Search

The Takestan area is in the western part of the Alborz magmatic arc. Magmatic rocks of the area consist of plutonic rocks (e.g. granitoids), effusive volcanic, and pyroclastic rocks. Using U-Pb zircon LA ICP-MS dating, we conclude that major parts of Takestan plutonic rocks were emplaced at 41–39 Ma (Late Eocene, Bartonian), but a small part of these rocks have ages of ~37 Ma (Late Eocene, Priabonian). The dacitic rocks have an age of ~39 Ma (Late Eocene, Bartonian) and the rhyolitic rocks are the youngest part of the magmatic rocks of the region with ages of 37–35 Ma (Late Eocene, Priabonian). Old zircons are present in all of granitoid and volcanic samples, except for a dacitic sample. They are interpreted both as earlier components in a long-lived magma chamber and inherited zircons from older continental crust. The age of magmatic rocks in the western part of the Alborz magmatic arc decreases from east to west, but the ages of the majority of them are limited to Palaeogene. The studied rocks like other Palaeogene magmatic rocks of Iran were possibly formed in a subduction related tectonic environment. Indeed, the Palaeogene magmatism of Iran is akin to geodynamic events related to Neotethyan subduction beneath Iranian micro-continent at the southern part of Eurasia. [ABSTRACT FROM AUTHOR]

The paper presents geochemical and geochronological data on gneisses and granitoids from three deep boreholes (Yalykskaya-4, Danilovskaya-532, Srednenepskaya-1) in the basement of the southwestern part of the Nepa-Botuoba anteclise. Based on U-Pb zircon dating, three stages of granitoid magmatism were identified: ∼2.8, 2.0 and 1.87 Ga. At ca. 2.8 Ga magmatic TTG protoliths of biotite–amphibole gneisses (Yalykskaya-4 borehole) were formed, these rocks represent the Mesoarchean crust and experienced thermal effects typical of the Tungus superterrane of the Siberian craton at the terminal Neoarchean (∼2.53 Ga). Biotite gneissic granites (∼2.0 Ga) (Danilovskaya-532 borehole), which correlate in age with the granitoids of the basement of the Magan terrane and the Akitkan orogenic belt, were derived from a metasedimentary source formed by the erosion of predominantly Paleoproterozoic juvenile crust rocks. The 1.88 Ga A-type granite (Srednenepskaya-1 borehole) corresponds to the main stage of post-collision granite magmatism within the South Siberian magmatic belt. The ca. 2.8 Ga biotite–amphibole gneisses mark the eastern boundary of the Archean crust with Paleoproterozoic juvenile crust in the south of the Tungus superterrane, which are separated by a transitional zone intruded by granites having intermediate isotopic characteristics. The isotopic composition of Paleoproterozoic gneisses and granitoids indicates that marginal southern Magan terrane in contact with the Tungus superterrane includes blocks of both Archean and Paleoproterozoic crust, thus showing similarity with the Akitkan orogenic belt and accretionary orogens. The final amalgamation of the Tungus superterrane with blocks of the eastern part of the Siberian platform basement corresponds to a milestone of 1.88 Ga. [ABSTRACT FROM AUTHOR]

Pressure–temperature estimates of a xenolith found within a post-obduction granodiorite in southern New Caledonia provide evidence for subcrustal, granulite facies, peak crystallisation conditions (ca. 850 °C—8.5 ± 1.0 kbar), followed by isobaric cooling to 700 °C, and final decompression with partial rehydration at ca. 650 °C—3.5 kbar. The xenolith, dated at 24.7 Ma (U-Pb zircon), i.e., the same age as the granodiorite host rock, has low SiO2 (35.5 wt%) and high Al2O3 (33.2 wt%) contents, suggesting that it is the restite of a previous melting episode, while the elevated Ca (Ba and Sr) contents suggest mantle metasomatism. Although the concentrations of Rb, K, Ca, Ba, and Sr have been strongly modified, some geochemical (REE patterns and some "immobile" trace element ratios) and isotopic (Sr and Nd isotopic ratios, U-Pb zircon age) characteristics of the granulite facies xenolith are similar to those of the xenoliths found in other Late Oligocene intrusions in southern New Caledonia; therefore, this rock is interpreted to be related to an early magmatic episode. The rock protolith was emplaced and equilibrated at the base of the crust where it underwent ductile deformation. Younger ascending magma picked it up and they eventually crystallised together at a shallow crustal level, near the tectonic sole of the ophiolite. The recrystallisation and ductile deformation at ~8.5 kbar suggest that a rheological discontinuity existed at about 25–28 km, probably representing the Moho. It is concluded that a continental crust of normal thickness must have existed beneath New Caledonia at about 24 Ma, i.e., 10 Ma after obduction. [ABSTRACT FROM AUTHOR]

A reconnaissance study of the Ash-Sharqi area displays that this area is covered by Tertiary rift-related volcanic rocks and their associated plutonic rocks with some exposures of Mesozoic sandstones. These volcanic rocks belong to the Yemen Trap Series (YTS) that form the lower part of the Yemen Volcanic Group (YVG), which consists of a part of the Afro-Arabian continental flood basalt province. The plutonic rocks are represented by intrusion composed of granitoid rocks located in the center of the study area, which is the subject of this paper. These granitoid rocks range in composition from granite (G) to quartz-monzonite - quartz-monzodiorite - quartz diorite (QM-QMD-QD) and are composed of plagioclase (An32-46: Andesine), K-feldspars, quartz, hornblende with minor, biotite, opaques, allanite and zircon. Secondary minerals are represented by chlorite, sericite calcite sphene, hematite epidote, and kaolinite. These rocks show variations in their colors (color index 6 to 47 vol. %) and grain sizes, which reflect changes in mineral composition and textures. They have equigranular, porphyritic, rapakivi, and anti-rapakivi textures and contain enclaves of various sizes of basalt and diorite blocks. Xenocrysts of pyroxene and plagioclase are found and detonated during the magma-mingling processes. Finally, these granitoid rocks are subjected to various degrees of hydrothermal alterations, including silicification, argillization, hematitization, chloritization, epidotization, sericitization, carbonation and spheronization. [ABSTRACT FROM AUTHOR]

Iron (Fe)-skarn mineralizations (Çambaşı, Dereli, Eğrikar, Karadağ, Kopuz, Sekü, Donguldere, Arnastal, Özdil, Ögene, İkizdere, Ovit Dağı, Kartiba, etc.) in the eastern part of the Pontides (NE Türkiye) are accommodated in the Pontide paleomagmatic arc and the eastern part of the Pontides Metallogenic Belt containing numerous various deposits. Fe-skarn mineralization around the Arnastal Plateau (Gümüşhane-Türkiye) is fragmentary in this area, which is covered with plants (grasses, flowers, etc.). Thus, it was attempted to describe the subsurface structures and Fe mineralization using an interpretation of the available geological and existing magnetic data in this area. Granitoid and volcano-sedimentary series (Upper Cretaceous) outcrop in the study area. These volcanosedimentary series consist of limestone, sandy limestone, marl, andesite, quartz andesite, basalt, and their equivalent pyroclastics. They include a thin layer of the red limestone (Upper Cretaceous) and olistolith recrystallized limestones (Jurassic-Lower Cretaceous). Zigana granitoid, intruding into all of these rocks, is high-K calc-alkaline and metaluminous and is classified as quartz monzonite, monzogranite, granite, and syenogranite as a result of its modal composition. Contact pyrometasomatic mineralization occurs in between the limestone and granitoids in the Arnastal Plateau. In addition to petrographic and mineralogical studies, magnetic methods were applied to an area of approximately 10 km2 to find any covered Fe deposits. Magnetic susceptibility values measured on the outcropped rocks ranged from 1 to 34 (10-7 SI) for limestone, 78 to 3750 (10-7 SI) for basalt, and 105 to 3946 (10-7 SI) for granitoids. It is considered that these ranges express the alteration (physical or chemical) of the rocks, their homogeneity, and the lack or presence of Fe minerals. The magnetic survey was conducted along a study area measuring 12,075 m long with 25 and/or 50 m station spacing. Processing of the magnetic data revealed the presence of eight buried Fe ores that could represent either massive or disseminated mineralization between the Sarıtaş and Kurtdere plateaus. Magnetite ore bodies may be present from the surface to a depth of approximately 15-25 m inside the limestone. In addition to the identification of new magnetite ore mineralization or bodies, a new geological map was designed by determining probable formation boundaries with this magnetic survey. [ABSTRACT FROM AUTHOR]

This work presents microscopic-, whole-rock geochemical-, and K-Ar age data for Tanjung Berikat Granitoid at the easternmost part of Bangka Island. Some selected samples are in the range of monzogranite and granodiorite based on microscopic analysis. The rocks are characterized by a wide range in SiO2 (62.75 - 70.17 wt %), high-K calcalkaline to shoshonitic affinity, and ferroan signature. Very good correlation values of bivariate SiO2 plotted against other major oxides, similar spider diagrams normalized to the composition of the N-MORB and chondrite-normalized REE diagrams demonstrate the same origin and crystallization mechanism of the granitoid. The I-type nature of the studied granite is based on the hornblende existence, metaluminous character, negative SiO2 to P2O5 correlation, and volcanic arc characteristics of the rock. Tanjung Berikat Granitoid was crystallized in the mid? late Early Cretaceous at 125.5 ± 2.8 Ma and 109.4 ± 2.5 Ma based on the K-Ar dating method. [ABSTRACT FROM AUTHOR]

Granitoid intrusion of several provinces on Sumatra is correlated with Southeast Asia tectonics that have occurred since the Permian. Granites from several volcanic arc provinces are located along the western part of Sumatra Island and are found near Bukit Barisan. This study describes the geochemical character of granitoid from the Tanggamus region and its surroundings near the Bukit Barisan cluster. After megascopic description in the field, major oxides, trace elements, and rare earth elements in rock samples were measured using X-ray fluorescence and inductively coupled plasma-mass spectrometry devices. The samples were intermediate to acidic intrusive rocks with SiO2 ranging between 61.35% and 75.29%. The rocks can be described as diorite to granodiorite and were formed as a result of subduction processes. The granitic rock samples showed I-type features of A/CNK value

In the Pra Basin of Ghana, groundwater is increasingly becoming the alternative water supply due to the continual pollution of surface water resources through illegal mining and indiscriminate waste discharges into rivers. However, our understanding of hydrogeology and the dynamics of groundwater quality remains inadequate, posing challenges for sustainable water resource management. This study aims to characterize groundwater recharge by determining its origin and mechanism of recharge prior to entering the saturated zone and to provide spatial estimates of groundwater recharge using stable isotopes and water level measurements relevant to groundwater management in the basin. Ninety (90) water samples (surface water and groundwater) were collected to determine stable isotope ratios of oxygen ( δ 18 O ) and hydrogen ( δ 2 H ) and chloride concentration. In addition, ten boreholes were installed with automatic divers to collect time series data on groundwater levels for the 2022 water year. The Chloride Mass Balance (CMB) and the Water Table Fluctuation (WTF) methods were employed to estimate the total amount and spatial distribution of groundwater recharge for the basin. Analysis of the stable isotope data shows that the surface water samples in the Pra Basin have oxygen ( δ 18 O ) and hydrogen ( δ 2 H ) isotope ratios ranging from −2.8 to 2.2‰ vrs V-SMOW for δ 18 O and from −9.4 to 12.8‰ vrs V-SMOW for δ 2 H , with a mean of −0.9‰ vrs V-SMOW and 0.5‰ vrs V-SMOW, respectively. Measures in groundwater ranges from −3.0 to −1.5‰ vrs V-SMOW for δ 18 O and from −10.4 to −2.4‰ vrs V-SMOW for δ 2 H , with a mean of −2.3 and −7.0‰ vrs V-SMOW, respectively. The water in the Pra Basin originates from meteoric source. Groundwater has a relatively depleted isotopic signature compared to surface water due to the short residence time of infiltration within the extinction depth of evaporation in the vadose zone. Estimated evaporative losses in the catchment range from 51 to 77%, with a mean of 62% for surface water and from 55 to 61% with a mean of 57% for groundwater, respectively. Analysis of the stable isotope data and water level measurements suggests a potential hydraulic connection between surface water and groundwater. This hypothesis is supported by the fact that the isotopes of groundwater have comparatively lower values than surface water. Furthermore, the observation that the groundwater level remains constant in months with lower rainfall further supports this conclusion. The estimated annual groundwater recharge in the catchment ranges from 9 to 667 mm (average 165 mm) and accounts for 0.6% to 33.5% (average 10.7%) of mean annual precipitation. The total estimated mean recharge for the study catchment is 228 M m 3 , higher than the estimated total surface water use for the entire Pra Basin of 144 M m 3 for 2010, indicating vast groundwater potential. Overall, our study provides a novel insight into the recharge mechanism and spatial quantification of groundwater recharge, which can be used to constrain groundwater flow and hydrogeochemical evolution models, which are crucial for effective groundwater management within the framework of the Pra Basin's Integrated Water Resources Management Plan. [ABSTRACT FROM AUTHOR]

Pressure–temperature estimates of a xenolith found within a post-obduction granodiorite in southern New Caledonia provide evidence for subcrustal, granulite facies, peak crystallisation conditions (ca. 850 °C—8.5 ± 1.0 kbar), followed by isobaric cooling to 700 °C, and final decompression with partial rehydration at ca. 650 °C—3.5 kbar. The xenolith, dated at 24.7 Ma (U-Pb zircon), i.e., the same age as the granodiorite host rock, has low SiO2 (35.5 wt%) and high Al2O3 (33.2 wt%) contents, suggesting that it is the restite of a previous melting episode, while the elevated Ca (Ba and Sr) contents suggest mantle metasomatism. Although the concentrations of Rb, K, Ca, Ba, and Sr have been strongly modified, some geochemical (REE patterns and some “immobile” trace element ratios) and isotopic (Sr and Nd isotopic ratios, U-Pb zircon age) characteristics of the granulite facies xenolith are similar to those of the xenoliths found in other Late Oligocene intrusions in southern New Caledonia; therefore, this rock is interpreted to be related to an early magmatic episode. The rock protolith was emplaced and equilibrated at the base of the crust where it underwent ductile deformation. Younger ascending magma picked it up and they eventually crystallised together at a shallow crustal level, near the tectonic sole of the ophiolite. The recrystallisation and ductile deformation at ~8.5 kbar suggest that a rheological discontinuity existed at about 25–28 km, probably representing the Moho. It is concluded that a continental crust of normal thickness must have existed beneath New Caledonia at about 24 Ma, i.e., 10 Ma after obduction.

Granitoid intrusion of several provinces on Sumatra is correlated with Southeast Asia tectonics that have occurred since the Permian. Granites from several volcanic arc provinces are located along the western part of Sumatra Island and are found near Bukit Barisan. This study describes the geochemical character of granitoid from the Tanggamus region and its surroundings near the Bukit Barisan cluster. After megascopic description in the field, major oxides, trace elements, and rare earth elements in rock samples were measured using Xray fluorescence and inductively coupled plasma-mass spectrometry devices. The samples were intermediate to acidic intrusive rocks with SiO2 ranging between 61.35% and 75.29%. The rocks can be described as diorite to granodiorite and were formed as a result of subduction processes. The granitic rock samples showed I-type features of A/CNK value <1.1, volcanic arc granite affinity, K2O/Na2O ratio, and magnesian properties. The total rare earth content was medium with an average of 43.97 ppm. The similarity of the rare earth normalized diagram against the chondrite value indicates that the samples come from an identical origin. [ABSTRACT FROM AUTHOR]

[Display omitted] • Phanerozoic granitoids are used to constrain the north boundary of the Alxa Block. • The granitoids show juvenile and ancient source provinces with contrasting isotopes. • Tectonic belts with juvenile crust (T DM 2 < 1.30 Ga) could be parts of CAOB. • Tectonic belts dominated by ancient crust (T DM 2 > 1.30 Ga) belong to the Alxa Block. The Alxa Block, located in the southern Alxa area of Inner Mongolia, is generally accepted as the westernmost part of the North China Craton (NCC), but there is still a controversy over the boundary between the southern CAOB and the Alxa Block. Currently, either the Enger Us ophiolite belt or Quagan Qulu ophiolite belt in the mid-eastern Alxa area is a candidate for the NCC-CAOB boundary, and the extension of the two ophiolite belts in the western Alxa area is ambiguous. In this study, we present a compilation of newly obtained and published zircon U-Pb age and Hf isotopic data from the Ordovician-Triassic granitoids in the Alxa area and discuss the implications of two contrasting isotope provinces for the NCC-CAOB boundary. Specifically, the granitoids in the Zongnaishan-Shalazhashan belt between the two ophiolite belts and the North Beidashan belt in the western Alxa area share similar emplacement ages (Carboniferous to Triassic) and juvenile zircon Hf isotopic compositions (two-stage mode ages < 1.30 Ga), and both Carboniferous to Permian granitoids in the Yabulai-Honggueryulin belt to the south of Quagan Qulu ophiolite belt and Ordovician to Devonian granitoids in the South Beidashan belt of the western Alxa area are characterized by similar ancient zircon Hf isotopic features (two-stage mode ages > 1.30 Ga), but most Late Carboniferous to Permian granitoids in the South Beidashan belt are characterized by juvenile zircon Hf isotopes. The two contrasting isotope provinces (juvenile in the north and generally ancient in the south) for the Phanerozoic granitoids could not result from differential denudation, but drastic differences in compositions of deep crusts. The Yabulai-Honggueryulin and South Beidashan belts with ancient crust sources are parts of the Alxa Block, whereas the Zongnaishan-Shalazhashan and North Beidashan belts with juvenile crust sources could be parts of CAOB, and thus the boundary between the CAOB and the Alxa Block is inferred located in between. [ABSTRACT FROM AUTHOR]

The coastal cliffs around the Roses Lighthouse (Cap de Creus, Mediterranean Costa Brava) display deformation structures generated during the emplacement of a syntectonic granodiorite and associated rocks (quartzdiorite enclaves and leucocratic dykes). These rocks were subjected to shearing and spectacular shear zones are present, which have been object of several scientific publications. The outcrops are considered of international high scientific value, being regularly visited by researchers and students from several European universities. In 2005, the site was included in the Geosite Inventory of Catalonia, but it does not have any special protection yet, despite decades of efforts to claim the need for protection and conservation in front of the constant deterioration and loss of outcrops due to strong urban and touristic pressure. A project of restoration, access improvement, and dissemination of geological values was finally executed between 2020 and 2021. The Roses case study leads us to the remark that urban and periurban geosites offer a good opportunity for promoting geological research, education, and tourism, provided its protection based on geoconservation criteria and a strong sustainable conservation management plan. [ABSTRACT FROM AUTHOR]

The study area is located about 30 km south of Ramsar, in the central Alborz zone. In addition to the Nusha granitoids (with an age of about 56 million years), the outcrops in this area, mainly include Paleozoic and Mesozoic rock units. Petrographically, the Nusha granitoids have diorite, syenite, monzonite, monzodiorite, granodiorite and quartz monzonite compositions. Moreover, mineralogically, feldspar is the principal mineral, and the texture superiority in them belongs to the granular type. In terms of magmatic series these rocks are metaluminous and range from high K calcalkaline to shoshonitic. The geochemical characteristics of the major and rare elements, as well as the petrographic ones indicate that these granitoids are I type granites, and at the same time they belong to high temperature ones based on the behavior of Ba, Ce and Y elements. Enrichment in LILE and LREE and low concentrations of heavy rare earth elements HREE and high field strength elements HFSE, together with Nb and Ti negative anomaly in the spider diagrams are signs of magmas related to the subduction zone. The high temperature nature and characteristics such as Y/Nb, Rb/Sr and Rb/Ba ratios show that the Nusha granitoids have the geochemical properties of both crustal and mantle origin materials with different ratios. Based on tectonomagmatic discrimination diagrams and trace element compositions, these granitoids belong to an active continental margin environment. The parental magma has originated from melting of an enriched mantle source and contaminated with continental crust during ascent. Introduction The study area is part of the Alborz-Azerbaijan magmatic belt. Many of the intrusive masses present in this area are high potassium calc-alkaline to shoshonite and are of I type granitoids (Aghazadeh, 2009; Aghazadeh et al., 2013; Nabatian et al., 2014; Taki, 2011). In this research study, we seek to determine the nature of the granitoids of the Nusha region by using geochemical characteristics and determine their origin and tectonomagmic setting. Exposed rock units in the study area, in addition to intrusive igneous rocks, include sedimentary carbonate and detrital rocks belonging to the Mobarak (Carboniferous), Dorood (Lower Permian), Ruteh (Upper Permian), Nesen (Upper Permian), Elika (Lower-Middle Triassic), Shemshak (Upper Triassic-Lower Jurassic) Formations and Cretaceous sedimentary and volcanic rocks. In this area, the granitoid intrusive masses have northwest-southeast trends and have intruded during the Eocene (56±2 million years ago) (Axen et al., 2001). The outcrop of the Nusha granitoids starts from the western slope of Sehezar Valley and extends north-westward to the south-west of Nusha. The granitoid unit is separated into two masses by a dextral fault. The southern border of this mass is completely faulted. This has resulted that the Upper Paleozoic assemblage has been thrusted onto the granitoids. Its northern border is also mainly faulted. The only normal contact present in the western part with Lower and Middle Jurassic sediments. Research method After sampling of intrusive rocks and petrographic studies of the study area, 10 samples of rocks related to intrusive masses were sent to the Zarazma company in Iran for chemical analysis and 7 samples were sent to the Actlabs company in Canada. In the laboratory of these companies, the ICP-OES method is used to measure the major elements and some minor elements, and the ICP-MS method is used to evaluate the abundance of rare and trace elements. In this research study, since iron is reported unseparated, the Irvine and Baragar method (1971) was used to calculate divalent and trivalent iron. Results and discussion The granitoids of the study area are petrographically composed of diorite, syenite, monzonite monzodiorite, granodiorite and quartz monzonite. Mineralogically, feldspar is the principal mineral and the granular is superior texture. Based on several geochemical characteristics such as aluminum saturation [the molar (Al2O3/(CaO+Na2O+K2O)) or ASI] and agapiitic [A.I.=molar (Na+K)/Al] indices, Na2O/K2O ratio, range of SiO2 content, Na2O weight percentages in acidic terms, average values of Na2O, Zr, Y, Ce and Rb/Sr, and diagrams of ANK-ACNK, normative corundum and P2O5 versus Rb, (A/CNK-Fe2O3+FeO), Th-Rb and P2O5-SiO2 as well as petrographic features like, petrographical composition ranges and the nature of enclaves and ferromagnesian minerals in the studied samples all confirm the I type nature of the Nusha granitoids. At the same time, the variations of Ba, Ce and Y elements in the Nusha granitoids are such that they first increase and then decrease with increase of silica content. Thus, they are high temperature I type granite and must have been originated from the melting of mafic rocks of crust or evolved mantle. These rocks have high K calc-alkaline to shoshonite magmatic series nature. REE patterns of all the studied samples are parallel and similar (so they have a common origin) and relatively highly enriched (than primitive mantle) and have no Eu anomaly (due to the participation of feldspar in the magma during partial melting of the source rock or lack of differentiation of this mineral during the fractional crystallization of the parental magma). Like many other active continental margin calc-alkaline rocks, these rocks have negative slope on the LREE side and are flat on the HREE side. Enrichment in LILE and LREE and low concentration of HREE and HFSE, along with negative anomaly of Nb and Ti in the spider diagrams are indicators of magmas related to the subduction zone. The very distinct Nb-Ta trough in the arc systems spider diagrams is due to crustal contamination or retention of these elements in the source during partial melting. Positive Pb-K anomalies and overall enrichment of LILE are also indicators of crustal contamination. The extreme U and Th enrichment in the spider diagrams indicate addition of pelagic sediments or altered oceanic crust in the melting process. The high Th/Ta and relatively low Nb/Th ratios indicate formation of magma in an arc environment, and the tectonomagmatic discrimination diagrams show continental arc one as well and according to their age, like many Cenozoic igneous rocks in the Alborz, Western Alborz-Azerbaijan and South Caucasus must have resulted from subduction of the Neotethys oceanic crust. In the Nb versus Rb/Zr diagram, the Nusha granitoids are in the range of normal to mature continental arcs. On the Sm/Yb-La/Sm and Rb-Sr diagrams, the continental crust is about 45 km and shows enriched mantle at the parental magma generation source. The wide range of variations in Y/Nb ratios indicates that the study area granitoids have the geochemical characteristics of both crustal and mantle origin materials. According to the Rb/Sr versus Rb/Ba diagram, the mantle to crust materials ratios are between 20 and 50%. The low Tb/Yb ratio and the multiple concentration of rare earth elements compared to the primitive mantle in the Nusha granitoids indicate a mantle source with the composition of spinel bearing peridotite without garnet origin.

Granitoids with evolved chemical signatures, intruding both oceanic crustal rocks and mantle peridotite, are well known in the Samail supra-subduction ophiolite of Oman and United Arab Emirates. The former are metaluminous tonalites and trondhjemites have positive εNd, relatively low δ18O values, resemble ridge 'tholeiitic' granitoids with MORB-like affinity, and formed by fractionation of basalt/gabbro or anatexis of oceanic crust. In contrast, the mantle-hosted granitoids are peraluminous, with negative εNd and high δ18O values. They can be modeled as having formed by mixing between partial melts of metabasalt and metasedimentary rocks with minimal mantle contribution. The mantle-hosted granitoids resemble typical peraluminous S-type granitoids (e.g. Himalaya, Variscan, Lachlan) but are compositionally distinct in having notably scattered data values of K2O, Na2O, CaO, Rb/Sr, relatively higher silica and, lower (Al2O3 + FeO + MgO + TiO2 wt%) and Th/Yb as compared to typical S-types. The mantle-hosted granitoids mainly originate from the subducted slab, and mostly intruded mantle peridotite in the lithospheric mantle, with no apparent association with the overriding oceanic plate and little interaction (e.g. assimilation) with the mantle. While the specific controls on geochemical variations remain speculative, results from this study show that the Samail mantle-hosted S-type granitoids are compositionally distinct from classic S-type granitoids formed in orogenic belts. While global S-type granitoids may be mineralogically similar, the Samail mantle-hosted granitoids preserve different geochemical signatures, reflecting their formation in distinct tectonic setting, including the mantle. [ABSTRACT FROM AUTHOR]

The bulk rock composition of granitoids reflects the composition of their source and the conditions of partial melting, which are functions of the geodynamic setting in which they formed. Granitoids in active continental margins (continental arcs) are dominated by calc-alkaline rocks with subordinate alkaline compositions, although how these different magma compositions formed is not well understood. Neoproterozoic magmatic rocks are widely distributed along the western margin of the Yangtze Block in South China to form the >1000-km long Panxi continental arc system, which is dominated by granitoids with minor mafic–ultramafic and intermediate plutons. The granitoids are subdivided into sodic and potassic variants that occur as belts along the western and eastern sides of the continental arc, respectively. Sodic granitoids from the western part consist of tonalite, granodiorite, and monzogranite with crystallisation ages ranging from 870 Ma to 740 Ma. They have low K2O/Na2O ratios (0.1–1.0) and high Na2O contents (3.5–6.7 wt%), high but variable SiO2 (61–75 wt%) concentrations, and negative to positive whole-rock εNd(t) values (−1.7 to +2.9). Zircon grains from the sodic granitoids have εHf(t) values ranging from +0.3 to +9.6 and δ18O from 3.90‰ to 7.71‰. The potassic granitoids from the eastern side consist of monzogranite and syenogranite with crystallisation ages from 820 Ma to 790 Ma. They have high K2O/Na2O ratios (0.6–2.2), K2O (2.6–5.9 wt%) and SiO2 contents (69–78 wt%), but whole-rock εNd(t) (−0.9 to +2.9) and zircon εHf(t) (+1.8 to +12.9), and δ18O values (2.98‰ to 6.41‰) similar to those of the sodic granitoids. The isotopic compositions of both the sodic and potassic granitoids are similar to those of spatially- and temporally-related mantle-derived (mafic to ultramafic) rocks, and are considered to have been derived from juvenile mafic continental crust. Phase equilibrium modelling shows that the H2O content of the granitoid source rocks played a key role in their petrogenesis, both in lowering solidus temperatures and in controlling the compositions of the derived partial melts. Our results indicate that calc-alkaline sodic granitoids can be formed by water-fluxed melting of juvenile mafic crust at 750–900°C and 9–12 kbar in which the required H2O was derived from the dewatering of underplating mafic arc magmas. By contrast, the potassic granitoids were generated by fluid-absent (H2O-undersaturated) partial melting of a similar juvenile mafic source at 725–900°C and 6–9 kbar. We conclude that the sodic granitoids were derived from partial melting of the newly-formed mafic lower crust in the continental arc, whereas the potassic granitoids were likely generated in the back-arc setting induced by upwelling of asthenospheric mantle. [ABSTRACT FROM AUTHOR]

The reddened granitoid facies in the basement of the Polish Sudetes exhibits two categories of alteration spatially arranged with respect to fractures: (1) saussuritization and sericitization within light-colored facies in the interior of fracture-bounded blocks and (2) albitization and hematization in reddened facies occurring adjacent to fracture walls. These alterations are associated with the chloritization of primary ferromagnesian minerals and the development of secondary minerals such as quartz, K-feldspar, apatite, prehnite, calcite, and titanite. We link these parageneses and the observed zonation to a unique alteration event consisting of an interplay of chemical reactions of variable spatial extent. The complete albitization of the feldspars (plagioclase and K-feldspar) adjacent to fractures points to a significant supply of Na for albite neoformation and the availability of oxygen to form the associated hematite. The dating of the iron oxides by paleomagnetism and the secondary monazite associated with the albitized facies by U-Th-Pbtotal unambiguously indicates their post-Variscan ages. In this context, the alterations are related to a regionally widespread post-Variscan paleosurface. The weathering profiles formed in phreatic groundwater environments downgradient of highlands that provided a hydrological head. Sodium supply likely originated from gigantic salt playas that characterized Permian and Triassic lowlands. Weathering was interrupted by the Mesozoic transgression. The recognition of these weathering profiles over extensive parts of the Variscan Belt provides the basis for reconstructing the post-Variscan paleosurface and constraining Triassic and post-Triassic geodynamics, including erosion rates and geomorphological evolution of the Paleozoic massifs in Europe. [ABSTRACT FROM AUTHOR]

This article describes silver specimens of the size of tenths to a few millimetres, found in small pegmatites and quartz veinlets of the porphyritic granitoid area in 22 sites in the eastern part of the Variscan granitoid Karkonosze pluton, from 20 of which native silver occurrences were previously not known. The sites are scattered on the whole surface of the granitoid. The native silver occurred in wire, rod, platy, dendritic, anhedral granular and euhedral cubic and octahedral habits; in some specimens twins and fenster faces were also found. Associated with native silver small amounts of acanthite crystallized commonly, sometimes apparently formed by sulphur diffusion into silver. Inclusions of native gold, electrum, galena, chalcopyrite and pyrite occurred in the native silver. The parent fluids of the specimens were epithermal, because the homogenization temperature (Th) of inclusions in quartz, calcite and cleavelandite that were the host minerals of the native silver was generally 91-165°C and for individual samples the Th range was 4-11°C. The total salinity of the fluid was 2.4-7.2 wt. % with Na and Ca (hydro)carbonates as the main dissolved components and admixtures of K, Mg, Fe, Al, S, Cl and F. The parent granitoid contains Ag in trace amounts (0.034-0.056 ppm) and was probably the source of this element for the crystals of native silver. Migration of Ag was made easier by the presence of fluoride ions in fluids. [ABSTRACT FROM AUTHOR]

Discrimination of granitoids bearing iron and corundum mineral deposits in the southeastern part of Banyo (Adamawa region of Cameroon) using Landsat 8 OLI data and provides essential information's for exploration. Field data and remote sensing traditional mapping techniques including false color composites (FCCs), principal component analysis (PCA), Crosta-PCA, band ratios (BR), constrained energy minimization (CEM), classification algorithm as maximum likelihood, and spectral angle mapper (SAM) were applied to the visible, near-infrared, and shortwave infrared bands of Landsat 8 OLI data. The results of this research demonstrated to be most effective to highlight potential locations of granitoids bearing iron and corundum deposits. In addition, iron deposit was mapped using band ratio 4/2 due to high reflectivity in the visible red region while corundum deposits are detected by applying the constrained energy minimization method to Landsat-8 OLI band ratio 6/7 highlighting bright tones. The results of remote sensing data were validated through fieldwork and laboratory analysis (thin section analysis). Furthermore, lineaments analysis revealed the prevalence of three major structural trends affecting the southeastern part of Banyo (N-S, E-W, and NE-SW to ENE-WSW) paired with mapped lithologies allows the potential emplacement of mineral deposits. The novelty of the present study relies in the integration of Landsat 8 OLI and field data enabling the identification of highly prospective lithological units, mineral deposits, defining exploration targets, and the minimisation of time consuming field reconnaissance in the study area. [ABSTRACT FROM AUTHOR]

Link for citation: Oitseva T.A., Dyachkov B.A., Bissatova A.Ye., Orazbekova G.B., Zinyakin S.S. Features of formation, material composition and geological structure of rare metal and pegmatite deposits of the Kalba region on the example of the Yubileinoe deposit. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 7, рр. 164-176. In Rus. The relevance of the research is caused by the lack of knowledge on the behavior of rare metal in pegmatite ore formation in the Kalba region and the need to expand the rare-metal mineral resource base of the region and to establish geological and mineragenic mapping. The main aims of the research are identification of features of geotectonic development, geological structure and material composition of the rare-metal deposit Yubileynoe (Kalba region). Study area: large industrial rare metal deposit Yubileynoe and its mineral complexes. Methods: detailed geological-geochemical and mineralogical study of the region of work, use of materials from works of previous years, stock literature, as well as laboratory studies (mass spectrometric, microprobe, geochronological and other studies). The structural relationships of minerals with each other, as well as the geochemical interpretation of the results of laboratory studies, were taken into account during diagnosing mineral complexes. Results. Spatial and genetic relationship of rare-metal pegmatite deposit (Nb, Ta, Be, Cs, Li, Sn) with granites of the I phase of the Kalba complex P1 (285 Ma), is distinguished. In the location of the Yubileinoe deposit, the leading ore-controlling role is given to the system of deep latitudinal faults of ancient origin, renewed in the Hercynian cycle. A geological and genetic model of rhythmically pulsating rare-metal pegmatite formation of the Yubileinoe deposit is presented, which reflects the zonal development of mineral complexes from oligoclase-microcline (barren) to albite, greisen, spodumene-containing and pollucite-bearing (ore) with an increasing concentration of mineralization. Information was obtained on the composition of pegmatite ores with the release of typomorphic minerals (clevelandite, lepidolite, colored tourmalines, spodumene, pollucite, ixiolite, etc.) and the main geochemical elements of rare metal ore formation (Nb, Ta, Be, Cs, Li, F, P, etc.).

Batuan granitoid di Provinsi Lampung dapat ditemukan di peta geologi regional lembar Kota Agung dan Lembar Tanjungkarang. Masih sedikitnya penelitian tentang batuan granitoid Formasi Granit Kapur di Lampung mendasari penelitian ini. Tujuan penelitian adalah untuk mengidentifikasi jenis batuan granitoid dan melihat komposisi mineral batuan granitoid Formasi Granit Kapur. Metode yang digunakan adalah observasi lapangan untuk deskripsi petrologi dan pengambilan sampel batuan dan dengan metode pengamatan petrografi. Dari hasil observasi lapangan didapatkan 3 jenis batuan granitoid di lokasi penelitian dengan warna, komposisi mineral dan ukuran kristal yang berbeda, 3 batuan tersebut adalah Tonalit, Granodiorit dan Monzogranit, komposisi mineral utama dari batuan granitoid di lokasi penelitian antara lain, plagioklas, potassium feldspar, kuarsa, hornblende dan biotit, dengan komposisi mineral sekunder antara lain klorit, apatit, muskovit, titanit, turmalin dan opak. Dari hasil penelitian dapat diinterpretasikan jika batuan granitoid di lokasi penelitian berasal dari satu magma yang sama dan hasil proses diferensiasi magma dimana tonalit membeku terlebih dulu dan monzogranit yang memiliki ukuran kristal paling besar dan diinterpretasikan merupakan hasil kristalisasi di tahap akhir dari pembekuan magma. Dari data kelimpahan mineral dapat diklasifikasikan jika batuan granitoid di daerah penelitian merupakan tipe KCG (K-rich and K-feldspar porphyritic Calc-alkaline Granitoids).

To constrain the behavior of K isotopes during granitic magmatic differentiation, we present high-precision K isotope data for bulk granitoids and their K-bearing minerals from Dabie and Himalayan orogens in China. Plagioclase displays extremely large K isotopic variation, with δ41K ranging from −0.56 to 1.91‰. Other minerals also have heterogeneous K isotopic compositions, with δ41K varying from −0.56 to −0.24‰ in hornblende, from −0.72 to −0.39‰ in biotite, from −0.79 to −0.47‰ in K-feldspar, and from −0.74 to −0.61‰ in muscovite. The general trend of 41K enrichment follows the order of plagioclase ≫ hornblende > biotite ≈ K-feldspar ≥ muscovite, which can be attributed to the difference in K O bond strengths. Both δ41K of plagioclase and K isotope fractionation factors between plagioclase and other minerals are negatively correlated with K concentration in plagioclase, suggesting a compositional control on isotope fractionations. Inter-mineral K isotope fractionations among other minerals are roughly temperature-dependent. Potassium isotopic compositions of whole rocks display measurable variations (δ41K = –0.69 to −0.28‰), which are correlated with proxies for plagioclase fractionation (e.g., Sr and Rb/Sr). The correlation indicates that fractional crystallization may account for the whole-rock K isotopic variations observed in high-silica igneous rocks, which is supported by modeling of fractional crystallization using the apparent isotope fractionation factors determined in this work. Our study demonstrates the existence of large K isotope fractionation during granitic magmatism, making K isotopes a potential tool for studying differentiation of felsic magmas. [ABSTRACT FROM AUTHOR]

We investigate the shape and strength of the magnetic fabrics (anisotropy of magnetic susceptibility (AMS) data) of various massive granitic plutons from different parts of India, using the eigenvalue method. The study aims to analyse eigenvalues and establish their relationship with various deformational attributes. It involves: (1) calculating eigenvectors and their corresponding eigenvalues from magnetic fabric datasets; (2) finding a link between the geometrical appearance of eigenvectors and the mechanistic issues involved with a specific deformation scenario; and (3) determining shape and strength parameters from the magnetic foliation data distribution. The statistical analysis for the unimodal magnetic fabric dataset of orthorhombic symmetry class implies that the plane, consisting of intermediate (V2) and minimum (V3) eigenvectors with pole V1, accurately traces the instantaneous stretching axis (ISAmax) of a particular material flow system under a pure shear regime. Moreover, for the distributions of similar symmetry and modality, we infer that the rotational characteristics of eigenvectors with respect to a fixed coordinate cause a distinct shift of such planes (V2–V3) from the ISAmax of a steady-state flow system under simple shear, where a substantial amount of rotational strain is involved. However, our findings also suggest that variation in symmetry and modality of magnetic fabric data distribution of different studied granitoids can directly influence the relative disposition of V2–V3 with respect to the direction of ISAmax. We conclude that eigenvalue analysis of magnetic fabrics is a powerful approach, which can be utilized while studying the salient deformational aspects of any syntectonic massive granitic body. [ABSTRACT FROM AUTHOR]

A whole-rock geochemical and zircon U–Pb and Lu–Hf isotope study of the Dengfeng complex in the Jishan area was performed to constrain the Neoarchean continental crust evolution in the southern margin of the North China Craton (NCC). The Dengfeng complex can be divided into supracrustal assemblage and plutonic intrusion. In the supracrustal assemblage, the detrital zircon of quartz schist from the Guojiayao Formation display oscillatory growth zones and streaky absorption with relatively high Th/U ratios (0.36–2.10), suggesting a magmatic origin. The 207Pb/206Pb ages range from 2963 to 2531 Ma, with a peak age of 2555 Ma, and the εHf(t) values are between + 2.3 and + 12.1. Combined with previous studies, the depositional age of the Guojiayao Formation can be constrained between 2542 and 2522 Ma, indicating that it mainly originated from the Neoarchean accretive basement material of the southern NCC. The Ruzhou gneissic syenogranites yield U–Pb ages from 2515 ± 13 Ma to 2504 ± 20 Ma, show that the plutonic intrusions also formed in the Late Neoarchean. They have high SiO2 (64.03–73.99 wt%) and Na2O + K2O (8.79–14.58 wt%) contents but low MgO (0.19–0.36 wt%) and CaO (0.02–0.27 wt%) contents, and belong to slightly peraluminous I-type granites with shoshonitic affinity. Magmatic zircon grains have positive εHf(t) values (+ 0.2 to + 6.7) with average crustal Hf model ages ranging from 2911 to 2671 Ma (average of 2765 Ma), indicating that the Ruzhou gneissic syenogranites were likely produced by partial melting of the accretive lower crust. The positive εHf(t) values and similarly ancient model ages suggest that a large-scale continental crust growth occurred in the southern margin of NCC at ca. 2.7 Ga. The Dengfeng complex was mainly derived from an arc-related setting associated with subduction in the Late Neoarchean. [ABSTRACT FROM AUTHOR]

Gunma and its neighboring region consist mainly of Tertiary to Quaternary sediments and volcanic rocks, with limited exposures of pre-Miocene basement units. Active volcanoes and their detritus also cover wide areas. Sr isotope ratios(87Sr/86Sr)of Quaternary volcanoes in this region show a large variation from about 0.704 to over 0.708. The large variation appears to represent diverse magma processes beneath this region, but the genesis of the wide variation is still a matter of discussion. Here we present new data of Sr isotope ratios for Miocene to Quaternary igneous rocks, which were collected from the border region between Gunma and Nagano Prefectures and were dated by the K-Ar method. The analyzed nine samples, seven andesites and two granitoids, yielded low initial 87Sr/86Sr ratios around 0.704, which is nearly the lowest values represented by Asama volcano in this region, suggesting limited contribution of continental crustal components. Large differences of 87Sr/86Sr ratios between Haruna and Akagi volcanoes and their basement volcanic rocks appear to reflect complicated crustal structure beneath these volcanoes, although detailed studies are required to clarify the genesis of the large differences. [ABSTRACT FROM AUTHOR]

With proven reserves of 9.836 × 1010 m3, the largest known natural gas reservoir among terrigenous basement rocks has been discovered within the granitoids of the northern Qaidam Basin. Due to their high heterogeneity, the genesis of basement reservoirs remains unknown. Herein, the structure of the weathering crust in granitoids and their potential controlling factors on the reservoir development mechanism are discussed using a multidisciplinary approach based on data from cores, thin sections, scanning electron microscopy (SEM), conventional and imaging logs, and physical property and major elements analyses. Moreover, the classification standard of the weathering crust structure is established. The dissolution belt holding diverse reservoir spaces accounts for more than 50% of the total porosity, while the disintegration belt is the main context for the development of cleavage fractures and crack fractures. The original pores exist mainly among the crystal grains of quartz and mica, while the secondary pores and fractures were generated by the alteration of aluminosilicate minerals as well as biotite or hornblende. The quality of these reservoirs is controlled by their mineral composition, tectonic uplift, faulting, and paleogeomorphology. The femic granitoid is the main reservoir-forming lithology in the case of dissolution, while the felsic granitoid is more likely to develop cracks. The formation of the disintegration belt is significantly linked to the presence of faulting. These belts were mostly induced by tectonic deformation along the Altyn fault belt from the late Oligocene to the early Miocene. The diversity in paleogeomorphology influences the extent of the weathering. The exhumation in the Altyn terrane from the late Jurassic to the Cenozoic corresponds to the weathering and hypergene leaching period of the weathering crust within granitoids. Three types of reservoirs are present in the rocks: fractured-porous (Type Ⅰ); porous (Type Ⅱ); and fractured (Type Ⅲ). The fractured-porous and fractured reservoirs were developed mainly in the granitic gneiss and granite, while the porous reservoir was formed in granitic diorite and granitic gneiss. The reservoirs that developed in the weathering crust of granitoids are dominated by Type Ⅰ and Type Ⅱ. The highest quality reservoir, which is the fractured-porous type, developed mainly in the dissolution belt of the weathering crust, and has a porosity ranging from 1.56% to 8.48% and a permeability ranging from 0.03 mD to 14.48 mD. The mechanisms of the development of weathering crust reservoirs provide further information for the hydrocarbon exploration of basement rocks worldwide. [ABSTRACT FROM AUTHOR]

The relationships between textural variations and structural trends of the aplite dyke enclosed in the Malanjkhand pluton were investigated in this study. The estimated zircon saturation temperature (747–835°C) and pressure of crystallization (2.5–6.1 kbar) suggested that the aplite dyke was emplaced in the lower-middle level in the continental crust. Water solubility calculations indicated that the aplite dyke originated from the silicic magma under water undersaturated conditions. Primitive mantle normalized spider diagram showed enrichment of large-ion lithophile elements (LILEs) and depletion of high field strength elements (HFSEs). The aplite dyke displayed LREE-enriched and MREE-depleted patterns, with significant positive Eu-anomaly in the REE patterns. This observation alluded the accumulation of plagioclase crystals before the crystallization of felsic magma in the reduced environment. The presence of the positive Eu-anomaly signified that the pre-existing granitic source at the lower-middle level of the crust generated aplitic magma owing to partial melting above the felsic source rock. Trace element discrimination diagrams presented evidence for possible extensional tectonic settings coupled with felsic magmatic episodes and granitic plutonic activity in a continental rift environment, thus favoring the emplacement of the aplite dyke. Th/U ratios in the aplite dyke implied that the melt fractionation in the magma chamber and the post-magmatic hydrothermal processes exerted negligible effect on the crystallization evolution of the aplitic magma. The aplite dyke pointed to a single pulse of silicic magmatism and a continuous process of injection, thus reflecting subtle variations in the physical conditions of the formation of the host Malanjkhand pluton. [ABSTRACT FROM AUTHOR]

Geothermal energy is a form of renewable energy with a long tradition in European countries, although it is scarcely used in Spain. One of the reasons for this is the poorly studied geothermal potential of the Spanish territory. In recent years, data published on terrestrial gamma radiation and the geochemistry of radioisotopes in rocks have suggested that the radiogenic heat production (RHP) in some areas of Spain is high. In this work, we assessed the RHP by analysing the U, Th, and K contents of the rocks underlying the most important campus of the University of A Coruña (northwest Spain), using in situ handheld gamma-ray spectrometry (GRS) and X-ray fluorescence spectrometry (XRF). Our results provide a good fit of the radioisotope contents and unexpectedly high RHP, compared with average data observed in similar rocks (granodiorite). These results reveal that GRS is a very reliable tool for studying the RHP of rock surfaces, and that geothermal energy can be used in the area (i.e., the studied campus, but also most of the city of A Coruña, as it is built on the same underlying rock) for central heating in buildings using ground-source heat pumps (GSHPs). [ABSTRACT FROM AUTHOR]

Geochemical analyses of individual minerals provide more detailed insights into the petrogenesis of igneous rocks than whole-rock analyses. This study conducted in situ geochemical and Nd isotope analyses of apatites from 10 Jurassic granitic plutons in the Yanbian area, NE China, to establish the petrogenesis and regional tectonic evolution. The results indicate that the apatite geochemistry of Jurassic granitoids in the Yanbian area was controlled primarily by the composition of parental melt. Post-magmatic alteration may lead to geochemical decoupling between apatite and parental melt, while Nd isotopes exhibit some resilience to such alterations. Apatites from Early Jurassic granitoids display characteristics that are consistent with an I-type origin, whereas those from Middle and Late Jurassic granitoids exhibit an adakitic affinity. Variations in apatite compositions indicate the fractional crystallization of other rare earth element (REE)-bearing minerals during magma evolution. The early crystallization of plagioclase and allanite led to decreases in Sr and Th contents in apatite, respectively, resulting in a negative Eu anomaly and light REE depletion. The fractional crystallization of titanite and hornblende resulted in the depletion of middle REE in apatite. Hornblende is regarded as the main residual phase in the magma source of Middle and Late Jurassic adakitic granitoids in the Yanbian area. Apatite Nd isotopic compositions suggest that the Jurassic granitoids in the Yanbian area originated from two crustal sources: the Central Asian Orogenic Belt and the North China Craton. Additionally, increasing trends in apatite Sr/Y and (La/Yb) N ratios from the Early to Late Jurassic suggest a gradual thickening of the regional crust, which is likely driven by the continentward migration of the subduction zone associated with the Paleo-Pacific Plate. • Apatite geochemistry is indicative of magma evolution and post-magmatic alteration. • Variations in apatite trace elements reveal mineral fractional crystallization. • Apatite geochemistry reveals the genetic types and magma sources of granitoids. • Jurassic granites in the Yanbian area were formed by the Paleo-Pacific Plate subduction. [ABSTRACT FROM AUTHOR]

The West Qinling Orogen (WQO) of the northeastern region of the Tibet Plateau occupies a key tectonic position at the junction between the Pan-Asian and the Tethyan tectonic domains. However, there are ongoing debates regarding the exact timing of final continental collision in the WQO and closure time for the Paleo-Tethyan ocean. Here, we present LA-ICP-MS zircon U Pb dating results along with major-trace elemental and Sr-Nd-Hf isotopic data for four granitic plutons across the western WQO, from north to south including Xiangyu, Tongren, Heri, and Wenquan. Notably, both the Tongren and Wenquan plutons contain abundant mafic microgranular enclaves (MMEs). Our new data indicate that the Xiangyu granites were emplaced at 249 Ma in a continental arc setting. These rocks are high-K calc-alkaline, formed by partial melting of Precambrian basement within the normal lower crust (< 40 km) followed by fractional crystallization of primary crustal melts. The Heri granitoids were emplaced at 237 Ma in a continental arc setting as well. They are also high-K calc-alkaline, but generated by partial melting of Precambrian basement at depths of 40–50 km. The Wenquan granitoids along with MMEs were emplaced at 234–233 Ma in a continental arc setting. The enclave magmas were formed through orthopyroxene-dominant fractional crystallization of primary mantle-derived melts originating from a phlogopite-bearing lherzolitic lithosphere at depths no more than 60 km, while the host granitoids were formed through mixing of the crustal melts resembling the Heri granitoids with approximately 40 to 60% enclave magmas. The Tongren granitoids along with MMEs were emplaced at 231–228 Ma in a back-arc setting. The enclave magmas originated from a phlogopite-bearing lherzolitic lithosphere at depths of 60–70 km, while the host granitoids were formed through mixing of the crustal melts resembling the Xiangyu granites with approximately 18 to 40% enclave magmas. We suggest that the Paleo-Tethyan (Anemaqen) oceanic crust had subducted northward approaching the northernmost WQO by 249 Ma followed by the initiation and gradual southward migration of the oceanic slab rollback. The slab subduction did not cease at least before 228 Ma. • We have investigated four Triassic granitic plutons in western West Qinling Orogen. • The 249–233 Ma granites and microgranular enclaves formed in continental-arc setting. • The 231–228 Ma granites and microgranular enclaves formed in back-arc setting. • The origin of these rocks recorded the Paleo-Tethyan oceanic crust advance to retreat. [ABSTRACT FROM AUTHOR]

In the Pra Basin of Ghana, groundwater is increasingly becoming the alternative water supply due to the continual pollution of surface water resources through illegal mining and indiscriminate waste discharges into rivers. However, our understanding of hydrogeology and the dynamics of groundwater quality remains inadequate, posing challenges for sustainable water resource management. This study aims to characterize groundwater recharge by determining its origin and mechanism of recharge prior to entering the saturated zone and to provide spatial estimates of groundwater recharge using stable isotopes and water level measurements relevant to groundwater management in the basin. Ninety (90) water samples (surface water and groundwater) were collected to determine stable isotope ratios of oxygen (δ18O) and hydrogen (δ2H) and chloride concentration. In addition, ten boreholes were installed with automatic divers to collect time series data on groundwater levels for the 2022 water year. The Chloride Mass Balance (CMB) and the Water Table Fluctuation (WTF) methods were employed to estimate the total amount and spatial distribution of groundwater recharge for the basin. Analysis of the stable isotope data shows that the surface water samples in the Pra Basin have oxygen (δ18O) and hydrogen (δ2H) isotope ratios ranging from −2.8 to 2.2‰ vrs V-SMOW for δ18O and from −9.4 to 12.8‰ vrs V-SMOW for δ2H, with a mean of −0.9‰ vrs V-SMOW and 0.5‰ vrs V-SMOW, respectively. Measures in groundwater ranges from −3.0 to −1.5‰ vrs V-SMOW for δ18O and from −10.4 to −2.4‰ vrs V-SMOW for δ2H, with a mean of −2.3 and −7.0‰ vrs V-SMOW, respectively. The water in the Pra Basin originates from meteoric source. Groundwater has a relatively depleted isotopic signature compared to surface water due to the short residence time of infiltration within the extinction depth of evaporation in the vadose zone. Estimated evaporative losses in the catchment range from 51 to 77%, with a mean of 62% for surface water and from 55 to 61% with a mean of 57% for groundwater, respectively. Analysis of the stable isotope data and water level measurements suggests a potential hydraulic connection between surface water and groundwater. This hypothesis is supported by the fact that the isotopes of groundwater have comparatively lower values than surface water. Furthermore, the observation that the groundwater level remains constant in months with lower rainfall further supports this conclusion. The estimated annual groundwater recharge in the catchment ranges from 9 to 667 mm (average 165 mm) and accounts for 0.6% to 33.5% (average 10.7%) of mean annual precipitation. The total estimated mean recharge for the study catchment is 228 M m3, higher than the estimated total surface water use for the entire Pra Basin of 144 M m3 for 2010, indicating vast groundwater potential. Overall, our study provides a novel insight into the recharge mechanism and spatial quantification of groundwater recharge, which can be used to constrain groundwater flow and hydrogeochemical evolution models, which are crucial for effective groundwater management within the framework of the Pra Basin’s Integrated Water Resources Management Plan.

To illuminate the migration and transformation of selenium (Se) in the igneous rock-soil-rice system, 285 pairs of rhizosphere soil and rice samples were collected from the granitoid and basalt areas in Hainan Province, South China. The contents of Se in soils derived from granitoid and basalt are, respectively, 0.19±0.12 mg/kg and 0.34±0.39 mg/kg, which are much higher than Se contents in granitoid and basalt. Selenium shows remarkable enrichment from granitoid and basalt to soils. The mobile fraction of Se in soils derived from granitoid is 0.0100±0.0034 mg/kg, which is significantly higher than that of basalt (0.0058±0.0039 mg/kg). Although soil derived from basalt shows higher Se contents, Se contents in rice samples, mobile fractions of Se in soils, and biological concentration factor (BCF) is similar or even lower than that from granitoid. Basalt consist of calcic plagioclase and pyroxene, and are much richer in Fe, Al, and Ca than granitoid. Correspondingly, the basalt-derived soils have higher goethite, hematite, kaolinite, cation exchange capacity (CEC) content, and higher pH than the granitoid-derived soils, which result in higher adsorption capacity for Se and relatively lower Se bioavailability. Soils derived from granitoid and basalt in tropical regions are beneficial to produce Se-rich rice.© 2022 China Geology Editorial Office.

A detailed structural study showed that the Mesoproterozoic Karadjilga granite–gneiss massif of the Kyrgyz North Tianshan represents a sheet intrusion, concordant to the bedding of the host Mesoproterozoic metasedimentary strata. The massif has a complex internal structure with strain gradients from unfoliated granite to mylonite. The boundaries of the mylonite, gneiss, and unfoliated granite zones, as well as the foliation in gneisses, are oriented subparallel to the contacts of the massif and are deformed into a single syncline together with the host sedimentary strata. The obtained U–Th–Pb (SHRIMP) age of unfoliated granite (1121 ± 13 Ma) is close to the previously obtained age estimates for granite–gneisses (~1090–1130 Ma), and indicates that, regardless of the degree of deformation, all the rocks of the massif belong to an unified igneous complex. [ABSTRACT FROM AUTHOR]

Vermiculite, a clay mineral of economic importance, is reported for the first time from the Bundelkhand Craton. The locales of the vermiculite occurrence are mapped within the Bundelkhand granitoids at several places. The identification of the fracture system and the zones of strain localization within Bundelkhand granitoids are critical for targeting the occurrences of vermiculite. A range of studies including meso‐, micro‐, and sub‐microscopic analyses were used to delineate the characteristic features of vermiculite along the brittle/ductile shear zones in the Bundelkhand Craton. SEM‐based EDS, EPMA, and XRD analyses confirm the ubiquitous dominance of vermiculite as fracture infills and/or channel infill materials along the zones of nucleation of ductile shear zones. It is postulated here that the occurrence of vermiculite is a result of supergene alteration of biotite present in the vein material. The parent material of the fracture infills from which the veins crystallized is genetically derived from the host rock (Bundelkhand granitoid), which later healed the fractures and prompted the nucleation of ductile shear zones in the Bundelkhand Craton. [ABSTRACT FROM AUTHOR]

The study area is located about 30 km south of Ramsar, in the central Alborz zone. In addition to the Nusha granitoids (with an age of about 56 million years), the outcrops in this area, mainly include Paleozoic and Mesozoic rock units. Petrographically, the Nusha granitoids have diorite, syenite, monzonite, monzodiorite, granodiorite and quartz monzonite compositions. Moreover, mineralogically, feldspar is the principal mineral, and the texture superiority in them belongs to the granular type. In terms of magmatic series these rocks are metaluminous and range from high K calcalkaline to shoshonitic. The geochemical characteristics of the major and rare elements, as well as the petrographic ones indicate that these granitoids are I type granites, and at the same time they belong to high temperature ones based on the behavior of Ba, Ce and Y elements. Enrichment in LILE and LREE and low concentrations of heavy rare earth elements HREE and high field strength elements HFSE, together with Nb and Ti negative anomaly in the spider diagrams are signs of magmas related to the subduction zone. The high temperature nature and characteristics such as Y/Nb, Rb/Sr and Rb/Ba ratios show that the Nusha granitoids have the geochemical properties of both crustal and mantle origin materials with different ratios. Based on tectonomagmatic discrimination diagrams and trace element compositions, these granitoids belong to an active continental margin environment. The parental magma has originated from melting of an enriched mantle source and contaminated with continental crust during ascent. [ABSTRACT FROM AUTHOR]

Chamatoo intrusive body with monzonite to granite composition located south of Amlash city and east of Guilan in the Western Alborz. Petrographically, the Chamatoo intrusive body is mostly made of alkali feldspars and plagioclase with biotite, pyroxene, opaque minerals, and different textures from granular to porphyry granular as the main textures and perthitic, graphic, poikilitic as the accessory textures. In the chondrite-normalized spider diagram, the granitoid rocks display subparallel, linear and homogeneous REE profiles with LILE enrichment as well as Ta and Ti negative anomalies. In addition, all samples have the characteristics of WPG. Overall, the Chamatoo body was formed during the subduction of the oceanic crust of the Southern Caspian Sea and owing to the activity of an subducted mid oceanic ridge towards south, in an extensional regime above the supra-subduction zone a Slab Window was formed. Finally, Slab Window tectonic regime caused the rise of asthenosphere and the alkaline OIB magmatism in the region, followed by the generation of A1- type granite and the per-alkaline Chamatoo granitoid from fractional crystallization of OIB magma source.

Introduction Fe skarn deposits are the largest skarn deposits which are exploited for Fe as well as by-products of Cu, Co, Ni and Au (Meinert et al., 2005). They are one of the most important Fe deposits in the Zanjan province which have been exploited in recent years. The Alamkandi Fe deposit is one of these Fe skarn deposits which is located at 35 km west of the Mahneshan within the Takab-Takht-e-Soleyman subzone, northern Sanandaj- Sirjan zone. In this area, alternation of amphibolite, amphibole schist and biotite schist with intercalations of marble belonging to Paleozoic and intruded by late Oligocene alamkandi granitoid exist. This intrusion has caused contact metamorphism and formation of Fe mineralization. Some of the Fe skarn deposits in the Zanjan province were studied during the past years (i.e., Nabatian et al., 2017; Mokhtari et al., 2019) and valuable information is present about their geological and mineralization characteristics. However, the Alamkandi granitoid and Fe deposit have not been studied until the present. In this research study, geochemistry and petrogenesis of the Alamhandi granitoid along with mineralogy, textures and geochemistry of Fe deposit and thermodynamic conditions for formation of contact metamorphic rocks have been studied. Materials and methods This research can be divided into two parts including field and laboratory studies. Field studies include recognition of different parts of granitoid intrusion and skarn aureole along with sampling for laboratory studies. During field work, 65 samples were selected for petrographic and analytical studies. 19 thin sections and 13 polished thin sections were used for petrographical and mineralogical studies. For geochemical studies, 15 samples from granitoid and ore skarn sub-zone were analyzed by XRF and ICP-MS methods at the Zarazma laboratory, Tehran, Iran. Results Based on petrographic studies, the Alamkandi granitoid is composed of granodiorite, quartz diorite and porphyritic diorite. Granodiorites with hetrogranular texture are composed of plagioclase, quartz, K-feldspar, hornblende and biotite. Quartz diorites indicate porphyroid to seriate and hetrogranular textures and are composed of plagioclase, clinopyroxene, hornblende and quartz. Porphyritic diorites have porphyritic texture with plagioclase and amphiboles phenocrysts. The Alamkandi granitoids demonstrate calc-alkaline to high-K calc-alkaline affinity and can be classified as metaluminous I-type granitoids. Primitive mantle-normalized (McDonough and Sun, 1995) trace elements patterns for the Alamkandi granitoids indicate LILE and LREE enrichment along with negative HFSE anomalies and positive Pb anomaly. Chondrite-normalized (McDonough and Sun, 1995) REE patterns for these rocks demonstrate LREE enrichment (high LREE/HREE ratio). Based on tectonic setting discrimination diagrams, the Alamkandi granitoids were formed in the active continental margin. Fe mineralization in the Alamkandi area crops out in discrete places as massive and lens-shaped bodies. The Northern outcrop body has 150m length and up to 50m width, while the southern outcrop body has 100m length and up to 20m width. Microscopic studies reveal that the skarn zone at the Alamkandi granitoid is composed of garnet skarn, pyroxene skarn, epidote pyroxene skarn, serpentine skarn, and ore skarn sub-zones. Magnetite is the main ore mineral along with some pyrite and chalcopyrite. Garnet, clinopyroxene, olivine, serpentine, epidote, actinolite, calcite and quartz are present as gangue minerals. Based on the field and microscopic studies, the Alamkandi Fe deposit has massive, banded, disseminated, brecciated, vein-veinlets, replacement and relict textures. Based on mineralogical and textural studies, the skarnization processes in the Alamkandi deposit can be divided into 3 stages including: (1) isochemical metamorphic stage, (2) prograde metasomatic stage and (3) retrograde metasomatic stage. Discussion Based on skarn mineralogy, the XCO2 vs. T and T vs. logƒO2 diagrams were used to determine the possible physio-chemical conditions. According to these diagrams and considering mineralogical and textural evidence, maximum temperature for formation of olivine in XCO2≈0.1 and P=1kb was about 450-600°C. Furthermore, garnet and clinopyroxene were formed simultaneously at 430-550°C and ƒO2 equal 10-18 to 10-22. In temperatures less than 450°C, olivine was replaced by serpentine while in temperatures less than 430°C and increasing ƒO2, garnet and clinopyroxene were replaced by epidote + quartz + calcite and actinolite + quartz + calcite, respectively. In temperatures less than 430°C, fluids in equilibrium with granitic intrusion and with relatively high sulfidation (ƒS2>10-6), were not in equilibrium with andradite. Therefore, andradite was replaced with quartz + calcite + pyrite. With reducing ƒS2 (

The timing of the Lhasa–Qiangtang collision following the closure of the Bangong–Nujiang Tethys Ocean has not been well constrained. An integrated study of whole-rock geochemistry and zircon U–Pb–Hf isotopes was carried out for Early Cretaceous quartz diorite-porphyrites and granites from the Yilashan and Amdo areas, northern Tibet. LA–ICP–MS zircon U–Pb dating reveal that the Yilashan and Amdo granitoids were emplaced at ~121–110 Ma. These granitic rocks display selective enrichment of light rare earth elements, large ion lithophile elements (e.g., Rb, U) and Th, but depletion of Sr and high field strength elements (e.g., Nb, Ta, Ti) compared to its neighboring elements. These new data, combined with regional geological setting, show that these igneous rocks were formed under a geodynamic setting of the Lhasa and Qiangtang (–Amdo) collision with oceanic slab breakoff and asthenospheric upwelling. The BNTO had been closed at ~121–110 Ma in the study area. Yilashan-Amdo granitoids roughly yield high (87Sr/86Sr)i ratios and obvious negative εNd(t) and zircon εHf(t) values along with old Nd TDM and zircon Hf TDM2 ages. Together with their variable U–Pb ages, these features indicate a Precambrian "hidden" crustal source beneath the northern Lhasa and Amdo terranes. The YLSS S-type granophyres were derived from partial melting of Paleoproterozoic lower crustal metagraywackes, whereas the YLSZ quartz diorite–porphyrites and the Amdo I- and A-type granites were mainly derived from partial melting of Paleo–Mesoproterozoic lower crustal mafic rocks with a certain amount of addition of mantle-derived melts. Minor amounts of the materials originated from the Amdo orthogneisses may also be involved in the formation of the YLSZ quartz diorite–porphyrites and the Amdo I-type granites. In addition, the Yilashan ophiolite was intruded by the ~112–108 Ma granophyric and quartz diorite–porphyritic intrusions before its final emplacement into the surrounding strata. [ABSTRACT FROM AUTHOR]

The Moldanubian Zone of the Bohemian Massif was intruded by three Variscan (c. 354–335 Ma) subduction-related plutonic suites. Their mantle sources evolved from CHUR-like (low-K calc-alkaline suite), through slightly enriched ( ε Nd 346 ~ − 3; high-K calc-alkaline suite—HKCA) to strongly enriched ( ε Nd 337 < − 7.5; (ultra-)potassic suite—UK). This evolution has been previously interpreted in terms of Andean-type subduction passing to deep subduction/relamination of the Saxothuringian continental crust, metasomatizing the mantle source of the HKCA and, more significantly, of the UK suite. This is in accord with the heterogeneity of lithospheric mantle fragments (spinel/garnet peridotites, garnet pyroxenites, eclogites, glimmerites...) sampled by the high-grade Moldanubian orogenic root. Newly acquired Mg isotopic compositions (δ26Mg = − 0.12 to − 0.53‰) vary over similarly broad intervals within each suite. Majority of the most magnesian samples fall within the range of local orogenic mantle peridotites (− 0.33 to − 0.29‰) or close to the global mantle average (− 0.25‰). This implies that the δ26Mg of the progressively metasomatized harzburgitic mantle was mostly buffered by the mantle end-member, while its mantle-incompatible elemental/related isotopic (Sr–Nd–Pb) signal was swamped by the crustally derived contribution. The crustal contaminant, source of the metasomatic fluids, had to be dominated by Mg-poor, felsic metaigneous > > clastic metasedimentary material. Subducted carbonates were of limited importance, as recorded by lowered δ26Mg values in several mafic UK samples and in a glimmerite vein cutting the peridotites (− 0.44‰). The Mg isotopic variation in less magnesian potassic rock types reflects a complex interplay between source heterogeneity, equilibrium fractionation during fractional crystallization, kinetic fractionation due to chemical diffusion during magma mixing and/or AFC-style contamination by carbonate-derived fluids. [ABSTRACT FROM AUTHOR]

[Display omitted] • Episodic crustal growth occurred in the microcontinents within the eastern CAOB. • Most of the continental crust in the microcontinents accreted in the Precambrian. • The varying rates of regional crustal growth are linked to supercontinent cycles. The crustal growth and reworking processes of accretionary orogen such as the Central Asian Orogenic Belt (CAOB) have been a controversial issue. Here, we present in situ zircon U–Pb and Lu–Hf isotopic data for granitoids from a microcontinent (the Songnen Massif) and an arc terrane (the Duobaoshan arc terrane), which generally represent two main crustal components in the eastern CAOB to establish a crustal growth model for an accretionary orogen and to trace the influence of the assembly and breakup of supercontinents on crustal evolution in an accretionary orogen. Neoproterozoic–Mesozoic granitoids distributed in the Songnen Massif show a step-like crustal growth pattern over time with three major periods of development: Paleoproterozoic crustal growth at 2.2–1.8 Ga, Mesoproterozoic growth at 1.6–1.0 Ga, and a third pulse of growth at 0.85–0.6 Ga, along with two short pauses at 1.8–1.6 Ga and 1.0–0.85 Ga. The assembly and collision phases of supercontinents corresponded to the enhanced and degressive crustal growth rates of the Songnen Massif, respectively, suggesting that the supercontinent cycles are responsible for the episodic crustal growth pattern in the region. Crustal reworking of the Songnen Massif occurred during 1000–180 Ma, with a fluctuation at 800–600 Ma, which provided a major contribution to the isotopic heterogeneity of lower continental crust. Isotopic compositions of granitoids from the Duobaoshan arc terrane located between the Xing'an and Songnen massifs, together with those of granitoids from other microcontinents, suggest that most of the continental crust beneath the microcontinents in the eastern CAOB generated during the Precambrian, whereas a significant amount of lateral crustal accretion occurred in continental arc settings during orogenies and amalgamation of microcontinents during the Phanerozoic. [ABSTRACT FROM AUTHOR]

Hainan Island is a key part of the eastern Tethyan region and contains detailed geological information that can enhance our understanding of the tectonic evolution of this region since the late Palaeozoic. In this paper, we report geochronological, geochemical, and Sr–Nd isotopic data for granitoids from Baomei and Chahe in the northern part of Hainan Island. Three new zircon U–Pb ages of 243.3 ± 1.7 Ma, 237.1 ± 5.1 Ma, and 257.0 ± 4.0 Ma were obtained for these granitoids. The late Permian Chahe granite (257 Ma) is weakly peraluminous to peraluminous, and has rare earth element patterns and Ga/Al and FeOT/MgO ratios typical of A‐type granites formed in an extensional tectonic setting. The Middle Triassic Baomei granitoids (243–237 Ma) are weakly peraluminous, and exhibit a negative correlation between P2O5 and SiO2, which is typical of I‐type granites. All the granitoids have EM II‐type‐enriched mantle Sr–Nd isotopic compositions, which indicate that they were derived from a mantle source that had experienced enrichment and metasomatism. Hainan Island was in an extensional tectonic setting from the late Permian to Middle Triassic when widespread A‐ and I‐type granites were generated. We speculate that Hainan Island was mainly affected by the Tethyan tectonic domain during the Permian–Triassic, which involved closure of the Palaeo‐Tethys Ocean, collision of the Indochina and South China blocks, and subsequent post‐collisional extension. [ABSTRACT FROM AUTHOR]

Major and trace element data are presented for Berguda granitoids within the Neoproterozoic basement rocks of southern Ethiopia, East African Orogeny. Geochemical and petrological constrains indicate the presence of two distinct types of granitoid rocks: (1) Wolena Bokosa granitoid (WBG) and (2) Hida Korma granitoid (HKG). WBG is granite in composition with high SiO2 content (73.38–79.38 wt.%) and wider Al2O3 values (10.68–14.81 wt.%). It has relatively high molecular values (ASI = 0.99–1.05) with low contents of CaO, MgO, Fe2O3, TiO2, and P2O5. WBG is shoshonitic to high-k calc-alkaline, Al-rich metaluminous, and more felsic I-type granitoid, whereas HKG is quartz-monzonite in composition (SiO2 = 65.31–68.26) with relatively low molecular values (ASI = 0.86–0.96) with high contents of CaO, MgO, Fe2O3, TiO2, and P2O5. HKG is also shoshonitic to high-k calc-alkaline, metaluminous, and more mafic I-type granitoid. The observed positive anomalies in Rb, Th, K, Pb, and Zr and negative anomalies of Sr, P, Ti, Nb, and Ta in both groups reflect the involvements of crustal materials in their petrogenesis. In terms of geodynamic setting, WBG is classified as volcanic arc (VAG) and syn-collisional (syn-COLG) granite and inferred as syn-orogenic, whereas the HKG is classified as within-plate granite (WPG) with post-orogenic emplacement. Furthermore, this study infers that the transition from syn-orogenic calcic-alkalic WBG to alkalic HKG magmatism is marking the cessation of subduction control magmatism of the East African Orogeny (EAO) at about 529 ± 11 Ma. The continuation of the magmatism after the cessation of subduction control magmatism is shown by emplacement of more alkalic post-orogenic HKG with volcanic arc chemical affinities possibly the effect of previous subduction process. [ABSTRACT FROM AUTHOR]

A complex magma mingling/interaction zone in the Bundelkhand craton, Central India, was formed when several pulses of mafic magma interacted with the still-crystallising felsic magma. Coeval emplacements of mafic−felsic magmas (marked by the cuspate−lobate boundary, crystal transfer, and hybrid rocks) produce various styles of interactions (besides the formation of the mafic magmatic enclaves). These are included in the mafic patches, hybrid enclaves, tabular sheet/dykes in the felsic rocks; granitoid back-veins and enclaves in the mafic rocks. Each interacting features exhibit distinct texture of minerals is documented. A model of coeval emplacements of mafic−felsic magmas is presented by the four successive stages of interaction. During stage I, a mixed boundary layer between the felsic and mafic phases was formed facilitating strong mechanical exchange. Mafic enclaves in the felsic phase were formed in stage II. During stage III, back-veining of the felsic melt into the mafic phase took place. Stage IV or the late stage of mingling is manifested by the formation of amoeboid titanites. Research highlights: A complex MMZ is present in the Bundelkhand craton. The MMZ involves four stages of the interaction of the mafic−felsic magmas. Each stage exhibits a distinct textural characteristic of minerals. [ABSTRACT FROM AUTHOR]

Well‐developed tors and associated boulder fields are present in exposed granitoid pluton, but their geomorphological origins have not been fully addressed. Although the tor‐like features are commonly attributed to the orthogonal joint system along which weathering proceeds and the weathering materials are removed, the majority of previous studies lack three‐dimensional (3‐D) morphological observations. One of the well‐known granitoid rock towers in Japan, namely, the obelisk at Mt. Jizogadake in the Japanese Southern Alps, was investigated using unmanned air vehicles (UAVs). A 3‐D observation of the granitoid obelisk found that it is shaped by columnar joints with an undulation along a long axis and irregularly shaped cross‐sections. Because of these features and intersection angles between the rock columns and exposure surfaces, the obelisk exhibits a peculiar morphology appearing as a heap of rock blocks when observed from the ground. The columnar jointing might have occurred in a marginal zone of the granitoid pluton due to faster cooling rates. The 3‐D observations also confirmed the columnar joints formation was predated by high‐angle, planar joints. The columnar joints divide the rock mass between those planar joints. This may imply that the high‐angle joints would have formed probably during cooling under the presence of tectonic and thermal stresses. [ABSTRACT FROM AUTHOR]