, we propose that the Late Permian rollback of the Paleo-Tethyan slab may induce upwelling of the asthenosphere mantle, resulting in melting of the mantle source and the generation of the Rongzharinian high-Mg andesites.

Identification of spatial clusters of potentially toxic elements in different soil types using unsupervised machine learning and compositional data analysis

Soil health is an important concept and the generation of soil chemical composition data, including potentially toxic elements (PTEs) is one of its conceptual components. This study aims to reveal the spatial distribution patterns of soil PTEs contents, identify their potential sources, and unveil their geochemical associations in Aragatsotn region (Armenia). For that purpose, the contents of Cr, V, Ti, As, Zn, Cu, Co, Fe, Mn, Ba, and Pb were determined using the X-ray fluorescence spectrometer (Innov X-5000). The results showed that mean contents of Cr and As exceeded their upper continental crust by 1.50 and 3.12 times and their maximum acceptable values by1.53, 1.50 times, respectively. The detailed analysis of the spatial distribution pattern of PTEs demonstrated the presence of sites where all these elements displayed comparatively higher values. The combined application of compositional data analysis and geospatial mapping allowed to reveal multivariate outliers which were located in structural-metallogenic zones with an active exploitation of ore deposits. The application of unsupervised machine learning algorithm unveiled three groups within the main dataset and the clr-biplot identified the source-specific elements. Particularly, Group I included Cu and displayed the highest mean value among the identified groups. The soil samples included in Group I were found in areas where Calcisols were developed and comparatively high Cu contents were attributed to agricultural activities (vineyards) and vehicle emissions. The Group II is represented by the geochemical association of Fe, Co, Cr, Mn, Zn, and As. The formation of this group is conditioned by volcanic rocks of the local geological origin. However, no spatial pattern was identified in Group II distribution aligned with the soil types. The Group III included Ti, V, Pb, and Ba. This group may have a mixed origin as it is spatially distributed in areas where regional highways pass through and where Group II elements also exhibit their higher values.

Late Triassic paleolatitude of the Southern Qiangtang terrane, central Tibet: Implications for the closure of the Longmu Co-Shuanghu Paleo-Tethyan Ocean

Studies on the paleogeographic evolution of the Southern Qiangtang terrane, as an integral component of the Cimmerian continent, are essential for understanding the geodynamic evolution of the Tethys domain. Here, we present a paleomagnetic study of Late Triassic volcanics (∼222–206 Ma) from the Southern Qiangtang terrane, with the aim of enhancing our understanding of the evolutionary processes of the Longmu Co-Shuanghu Paleo-Tethyan Ocean. The characteristic remanent magnetizations (ChRMs) carried by magnetite and hematite, which formed during the high-temperature oxidation in the initial cooling phase of the volcanic rocks, are effectively isolated through successive thermal demanetizations. The ChRMs pass the fold test, indicating a primary magnetization. It appears to average out paleosecular variation well enough to yield a reliable paleolatitude estimate. Following tilt correction, the ChRMs yield an overall mean direction of Ds = 185.4°, Is = 53.8°, ks = 94.3, α95 = 3.8°, N = 16, indicating a paleolatitude of 34.3°N and a paleopole located at –22.5°N, 82.9°E with A95 = 4.4°. Comparing the Triassic latitudinal history of the Southern Qiangtang with that of the Northern Qiangtang suggests that the western part of Longmu Co-Shuanghu Paleo-Tethyan Ocean likely closed during the early Late Triassic. Moreover, integration with other geological evidence from the Southern Qiangtang terrane suggests that the Longmu Co-Shuanghu Paleo-Tethyan Ocean closed diachronously from east to west.

Comparison of geosite and geomorphosite quantitative analysis for geotourism purposes in Baturraden (Purwokerto) and Guci (Tegal) hot springs tourism area, Central Java

Baturraden (Purwokerto) and Guci (Tegal) are popular tourist attractions on the hill of Gunung Slamet, Central Java Province. Each location has an object that can be analyzed as a geotourism potential, as the manifestation of hot springs. Regionally, the research area is included in the Slamet Volcano Lava Rock (Qvls), which is composed of Quaternary andesitic vesicular andesitic lava, and Undifferentiated Slamet Volcano Rock (Qvs), which is composed of Quaternary volcanic breccia, lava, and tuff. The research was carried out using three stages of research, e.g: the literature study stage, the field research stage, and the geosite and geomorphosite analysis stage, using a quantitative assessment method, according to Kubalikova (2013). Five geosites and geomorphosite are assessed: Pancuran-7 and Pancuran-3 (Baturraden), as well as Pancuran-13, Pancuran-5, and Sigeong hot spring (Guci). The results of the quantitative analysis based on the existing parameters sequentially are 82%, 75%, 79%, 79%, and 63%. These results indicate that Pancuran-7, Pancuran-3, Pancuran-13, and Pancuran-5 sites are very feasible for geotourism-based tourist objects. The Sigeong site needs to be improved in several aspects, especially infrastructure. Parameters that need to be considered for all objects are conservation values due to disaster risk factors that already exist and disaster risk factors that are still potential and have yet to occur, such as volcanic eruptions and landslides, as well as the process of destruction that occurs in several objects that can threaten the sustainability of tourist sites. In addition, it is necessary to increase the understanding of residents and visitors who come about geological information related to the formation of hot springs, both in the form of information boards posted around the site and information displayed on local websites.