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Based on the comparison of zircon ages with source terranes, they inferred that the likely source for Cenozoic zircon grains was the Eastern Alkaline Province of Mexico, which comprises various volcanic fields of Cenozoic age. Armstrong-Altrin et al. (2021) reported the detrital zircon grain surface features, chemistry, and U-Pb ages in the Chachalacas beach sediments, Gulf of Mexico. Armstrong-Altrin et al. (2020) discussed the U-Pb ages of detrital zircon grains, which we reported from the Chachalacas beach in the western Gulf of Mexico. [Extracted from the article]

Heavy mineral separation reveals the presence of garnet-group minerals and magnetite as well as native gold. Magnetite crystals display the same variability in transport indicators as garnet, and there is a notable decrease in the size of individual crystals and the proportion of magnetite between samples relative to their downstream position. Crystals of smoky quartz and amazonite are present as well as a number of accessory minerals, including several beryllium mineral species. The single-crystal diffraction data of eight plutonic labradorite crystals and one metamorphic labradorite crystal show that they all have the incommensurately modulated structures, characterized by the satellite reflections ( I e i -reflections), which cannot be indexed by integer Miller indices. [Extracted from the article]

Abstract González-Acebrón et al. (2016) attributed the coastal deposits of Torre Bermeja-La Barrosa area (Cádiz, SW Spain) to the Early Pleistocene (1.3 Ma). They also considered that an extremely high-energy event, such as a tsunami, affected the basal deposits of the sequence. In this paper, both the chronological attribution and the stratigraphic-sedimentary model are discussed. Previous information shows that Sequence 1 is late Pliocene-lowermost Early Pleistocene based on biostratigraphic, magnetostratigraphic, and regional-scale stratigraphic correlation. In addition, stratigraphic, facies, and sedimentary analyses indicate that sediments attributed to Sequence 1 were formed due to south-easternward longshore currents reworking wave- and tidal-dominated coarse-grained delta sediments deposited further to the north. Highlights • Coarse-grained deposits cropping out at La Barrosa (Cádiz, SW Spain) are late Pliocene-lowermost Early Pleistocene in age. • They were formed in coastal settings related to longshore currents reworking of wave- and tide-dominated delta deposits • The age assignment and the sedimentary interpretation challenge results recently published by González-Acebrón et al. [ABSTRACT FROM AUTHOR]

Determining the absolute duration of magmatic-hydrothermal events leading to the formation of porphyry systems (i.e., including porphyry copper, skarn, and epithermal deposits) is one of the key questions in ore geology. This is so because the duration of magmatic-hydrothermal events in porphyry systems is instrumental to the development of genetic models necessary to explore a category of mineral deposits that provide most of the copper and significant amounts of base and precious metals to our economy. The problem of determining the absolute duration of magmatic-hydrothermal events in porphyry systems has been addressed through thermal modeling of cooling intrusions and time needed to precipitate specified metal amounts from active hydro-thermal systems with known metal concentrations and fluid fluxes. Both these methods have shown that the likely duration of hydrothermal systems is on the order of a few tens of kilo-annum (ka). Isotopic dating in contrast is the only possible way to determine the life span of magmatic-hydrothermal events in fossil porphyry systems. Analytical and methodological developments during the last decade in the fields of the most robust isotopic systems commonly used for absolute dating (U-Pb, 40Ar/39Ar, Re-Os) allow us to date minerals with internal precisions <0.2% (2σ). For a 10-Ma-old mineral this corresponds to a <20-ka uncertainty, which is marginally sufficient to discriminate the duration of hydrothermal systems at the tens of kilo-annum scale. However, many geochronological studies on fossil porphyry systems have shown that these are most often formed through repeated cycles of several intrusion events, which extend the overall life of the porphyry systems to a few 0.X and up to ~2 Ma in some cases. Internal precisions of the above mentioned dating methods allow us, in theory, to comfortably discriminate events at the O.X scale and the combination of U-Pb, 40Ar/39Ar, and Re-Os geochronology is a tool widely used by ore geologists to bracket the duration of cyclic magmatic-hydrothermal events in porphyry systems. In this review we discuss some fundamental problems that are systematically overlooked in most geochronological studies trying to bracket the life span of porphyry systems. We show that if these problems are not adequately taken into account and tackled the result will be that fundamentally wrong life spans of porphyry systems will be estimated. We also provide basic guidelines to follow when trying to resolve the duration of magmatic-hydrothermal events in porphyry systems with the highest accuracy and precision currently achievable. [ABSTRACT FROM AUTHOR]

We thank Patil Pillai et al. for preparing a critique on our article (Joy et al., 2018). Patil Pillai et al. contest the analytical procedure utilized for the carbonates and "geological information" documented in our research article and raise concerns on our conclusions. We hereby provide our reply to each of their comments. [ABSTRACT FROM AUTHOR]

The uplift rates calculated for Tasmania by Shin (2013) are not supported by the data presented in his paper. The OSL ages obtained indicate a Last Glacial age and fluvial origin for many of the deposits analysed. OSL ages obtained on sediments at Mary Ann Bay in southern Tasmania confirm recent research indicating a Last Glacial age and aeolian deposition of the sands rather than marine (Last Interglacial) deposition. Anomalously high uplift rates for southern Tasmania, proposed by earlier researchers and Shin (2013), are discounted. [ABSTRACT FROM AUTHOR]

Complications of detrital zircons databases provide a means for statistically analysing a variety of significant geological problems. In this work, we tried to collect a database about the South China Phanerozoic detrital zircon geochronology data. The data statistics of this paper rely on the OneSediment Working Group of The Deep‐time Digital Earth program (DDE). By November 2022, the database contains a total of 699 samples with 55,532 U–Pb ages and 3,770 effective Hf isotope data, from 130 papers. Abundant information including reference title, sample ID, locality, rock type, research institution, GPS coordinates, U–Pb ages, εHf(t) values, etc., have been involved in our database, and all data can be downloaded from DDE Data Publish & Repository website, https://repository.deep‐time.org/. Through the integrated data, we can improve the previous studies and avoid the waste of resources caused by a large number of repeated studies. [ABSTRACT FROM AUTHOR]

One was the Planetary Boundaries framework, introduced by Johan Rockström and colleagues in 2009, which aims to provide a natural-science based framework for describing a Holocene-like state of the Earth System and the intrinsic boundaries of the Earth System that should not be transgressed if such a stable state is to be maintained (Rockström et al. [10]). Introducing the Anthropocene: The human epoch: This article belongs to Ambio's 50th Anniversary Collection. The other is the polycentric governance systems approach introduced by the late Elinor Ostrom ([9]), which, in the context of the S et al. paper, was proposed as a more appropriate governance system for the Anthropocene than the present governance systems that are driving us deeper towards a planetary crisis. The SCM paper foreshadowed the debate on the start date for the Anthropocene, which became prominent from 2009 with the formation then of the Anthropocene Working Group to explore the Anthropocene as a potential new interval in the Geologic Time Scale (AWG [1]). [Extracted from the article]

Since the advent of detrital geochronology, significant progress has been made in the study of sedimentary sources. The detrital zircon U–Pb age spectrum, especially when combined with zircon Hf isotopes, provides a powerful tool for determining the provenance location, nature, and evolutionary history of sediments. The Western Qinling–Songpan tectonic junction, located in central China, is a giant structure on the crustal scale. A total of 20,640 zircon U–Pb ages of 281 sandstone samples from the Songpan–Ganzi and Western Qinling terranes were obtained. Among these, 1,636 zircons from 33 samples contained Hf isotopic data. Moreover, we compiled data on papers, samples, analytical methods, and results and obtained a total of 76 zircon U–Pb and 60 Hf isotope data heads. The obtained dataset has multiple data interfaces, which can be well associated with research or applications in different fields, for provenance analysis, climate change, and paleogeographic reconstruction studies. [ABSTRACT FROM AUTHOR]

Carbon capture and storage (CCS) is a developing technology that seeks to mitigate against the impact of increasing anthropogenic carbon dioxide (CO2) production by capturing CO2 from large point source emitters. After capture the CO2 is compressed and transported to a reservoir where it is stored for geological time scales. Potential leakages from CCS projects, where stored CO2 migrates through the overlaying sediments, are likely to have severe implications on benthic and marine ecosystems. Nonetheless, prokaryotic response to elevated CO2 concentrations has been suggested as one of the first detectable warnings if a CO2 leakage should occur. Applying properties of prokaryotic communities (i.e. community composition and metabolic status) as a novel CO2 monitoring application is highly reliable within a multidisciplinary framework, where deviations from the baseline can easily be identified. In this paper we review current knowledge about the impact of CO2 leakages on marine sediments from a multidisciplinary-based monitoring perspective. We focus on aspects from the fields of biology, geophysics, and chemistry, and discuss a case study example. We argue the importance of an integrative multidisciplinary approach, incorporating biogeochemistry, geophysics, microbial ecology and modelling, with a particular emphasis on metagenomic techniques and novel bioinformatics, for future CCS monitoring. Within this framework, we consider that an effective CCS monitoring programme will ensure that large-scale leakages with potentially devastating effects for the overlaying ecosystem are avoided. Furthermore, the multidisciplinary approach suggested here for CCS monitoring is generic, and can be adapted to other systems of interest. [ABSTRACT FROM AUTHOR]

In the same year as that paper, Roger published a wide-ranging standalone discussion of various aspects of New Zealand terrane concepts, age, content, interpretation, and paleogeography, including descriptions of the Brook Street Terrane and other Eastern Province terranes (Cooper [13]). Roger Cooper (1939-2020) was one of the pre-eminent New Zealand paleontologists and geologists of the twentieth century. At the same time, and in collaboration with Professor Pete Sadler (University of California, Riverside), Roger pioneered the use of innovative, quantitative methods in biostratigraphic correlation and timescale calibration, in the context both of New Zealand sedimentary basin analysis (Cooper et al. [15]) and international timescale calibration. Much of this research was concerned with graptolites (e.g. Cooper [8], [10]; Cooper and McLaurin [22]) but, in collaboration with others, his interests quickly expanded to include conodonts, brachiopods, molluscs, trilobites and graptolites from New Zealand, Australia, Antarctica and Spitsbergen (e.g. Cooper and Druce [16]; Shergold et al. [48]). Roger's career at the New Zealand Geological Survey began in 1969 and was focussed initially on the taxonomy, biostratigraphy, evolution, biogeography and paleobiology of early Paleozoic fossils in New Zealand. [Extracted from the article]

Spatial and temporal scales are essential components of geological sciences; both are almost always imbricated in complex ways, challenging geoscientific knowledge among nonspecialists and students. The present paper focuses on the efforts made by the French naturalist Simon-Suzanne Nérée Boubée (1806–62) regarding popular education on geology. Though Boubée is poorly known nowadays, he experienced some prestige during his lifetime. He worked as an independent teacher, offering private as well as free public courses. Boubée, as a nineteenth-century science popularizer, repeatedly insisted on his disposition for "spreading science for all." He extensively published books and journals on geology, all aimed at popularizing geological scientific knowledge, considered to be of paramount relevance. This paper analyzes three visual examples extracted from his works: the Tableau Mnémonique des Terrains Primitifs, destiné au géologue voyageur, avec son explication (1831), the Tableau de l'État du Globe à ses différents âges (1832), and the Tableau figuratif de la structure minérale du globe, ou résumé synoptique du Cours de géognosie de M. N. Boubée (1839), supplemented with images from the travel guide Deux Promenades au Mont Doré (1834). Our goal is to understand Boubée's efforts to synthesize information, scaling down geologic time and space into foldable materials that made geological knowledge cognitively and materially accessible to laypeople. [ABSTRACT FROM AUTHOR]

The paper presents first data on isotopic U–Pb study (LA-ICP-MS method) of zircon from intrusive rocks of the Kensu pluton situated in the eastern part of the deep-seated fault system of the "Nikolaev Line." This pluton of high-potassic (shoshonitic series) rocks is accompanied by the Kensu deposit and other occurrences of skarn and porphyry W–Mo–Cu–Au mineralization. Together with the other Au, W, and Cu deposits and occurrences, they are parts of the extended metallogenic belt of Tien Shan. The concordant isotopic U–Pb age data for zircon autocrysts from the rocks of the consecutive intrusive phases span over the interval of approximately 325 to 302 Ma. This interval comprised the crystallization of monzogabbro (321 ± 4 Ma), monzonite (319 ± 4 Ma), camptonite (306 ± 4 Ma), syenite (307 ± 6 Ma), quartz syenite (305.5 ± 2 Ma), and quartz monzonite (305 ± 3 Ma). Zircon antecrysts dated at 316–325 Ma to 335–345 Ma have also been identified. The age data obtained are consistent with the age of subduction processes defined for the western part of the Middle Tien Shan. However, both geochemical characteristics of the rocks from the Kensu pluton and a distinct W–Mo mineralization related to this pluton contradict the subduction-related setting of the pluton emplacement but, instead, point out the post-collisional setting of the intrusion emplacement. This discrepancy can be explained by a "scissor-like" (from east to west) closure of the Turkestan paleoocean that has resulted in the post-collisional regime in the eastern part of the "Nikolaev Line," whereas subduction continued in its western part. The rocks also contain zircon xenocrysts with a much older age (in to order of 1.9 Gb) that probably represents the age of the Tarim craton basement rocks; this indicates an involvement of the ancient material in the magma generation. [ABSTRACT FROM AUTHOR]

In this article, we present a brief introduction to the procedure, methods and results of the collection and summarization of an updated detrital zircon U–Pb geochronology database for the Qilian‐Qaidam‐Kunlun collage in northern Tibet. A total of 620 samples with 59,830 raw data were compiled from 121 published papers, including 70 samples with in‐situ detrital zircon Lu–Hf isotopes. Samples from seven different geologic subunits are categorized. For sediments with different ages of deposition, we highlight the characteristics of age spans, probability density distributions, major peaks and εHf(t) values. Further syntheses of this metadata collection, the detailed raw data of which will be periodically accessible in the Deep‐Time Digital Earth repository, would be effectively applied to a variety of scientific attempts concerning the geologic history of the Qilian‐Qaidam‐Kunlun collage, in particular, provenance analyses, crustal evolution studies and supercontinent reconstructions. [ABSTRACT FROM AUTHOR]

The Tatun Volcano Group (TVG) is located at the northern end of Taiwan, ~ 15 km from the center of Taipei, a metropolitan area of over seven million inhabitants. A volcanic eruption by the TVG of any type or scale could cause catastrophic human and economic impacts. This paper summarizes previous geochemical, geophysical, and geochronological reports and highlights why the widely accepted age model does not comport with the latest observations. This study also reports novel 40Ar/39Ar ages for two andesite samples and one basalt sample from the TVG. A sample collected from Chihsingshan yields a robust 40Ar/39Ar age of 0.081 ± 0.005 Ma. This provides the first direct evidence of TVG volcanic activity after 0.1 Ma. Two samples yield 0.28 ± 0.02 Ma for Tatunshan and 0.159 ± 0.017 Ma for Honglushan. The younger ages refute previously proposed age models for the TVG. Along with new drone photos and LiDAR images, the age data help resolve eruptive history and advance understanding of volcanic hazards and hazard mitigation in Taiwan and surrounding areas. [ABSTRACT FROM AUTHOR]

The Lesser Xing'an—Zhangguangcai Range of northeast China is located in the eastern segment of the Central Asian Orogenic Belt (CAOB), which records intense magmatism during the Mesozoic. The petrogenesis and geodynamic setting of the Early Jurassic intrusive rocks in this region are unclear. In this paper, we present new zircon U–Pb age and whole-rock geochemical data for these intrusive rocks to investigate their origins and tectonic setting. Zircon U–Pb dating suggests these intrusive rocks were emplaced during the Early Jurassic (197–187 Ma). The granites are enriched in silica and alkali, and depleted in MgO and CaO. They are metaluminous to weakly peraluminous, and have high A/CNK values and low zircon saturation temperatures (TZr ~ 779°C), suggesting they are highly fractionated I-type granites derived by partial melting of lower crustal materials. The granites exhibit negative Nb, Ta, P, Eu, and Ti anomalies due to fractional crystallization. The diorites and gabbros have low SiO2 contents and high Mg# values, and are enriched in light rare earth and large-ion lithophile (Ba, K, and Sr) elements, and depleted in heavy rare earth and high field strength (Nb, Ta, and Ti) elements. The geochemical characteristics show that the mafic magmas were derived by partial melting of mantle that had been metasomatized by subduction-related fluids. Based on the geochemical characteristics of coeval intrusive rocks and the regional geological setting, we suggest the Early Jurassic intrusive rocks in the Lesser Xing'an—Zhangguangcai Range were formed along an active continental margin, possibly as a result of bidirectional subduction of the Mudanjiang Oceanic plate between the Jiamusi and Songnen—Zhangguangcai Range massifs. [ABSTRACT FROM AUTHOR]

The core challenges to automatic full-horizon tracking are how to establish a potential local connection relationship between the horizon points, conduct accurate global diffusion in a three-dimensional space, and finally, how to form a complex horizon surface. The existing attribute-based horizon-tracking methods based on waveform similarity, dip guidance, and RGT (relative geological time) can not solve the problems of local connection and global diffusion at the same time. In view of this challenge, this paper proposes an automatic 3D seismic horizon-tracking method based on global corrugated diffusion, which can completely integrate local connection and global diffusion so that all horizons in the whole data volume can be interpreted simultaneously. For the problem of local horizon-point connection, this paper uses the correlation between seismic trace pairs based on DTW (dynamic time warping) correlation to mine the connection mode between horizon points. For the global diffusion problem, this paper proposes the realization of global modeling based on the relationship between seismic samples, constructing a complex 3D horizon through a central ripple-diffusion process. The example shows that the horizon tracked by this method well reflects the original stratum occurrence and stratum-contact relationship, retains the structural details, accurately reflects the structural shape, and realizes automatic tracking across faults. [ABSTRACT FROM AUTHOR]

Magnesian Limestone zoned dolomite (red and non-luminescent zones) now partly dedolomitized), calcite (yellow luminescence), blue luminescent albite has non-luminescent overgrowths) Mansfield Quarry, Nottinghamshire. Modern tropical carbonate sediments are generally aragonite and high-Mg calcite with high porosities (Enos & Swatsky, [16]), yet ancient carbonates (Miocene and older) are generally calcite or dolomite with far lower porosity. Dissolution of aragonite and Mg calcite with precipitation of calcite cements with 2-8 mol% MgCO SB 3 sb occur in sea water undersaturated with respect to aragonite and high-Mg calcite, but supersaturated with respect to low-Mg calcite. The Xiong et al. compilation shows that the cycles of aragonite/high-Mg calcite were more variable than previously recognised, with the first inferred transition from a high-Mg calcite to low-Mg calcite sea occurring during early Cambrian stage 3. [Extracted from the article]

New isotopic data are presented in this paper that make it possible to determine the stratigraphic position of the Talja Formation on the regional stratigraphic scale of the Early Precambrian. The U‒Th‒Pb age of 1926 ± 7 Ma obtained for the first time for metarhyodacites of the Talja Formation indicates that this formation is coeval to the Kaskama Formation, which, together with the similar isotope–geochemical composition of the type varieties of the Kaskama and Talja formations (komatiitic basalts, aluminous metabasalts, and metarhyodacites), significantly expands the understanding of the extent of the area composed of the Paleoproterozoic Kalevian Superhorizon within the Kola–Norwegian region of the Fennoscandian shield. [ABSTRACT FROM AUTHOR]

The authors comment on two papers concerning the age and deposition of the Bushmanland Group in South Africa. According to the authors, the samples employed in the two papers for isotopic analyses are related to their stratigraphic sequence. The authors admit the difficulty of dating zircons in metamorphic rocks but thinks that a good advance has been made concerning possible ages of the provenance rocks of the Bushmanland Group.

This special issue (Volume 3) belongs to the special issues on the orogens along the Silk Road. We selected 34 papers to focus on the mineral deposits, orogeny‐links, geochemistry, geochronology, and environments related to the Tianshan Orogen of the Silk Road. We hope that these papers will highlight more geological research along the Silk Road to promote the construction and development of the Road and Belt. [ABSTRACT FROM AUTHOR]

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This paper presents a detailed study including LA-ICP-MS zircon U-Pb dating, geochemical, zircon Hf isotope, and whole rock Sr-Nd isotope analysis of magmatic rocks from the Yitong County, Jilin Province, NE China. These data are used to better constrain the Middle Silurian–Middle Devonian tectonic evolution in the eastern segment of the northern margin of the North China Craton (NCC). Zircon U-Pb dating results show that the Ximangzhang tonalite formed in the Late Silurian (425 ± 6 Ma); the basalt, andesite, and metamorphic olivine-bearing basalt in the Fangniugou volcanic rocks formed in the Middle Silurian (428 ± 6.6 Ma) and Middle Devonian (388.4 ± 3.9 Ma, and 384.1 ± 4.9 Ma). The Late Silurian tonalites are characterized by high SiO2 and Na2O and low K2O, MgO, FeOT, and TiO2, with an A/CNK ratio of 0.91–1.00, characteristic of calc-alkaline I-type granite. They are enriched in Rb, Ba, Th, U, and K, and depleted in Nb, Sr, P, and Ti, with positive εNd(t) (+0.35) and εHf(t) (+0.44 to +6.31) values, suggesting that they mainly originated from the partial melting of Meso–Neoproterozoic accretionary lower crustal material (basalt). The Middle Silurian basalts are characterized by low SiO2, P2O5, TiO2, and Na2O and high Al2O3, FeOT, and K2O, enriched in Rb, Ba, Th, U, and K and depleted in Nb, Ta, Sr, P, and Ti, indicative of shoshonitic basalt. The Late Silurian tonalites have positive εNd(t) (+4.91 to +6.18) values and primarily originated from depleted mantle magmas metasomatized by subduction fluids, supplemented by a small amount of subducted sediments and crustal materials. The Middle Devonian volcanic rocks exhibit low SiO2, TiO2, and Na2O and high K2O, and MgO, enriched in Rb, K, and LREEs and depleted in Nb, Ta, Sr, and HREEs, characteristic of shoshonitic volcanic rocks. Their εNd(t) (+2.11 to +3.77) and εHf(t) (+5.90 to +11.73) values are positive. These characteristics indicate that the Middle Devonian volcanic rocks primarily originated from depleted mantle magmas metasomatized by subduction fluids, with the addition of crustal materials or subducted sediments during their formation. Based on regional geological data, it is believed that the study area underwent the following evolutionary stages during the Silurian–Devonian period: (1) active continental margin stage of southward subduction of the Paleo–Asian Ocean (PAO) (443–419 Ma); (2) arc-continent collision stage (419–405 Ma); (3) post-collision extension stage (404–375 Ma); (4) active continental margin stage, with the PAO plate subducting southward once again (375–360 Ma). [ABSTRACT FROM AUTHOR]

The axion anti-quark nugget (A Q ¯ N) model was developed to explain in a natural way the asymmetry between matter and antimatter in Universe. In this hypothesis, a similitude between the dark and the visible components exists. The lack of observability of any type of dark matter up to now, in particular A Q ¯ Ns, requires finding new ways of detecting these particles, if they exist. In spite of strong interaction with visible matter, for such objects a very small ratio of cross section to mass is expected and thus huge detector systems are necessary. This paper presents a new idea for the direct detection of the A Q ¯ Ns using minerals as natural rock deposits acting as paleo-detectors, where the latent signals of luminescence produced by interactions of A Q ¯ Ns are registered and can be identified as an increased and symmetrical deposited dose. The estimates were made for minerals widely distributed on Earth, for which the thermoluminescence (TL) signal is intense and if the thermal conditions are constant and with low temperatures, the lifetime of the latent signals is kept for geological time scales. [ABSTRACT FROM AUTHOR]

The paper presents new isotopic U–Pb data (LA-ICP-MS method) of zircon from the main types of intrusive rocks at the Kuru-Tegerek gold-copper-molybdenum skarn deposit situated in the Chatkal segment of the Middle Tien Shan. This and other gold, copper, tungsten and molybdenum deposits are parts of the extended Late Paleozoic metallogenic belt of Tien Shan. The concordant isotopic U–Pb values obtained for zircon autocrysts from the rocks of sequential intrusive phases span over the interval from approximately 323 to 311 Ma. This interval comprises the crystallization of gabbro-diorite (from 323.5 ± 2.5 Ma to 323.2 ± 6.8 Ma) and tonalite (from 321.4 ± 3.8 Ma to 311 ± 3.8 Ma). The age dates obtained for these zircon autocrysts correspond to the emplacement of these moderate-potassic intrusions in the Late Carboniferous and are almost coincident with the isotopic dates previously known for the high-potassic intrusions of the porphyry Cu–Au–Mo deposits of the Almalyk mineralized cluster (Kurama segment of the Middle Tien Shan), which were also emplaced in the Late Carboniferous (about 330–310 Ma). This corresponds to the subduction tectonic regime occurred in this region in relation to the steep-dipping (in the Kurama segment) or flat (in the Chatkal segment) subduction of a tectonic plate toward the north, under the structures of the Kazakhstan–North Tien Shan continental massif and accreted segments of the Middle Tien Shan. The intrusive rocks studied at the Kuru-Tegerek deposit contain also zircon xenocrysts (including these in the core of complex crystals) with the isotopic U–Pb age of some 1.9–2.1 Ga. These dates are in agreement with the age of metamorphic rocks in the Tarim craton basement and indicate the presence of the ancient continental crust in this segment of the Middle Tien Shan. [ABSTRACT FROM AUTHOR]

Within the Himalayan collisional belt, granites occur along two subparallel belts, namely, the Tethyan Himalayan Sequence (THS) and the Greater Himalayan Crystalline Complex (GHC). In this study, Eocene adakitic rocks and leucogranite are found only in the northern Himalayas, so further research is required to constrain their origin. Here, we present zircon U–Pb and monazite U–Th–Pb ages, Sr–Nd–Pb and Hf isotopes, and whole-rock major and trace elements for Liemai muscovite granite in the eastern Himalayan region. The U–(Th)–Pb results show that Liemai muscovite granite was emplaced at 43 Ma, and that its geochemical characteristics are similar to those of adakitic rocks of the same age (Dala, Quedang, Ridang, etc.). Combined with previous studies, both Eocene adakitic rocks and leucogranite are high-potassium calc-alkaline peraluminous granites. The former is relatively rich in large-ion lithophile elements (LILEs), such as Ba and Sr, and relatively deficient in high-field-strength elements (HFSEs), such as Nb, Ta, Zr, and Y, with weak or no Eu anomalies, and the average light rare earth element (LREE)/heavy rare earth element (HREE) ratio is 17.8. The latter is enriched in LILEs (such as Rb) and U, Ta, and Pb, and depleted in HFSEs (such as Nb and Zr), La, and Nd, with obvious negative Sr, Ba, and Eu anomalies and a mean LREE/HREE ratio of 10.7. The 87Sr/86Sr of the former is in the range of 0.707517–0.725100, εNd (t) ranged from −1.2 to −14.7, the average is −11.6, εHf (t) ranged from −0.5 to −65, the average is −12.2. The average values of (206Pb/204Pb) i, (207Pb/204Pb) i and (208Pb/204Pb) i are 18.788, 15.712 and 39.221, respectively; The 87Sr/86Sr of the latter is in the range of 0.711049~0.720429, εNd (t) ranged from −9.8 to −13.8, the average is −12.3, εHf (t) ranged from −4.2 to −10, the average is −6.7. The isotopic characteristics indicate that adakitic rocks and leucogranites are derived from the ancient lower crust, and both may be derived from metamorphic rocks of the GHC. In this paper, the origin of the two is associated with the transformation of the Himalayan tectonic system during the Eocene, and it is inferred that the deep crust may have altered the tectonic environment (temperature and pressure), resulting in an obvious episodic growth trend of leucogranite and significant development of adakitic rocks from 51 to 40 Ma. From 40 to 35 Ma, the development of Eocene magmatic rocks was hindered, and adakitic rocks disappeared. It is proposed that the genetic difference is related to the transition from high to low angles of the subducting plate in the crustal thickening process. [ABSTRACT FROM AUTHOR]

In the present work, a new electrothermal combined stress test cell has been designed and fabricated to conduct accelerated electrothermal ageing. The fabricated test cell includes all possible real working conditions of the transformers. The effects of accelerated electrothermal ageing on the performance of power transformers with thermally upgraded Kraft (TUK), Nomex-910 and Nomex-410 solid dielectrics in conjunction with mineral oil have been investigated. The accelerated electrothermal ageing has been performed for a temperature range of 100°C to 220°C, along with 10 kV electrical stress. Subsequently, several electrical, thermal, mechanical and chemical properties of transformer oil and different paper dielectrics have been determined. It has been observed from the diagnostic test results that Nomex impregnated mineral oil samples have better electrothermal performance as well as oxidation stability when compared to the thermally upgraded Kraft oil samples. Therefore, Nomex insulating materials in conjunction with mineral oil are suggested as alternative solid dielectrics for power transformers in order to achieve better oxidation stability, improved thermal performance for long service runs and reduced operating and maintenance costs. It is envisioned that the present experimental study will be very beneficial to utility managers and end-users of power transformers. [ABSTRACT FROM AUTHOR]

How and when sedimentary rocks record Earth's magnetic field is complex. Most studies assume a time‐progressive lock‐in mechanism during sediment deposition called depositional remanent magnetization (DRM). However, magnetic minerals can also form in situ, recording a chemical remanent magnetization (CRM) that is discontinuous in time. Disentangling the two mechanisms represents a major hurdle, and differences in their recording efficiencies remain unexplored. Here, our theoretical solutions demonstrate that CRM intensities exceed DRM by a factor of six when acquired in the same magnetic field. Novel experiments growing greigite (Fe3S4) in sediments and subsequent redeposition under identical magnetic field conditions confirm the predicted difference in recording efficiency. Thus, if left unrecognized, CRM leads to overestimated paleointensity and deserves more attention when interpreting Earth's magnetic history from sedimentary records. Recognition of fundamental differences between CRM and DRM characteristics provide a way forward to distinguish the recording mechanisms through routine laboratory protocols. Plain Language Summary: Remanent magnetizations preserved in sedimentary rocks serve as a continuous record of Earth's magnetic field history and play a fundamental role in understanding the Earth system. It is commonly assumed that magnetic minerals align with the magnetic field as a particle settles through the water column, known as a depositional remanent magnetization (DRM). However, diagenesis can lead to chemical growth of magnetic minerals, known as a chemical remanent magnetization (CRM). CRM lacks stratigraphic continuity and can obscure or completely overprint the original magnetization any time after sediment deposition, leading to a magnetic record that is uncorrelated with the age of the rock. Yet, CRMs go largely unrecognized. Theory and experiments in our paper document that CRMs record the magnetic field six times more efficiently than DRMs. Our work provides a way to distinguish the two through routine laboratory protocols. Key Points: Recording efficiency of chemical remanent magnetization (CRM) is six times higher than depositional remanent magnetization (DRM)Undetected chemical remanences lead to overestimated relative paleointensity estimatesComparison of natural and laboratory magnetization and demagnetization behavior help identify chemical remanent magnetizations in sediments [ABSTRACT FROM AUTHOR]

Accurately determining the timing and mechanism of metallogenesis of ore deposits is essential for developing a robust genetic model for their exploration. In this paper, we analyze the formation conditions of cassiterite in five major deposits of southern Hunan Province, one of the most important tungsten-tin (W-Sn) provinces in South China, using a combination of cathodoluminescence imaging, in situ U-Pb geochronology, and trace-element concentration data. In situ cassiterite U-Pb geochronology constrains the main period of Sn mineralization to between 155.4 and 142.0 Ma, demonstrating a temporal and genetic relationship to silicic intrusive magmatism in the same area. Three stages of magmatic activity and metallogenic evolution are recognized: (1) Early Paleozoic and Triassic: the initial enrichment stage of tungsten and tin; (2) Jurassic: the metasomatic mineralization stage; and (3) Cretaceous: the magmatic-hydrothermal superposition stage. The cassiterite in these deposits takes four forms, i.e., quartz vein-type, greisen-skarn-type, greisen-type, and granite-type, representing a progression characterized by the increasing content and decreasing range of variation of high field strength elements (HFSEs), and reflecting a general increase in the degree of evolution of the associated granites. Rare earth element (REE) concentrations suggest that precipitation of cassiterite was insensitive to the redox state of the fluid and that precipitation of cassiterite in the southern Hunan Sn deposits did not require a high-fO2 environment. These findings provide new insights into tin mineralization processes and exploration strategies. [ABSTRACT FROM AUTHOR]

Shoshonitic rocks are widely distributed in post-collisional settings and provide key information on deep geodynamic mechanisms and magmatic evolution. In this paper, we present petrographic, zircon U-Pb age-related, trace elemental, Hf isotopic, bulk-rock elemental, and Sr-Nd isotopic data of the Dalongtan shoshonitic syenite porphyries (DSSPs) in central Yunnan, southeastern Tibet. The DSSPs formed at 33.2 ± 0.3 Ma in a post-collisional setting. They define linear trends on Harker diagrams, and they display similar trace element patterns and enriched bulk-rock Sr-Nd isotopes [(87Sr/86Sr)i = 0.70964–0.70968, εNd(t) = −12.9 to −12.7] and zircon Hf isotopes (εHf(t) = −15.7 to −13.1) to the coeval mantle-derived potassic mafic rocks. This suggests that the DSSPs were fractionated from the lithospheric mantle-derived mafic magmas. The DSSPs, along with the coeval felsic and mafic magmatic rocks (37.2–32.3 Ma), exhibit a planar distribution on the SE Tibet and predate the left-lateral shearing of the Ailaoshan–Red River shear zone (ARSZ) (32–22 Ma), suggesting that there are no genetic relationships between them. The DSSPs have geochemical characteristics similar to those of A-type granites, with high total alkalinity (10.39–11.17 wt.%), HFSE concentrations (Zr + Nb + Ce + Y = 890.2–1054.3 ppm), Ga/Al ratios (10,000 × Ga/Al = 2.95–3.46), whole-rock zircon saturation temperatures (906–947 °C), and oxygen fugacity (ΔFMQ = +3.30–+4.65), indicating that they are products of the high-temperature melting of the lithosphere as a result of asthenosphere upwelling in extensional settings. Based on our data and regional observations, it is proposed that the generation of the DSSPs may be linked to the convective thinning of the thickened lithospheric mantle following the India–Asia collision. [ABSTRACT FROM AUTHOR]

The development of trench-arc-backarc (TABA) systems is uniquely associated with modern-style plate tectonics on Earth. The Qilian orogenic belt in NW China records the evolution history of the Proto-Tethys Ocean at the transition time from the Proterozoic to Phanerozoic. This paper presents systematic studies of petrography, U–Pb chronology and geochemistry on various rocks from a middle-ocean ridge (MOR)-type ophiolite belt, active continental margin and back-arc basin in the Qilian orogenic belt to address the development of a modern-style TABA system. Arc magmas include felsic intrusions with ages of 531 to 477 Ma and felsic-mafic arc volcanic rocks with ages of 506 to 439 Ma, showing distinctive features of typical magmatic rocks formed at an Andean-type continental margin. The back-arc basin is recorded by a 490- to 448-Ma suprasubduction zone (SSZ)-type ophiolite with boninite, and Silurian turbidite flysch formation. We establish a three-stage tectonic history from the initiation of subduction to the formation of a mature Japan-Sea-type back-arc basin at the active continental margin in the Early Paleozoic era. (1) Northward subduction of Proto-Tethys Ocean initiated and the Andean-type continental arc developed at ~530 to 500 Ma with continual crustal thickening; (2) a tectonic transition occurred from an Andean-type active continental margin to a West Pacific-type active continental margin at ~500 to 490 Ma with rapid thinning of crust to ~35 km; and (3) mature ocean basins and back-arc-basin (BAB) ophiolites were formed in the back-arc extensional environment at ~490 to 450 Ma. [ABSTRACT FROM AUTHOR]

Magmatism is a very important manifestation of the deep activity of the Earth. The geochronology and geochemistry of the Zhaojinggou monzogranite pluton indicate that magmas were derived from the late Paleoproterozoic to Mesoproterozoic lower crustal mafic materials. It was established a magma plumbing system that provides new constraints for magma evolution. [Extracted from the article]

This paper aims to formulate a damage propagation criterion in microfractured viscoelastic materials, relying upon a micromechanics reasoning together with thermodynamics concepts. The fracture density is regarded as damage parameter at macroscopic scale. The equivalent behavior of the heterogeneous material (solid matrix + fractures) is first formulated within the framework of viscoelastic homogenization theory. In this context, relevant relationships relating local fields to macroscopic fields are derived, thus allowing a clear micromechanical interpretation of quantities involved in the upscaling process, such as the residual or viscous strains. Based on thermodynamic concepts, the energy dissipation and the free energy of the homogenized viscoelastic material are deduced at the macroscopic scale. The formulation of an energetic‐based criterion for damage propagation in viscoelastic fractured materials is then achieved by viewing the macroscopic energy release rate as the thermodynamic force responsible for propagation. Due to the delayed deformation component, the formulation is time‐dependent. Since it is formulated directly at the homogenized material level, the main advantage of the approach developed in this work is the rigorous determination of the energy release rate expression, without neglecting any residual term. In the last part of the paper, several numerical applications are performed to illustrate the main features of the modeling and to provide comparison with available simplified formulations. Finally, the proposed damage propagation criterion is applied to give qualitative insights on fracturing process of sedimentary layered rocks at geological times scale viewed as a long‐term mechanical damage problem, emphasizing the viscosity effects in preventing fracture propagation. [ABSTRACT FROM AUTHOR]

This large and relatively poorly studied part of the Karelian craton was cloaked in many geological mysteries, into which Vyacheslav Stepanovich and Viktoria Vladimirovna delved when working at the Institute of Geology of the Karelian Research Center, Academy of Sciences of the Soviet Union (and then Russia). In the year of 2020, Yana Vyacheslavovna Bychkova (nee Kulikova), Viktoria Vladimirovna Kulikova, and Vyacheslav Stepanovich Kulikov, a family of geologists, passed away. Vyacheslav Stepanovich Kulikov, Viktoria Vladimirovna Kulikova, and Yana Vyacheslavovna Bychkova (Kulikova). [Extracted from the article]

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A search has been carried out for Magnetized Quark Nuggets (MQNs) accumulating in iron ore over geologic time. MQNs, which are theoretically consistent with the Standard Models of Physics and of Cosmology, have been suggested as dark-matter candidates. Indirect evidence of MQNs has been previously inferred from observations of magnetars and of non-meteorite impact craters. It is shown in this paper that MQNs can accumulate in taconite (iron ore) and be transferred into ferromagnetic rod-mill liners during processing of the ore. When the liners are recycled to make fresh steel, they are heated to higher than the Curie temperature so that their ferromagnetic properties are destroyed. The MQNs would then be released and fall into the ferromagnetic furnace bottom where they would be trapped. Three such furnace bottoms have been magnetically scanned to search for the magnetic anomalies consistent with trapped MQNs. The observed magnetic anomalies are equivalent to an accumulation rate of ~1 kg of MQNs per 1.2 × 108 kg of taconite ore processed. The results are consistent with MQNs but there could be other, unknown explanations. We propose an experiment and calculations to definitively test the MQN hypothesis for dark matter. [ABSTRACT FROM AUTHOR]

The Kresty volcano–plutonic complex (KVPC) is one of the representatives of the alkaline–ultrabasic magmatism in the Maymecha-Kotuy Alkaline Province in Polar Siberia. The geological structure of the KVPC consists of intrusive formations of olivinite–pyroxenite and melilitolite–monticellitolite bodies, a series of rocks that break through dikes of trachydolerites, syenites, granosyenites, alkaline picrites and lamprophyres. This paper summarizes the results of the authors' long-term research on the geological structure and features of the material composition of the intrusive magmatic rocks, including geochemistry, mineralogy, distribution of rare earth elements (REE), as well as the results of isotope studies. The multielement composition of the KVPC intrusions demonstrates a complex geodynamic paleoenvironment of the formation as plume nature with signs of subduction and collision. For the ultrabasic series with normal alkalinity from the first phase of the KVPC, a Sm-Nd isochron age yielded an Early Triassic (T1) result of 251 ± 25 Ma. Here, we present U-Pb dating of zircons and perovskite of high-calcium intrusive formations and a dyke complex of alkaline syenites. Thus, for the intrusion of kugdite (according to perovskite), the age determination was 249 ± 4 Ma, and for the crosscutting KVPC dykes of syenites (according to zircon) 249 ± 1 Ma and 252 ± 1 Ma. The age of the most recent dike is almost identical to the age of the main intrusive phases of the KVPC (T1), which corresponds to a larger regional event of the Siberian LIP—251 Ma. According to isotopic Sr-Nd parameters, the main source of KVPC magmas is a PREMA-type material. For dyke varieties, we assume there was an interaction of plume melts with the continental crust. The new age results obtained allow us to further constrain the episodes of alkaline–ultrabasic intrusions in Polar Siberia, taking into account the interaction of mantle plume matter and crustal material. [ABSTRACT FROM AUTHOR]

During the existence of Proto-Tethys Ocean (550–430 Ma), microcontinents in northern East Gondwana merged with the northern margin of India-Australia, completing the assembly of Gondwana. Ongoing controversy surrounds the disappearance of the Proto-Tethys Ocean, the dynamic mechanisms of suturing and the palaeogeographic relationships among microcontinents in northern East Gondwana, contributing to the uncertainty about the tectonic evolution of the region. This paper concerns the lower Silurian Zusailing Formation in the Hainan Island and focuses on the affinity between Hainan Island and various microcontinents in northern East Gondwana during the early Silurian. We use detrital zircon geochronology to reconstruct the closure process of the Proto-Tethys Ocean and show that the detrital zircon U–Pb age groups of the lower Silurian Zusailing Formation are 2800–2200, 2100–1350, 1250–950, 600–480 and 480–430 Ma, with a significant age peak of ca. 449 Ma. Furthermore, the analysis of detrital zircon geochemistry and europium anomalies shows that the Hainan Island crust continued to thicken during 600–434 Ma. Comparing the age spectrum of early Palaeozoic detrital zircons from Hainan Island and various microcontinents in northern East Gondwana, as well as the affinity among them during the Silurian, we conclude that the closure of the eastern Proto-Tethys Ocean evolved from unidirectional subduction (600–480 Ma) to bidirectional subduction (480–430 Ma). [ABSTRACT FROM AUTHOR]

Speleothems are unique archives of information on climate, geomagnetism, and environmental conditions of the past, and have been successfully used for paleoclimatic and paleomagnetic studies in the last two decades. The uniqueness of these geological objects lies in the peculiarities of their formation and preservation of a wide range of geochemical, geological and geophysical proxies, and, most importantly, in the ability to obtain time series of the corresponding characteristics in an unprecedentedly accurate resolution using isotope-geochronological dating methods and incremental chronology. This paper presents the first results of dating the Vor speleothem from the Vorontsovskaya Cave (Krasnodar region), which preserved a record of the geomagnetic excursion, obtained by 230Th/U α-spectrometry, 14C dating, and incremental chronology. Such studies have been carried out in Russia for the first time. Despite the limitations of using the methods of isotope geochronology, it was possible to obtain an upper limit on the age of the excursion, which probably occurred no earlier than 5500–6000 years ago. By the method of incremental chronology, the duration of the main phase of the excursion Vor – 871 ± 16 years – was determined with great accuracy. [ABSTRACT FROM AUTHOR]

The southern Great Xing'an Range is located in the eastern Central Asian Orogenic Belt, where voluminous igneous rocks developed during the Late Mesozoic period. The east slope of the southern Great Xing'an Range has been the topic of numerous debates on the level of influence of the Mongol-Okhotsk and the Paleo-Pacific regimes in the Late Mesozoic period. Therefore, this area is a suitable region in which to study the temporal changes in magma sources and tectono-magmatic evolution. In this paper, whole-rock geochemical data, zircon U-Pb geochronology, and zircon Hf isotope studies were carried out on the granitoids in the east slope area of the southern Great Xing'an Range. LA-ICP-MS zircon U-Pb dating revealed the ages of four granitoid samples: 135.0 ± 0.6 Ma, 130.7 ± 1.4 Ma, 130.4 ± 1.0 Ma, and 127.6 ± 0.8 Ma, respectively. The Hf isotope values 176Hf/177Hf = 0.282751–0.283015, εHf (t) = +2.0~+11.5, and T2DM = 583~1442 Ma suggest that the magma was generated by partial melting of Meso- and Neoproterozoic accreted and thickened low crust. The whole-rock geochemical data implied that these granitoids are A-type granite and their formation is closely linked to the subduction of the Paleo-Pacific Ocean plate. These geochemical, isotopic, and geochronological data suggest that the Early Cretaceous magmatism in the east slope area of the southern Great Xing'an Range formed in an extensional back-arc tectonic setting associated with the slab roll-back of the Paleo-Pacific plate subduction. [ABSTRACT FROM AUTHOR]

This paper interrogates how the two major competing frameworks in the debates over framing our geological epoch – the Anthropocene and the Capitalocene – are unified in the reproduction of a Eurocentric assumption that functions to confirm the historical priority of Euro-Western geological agency, the corollary of which is the rendering derivative of non-European peoples as lacking in such capacity until mobilized by Euro-Western forces. Rather than assume that humanity in general, or colonial capitalism more specifically, has generated a novel geological epoch by disrupting the 'natural' temporal divide between deep geological time, medium run biological time, and human history, this paper argues for a more co-constitutive relation between geological, biological, and social space-times. Locating ourselves within an irreducible socio-bio-geological space-time, we re-encounter the earth as multiple earth-worldings co-constituted by Indigenous and Black peoples in ways that precede, and exceed, the hitherto understood to be 'originary' geological capacity of Euro-Western colonial capitalism. [ABSTRACT FROM AUTHOR]

Metallogeny is the science of ore and mineral deposit formation in geological space and time. Metallogeny is interdisciplinary by nature, comprising elements of natural science disciplines such as planetology to solid state physics and chemistry, and volcanology. It is the experimental forefront of research and bold thinking, based on an ever-growing foundation of solid knowledge. Therefore, metallogeny is not a closed system of knowledge but a fast-growing assemblage of structured and unstructured information in perpetual flux. This paper intends to review its current state and trends. The latter may introduce speculation and fuzziness. Metallogeny has existed for over 100 years as a branch of Earth Science. From the discovery of plate tectonics (ca. 1950) to the end of the last century, metallogeny passed through a worldwide phase of formally published 'metallogenetic' maps. In the last decades, a rapidly growing number of scientists, digitization and splendid new tools fundamentally boosted research. More innovations may be expected by the growing use of an evolving systematic 'Geodata Science' for metallogenic research by an increasingly global human talent pool. Future requirements for metallic and mineral raw materials, especially the critical natural elements and compounds that are needed for the nascent carbon-free economy, already drive activities on stock markets and in the resource industry. State geological surveys, academia and private companies embrace the challenges. The new age requires intensified metallogenic backing. In this paper, principles of metallogeny are recalled concerning concepts and terms. A metallogenic classification of ore and mineral deposits is proposed, and the intimate relations of metallogenesis with geodynamics are sketched (ancient lid tectonics and modern plate tectonics). Metallogenic models assemble a great diversity of data that allow an ever better understanding of ore formation, foremost by illuminating the geological source-to-trap migration of ore metals, the petrogenetic and geodynamic–tectonic setting, the spatial architecture of ore deposits and the nature and precise timing of involved processes. Applied metallogeny allows companies to choose strategy and tactics for exploration investment and for planning the work. Based on comprehensive metallogenic knowledge, mineral system analysis (MSA) selects those elements of complex metallogenic models, which are detectable and can guide exploration in order to support applications such as mineral prospectivity mapping, mineral potential evaluation and targeting of detailed investigations. MSA founded on metallogenic models can be applied across whole continents, or at the scale of regional greenfield search, or in brownfields at district to camp scale. By delivering the fundamental keys for MSA, supported by unceasing innovative research, the stream of new metallogenic insights is essential for improving endowment estimates and for successful exploration. [ABSTRACT FROM AUTHOR]

The Eastern Pontide Orogenic Belt (EPOB), a well-preserved palaeo-magmatic arc, exists south of the Black Sea, from Bulgaria to Georgia. The region, which forms an essential part of the Alpine-Himalayan belt, contains volcanic rocks formed in the Late Cretaceous. This paper aims to investigate the petrogenesis of the Late Cretaceous volcanic rocks using both new and previously existing geochemical and geochronological data. Based on the geochemical features, the studied volcanics are divided into Group I (dacite/rhyolite) and Group II (basalt/basaltic andesite). According to LA-ICP-MS zircon U–Pb data, the crystallization age of Group I is 83.43 ± 0.87 Ma. The εNd(t) values of Group I are −1.4 and + 4.5, and the εNd(t) value of Group II is +3.0. The Lu–Hf isotope data from zircon shows that Group I have positive εHf(t) values (+14.20 - +12.15), and their crustal model age is 240–339 Ma. The εHf(t) values indicate that the Group I rocks are derived from the melting of a depleted mantle source. Whole-rock geochemistry data show that Group II samples were formed by partial melting of metasomatised spinel-bearing lherzolites at shallow depths. It is thought that the Late Cretaceous volcanic rocks are the products of arc magmatism associated with the northward subduction of the Neotethys oceanic lithosphere under the Eurasian plate, and the EPOB was an active continental margin arc during the Late Cretaceous. [ABSTRACT FROM AUTHOR]

The Dakrong-A Luoi area is located in the South Truong Son belt in the Indochina block and has been affected by multiple stages of magmatic-metamorphic events. In this paper, Paleozoic-Mesozoic granitoids from the Dakrong-A Luoi area were studied using LA ICP-MS U-Pb zircon geochronologies, Hf isotopes on zircon and whole-rock geochemistry of the Paleozoic to examine the tectonic-magmatic history of the Southern Truong Son belt. The magmatism history of the area can be divided into three phases, at ~ 452 Ma (Ordovician), ~259 Ma (Permian), and ~ 243 Ma (Triassic). The Ordovician granites were exposed in the narrow belt of NW-SE trending, while the later two granite phases were exposed in E-W trending. The Ordovician granites show consistent LA-ICP-MS zircon ꜪHf(t) values from + 6.2 to + 8.3. Their corresponding Hf model ages (TDM2) from 0.9 Ga to 1.0 Ga suggest that the Ordovician granite was derived from the partial melting of ancient crustal rocks, which is related to the subduction of the Tam Ky-Phuoc Son (TKPS) ocean beneath the Truong Son belt. The Permian granites have Hf isotopic natures (ꜪHf(t)=-1.6 to 1.3, TDM2 = 1.2–1.3 Ga) of partial melting from ancient mantle components with minor Paleoproterozoic ancient continental crust The Triassic granites have negative ɛHf(t) values ranging from −11.9 to −7.0 and Hf model ages of 1.7–2.0 Ga suggesting that they were a product of partial melting from the Paleoproterozoic crust, corresponding to subduction/collision of the Paleo-Tethys ocean beneath the Indochina block along the Song Ma suture. [ABSTRACT FROM AUTHOR]

Columbite-group minerals (CGMs) have been widely used in U-Pb geochronological analysis of granite and pegmatite Nb-Ta deposits due to their high U and low common Pb characteristics. Due to the equivalent replacement of elements in the mineral structure and complex geological processes, CGMs often exhibit strong, local, and complex chemical zoning. Multiple types of composition zonation of CGMs can reflect the process of niobium-tantalum mineralization. However, the laser resolution of the currently established U-Pb methods cannot be used for in situ dating of CGMs with zonation with a width less than 20 mm. Additionally, there is no consensus on whether significant matrix effects could be observed among CGMs when nonmatrix-matched calibrations were performed. These limitations hinder the advancing understanding of niobium-tantalum differentiation and enrichment mechanisms in the formation of CGMs. In this study, we utilized the widely used geochronological reference material Coltan139 as the primary standard, established a high-resolution LA-MC-ICP-MS U-Pb analysis method using homogeneous CGM samples from the Dakalasu and Jingerquan deposits in the Altai and East Tianshan orogenic belts, Xinjiang, China. This method has a resolution of up to 10 mm. We applied this method to sample JEQ-2, which was collected from the Jingerquan Li-Be-Nb-Ta deposit and exhibited a variety of compositional zonations. Through a comparison of the ages calibrated using the ferrocolumbite Coltan139 and ferrotapiolite CT1 standards, we propose that the major matrix effect for U-Pb dating of CGMs correlates with the Ta/(Nb + Ta) ratios under small beam spot conditions. The matrix effect is likely to increase with the increase in Ta/(Nb + Ta) differences between reference materials and the samples. Furthermore, the U-Pb age results of sample JEQ-2 confirm that CGM grains with normal and oscillatory zonings are magmatic contemporaneous products. A new in-house standard material sample DKLS-27 was also reported with a reliable and stable U-Pb age for CGM U-Pb dating analysis. The 206Pb/238U weighted mean age obtained from long-term monitoring is 250.2 ± 0.3 Ma (2 s, MSWD = 0.52, n = 141). This study offers a new analysis method for the fine geochronology of rare metal deposits. [ABSTRACT FROM AUTHOR]

Late Permian to middle Triassic volcanic activities were very strong, however, volcanic records in the early Triassic strata are less reported than those of the Permo-Triassic boundary and the Triassic Olenekian-Anisian boundary in the Yangtze plate, especially within the Sichuan basin. We conduct zircon U-Pb dating and geochemical analysis of the tephra which was first found in the early Triassic Jialingjiang Formation from the Maliuping section, Hechuan, Chongqing. The volcanic ash in the paper yields the new 248.5 ± 0.7 Ma U-Pb age consistent with those of volcanic ashes in these contemporaneous strata in the Yangtze plate. Geochemical characters of whole-rock samples show lower contents in SiO2, K2O and higher components in Al2O3, CaO, MgO, relatively enriched LREE and depleted HREE with distinct negative Eu anomaly, and conspicuous Ba, Nb, Ta, Sr, P, Ti depletion and Th, U, K, Nd enrichment, which is similar to those of the Mung Bean rock of the Triassic Olenekian-Anisian boundary, and those of acidic volcanics from the Sanjiang orogenic belt and Shiwandashan-Qiangfang suture zone during the Early-Middle Triassic. Trace elements of whole rock and analysed zircons of the tuff imply its primary magma derived from Rhyodacite/Dacite and its tectonic setting of volcanic arc granite with continental crust affinity. The early Triassic volcanism during the syn-collision stage of the Paleo-Tethys evolution was less active than those of the Permo-Triassic boundary and the Triassic Olenekian-Anisian boundary, while the volcanic event may have a crucial effect on prolonging fully biotic recovery and entirely ecosystem turnover soon after the Permian-Triassic mass extinction. [ABSTRACT FROM AUTHOR]