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Zircon stability in silicate melts—which can be quantitatively constrained by laboratory measurements of zircon saturation—is important for understanding the evolution of magma. Although the original zircon saturation model proposed by Watson and Harrison (Earth Planet Sci Lett 64(2):295–304, 1983) is widely cited and has been updated recently, the three main models currently in use may generate large uncertainties due to extrapolation beyond their respective calibrated ranges. This paper reviews and updates zircon saturation models developed with temperature and compositional parameters. All available data on zircon saturation ranging in composition from mafic to silicic (and/or peralkaline to peraluminous) at temperatures from 750 to 1400 °C were collected to develop two refined models (1 and 2) that may be applied to the wider range of compositions. Model 1 is given by lnCZr(melt) = (14.297 ± 0.308) + (0.964 ± 0.066)·M − (11113 ± 374)/T, and model 2 given by lnCZr(melt) = (18.99 ± 0.423) − (1.069 ± 0.102)·lnG − (12288 ± 593)/T, where CZr(melt) is the Zr concentration of the melt in ppm and parameters M [= (Na + K + 2Ca)/(Al·Si)] (cation ratios) and G [= (3·Al2O3 + SiO2)/(Na2O + K2O + CaO + MgO + FeO)] (molar proportions) represent the melt composition. The errors are at one sigma, and T is the temperature in Kelvin. Before applying these models to natural rocks, it is necessary to ensure that the zircon used to date is crystallized from the host magmatic rock. Assessment of the application of both new and old models to natural rocks suggests that model 1 may be the best for magmatic temperature estimates of metaluminous to peraluminous rocks and that model 2 may be the best for estimating magmatic temperatures of alkaline to peralkaline rocks. [ABSTRACT FROM AUTHOR]

The paper reports the results of melting experiments on the fluorite-enriched rhyolites of the Nyalga Basin (Central Mongolia). The fluoride–calcium (F–Ca) melt was obtained in a wide range of P-T parameters (1250–750°С, 5.5–1 kbar). Fluoride–silicate liquid immiscibility was observed at F > 2.5 wt % and CaO > 5.3 wt % in the initial system. An increase of temperature and pressure was accompanied by a significant increase in the concentrations of REE, Y, Sr, P, Th, U, Nb, Co, Cu, Sn, Sb, and Mo in the F–Ca melt. The peculiarity of the DREE distribution coefficients between F–Ca and silicate melts can lead to the formation of M-type tetrad effects for the first, third, and fourth tetrads in the chondrite-normalized REE patterns of silicate melt. The F–Ca melt has existed up to subsolidus temperatures of the rhyolitic melt. None of the models of magmatic crystallization of fluorite in haplogranitic melts or subsolidus postmagmatic and hydrothermal fluoritization can explain the origin of fluorite-enriched rhyolites. It is suggested that these rocks were formed from magma containing the emulsion of rhyolitic and F–Ca melts. The fluoride–silicate liquid immiscibility resulted in the redistribution of trace elements (REE, Y, Sr, P, Zr, Hf, Ta, Nb, Sc, Li, Be, and Rb) between melts. The formation of rock matrix was accompanied by degassing of the rhyolitic melt. An effective viscosity of the magma (melts emulsion with fluid bubbles) is comparable with the viscosity of a liquid. The F–Ca melt was quenched into F–Ca phase consisting of submicron fluorite particles, while solidification of the rhyolitic melt and silicate glass devitrification resulted in the formation of quartz–sanidine symplectites. The F–Ca phase has the elevated contents of O, Sr, LREE, Y, Si, sometimes Sc, P, and Al. The isomorphous substitution of O2– → F– in the fluorite structure led to the formation of aggregates of oxygen-vacancy centers, which are responsible for the laser-induced luminescence of the F–Ca phase in the rhyolite matrix. The wide variations of the REE, Y, Sr, Th, Nb, Ta, Zr, and Hf contents in the F–Ca phase are related to its recrystallization under the effect of fluid, which was released during degassing of rhyolitic melt. The submicron-sized fluorite particles in the F–Ca phase during the interaction with fluid were gradually liberated from impurities (besides Sr) and transformed into larger crystalline segregations. It is suggested that the oxygenated F–Ca melt exists in a metastable supercooled state under oxidizing conditions during eruption of rhyolitic magma. This is inconsistent with previously obtained experimental data on crystallization of fluorite from CaF2- and H2O-saturated haplogranitic melts at < 950°С and 1–2 kbar. Using rhyolites as example, it is shown that fluorite and associated ore mineralization (monazite-group minerals, cerianite) were derived from F–Ca melt with elevated REE and Y contents. In many igneous rocks and magmatogenic ores, fluorite could be a product of transformation of the F–Ca melt. [ABSTRACT FROM AUTHOR]

The Early Cretaceous Shengli River–Changshe Mountain marine oil shale belt, located in the northern Qiangtang Basin, Tibet, is estimated to be the largest marine oil shale resource in China. However, its palaeoweathering, provenance, and tectonic setting during the depositional history have received little interest. In this paper, 19 outcrop marine oil shale samples from the ChangsheMountain (CSM) area were studied to investigate the provenance, palaeoclimate, palaeoweathering, and tectonic setting during the marine oil shale deposition. The total organic carbon and organic sulphur contents of the CSM oil shales range from 2.2% to 13.44% and 0.19% to 1.08%, respectively. The CSM oil shale samples contain abundant carbonate (e.g., calcite and dolomite), quartz, and clay minerals. The clay minerals of the CSM oil shale samples is dominated by illite and then by smectite. Other minerals, including haematite, apatite, pyrite, baryte, and celestite, were also identified by scanning electron microscope–energy‐dispersive X‐ray spectrometer. The total rare earth element (∑REE) contents of the oil shales range from 9.01 to 105.96 ppm (average 57.56 ppm), close to the average REE contents of U.S. coals. The REE contents in oil shale samples are mainly controlled by terrigenous input. The CSM oil shales show LREE‐enriched, HREE‐depleted, with the LREE/HREE ratios ranging from 5.12 to 10.18, negative Eu anomalies (0.56–0.84) and slightly negative Ce anomalies (0.87–1.05). The chemical index of alteration values of the CSM oil shales range from 67 to 76 (average 73), indicating a moderate chemical weathering condition. Sr/Cu and Rb/Sr ratios suggest the CSM oil shales were mainly deposited under a warm and humid climate regime. Sr/Ba ratios, ranging from 0.54 to 7.84, suggest a palaeoenvironment with fluctuant salinity. Major element, trace element, and REE relationships indicate that the CSM oil shales are mainly from the felsic and intermediate igneous rocks. The REE distribution patterns of the CSM oil shales are similar to the Late Triassic Nadi Kangri felsic volcanic rocks in the Qiangtang Basin, indicating that the CSM oil shale may be derived from the Late Triassic volcanic rocks and the oil shales were mainly formed in rift tectonic setting. Favourable preservation condition (e.g., warmer palaeoclimate, higher palaeosalinity, and dysoxic to anoxic water column environment) could be the main controlling factor for organic matter accumulation. [ABSTRACT FROM AUTHOR]

This paper reports in situ U–Pb ages and Hf isotopic data on detrital zircons from Palaeozoic strata in central‐eastern Jilin Province, NE China, with the aim of constraining the timing of final closure of the Paleo‐Asian Ocean and the tectonic evolution of the eastern segment of the Central Asian Orogenic Belt (CAOB). Zircons from Middle to Late Permian Fanjiatun and Yangjiagou formations in central Jilin Province are characterized by four major groups of age populations (2.5–2.3 Ga, 1.9–1.7 Ga, 1.3–1.0 Ga, and Late Palaeozoic ages). The Paleo‐Mesoproterozoic and Cambrian zircons have positive εHf(t) values, suggesting that the source was mainly locally derived from the CAOB, whereas a lesser amount of Archean zircons with positive εHf(t) values, indicating that source from the North China Craton (NCC). The Phanerozoic zircons have both positive and negative εHf(t) values indicates that material from bidirectional provenances in the CAOB and the NCC. However, Late Permian Kaishantun Formation in eastern Jilin Province contain a single group of Phanerozoic zircons with positive εHf(t) values, distinct from known igneous zircons in the NCC, suggesting a local source. These observations, along with the results of previous studies on Middle–Late Permian igneous rocks in Jilin Province, indicate that the eastern segment of the Paleo‐Asian Ocean underwent the initial closure in central Jilin Province during the Middle Permian and the final closure in eastern Jilin Province in the Late Permian–Early Triassic. The detrital zircon geochronological data clearly record two stages of tectonic evolution and the scissor‐like closure model of the Paleo‐Asian Ocean in the eastern segment of the CAOB. [ABSTRACT FROM AUTHOR]

Molar element ratio analysis of element concentrations consists of four basic tools that provide substantial insight into the lithogeochemistry (and mineralogy) of rocks under examination. These tools consist of: (1) conserved element ratio analysis; (2) Pearce element ratio analysis; (3) general element ratio analysis; and (4) lithogeochemical mineral mode analysis. Conserved element ratio analysis is useful in creating a chemostratigraphic model for the host rocks to mineral deposits, whereas Pearce element ratio analysis and general element ratio analysis are primarily used to identify mineralogical and metasomatic controls on rock compositions and to investigate and quantify the extent of the material transfers that formed the host rocks and mineralization. Lithogeochemical mineral mode analysis converts element concentrations into mineral concentrations using a matrix-based change-of-basis operation, allowing lithogeochemical data to be interpreted in terms of mineral modes. It can be used to provide proper names to rocks, an important activity for an exploration geologist because of the implications that rock names have on genetic processes and mineral deposit models. This paper provides a review of the theoretical foundations of each of these four tools and then illustrates how these techniques have been used in a variety of exploration applications to assist in the search for, evaluation and planning of, and the mining of mineral deposits. Examples include the evaluation of total digestion lithogeochemical datasets from mineral deposits hosted by igneous and sedimentary rocks and formed by hydrothermal and igneous processes. In addition, this paper illustrates a more recent geometallurgical application of these methods, whereby the mineral proportions determined by lithogeochemical mineral mode analysis are used to predict rock properties and obtain the ore body knowledge critical for resource evaluation, mine planning, mining and mine remediation. Thematic collection: This article is part of the Exploration 17 collection available at: https://www.lyellcollection.org/cc/exploration-17 [ABSTRACT FROM AUTHOR]

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Proterozoic igneous rocks in the southern margin of the North China Craton can place constraints on its crustal evolution. This paper reports geochemistry, zircon U-Pb ages, Sr-Nd isotopes and Lu-Hf isotopes for the Proterozoic Angou granite from the southwestern margin of the North China Craton (NCC). The Angou granite has zircon LA-ICP-MS U-Pb age of 1819 ± 14Ma (MSWD = 1.3, n = 37), which is synchronous with the Proterozoic Xiong'er Group in the southeastern margin of the NCC. The granite has A-type granite affinity: (1) high SiO2 (67.12% to 73.16%) and alkali (Na2O+K2O = 7.18% to 8.75%) contents, with K2O/Na2O ratios of 1.04 to 4.78; (2) high FeOT/MgO values (4 to 36); (3) significantly negative Eu anomalies (Eu*/Eu = 0.33 to 0.53) and negative Sr anomalies (38.1 to 102ppm); (4) high 104× Ga/Al (2.55 to 4.75, with an average of 3.43) values and Zr+Ce+Nb+Y (634 to 1022ppm) contents; (5) high zircon saturation temperatures (871 to 957°C). In combination with its slightly peraluminous (A/CNK = 1.02 to 1.26) nature, the Angou granite can be classified as slightly peraluminous A-type granite. It displays negative ɛNd(t) values of −2.0 to −3.9, variable εHf(t) values (−8.81 to +1.98) with Hf model ages of 2194 to 2721Ma, combined with its high Rb/Sr (1.05 to 3.26) and low Rb/Ba (0.08 to 0.18) ratios, suggesting that the Angou granite was derived from high temperature melting of tonalite in middle-lower crust. The formation of Angou A-type granite is consistent with the mafic dyke swarms and Xiong'er bimodal volcanic rocks in NCC, indicating a Paleoprotozoic extensional setting in the southwestern margin of the NCC. [ABSTRACT FROM AUTHOR]

To mine coal resources under extremely thick igneous rock safely, this paper analysed the disaster-causing mechanism of extremely thick igneous rock by the methods of theoretical analysis, physical simulation, and numerical simulation, which was based on the engineering condition of Panel No.104 in Yangliu Coal Mine. The movement laws of overlying strata were obtained through analysing fracture development and rock breaking under extremely thick igneous rock after mining. The breaking interval of extremely thick igneous rock overlying working face that has one side adjacent to goaf area was derived by establishing and calculating a thin elastic plate mechanical model with three fixed sides and one simply supported side. The research shows that the trigger for dynamic disasters under extremely thick igneous rock is the coupling process of stress field and fracture field. After breaking of igneous rock, the fracture field, flow field and gas concentration field coupled, resulting in dynamical gas disaster; energy field, impact field and stress field coupled, resulting in rock burst. From the perspective of controlling the stress field and fracture field development, backfill mining method is proposed to prevent extremely thick igneous rock from sudden breaking. [ABSTRACT FROM AUTHOR]

In the past ten years, a great deal of geological study has been reported on the magmatic rocks exposed in the central and western region of the Kuluketage Block, while similar research in the eastern region has rarely been reported. In this paper, we report zircon U–Pb geochronological, zircon Lu–Hf isotopic, whole-rock elemental and Sr–Nd–Pb isotopic data for the Dapingliang intermediate-acid intrusive rocks in the eastern Kuluketage Block, in order to evaluate its petrogenesis and tectonic significance. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) zircon U–Pb dating provided a weighted mean 206Pb/238U age of 735 ± 3 Ma for the albitophyre (D1), 717 ± 2 Ma for the granite porphyry (D2) and 721 ± 1 Ma for the diorite porphyrite (D3). Geochemical analyses reveal that D1 and D2 belong to Na-rich alkaline A-type granites, and D3 shows the features of high-K calc-alkaline I-type granite. D1 and D2 are characterized by light rare earth element (LREE) enrichment and relative depletion of high field strength element (HFSE), with relatively flat heavy rare earth element (HREE) patterns and obviously negative Eu anomalies. D3 is characterized by the enrichment of LREE and depletion of HFSE, with negative slope HREE patterns and slightly negative Eu anomalies. In tectonic discrimination diagrams, D1 and D2 fall in the within-plate granite (WPG) field, indicating a rift setting. Although D3 falls within the volcanic arc granite (VAG) field, it most likely formed in a rift setting, as inferred from its petrology, Sr–Nd–Hf isotopes and regional tectonic evolution. Based on pronounced ε Nd(t), ε Hf(t), Pb isotopic data, T DM2 and high (87Sr/86Sr)i and elemental compositions, D1 was derived from the partial melting of basement amphibolites of the old lower crust. D2 originated from a mixture of the old lower crust and depleted mantle-derived magmas and was dominated by partial melting of the basement amphibolites of the lower crust. D3 could have been formed by partial melting of K-rich hornblende in the lower crust. Combining previous studies, we think that the c. 745–710 Ma magmatic rocks were formed in a continental rift setting. A partial melting scheme, triggered by underplating of mantle plume-derived magmas, is proposed to interpret the formation of c. 745–710 Ma A-type and I-type granitoids, mantle-derived mafic dykes, bimodal intrusive rocks, adakitic granites and volcanic rocks. These magmatic activities were probably a reflection of the break-up of the Rodinia supercontinent. Highlights: (1) Circa 720 Ma magmatism in the eastern Kuluketage Block. (2) Na-rich granite was derived from partial melting of basement amphibolites. (3) The c. 745–710 Ma magmatic rocks were formed in a continental rift setting. (4) The underplating of mantle plume-derived magmas is proposed. [ABSTRACT FROM AUTHOR]

Resilient modulus is an important design parameter for highway pavement structures because it represents the structural strength of pavement layers. The resilient modulus depends on the factors such as applied stress, loading time, water content, dry density and gradation. This paper demonstrates the applicability of regression methodology for estimating the (Mr) Resilient modulus of pavement layers using the results of dynamic triaxial tests. Aggregate samples were collected from several different quarries of central Anatolia. All of the aggregate sources were igneous rock (basalt, and trachy-basalt). Initial work content of triaxial tests to obtain the resilient modulus of cylindrical aggregate samples. Than new mathematical model proposed by using the results of dynamic triaxial tests. In the regression model; aggregate physical properties, aggregate mixture properties and loading factors (a total of 8 variables) which are used as input parameters and the resilient modulus of the aggregate mixture obtained as output. In order to compare the effectiveness of the new method, coefficients for the Uzan constitutive model were also determined for laboratory testing and were compared with the approach described in this paper. Performance parameters of R²:0.98 and Standard error: 10.51 was obtained from model prediction. These results are quite sufficient, and the regression model assumed the resilient response to be like a function by using the stated material parameters. So, this approach makes it possible to estimate the resilient modulus of the different aggregates samples in real-time. [ABSTRACT FROM AUTHOR]

In order to provide references of the subduction process of the Paleo‐Pacific Plate beneath the Jiamusi Block, this paper studied the clastic rocks of the Nanshuangyashan Formation using modal analysis of sandstones, mudstone elements geochemistry, and detrital zircon U–Pb dating. These results suggest the maximum depositional age of the Nanshuangyashan Formation was between the Norian and Rhaetian (206.8 ±4.6 Ma, mean standard weighted deviation (MSWD) = 0.17). Whole‐rock geochemistry of mudstone indicates that source rocks of the Nanshuangyashan Formation were primarily felsic igneous rocks and quartzose sedimentary rocks, which were mainly derived from the stable continental block and a magmatic arc. Detrital zircon analysis showed the Nanshuangyashan Formation samples recorded four main age groups: 229–204 Ma, 284–254 Ma, 524–489 Ma and 930–885 Ma, and the provenances were attributed to the Jiamusi Block and a Late Triassic magmatic arc near the study area. Furthermore, the eastern Jiamusi Block was a backarc basin, affected by the subduction of the Paleo‐Pacific Plate in the Late Triassic, but the magmatic arc related to the subduction near the study area finally died out due to tectonic changes and stratigraphic erosion. [ABSTRACT FROM AUTHOR]

The Jiapigou gold ore belt is located in the northeastern corner of the wedge‐shaped North China Craton and is hosted by Neoarchean basement gneiss and amphibolite, along with late Palaeozoic and Mesozoic granitoids. In this paper, whole‐rock major and trace element geochemistry together with zircon U–Pb ages and Lu–Hf isotope compositions are reported for Late Permian to Triassic igneous rocks from the gold belt. The dominant population of zircons in all these rocks shows oscillatory growth zoning in CL images, and relatively high Th/U ratios (0.10–5.23) that are indicative of a magmatic origin. Zircon U–Pb data indicate that the igneous rocks formed during two major phases: ca. 252 Ma and ca. 230–213 Ma. Geochemically, the Late Permian (ca. 252 Ma) diorites are high‐K calc‐alkaline in composition and low total Fe2O3, MgO, and CaO contents, and represented by enrichment in LILEs relative to HFSEs and HREEs, all of which are indicative of a postcollision high‐K calc‐alkaline granite affinity. In contrast, the Late Triassic (ca. 230–213 Ma) igneous rocks are mainly quartz syenite porphyries, felsites, and granodiorites, and are variable medium‐ to high‐K calc‐alkaline series and exhibit a negative Eu anomaly with A‐type affinities, indicating an extensional environment. In addition, in situ Hf isotopic analyses of zircons from four dated samples reveal that they have εHf(t) values of −3.0 to +2.2, with two‐stage model (TDM2) ages range from 964 to 1,210 Ma, indicating that they probably originated from the partial melting of a dominantly Mesoproterozoic to Neoproterozoic crustal source. On the basis of the geochemical data and regional geological investigations, we further propose that the Jiapigou gold ore belt in the Late Permian was formed in a postcollisional tectonic setting, whereas an extensional tectonic setting in the Late Triassic that caused lithospheric thinning during a postorogenic event. [ABSTRACT FROM AUTHOR]

The Lesser Xing'an–Zhangguangcai Range is located in the eastern part of the Central Asian Orogenic Belt (CAOB). Early Mesozoic igneous rocks in this area can place constraints on the crustal growth mechanism in the Northeastern China. This paper reports a suite of Late Triassic high‐Mg diorites and mafic dikes from the southern Lesser Xing'an–Zhangguangcai Range. The mafic dikes have younger zircon U–Pb ages of 195 ± 2 Ma. They display intermediate SiO2 (50.58% to 58.20%) and high Na2O/K2O ratios of 1.90 to 3.20, low A/CNK ratios of 0.75 to 0.84, low (87Sr/86Sr)i ratios of 0.7045 to 0.7046, and high εNd(t) values of +3.1 to +3.5. Most zircons in the mafic dikes exhibit positive εHf(t) values from +8.6 to +16.0, with single‐stage Hf model ages ranging from 0.2 to 0.5 Ga in combination with their enrichment in LREE and LILEs and depletion in HFSEs. They are considered to be formed by melting of metasomatized subarc lithosphere mantle. The diorite and quartz diorite have older zircon U–Pb ages of 200 ± 3 and 202 ± 2 Ma, respectively. They have SiO2 = 54.45% to 61.18%, Al2O3 = 17.16% to 19.10%, TiO2 = 0.74% to 1.13%, and Mg# = 46.6 to 49.5, and they also display moderately depleted Sr–Nd (εNd(t) = +2.3 to +4.3) and zircon Lu–Hf (εHf(t) = +8.6 to +16.0) isotopic compositions. These features suggest that they were formed by melting of juvenile arc crust in active continental margin. Considering the occurrence of the contemporaneous and latter igneous rocks in the Zhangguangcai Range, we argue that the diorite, quartz diorite, and mafic dikes from the Lengshan area were also related to the westward subduction of Palaeo‐Pacific Plate (Izanagi Plate) beneath the Eurasian Plate. The strike‐like fault along the eastern margin of the Songneng–Zhuangguangcai Block may play an important role in the genesis of diorite melt. [ABSTRACT FROM AUTHOR]

Silicon is one of the major elements in the solute of subduction zone fluids. The source information of Si in the fluids is useful for constraining the material exchange between the oceanic crust and mantle. Myanmar jadeitites result from crystallization of subduction zone fluids at high pressures, which can be used as a proxy for the chemical composition of the fluids. This paper reports high-precision Si isotope data of jadeitites, and associated amphibole-rich blackwall, serpentinites, and mica quartz schists to constrain the Si isotope composition of subduction zone fluids. The white jadeitites have higher δ30Si (− 0.04‰ to 0.23‰) than any igneous rocks reported in literature. The δ30Si of green jadeitites (− 0.35‰ to 0.03‰) and amphibole-rich blackwall (− 0.33‰ to 0.05‰) are generally lower than the values of white jadeitites. These data indicate that the jadeitite-forming fluids in the source subduction zone have heavy Si isotope compositions relative to the bulk silicate Earth. Based on the Si isotope fractionations among quartz, white jadeite, and the fluid, it is inferred that the subduction zone fluids have high δ30Si of about 0.7‰ to 1.2‰. The δ30Si of jadeitites and amphibole-rich blackwall show a positive correlation with SiO2 content with a slope of 0.0639, larger than that of the igneous rock array (0.0056). Such a correlation cannot be produced by magmatic differentiation or mineral fractional crystallization from fluids. Instead, it is more likely explained by a binary mixing model between fluids and mafic–ultramafic rocks. The model shows that about 0 to 25% of Si in green jadeitites and amphibole-rich blackwall is from the subduction zone fluids. In light of the relatively low δ30Si of abyssal clay sediment, altered oceanic crust, and mantle serpentinite, it is proposed that the deep-sea siliceous rocks with high δ30Si are likely the main source of Si in subduction zone fluids. In summary, this study shows that Si isotopes have useful application in tracing the source of solute in fluid-mediated processes. [ABSTRACT FROM AUTHOR]

With the improvement of regional geological research surrounding the Junggar Basin, whether Junggar terrane has a Precambrian basement is becoming one of the most popular topics of study. The Alashankou area, situated in the west of the Laba unit, is a westernmost trailing-shaped part of the Junggar terrane in the Central Asian Orogenic Belt. Precise petrological, geochronological and geochemical constraints of the metamorphic igneous rocks in the Alashankou area provide a better understanding of the tectonic evolution of the Laba unit, and combining these constraints with the previously geochronological and geophysical results is crucial to reevaluate the nature of the basement of the Junggar terrane. In this paper, our diagnostic results reveal that (1) the two-mica plagioclase schist, biotite amphibole plagioclase schist and granitic mylonite were formed in 447.6 Ma, 443.7 Ma and 428.8 Ma, and their protoliths are possible acidic tuff, andesite, and granite (porphyry), respectively; (2) these rocks have geochemical signatures that originated from typical continental arcs, including intermediate-acid calc-alkaline series rocks; the enrichment of enriched in large ion lithophile elements (LILE), Zr, and Hf; the depletion of Ta, Nb, P and Ti; (3) the granitic mylonite has 0.90 Ga–2.58 Ga inherited zircons, low εHf(t) to 8.11 and old TDM2 (Hf) age to 2.91 Ga, suggesting the existence of a Precambrian crust or similar materials as their sources. Based on these parameters, we suggest that (1) the metamorphic igneous rocks were formed in an Early Paleozoic continental arc along the west margin of the Junggar terrane, and (2) the Southern and Eastern Junggar Basin possibly has Precambrian basements, whereas the Northern Junggar Basin consists of accretionary complexes. Southward subduction of the Junggar oceanic plate beneath the Laba unit occurred in the Late Ordovician to Middle Silurian, and the regional continental accretion and metamorphism of the Laba unit happened in the Early Devonian. [ABSTRACT FROM AUTHOR]

The aim of this paper is to provide an overview of Li contents and their trends in pre-Variscan and Variscan granitoids in the Czech part of the Bohemian Massif. All igneous systems with significant Li enrichment are described (Fig. 1). Among other plutons, only some typical examples are selected. A special attention is given to rocks with sufficiently robust data sets on Li contents. Bulk-rock contents of Li in granitoids were assessed within several projects of the Czech Geological Survey (CGS) and the Institute of Geology of the Czech Academy of Sciences (GLÚ) in 1985-2019. Lithium was determined mostly by the AAS method in laboratories of the CGS. Analyses of micas can be divided into three groups according to the methodology: (i) classic wet complete chemical analyses of mica concentrates (from years 1985-90); (ii) a combination of AAS-Li analyses of mica concentrate and determination of other elements using a microprobe in thin sections (mostly from years 1990-2010); and (iii) a combination of Li analyses and trace element analyses using laser-ablation ICP-MS and major elements using a microprobe. The method of laser ablation was performed at Faculty of Sciences, Masaryk University in Brno, microprobe analyses in GLÚ and wet chemical analyses in CGS. Pre-Variscan granitoids in the Bohemian Massif are generally Li-poor (Fig. 2). Relatively highest Li values (0.08 wt.% Li2O + elevated P, B, and Sn) were found in the Blaník-type orthogneiss in the NE part of the Moldanubicum. Lithium is hosted in micas: ca. 0.1-0.6 wt.% Li2O in biotite and 0.2-0.4 wt.% Li2O in muscovite. Among Variscan igneous rocks (Fig. 3), Li is slightly enriched in some two-mica and muscovite granites in the Moldanubicum, and particularly in Li-biotite and zinnwaldite granites in the Krušné Hory - Erzgebirge (Saxothuringicum). Two-mica granites of the Eisgarn type in the South Bohemian pluton in the Moldanubicum contain up to 0.05 wt.% Li2O; small bodies of late muscovite granites near the Czech-Austrian border up to 0.16 wt.% Li2O. Biotite and muscovite from the two-mica granites contain about 0.1-0.5 wt.% Li2O and 0.03-0.14 wt.% Li2O, respectively. Muscovite of the Homolka muscovite granite contains up to 1.0 wt.% Li2O. In the Kreuzstein granite (0.12 wt.% Li2O), situated at Czech-Bavarian border in the NW edge of the Moldanubicum, zinnwaldite is the Li carrier; this makes this granite more similar to evolved Saxothuringian granites. Variscan granites in the Erzgebirge should be divided into two groups. The first group includes strongly peraluminous granites which dominate the western part of the area forming the Smrčiny-Fichtelgebirge, Nejdek-Eibenstock and Slavkovský les plutons (Fig. 4). These granites evolved from biotite to zinnwaldite facies containing 0.04-0.20 wt.% Li2O. Hydrothermal greisens, forming cupolas in the uppermost part of granite intrusions at Krásno, are also enriched in Li (0.6 wt.% Li2O), while vein-shaped and pericontact greisens in northern and northeastern parts of the Nejdek pluton are Li-poor (usually below 0.1 wt.% Li2O). The second group, only slightly peraluminous A-type granites, form a large volcano-plutonic complex of the Teplice caldera in the eastern Erzgebirge (Fig. 5). While early rhyolite tuffs are Li-poor (< 0.05 wt.% Li2O), later granites contain up to 0.2 wt.% Li2O in zinnwaldite facies in the upper parts of the cupolas at Cínovec and Krupka. Hydrothermal greisenization in the uppermost parts of cupolas increased the Li contents up to 0.4-1 % wt.% Li2O (0.6 wt.% Li2O on average). The only Li carrier is represented by trioctahedral Li-Fe micas with the contents from 0.25 wt.% Li2O in biotite to 4.8 wt.% Li2O in zinnwaldite (Fig. 6). The Cínovec-Zinnwald represents the only potential Li deposit in the Czech Republic. [ABSTRACT FROM AUTHOR]

Biotite is an important hydrated ferromagnesian silicate mineral in igneous rocks and porphyry deposits. The determination of chemical compositions of biotite plays an important role in both igneous petrology and ore forming processes. This paper summarizes research results of magmatic and hydrothermal biotites exemplified by the Lakange porphyry Cu–Mo deposit and the Qulong porphyry Cu deposit in the Gangdese porphyry–skarn metallogenic belt, Tibet. Biotite mineral chemistry can provide critical insights into classification, geothermometer, geothermobarometry, oxygen fugacity, petrogenesis and tectonic setting, evaluating magmatic‐hydrothermal process by halogen and halogen fugacity ratios, and distinguishing between barren and mineralized rocks. Biotite provides the latest mineralogical evidence on metallogenic prognosis and prospecting evaluation for porphyry Cu polymetallic deposits or magmatic hydrothermal deposits. [ABSTRACT FROM AUTHOR]

Xuanwei Formation is composed of mudstone, siltstone, and sandstone, with local conglomerate. However, its provenance and tectonic setting have been scarcely studied. In this paper, we use sedimentology, electron probe microanalysis (EPMA), and detrital zircon dating to investigate its source area and depositional tectonic setting. The facies assemblages indicate that it formed in alluvial fan and fluvial river sedimentary environments. The strata thicknesses and facies distribution indicate that the sediment supply was from the west. The results of EPMA show that chromian spinels within the sediments are characterized by high Cr# and varying Mg#. Discrimination plots suggest that these spinels were sourced from large igneous province (LIP) magmatic rocks. The laser ablation inductively coupled plasma mass spectrometry (LA‐ICP‐MS) U–Pb chronology of detrital zircons suggests that the sediments were derived from intermediate–acid igneous rocks dating back to 251–260 Ma. We could, therefore, conclude that the provenance of the Xuanwei Formation is from Emeishan basalt and synchronous felsic igneous rocks, which is consistent with the composition of the detrital framework. The detrital zircon dates also suggest that felsic magmatism occurred during the Late Permian, not after the eruption of the Emeishan basalt. Based on the sedimentary successions and provenance analysis, the tectonic setting for Xuanwei Formation deposition was a volcanic rifted margin. [ABSTRACT FROM AUTHOR]

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This paper determined the fixed-ammonium (NH4*) contents of lamprophyres in the Zhenyuan gold orefield, Yunnan Province, China. The results show that the NH4* contents of minettes in the orefield range from 120 x 10-6 to 469 x 10-6 and those of kersantites from 74. 3 X 10-6 to 136 X 10-6. These values are higher than those of other mantle-derived rocks (less than 50 X 10-6) , but lower than those of carbonaceous wall rocks in the orefield (from 1200 x 10-6 to 1343 X 10-6). Combining with the Sr isotopic composition, this paper suggested that lamprophyres in the orefield with high NH4* contents relative to other mantle-derived rocks would not have resulted from the primary magma contaminated by crustal materials in the process of rising or in the magma chamber, but from mantle metasomatism. [ABSTRACT FROM AUTHOR]

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Comments on the gathering of lichenologists in Tartu, Estonia for the Fifth Symposium for Lichenology. Presentation of papers pertaining to genes, physiology and structure; Publication of papers dealing with aspects of thallus structure; Investigation of the Antarctic endolithic lichen communities in which analysis of sections of colonized granite provided evidence of fungal-algal interactions.

Commingling between contemporaneous mafic and felsic magmas is now widely recognized in a broad range of intrusions and intrusive complexes. These interactions are important features for two main of reasons: (1) the rapidly chilled margins of mafic magma against silicic magma commonly preserve the compositions of mafic liquids, and (2) because the mafic magma solidifies rapidly, the resulting (final) configurations of mafic and felsic magmas can provide insights into physical processes and changing viscosity contrasts and rheologies of magmas and felsic crystal mush during crystallization of the mafic magma. Mingling of contrasted magmas was first recognized in the 1950s. Wider recognition of interactions between mafic and silicic liquids led to concepts of "net-veining" in the 1960s, "intramagmatic flows" (chilled basaltic layers separated by felsic cumulates) in the 1970s, and in the 1990s to "mafic-silicic layered intrusions" (MASLI), which could be as much as a few kilometers thick and more than 100 km2 in area. It was quickly appreciated that these MASLI preserved stratigraphic records of mafic replenishments into silicic magma chambers floored by felsic crystal mush. Volcanic studies had anticipated the occurrence of this last type of intrusion on the grounds that extensive ponding of basaltic magmas beneath silicic chambers was seen to be essential to keep large silicic systems like Yellowstone active for millions of years. This paper looks at the history of changing perceptions and interpretations of magma mingling and whether or not "sill complexes" are distinct from mafic-silicic layered intrusions. The stratigraphy of mafic-silicic layered intrusions records changing magmatic compositions, events, and processes in a temporal framework comparable to that provided by coeval volcanic rocks. As a result, careful study of MASLI has great potential for linking plutonic and volcanic processes and events. [ABSTRACT FROM AUTHOR]

The Central and South Pamir tectonic blocks contain scarce Late Cretaceous mafic and intermediate–silicic igneous rocks that represent typical intraplate magmatism distant from a continental margin. This paper presents new zircon U Pb age and Hf O isotope, and whole-rock geochemical and Sr Nd isotope data for these rocks in the western part of Central and South Pamir in order to constrain their petrogenesis and geodynamic setting. Zircon U Pb ages show that the Rushan mafic dikes and Bartang diorites formed concurrently at 67–66 Ma, while the Khorog diorites–granodiorites formed at 77–76 Ma. The Rushan mafic dikes have low SiO 2 (46.6–54.5 wt%) and high MgO (4.3–7.6 wt%) and total alkali (K 2 O + Na 2 O = 5.1–7.6 wt%) contents, and exhibit enrichments in large-ion lithophile elements and depletions in high-field-strength elements. They have depleted Sr–Nd–Hf isotopic compositions (87Sr/86Sr i = 0.7068, ε Nd [t] = 2.2–3.5, and zircon ε Hf [t] = 5.1–7.7) and mantle-like zircon δ18O values (4.6‰–6.0‰). These dikes by through low-degree partial melting of a mixed source consisting of ∼80% asthenospheric mantle and ∼ 20% metasomatized lithospheric mantle within the stability field of spinel–garnet. The Bartang diorites have a wide range of SiO 2 (58.0–66.3 wt%) and MgO (0.3–3.6 wt%) contents. They also have depleted isotopic compositions (87Sr/86Sr i = 0.7066–0.7072, ε Nd [t] = 0.1–1.0, and ε Hf [t] = 4.0–6.5) and mantle-like zircon δ18O values (4.8‰–5.3‰), similar to those of the Rushan mafic dikes. These diorites formed by fractional crystallization of hornblende, biotite, plagioclase, Fe Ti oxides, and apatite from mafic magmas represented by the Rushan mafic dikes. The Khorog diorites–granodiorites have intermediate SiO 2 contents (59.9–69.4 wt%), enriched isotopic compositions (87Sr/86Sr i = 0.7050–0.7145, ε Nd [t] = −2.7 to −3.5, and ε Hf [t] = −0.2 to −4.0), and crust-like zircon δ18O values (7.0‰–8.4‰). They formed by partial melting of a mixed source consisting of ∼60% ancient crustal basement rocks and ∼ 40% juvenile crustal rocks. We propose that edge-driven convection caused by the disparity in lithospheric thickness between the Central and South Pamir tectonic blocks and the Karakum Craton resulted in decompression melting of the mantle and lower crustal sources, and generated the intraplate magmatism. • Late Cretaceous small-scale intraplate magmatism occurred in Central–South Pamir. • Mafic dikes formed by melting of mixed asthenospheric and lithospheric mantle. • Diorites were generated via fractional crystallization of mafic magmas. • Granitoids formed by melting of a mixed ancient and juvenile crustal source. • Intraplate magmatism in Central–South Pamir generated by edge-driven convection. [ABSTRACT FROM AUTHOR]

Mantle-derived magmas are traditionally assumed to originate by melting of an upper mantle consisting of uniform spinel- or garnet peridotite dominated by olivine. However, extensive studies of mantle-derived basalts suggest that the mantle is more mineralogically heterogeneous, so that the genesis of even the most common magmas requires consideration of mixed source regions within the mantle involving pyroxenites and hydrous minerals. We refer to these with the group term metasomes. However, most experimental studies on mantle melting have assumed a homogeneous source composition, presenting a challenge in quantifying the impact of these heterogeneities. This paper provides a comprehensive review of recent advances in reaction experiments that depart from traditional approaches assuming a homogeneous mantle. We begin by assembling evidence for the existence of metasomes, discussing their formation and integration into basaltic melts. Further, we introduce the reaction experiments combining peridotite with hydrous assemblages, such as phlogopite, amphiboles, and apatite, leading to more accurate simulations of natural magmatic processes. These experiments reveal that the melting of hydrous metasomes and subsequent melt-peridotite interactions are key to producing the high alkali contents observed in natural lavas. The melting of hydrous metasomes occurs at lower temperatures than peridotite, resulting in diverse melt compositions. The interaction between metasome-derived melts and peridotite further modifies these melts, influenced by the pressure-dependent melting behaviors of minerals like orthopyroxene and olivine. This dynamic process leads to the generation of K- and Na-alkaline melts with varying silica and alkali contents, reflecting the complex interplay of melting and reaction mechanisms in the mantle. Formation of hydrous metasomes have also been studied by reaction experiments. Experimental studies have predominantly focused on potassium-rich systems due to the geochemical signatures of potassic igneous rocks suggesting sedimentary rock contributions to their sources. These studies simulate interactions between melts and mantle peridotite, particularly in sub-arc regions, leading to potassium-rich metasomes. More experimental studies are needed on sodium-rich alkaline systems to understand the formation of amphibole-rich metasomes and bridge knowledge gaps. Future studies should emphasize the detailed compositional variability of melts from metasomes, their reactions with peridotites, and comparisons with surface lavas. Understanding the kinetics of these reactions and the melting mechanisms of metasome-derived melts is essential. However, the considerable mineralogical diversity of hydrous metasomes poses a primary challenge facing experimental studies. It underscores the need for more experiments on additional melt source rocks and their reaction with peridotites, as the story about the reaction of melts from hydrous metasomes with mantle peridotites has only just begun. [ABSTRACT FROM AUTHOR]

Upper Miocene volcanic and plutonic rocks on Kos island preserve a record of magmatic and tectonic events in the transition zone between the Aegean and Anatolian microplates. Their field setting, syn-intrusion deformation, mineralogy, and geochemistry were investigated. Volcanic rocks, including trachyandesite flows and trachyandesite to rhyolite domes, were extruded on a central E–W horst and directly overlie Alpine basement. Thick successions of trachytic flow tuffs are interbedded with fluvial and lacustrine basinal sediments to the south of this horst. Volcanism was synchronous with the emplacement of the Dikeos monzonite pluton, which is geochemically similar to some lithic clasts in the thick flow tuffs and is cut by mafic dykes including lamprophyres. Two main types of mafic magma were present: a K-rich lamprophyric magma that evolved to trachyandesite and more calc-alkaline magma similar to mafic enclaves in the monzonite. Syn-intrusion structures in the monzonite indicate emplacement during E–W sinistral strike-slip faulting that created local transtensional deformation, providing accommodation for a Dikeos magma reservoir. A change in the style of deformation in the Late Miocene led to NW-striking extension in the footwall, occupied by mafic dykes and mineralized veins, and extensional detachment of the hanging wall, resulting in unroofing of the monzonite. [ABSTRACT FROM AUTHOR]

Petrographic studies have been carried out on the Early Miocene Darnó Conglomerate Formation, which consists only of debris of ophiolitic mélange and is found today on Darnó Hill in SW Bükk, NE Hungary. The studied sediments are bounded by the Darnó line from Darnó Hill. The aim of this work was to show if it is possible to reconstruct the petrographic composition of the source area only from its debris. The rock types were determined in thin sections using a polarizing microscope, and a quantitative analysis of the different rock types was carried out using the grain counting method, the results of which were interpreted as volume ratios. The main rock types observed in the studied samples (textural varieties of basalt, dolerite/microgabbro, claystone, siltstone, and radiolarite) are similar to the rock types of the mélange assemblage of Darnó Hill. Based on the volume calculations of basaltic detrital grains with different textures characteristic for pillow basalts, it could be established that pillow basalts dominated the igneous rocks in the source area of the Darnó Conglomerate on Darnó Hill already in the Miocene. Thus, this work shows that the lithological composition of a source area can be precisely outlined by a detailed petrographic analysis of the debris eroded from the immediate vicinity. [ABSTRACT FROM AUTHOR]

To study the oil and gas enrichment characteristics of the reservoir rocks in the second Member of the Nantun Formation (N2) of the F1 fault in the Beier Depression, this research focuses on the mechanism of shortening the sealing time of the regional mudstone cap due to faults and the factors influencing the sealing duration. The period during which the regional mudstone cap seal began is determined by analyzing the relationship between the diagenetic index of the regional mudstone cap and its underlying reservoir rocks and time. This relationship between the rock-formation index and time helps establish the onset of regional mudstone cap seal, and from this, the index of shortening time due to faults is derived. A research framework to study the sealing time shortening of regional mudstone cap seal caused by a fault was developed, which was further applied to analyze the relationship between the fault-induced shortening time of the seal in the lower of the first Member of the Damoguaihe Formation section ( D 1 x ) of the Beier Depression and hydrocarbon concentrations in the N2 Formation. The results show that the F1 fault at measurement points 1–4, 6, and 9–11 reduced the blocking time of the regional mudstone cap in  D 1 x  to 100%, hindering hydrocarbon accumulation and preservation in the N2. Conversely, the F1 fault at measurement points 5, 7, 8, and 12–15 reduces the blocking time of the regional mudstone cap in the  D 1 x  by 37–99%, which is more conducive to hydrocarbon accumulation and preservation in N2, resulting in positive oil and gas shows. Based on the test results, a discussion on the feasibility, applicability, and limitations of the new method is conducted, yielding the following conclusions: (1) The relationship between oil and gas indications in the reservoir rocks of the Nan'er Member confirms the feasibility of the new method. The research findings of the new method on the F1 fault align with current oil and gas exploration realities, indicating its potential use in studying the degree to which faults shorten the sealing time of regional mudstone caprocks. (2) The new method is primarily applicable to the study of the modification effects of tensile normal faults on regional mudstone caprocks and their impact on oil and gas sealing capacities. However, its application to other types of faults may have limitations. (3) The new method is mainly suitable for caprocks dominated by mudstone. When studying other types of caprocks, such as carbonate rocks, evaporites, igneous rocks, and metamorphic rocks, different research methods and technical means are required. These findings provide valuable insights for oil and gas exploration efforts near fault zones. [ABSTRACT FROM AUTHOR]

The distribution of zircon crystallisation ages in igneous rocks has been proposed to provide insights into the dynamics of underlying magma reservoirs. However, the ability to interpret magmatic processes from an age distribution is challenged by a complex interplay of factors such as sampling biases, analytical uncertainties and incorporation of extraneous zircon grains. Here, we used a compilation of magmatic zircon U-Pb ages measured by chemical abrasion isotope dilution thermal ionisation mass spectrometry (CA-ID-TIMS) to quantify the differences that exist among zircon U-Pb age distributions from different magmatic systems. The compiled dataset was rigorously filtered through a number of processing steps to isolate age distributions least impacted by sampling biases and analytical factors. We also filter the database using a new algorithm to systematically identify and remove old outliers from age distributions. We adopt the Wasserstein distance as a dissimilarity metric to quantify the difference between the shapes of age distributions. Principal component analysis of a dissimilarity matrix of pairwise Wasserstein distances of age distributions reveals a difference between zircon age distributions found in plutonic, porphyry and volcanic rocks. Volcanic and porphyry zircon populations exhibit a skew towards younger ages in their distributions, whereas plutonic age distributions skew towards older ages. Using a bootstrap sampling approach to generate synthetic age distributions, we show that this difference can be predominantly ascribed to truncation of zircon crystallisation during volcanic eruptions and porphyry dyke emplacement, which leads to a younger skew. We also find that higher magmatic flux can contribute to the younger skew of volcanic and porphyry zircon age distributions, though we emphasise that no difference in flux is required given the strong effect of truncation on zircon age distributions. Given the multitude of factors that influence zircon age distributions, we urge caution when quantifying the thermal evolution of crustal magma bodies using zircon age distributions integrated with numerical models. [ABSTRACT FROM AUTHOR]

The late Mesozoic igneous rocks along the coastal South China Block (SCB) exhibit complex parental sources involving a depleted mantle, subducted sediment-derived melt, and melted crust. This period aligns with the magmatic flare-up and lull in the SCB, debating with the compression or extension in coastal region. Our study employs numerical models to investigate the dynamics of the ascent of underplating magma along the Changle–Nan'ao Belt (CNB), simulating its intrusion and cooling processes while disregarding the formational background. The rheological structure of the lithospheric mantle significantly influences magma pathways, dictating the distribution of magmatism. This work reveals that the ascent of magma in the presence of faults is considerably faster than in the absence of faults, and contemporaneous magmatic melts could produce different cooling and diagenetic processes. Additionally, the influence of pre-existing magma accelerated the emplacement of underplating magma. The magma beneath the fault ascended rapidly, reaching the lower crust within 20 million years, with a cooling rate of approximately ∼ 35 °C Myr -1. Conversely, the thickened magma took 40–50 million years to ascend to the lower crust, cooling at a rate of ∼ 10 °C Myr -1. In contrast, magma without thickening and fault would take a considerably longer time to reach the lower crust. The ascent of magma formed a mush-like head, contributing to magmatic circulation beneath the crust and decreasing crustal thickness. Multiphase magmatism increases the geothermal gradient, reducing lithospheric viscosity and promoting underplating magma ascent, leading to magmatic flare-ups and lulls. Our findings suggest that the Cretaceous magmatism at different times in the coastal SCB may be associated with the effects of lithospheric faults under similar subduction conditions. Boundary compression forces delay magma ascent, while rising magma induces a significant circulation, decreasing the crustal thickness of the coastal SCB. This study provides new insights into the complex interplay of magmatic processes during subduction, emphasizing the role of lithospheric structure in shaping the temporal and spatial evolution of coastal magmatism. [ABSTRACT FROM AUTHOR]

New U–Pb zircon geochronology identifies a latest Triassic (ca 214–201 Ma) igneous suite of tuff, hypabyssal dikes, and a pluton on the southern Kenai Peninsula, Alaska. The igneous suite was emplaced within Upper Triassic sedimentary rocks along the southern margin of Western Wrangellia, the western-most fragment of the Wrangellia composite terrane. The igneous rocks range from mafic (50.6% SiO2) to felsic (78.3% SiO2), characteristically have less than 1.55% K2O, and generally have low trace element abundances. The tonalitic and trondhjemitic magmas were largely sourced in mafic-rich lower crust and incompletely assimilated quartz and other mineral xenocrysts are common. Fractionation involving plagioclase and amphibole is indicated for some magmas and composite intrusions and igneous xenoliths indicate magma mixing was possible. Paleozoic and Precambrian inherited zircons and initial 87Sr/86Sr (0.704103–0.705609) and 143Nd/144Nd (0.512396–0.512777) ratios indicate that the Western Wrangellia crustal sources are heterogeneous and contain sialic components. The latest Triassic magmatism reflects processes that preceded Early Jurassic subduction along the Wrangellia composite terrane and Pacific Ocean plate boundary. These processes involved heating and melting of mantle lithosphere and lower crust as mantle instabilities accompanied the breaking of the plate boundary linkages. The Late Triassic transition to subduction along the Wrangellia composite terrane margin coincided with the transition to subduction cessation in the Late Triassic arcs of the western Intermontane terranes of Canada. The shift to subduction along the outboard Wrangellia composite terrane margin marks the beginning of the Pacific Ocean–Cordillera plate interactions that came to dominate the tectonic evolution of the northern Cordillera from the Early Jurassic to today. [ABSTRACT FROM AUTHOR]

The main ocean–continent transformation stage of the Qinling and Qilian conjunction zone happened in the Early Paleozoic with the occurrence of a lot of subduction–collision–related magmatic rocks. However, there is still considerable controversy over the duration of the subduction–collision orogeny process of the Proto-Tethys Ocean, here termed as the Wushan–Shangdan Ocean. We provide geochronological, geochemical, and Lu-Hf isotopic data for typical Early Devonian igneous rocks there, named Tailu pluton. The Tailu pluton at 410 Ma comprised K-rich, calc-alkaline, metaluminous A-type granite with low Y/Nb ratios (0.85 to 1.35) and A/CNK values (0.90 to 1.01); with high SiO2 contents (65.44 to 74.46 wt%), Mg# values (39.2 to 50.7), and zircon saturation temperatures (745 to 846 °C); and with negative εHf (t) values (−8.0 to −1.9); therefore, they resulted from the partial melting of the ancient felsic lower crust accompanied by the incorporation of mantle-derived material during the intraplate magmatism process. Research on Tailu pluton has provided more sufficient evidence for the evolution process of the Qinling–Qilian conjunction zone in the Early Paleozoic, associated with evolution of the Wushan–Shangdan Ocean, the northern part of the Proto-Tethys Ocean. [ABSTRACT FROM AUTHOR]

This study presents the chemical and mineralogical composition of clay deposits and associated rock types within the Ropp Complex in order to assess the influence of parent lithology on the kaolinization, genesis, and utility of the deposit. Representative kaolin samples from E horizons of the weathering profiles and their bedrocks were collected from six sites in the Ropp Complex. Clay mineralogy was determined via the XRD technique, while a geochemical analysis was conducted using XRF, SEM coupled with EDS, and ICP-MS. The results showed that all kaolins dominantly contain kaolinite with a content of 77%–98% except for the AS1 kaolin with only minor kaolinite (20%) but mainly illite (65%). The notably lower crystallinity of kaolinite (HI value of 0.53–1.1) as well as its markedly small grain size is consistent with the formation of kaolinite from intensive chemical weathering of igneous rocks. The AS1 kaolin was probably formed from hydrothermal alteration in the burial stage due to the heating of groundwater by the late volcanism. Mobile trace elements (Sr, Ba, and Eu) exhibited a depletion trend, while immobile elements (Hf, Ta, Th) showed enrichment. The relatively more zirconium in kaolins implies the formation of low-temperature kaolinization. The notably high kaolinite content, accompanied by reasonable levels of Fe2O3 and TiO2, signifies a medium-grade quality. Furthermore, chondrite-normalized rare earth element (REE) patterns exhibit congruent trends in rocks and kaolin samples, indicating a relative enrichment in light rare earth elements (LREEs) alongside a discernible negative Eu anomaly. The abundant kaolinite and silicon–aluminum composition make the kaolins suitable for refractories, pharmaceutics, cosmetics, and supplementary cementitious material (SCM). [ABSTRACT FROM AUTHOR]

Abstract -- This paper reports on the identification of peperite, a breccia comprising angular to lobate variably vesiculated basalt clasts in a mudstone matrix, at the upper margin of a basalt sheet of the Sable River Basalt Formation, northern Lebombo. The peperite formed as a result of emplacement of the basalt sheet as a shallow sill that burrowed into and migrated laterally within an unconsolidated water-saturated sediment pile. Although breccias at the upper margin of basalt units are widely recognized from the Karoo of southern Africa, they have generally been interpreted as blocky 'autobreccia' or 'flow-top breccia' on lavas. Consequently, many mixed basalt-sediment breccias may have been viewed as sedimentary infill of these 'flow-top breccias'. To the best of our knowledge, this paper represents the first documentation of an intrusive or invasive mode of formation. The new shallow sill or invasive flow interpretation has significant implications on the perceived sedimentary architecture and basalt emplacement model for the Karoo, and perhaps other flood asalt provinces. It is suggested that the widespread distribution and consistent thickness of individual 'flows' in the Sable River Basalt Formation can sometimes be attributed to emplacement as shallow sills that have propagated through a regionally extensive sediment pile. [ABSTRACT FROM AUTHOR]

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Barros et al. (2022) [[3]] study the exomorphic halos in wall rocks of Li-Cs-Ta albite-spodumene-type pegmatites of the Leinster pegmatite belt in southeast Ireland. This Special Issue of I Minerals i , section Mineral Deposits, on the topic of "Petrology and Mineralogy of Pegmatite Deposits", was inspired by the currently growing scientific and economic interest in pegmatites. The results indicate that amphibolite/granulite facies conditions, found at 7.6 kbar/700 °C for garnet crystallization in spodumene-free pegmatites, are significantly higher than previously suggested for pegmatite formation in the Koralpe Mountains. [Extracted from the article]

The article offers information regarding a comprehensive geochronological study of the Okcheon Metamorphic Belt by a Korean-Japanese research team. The research team has thoroughly reviewed existing data on this region and have concluded that there was a late Paleozoic medium P/T metamorphism followed by a Jurassic low P/T metamorphism associated with granite intrusion. It also presents information on one of the researchers named Chang Whan Oh. The author is said to have been working for has been working for the Geological Society of Korea as a General Director since January 2008.

Coronitic microstructures have been used to interpret the late-stage solidification history of igneous rocks and to constrain the corresponding chemical and/or physical changes. Coronas with three shells were also recognized in the Miaowan olivine norite, Yangtze Craton, South China. In our study, orthopyroxene intergrowth with vermicular magnetite in the inner shell is in optical continuity with magnetite-free orthopyroxene in the middle shell. In the outer shell of brown amphibole remaining magnetite-free orthopyroxene inclusions sporadically occur. Meanwhile Mg# values of orthopyroxene (76–80) in the inner and middle shells are basically consistent with olivine (78–81). In this paper, we propose a multi-stage genetic model for the formation of coronas in the Miaowan olivine norite. In the first stage, the magnetite-free orthopyroxene shell formed through reaction between primocrystal olivine with the residual Si-rich melt at 990–1 053 °C and 6.2–6.5 kbar. In the second stage, the orthopyroxene-magnetite symplectite shell formed when primocrystal olivine reacted with the late-stage residual Fe-rich melt promoted by high oxygen fugacity condition at 927–1 035 °C and 6.0–6.5 kbar. In the third stage, the brown amphibole shell formed as the presence of residual hydrous melt and replaced the middle shell at 821–900 °C and 5.5–6.0 kbar. [ABSTRACT FROM AUTHOR]

The Korean Peninsula (KP) occupies a junction area of three big tectonic domains that are the Paleo-Central Asian Orogenic Belt, Paleo-Tethyan Orogenic Belt and the Western Pacific Orogenic Belt. Therefore the KP is a key area to understand the Northeast Asian and even global geotectonic evolution. In terms of geological unit division, the KP has long been thought to be closely tied with the mainland of China, with using collective term the Sino-Korea Craton for the North China Craton (NCC). However, such correlation suffered from the absence of relevant geological information in North Korea (NK). To bridge this knowledge gap, our group carries out a long-term collaborative study between the two-sides of the KP and China，and organized united field investigation in the North Korea, South Korea (SK) and China as possible. This paper introduces general geology in the North Korea，and simply make comparison with the NCC and South Korea. These pioneering works culminated in the following summaries. (1) The KP comprises three major Precambrian massifs, i.e., Rangnim, Gyeonggi and Yeongnam massifs. The Rangnim and Gyeonggi massifs are separated by the Imjingang Structural Belt, while the Gyeonggi and Yeongnam massifs are separated by the Ogcheon Structural Belt. (2) The basement of the Rangnim massif is correlated with that of the NCC. The characteristic metamorphic rocks of high- temperature/high-pressure granulite facies including meta- sedimentary rocks (kondalites and meta-sandstones and marbles) with ~1.9–1.8 Ga metamorphic ages occur in the three massifs, similar to the NCC. (3) The Proterozoic rift sedimentary sequences are developed in the NCC and North Korea, but Lower Paleoproterozoic strata are rare, and Neoproterozoic strata are more developed in North Korea relative to the NCC. (4) Two main Paleozoic basins within the Rangnim massif and within the Gyeonggi and Yeongnam massifs are the Phyongnam basin and Taebaeksan Basin. Both of them have a similar Paleozoic tectono-stratigraphy to the NCC. (5) Although the nature and tectonic significance of the Imjingang belt remains controversial, it doesn't show characteristics and natures of collisional orogenic belt. (6) The eclogite-bearing Hongseong Complex (HSC) is located in the southwestern part of the Gyeonggi Massif in South Korea, but no similar rock unit has been found in North Korea. (7) Mesozoic igneous rocks are widespread throughout the northern and southern parts of the KP. Triassic magmatism is related to Indosinian orogeny. Jurassic and Cretaceous igneous rocks are different and irregular from those in the NCC on age and spatial-temporal distribution. This paper also suggests several key and controversial academic issues that are worthwhile to study in the future. Unlabelled Image • The Archean Rangrim massif is divideded into the Rangrim and Kwanmo submassifs, high-grade region and greenstone belt, respectively. • Early Paleoproterozoic rocks underwent metamorphism up to granulite facies, which may be correlated to the Jiao-Liao-Ji mobile belt in the NCC. • Proterozoic rift sequences in North Korea are similar to those in the NCC with rare late Paleoproterozoic strata and more Neoproterozoic strata. • Both main Paleozoic basins, the Phyongnam basin in NK and the Taebaeksan Basin in SK, have a similar Paleozoic tectono-stratigraphy to the NCC. • Mesozoic igneous rocks are extensively distributed in the KP. [ABSTRACT FROM AUTHOR]

The Longshan area is located in the junction zone between the Qinling and eastern Qilian orogenic belts. Early Palaeozoic igneous rocks in this area can provide important insights into the evolution of Shangdan Ocean. This paper reports new petrology, chronology, major and trace element geochemistry, Sr–Nd isotope, and zircon Lu–Hf isotopic compositions for the Early Silurian pyroxene diorite in the Longshan area. The pyroxene diorite has a zircon U–Pb age of 432 ± 1 Ma (MSWD = 0.25, n = 27). The pyroxene diorite intrusion displays low SiO2 (53.34 to 56.32 wt.%), high Na2O (3.11% to 3.79 wt.%) and Sr (1112 to 1234 ppm) contents, and moderate Mg# (52.70 to 55.00) values, high Sr/Y (67 to 84) ratios, depleted in Y and HREE; these features are identical with the low‐Si adakite or sanukitoids that derived from melting of metasomatized mantle wedge. The pyroxene diorite intrusion has evolved Sr–Nd isotopic compositions, (87Sr/86Sr) i = 0.705286 to 0.705310, εNd(t) = −3.4 to −3.9. Zircons from the pyroxene diorite display variable εHf(t) values of −3.6 to +0.1. These features suggest that the pyroxene diorite intrusion was derived from a hydrous melting metasomatized mantle wedge which has been modified by slab melts. The occurrence of pyroxene diorite indicates an Early Silurian active continental margin setting in the south‐eastern Qilian Orogenic Belt. [ABSTRACT FROM AUTHOR]

The detection of deep targets has always been a challenging topic for controlled source electromagnetic methods; however, the time-frequency electromagnetic method (TFEM) can overcome some of these challenges. In this paper, we introduce the method and showcase the technique for imaging deep targets using optimal offsets and transmission periods. In addition, we implement a simulated annealing constrained inversion, based on well-seismic data, to illustrate improvement in the effective detection depth and the ability to identify deep targets. We apply TFEM for two targets in North Xinjiang to show that internal multiple sets of layered series in a deep Carboniferous system and the volcanic rock mass developed in this area can be imaged. We conclude that the low-resistivity layer inside the Carboniferous system is the response of hydrocarbon source beds of muddy clastic rocks and predict that the high-resistivity layer is a favorable reservoir of volcanic rocks. Subsequent drilling confirmed the structural characteristics of the Carboniferous system revealed by TFEM data. [ABSTRACT FROM AUTHOR]

The South Tianshan Terrane (STT) is located in the boundary between the south‐western Central Asian Orogenic Belt (CAOB) and the Tarim Craton and is a key area for understanding the geologic and tectonic history of the craton and the orogenic belt. In this paper, we report detrital zircon ages from the Late Palaeozoic and Mesozoic clastic sedimentary rocks from the southern part of STT. In combination with the U–Pb ages for felsic igneous and meta‐igneous rocks exposed in the STT and adjacent tectonic units, we identify several distinct age populations. Provenance analysis suggests that the detrital zircon grains were predominately derived from the felsic magmatic rocks in the Tarim Craton and South Tianshan Terrane. The pre‐Neoproterozoic age populations may be associated with the early history of the Tarim Craton. Several pulses of Neoproterozoic magmatism are revealed by our dataset, presumably related to the assembly and break‐up of the supercontinent Rodinia. The 995 to 901 Ma detrital zircon grains were likely sourced from magmatic rocks associated with the assembly of Neoproterozoic Tarim to Australia. Among the age population of 886 to 752 Ma, the older group might be related to the subduction‐related magmatism after the assembly of Rodinia, and the younger one records a protracted magmatic event in a continental rift‐related setting associated with the break‐up of Rodinia. Two younger Neoproterozoic age populations (736 to 694 Ma and 665 to 610 Ma), showing narrow spreads with weak peaks, represent the waning stages of igneous activities related to the break‐up of Rodinia. Regarding the Palaeozoic evolution, together with other evidence, our data indicate a two‐stage subduction model for the SW Palaeo‐Asian Ocean. The 490 to 384 Ma age population corroborates the existence of Early Palaeozoic continental arc magmatism at the northern margin of Palaeozoic Tarim generated by the bidirectional subduction of the South Tianshan Ocean. After a ~30 My period of tectonomagmatic quiescence, the second stage is marked by the northward subduction of the South Tianshan Terrane during Late Devonian to Early Carboniferous. The final collision of Tarim and the south‐western CAOB likely occurred during the Late Carboniferous, followed by syn‐ and post‐collisional magmatism, as represented by the 320 to 265 Ma age population. Based on the detrital zircon ages in conjunction with the Hf isotopic features of zircons from Palaeozoic igneous rocks, our study does not support the model of large‐scale Phanerozoic net continental growth in the South Tianshan Terrane. [ABSTRACT FROM AUTHOR]

Early Cretaceous magmatic rocks associated with the Kerguelen mantle plume are widespread in the Comei area with a chronology concentrated from 134 to 130 Ma. However, less data for the earliest Early Cretaceous magmatic rocks cropping out in the Comei area have been reported. The earliest Early Cretaceous magmatic rocks from the Kada area comprise mafic rock (diabase) and felsic rocks (granite, dacite, and quartz monzonite). This paper presents a detailed LA‐ICP‐MS zircon U–Pb chronology with major and minor (trace) elements and Lu–Hf isotope data from Kada igneous rocks to identify the extent of the early activity of the Kerguelen mantle plume and the initial break‐up of eastern Gondwanaland. The LA‐ICP‐MS zircon U–Pb dates reveal that the age of Kada magmatic rocks range from 136.9 to 143.5 Ma. Kada mafic rocks exhibit both OIB (Samples KD3 and KD06) and N‐MORB (Sample KD7‐1) characteristics. The N‐MORB‐type mafic rocks were derived from partial melting of depleted spinel lherzolite. However, the OIB‐type mafic rocks were derived from partial melting (~60–80 km) of spinel + garnet lherzolite. Kada felsic rocks show obvious enrichment of light rare earth elements and negative Eu anomaly features. Among these, dacite and quartz monzonite rocks show flat heavy rare earth elements and clear Nb, Ta, P, and Ti negative anomalies with depleted εHf(t) characteristics (−11.0 to −21.0). This is indicative of partial melting of specific crustal rocks in an intraplate environment caused by underplating of coeval basaltic magmas. However, granite is characterized by high heavy rare earth element fractionation and high and dispersed εHf composition (−1.5 to +8.9), thus indicating that granite is derived from extensive fractional crystallization of mantle‐derived melts from an AFC process. The Kada felsic rocks show A‐type granitic characteristics in an extensional environment. Based on the evidence from palaeomagnetism reconstructions, Kada rocks and Bunbury basalts are both distributed in and influence the scope of the Kerguelen mantle plume. They are also coeval with the initial break‐up of eastern Gondwana. We suggest that Kada magmatic rocks in southern Tibet represent the earliest activity of the Kerguelen mantle plume and that they played a role in the initial break‐up of eastern Gondwana. [ABSTRACT FROM AUTHOR]

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One of the most important steps in the mineral resource estimation and detailed exploration of porphyry copper deposit is separating the alteration zones as a control parameter of the copper grade. The most popular method for this separation is petrological investigations (other methods are not much popular), but the method lacks the ability to predict alteration zones of the un-sampled points. In this paper a new method has been proposed which is based on the support vector machine (SVM) classification of the analyzed whole rock samples and it has been used in Sungun porphyry copper deposit to separate potassic, phyllic and transition alteration zones. To apply the SVM method, use has been made of the radial basis function (RBF) as the kernel function and to obtain the optimal values for the SVM parameters (γ and C being the most important); the grid search method has been used. The best values for γ and C that have had good performance in the training and test steps are 0.0625 and 32, respectively. Results have revealed that the SVM classification (used in this study) can effectively separate the alteration zones in the Sungun deposit. Specifically, the accuracy of this method has been 75% which proves that the support vector machine can offer an inexpensive, fast and robust classification technique and it can be a valid alternative to the well established methodologies in this area. [ABSTRACT FROM AUTHOR]