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The paper presents the first isotopic U–Pb study data (LA–ICP–MS method) of zircon from intrusive rocks of the Molo-Sarychat pluton situated along the deep-seated fault system of the "Nikolaev Line" in the eastern Kyrgyzstan. The intrusive rocks from this pluton belong to the high-potassic calc-alkaline to shoshonitic series. Intense Mo(–W–Cu–Au) (mainly molybdenum-porphyry) mineralization is spatially and genetically associated with this pluton. Together with the other Au, W and Cu deposits and occurrences, this mineralization is part of the extended metallogenic belt of Tien Shan; however, occurrences of molybdenum-porphyry mineralization are still rare in this belt. The concordant isotopic U–Pb ages of zircon autocrysts indicate the crystallization of quartz monzonite (293.3 ± 4.2 Ma) and monzogranite (286.6 ± 2.4 Ma) in the Early Permian. Zircon antecrysts dated at 306–320 Ma are also present. The crystallization age obtained corresponds to a post-collisional epoch of the development of this territory but the presence of the antecrysts expands the pluton emplacement to the Late Carboniferous-Early Permian, which, as a result, spanned over initially subduction-related and then post-collisional tectonic settings. Correspondingly, a post-collisional setting of the Mo(–W–Cu–Au) (molybdenum-porphyry) mineralization is established; it is related to the pluton studied and was formed after the emplacement of quartz monzonite (early stage) and monzogranite (late stage). Significant enrichment in Mo can be related to its progressing accumulation during magmatic differentiation causing the emplacement of quartz monzonite and especially monzogranite. These processes occurred under the more mature post-collisional tectonic regime, with possible formation of intermediate magma chambers in the Paleoproterozoic metamorphic rocks and ancient granitoids. The age dates determined for rocks from the Molo-Sarychat pluton are similar to those identified for the igneous and metasomatic rocks of the large Kumtor gold deposit that is also associated with the "Nikolaev Line." [ABSTRACT FROM AUTHOR]

Delamination of lower continental lithosphere is known to have occurred under different tectonic settings. However, its fate in the mantle is poorly understood. By analyzing global seismic models, we find that most of likely lithosphere that delaminated during the Cenozoic and Mesozoic is preserved in the mantle transition zone, especially beneath North America and Africa. Numerical experiments indicates that delaminated lithosphere can remain stagnant in the mantle transition zone for tens of millions of years, followed by its potential sinking into the lower mantle or re‐rising to shallower depths depending on its density, the Clapeyron slope of the spinel‐to‐post‐spinel phase change and increase in mantle viscosity at ∼660–1,000 km depths. Re‐ascent occurs when delaminated lithosphere is reheated so that its effective density becomes lower than its surrounding ambient mantle after ∼100 Myr. Delaminated fragments can also potentially be mobilized by underlying global mantle flow to move horizontally away from plume regions. Plain Language Summary: The phenomenon of lower lithospheric delamination has been recognized in various tectonic settings, but the ultimate fate of these delaminated fragments within the mantle remains poorly known. From global seismic tomographic models, we gain first‐order constraints on the potential locations of geologically recent (<250 Ma) delaminated lithosphere, particularly in regions distant from subduction zones. A significant portion of Cenozoic and Mesozoic delaminated lithosphere appears to still be sequestered within the mantle transition zone, with pronounced concentrations beneath the Mesozoic and Cenozoic locations of North America and Africa. Numerical simulations further corroborate the hypothesis that these fragments of delaminated lithosphere can remain stagnant within the mantle transition zone over these geologically interesting timescales. Delaminated lithosphere can also re‐rise or move horizontally depending on underlying global mantle flow. Key Points: Seismic tomographic models provide first‐order constraints on the location of recent delaminated lithosphere in the upper and mid‐mantleDelaminated lithosphere can remain stagnant in the mantle transition zone for tens to hundreds of millions of yearsDepending on underlying mantle flow, delaminated lithosphere can also eventually warm and rise, or even move horizontally [ABSTRACT FROM AUTHOR]

The Early Paleozoic tectonic setting and geological processes of the South China Block have long been a subject of debate. This study presented zircon U-Pb geochronology and Hf isotope, and whole-rock geochemical analyses for the Early Paleozoic granitoids in the Baoshan deposit of the Dayaoshan Uplift. LA-ICP-MS zircon U-Pb results suggest that the diorites, granite porphyries, granodiorites and its mafic microgranular enclaves in the Baoshan deposit formed at 449-430 Ma. Their formation ages are consistent with those of granite, MMEs and mafic rocks found in the Dayaoshan region. The granite porphyries, granodiorites, diorites and their MMEs in the Baoshan deposit have high Eu/Eu*ratios, low Zr + Nb + Y + Ce contents, 10,000xGa/Al values, and A/CNK ratios (0.74-1.08), belonging to metaluminous to weakly peraluminous calc-alkaline I-type granitoids. Based on zircon Hf isotopic compositions (eHf(t) from -5.5 to +3.1), it is unlikely that these rocks were solely originated from a crustal source, and mantle-derived magma also played a significant role in the formation of these intrusive rocks. It is inferred that the granitoids in the Baoshan deposit were probably formed through the underplating of mantlederived magmas during a transitional collision to extension tectonic setting, which led to the remelting of Mesoproterozoic crust. [ABSTRACT FROM AUTHOR]

The paper presents first data on isotopic U–Pb study (LA-ICP-MS method) of zircon from intrusive rocks of the Adyrtor intrusions – a group of small intrusives situated in the easternmost part of the deep-seated fault system of the "Nikolaev Line." Here, these intrusions cut through one of the oldest (1.8–2.6 Ga) complexes of the basement rocks of Tien Shan (metamorphic rocks of the "Kuilyu suite"). These intrusive rocks belong to the high-potassic calc-alkaline to shoshonitic series, with some geochemical signatures also of anorogenic (A-type) magmatism. These intrusions are accompanied by 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 indicate the crystallization of quartz syenite (330.7 ± 4.3 Ma) and quartz monzonite (329.5 ± 5.8 Ma) in the latest Early Carboniferous. The distinct W–Mo specialization of ore mineralization related to the intrusions studied is in agreement with the post-collisional tectonic setting during their emplacement, despite their older or similar age compared to the ore-bearing plutons in more western segments of the Middle Tien Shan, which corresponded to a subduction-related setting. This supports the possibility of the "scissor-like" (from east to west) closure of the Turkestan paleoocean that resulted in the earlier cessation of subduction in the eastern Tien Shan compared to the western Tien Shan. The rocks also contain zircon xenocrysts with older (on the order of 1.7–2.6 Ga) age, which is in agreement with the age of the host metamorphic rocks of the Tarim craton basement. This highlights the possibility of magma chamber development in the continental crust, together with the magma chambers in the metasomatically-enriched subcontinental upper mantle, the latter being common for high-potassic magmatism. [ABSTRACT FROM AUTHOR]

This study explores the capability of amphibole in tracing the physicochemical process of magma mixing through spatially associated gabbros, mafic microgranular enclaves (MMEs) and granodiorites from central Tibet. These rocks share similar zircon ages as well as zircon Hf‐O and plagioclase Sr isotopes. However, the amphiboles within the gabbros and granodiorites have different Sr and B isotope compositions, while amphiboles with both heterogeneous isotopic imprints occur in the MMEs. According to data and modeling, significant mixing of two isotopically distinct magmas is recorded by amphibole but not by zircon and plagioclase. Based on a synthesis of petrography, geochemistry and thermobarometry, we interpret this inconsistency by the crystallization order of minerals and propose that magma mixing occurred after the parent magma was emplaced at ∼10 km and cooled to ∼750°C. Our study highlights that amphibole may be a more sensitive tracer of magma mixing relative to other commonly used methods. Plain Language Summary: Magma mixing significantly shapes the composition of silicic igneous rocks representing the major constituent of the upper continental crust. Since bulk‐rock composition may only bear the average of mixed sources, in situ techniques such as Hf‐O isotopes in zircon and Sr‐Pb isotopes in plagioclase are widely used to investigate the details of magma mixing. However, these methods cannot constrain how magma mixing operates in the deep crust. This study novelly uses in situ Sr‐B isotopes and trace elements in amphibole to trace the physicochemical process of magma mixing through spatially associated gabbros, mafic microgranular enclaves and granodiorites from the central Tibetan Plateau. Our data show that significant mixing of two isotopically distinct magmas is recorded by amphibole but not by zircon and plagioclase. We demonstrate that the amphibole geochemistry (i.e., trace element, Sr‐B isotope compositions) may be more sensitive in tracing magma mixing relative to traditional isotopic tools and has the potential to unravel the physicochemical process(es) of magma mixing in the deep crust. In addition, our work reinforces the use of B isotopes in amphibole to discern the nature (fluids released from altered oceanic crust vs. residual slab) of the slab components that metasomatized the supra‐subduction mantle. Key Points: The amphiboles in central Tibetan magmatic complex have contrasting geochemical and Sr‐B isotopic compositionsSignificant magma mixing is well recorded by amphibole but not by zircon and plagioclaseAmphibole is a more sensitive tracer of magma mixing relative to zircon and plagioclase [ABSTRACT FROM AUTHOR]

Introduction: The early Jurassic granitoids in the Qinling Orogenic Belt (QOB) play a crucial role in understanding the tectonic implications for the geological evolution of China. To elucidate the early Jurassic tectonic setting of QOB, we performed a comprehensive analysis of zircon U-Pb ages, whole-rock geochemistry, and in situ zircon Lu-Hf isotopes from early Jurassic monzodiorite and Kfeldspar granite within the Baoji batholith in western QOB. Geochronology Method and Results: The intrusions yielded zircon U-Pb ages of 186 ± 2 Ma and 188 ± 2 Ma, respectively. Geochemistry Results: The monzodiorites are characterized by relatively high MgO, Rb, Th, U, and LREE contents, as well as low P, Ti, and HREE contents. They also exhibit high Nb/Ta ratios (20.6-23.4). The zircon ε[sub Hf](t) values for the monzodiorite sample range from -4.36 to 6.47, indicating significant contributions from a fertile continental lithospheric mantle with the involvement of crustal components. The K-feldspar granites are enriched in K2O+ Na2O, Rb, Zr, Hf, and Nb, and lower Ba, Sr, Ti, and P. They exhibit high Nb/Ta and Ga/Al ratios but low Y/Nb and Yb/Ta ratios. Their geochemical characteristics reveal an A-type granite affinity with elevated zircon saturation temperatures (848°C-900 °C). Additionally, the K-feldspar granite exhibits REE and trace element patterns similar to those observed in the monzodiorite. However, a wide range of zircon εHf(t) values (-4.72 to 3.98), differing from those of the monzodiorite, indicate that the parental magma of the K-feldspar granite experienced magma mixing between a monzodioritic magma and a crustal-derived felsic magma. Discussion: These findings suggest that both A-type K-feldspar granite and monzodiorite likely formed during post-orogenic processes. Additionally, the QOB commenced its postorogenic evolution as an extensional tectonic environment during the early Jurassic period. [ABSTRACT FROM AUTHOR]

Ocean island volcanism provides a unique window into the nature of mantle composition, dynamics and evolution. The four Macaronesian archipelagos-Cape Verde, the Canaries, Madeira and the Azores-are the main magmatic systems of the Central-East Atlantic Ocean with volcanic activity that in some islands poses significant risk for the population. The recent development of regional seismic networks in these settings has provided an important step forward in mapping the underlying mantle. However, difficulties in resolving the small-scale structure with geophysical techniques persist leading to discrepancies in the interpretation of the mechanisms responsible for volcanism. Here we review results from a number of studies on the seismic mantle structure beneath the Macaronesian archipelagos including seismic tomography, receiver functions, precursors and shear-wave splitting. Several regional models show low-velocity features in the asthenosphere below the islands, a relatively thinned transition zone and complex anisotropic patterns and attribute the volcanism to mantle plumes. This inference is supported by whole-mantle tomography models, which find broad low-velocity anomalies in the lower mantle below the Central-East Atlantic. Other models call for alternative mechanisms associated with shallower mantle upwellings and purely plate tectonism. Thus, there is still no generally accepted mechanism that explains volcanism in the Macaronesia region. Future research requires improvements in the resolving power of seismic techniques to better illuminate the velocity structure at a much higher resolution than the currently achieved and ultimately define the mechanisms controlling the ocean island volcanism. [ABSTRACT FROM AUTHOR]

Omission surfaces represent a gap in the sedimentary record on a particular environment, constituting an important tool for basin analyses. Nevertheless, not always these surfaces constitute key sequence-stratigraphic surfaces, and their correct interpretation is highly important for the recognition of genetically related strata. Documentation and interpretation of ichnological data from stratigraphic surface can refine the sedimentological model. The Puesto El Moro Formation (lower Upper Cretaceous) in the Austral-Magallanes Basin, southern Patagonia (Argentina), shows excellent examples of several omission surfaces stacked during a transgressive context associated with the beginning of the foreland stage. Each of these surfaces, interpreted as Tidal Ravinement Surfaces, contain Thalassinoides isp. and Sinusichnus isp., which represent opportunistic colonization by crustaceans into a predominantly firm substrate. In this case study, the vertical recurrence of substrate-controlled trace fossil suites is the result of high-frequency repeated coastal conditions during the transgression; the associated surfaces, which have limited lateral extension, have low potential for correlation at basin scale. [ABSTRACT FROM AUTHOR]

Computed tomography (CT) is a relatively new technique in ichnofossil analysis, which permits superior identification of individual trace fossils, their morphology, infill, tiering relationships, and preservation potential, thus providing better environmental interpretations. It also allows non-professional ichnologists to interpret trace fossils in 3D slices with ease, especially in relatively homogeneous and mud-rich sediments. Herein, CT imagery results have been compared with conventional core logging results based on two push core samples from a muddy tidal flat of the Mira River estuary, Portugal. CT images provide a significantly more accurate description of cores and their environmental interpretation due to enhanced visibility of physical and biogenic sedimentary structures. They also reveal complex tiering relationships between burrows with preferential preservation of deeper tiers. The appearance of stacked Scalichnus-like and other siphonichnidal burrows made by infaunal bivalves indicates discontinuous deposition on a tidal flat likely caused by seasonally related fluctuations in an estuarine environment. [ABSTRACT FROM AUTHOR]

Background: Natural products are widely used for primary insomnia (PI). This systematic review with trial sequential analysis (TSA) aimed to summarize evidence pertaining to the effectiveness and safety of Zao Ren An Shen (ZRAS) prescription, a commercial Chinese polyherbal preparation, for treating PI. Methods: Controlled clinical trials appraising ZRAS compared to controls or as an add-on treatment were systematically searched across seven databases until January 2024. Cochrane ROB 2.0 and ROBINS-I tools were adopted to determine risk of bias. Quality of evidence was assessed using the GRADE framework. Results: We analyzed 22 studies, involving 2,142 participants. The effect of ZRAS in reducing Pittsburgh Sleep Quality Index scores was found to be comparable to benzodiazepines [MD = 0.39, 95%CI (-0.12, 0.91), p = 0.13] and superior to Z-drugs [MD = -1.31, 95%CI (-2.37, -0.24), p = 0.02]. The addition of ZRAS to hypnotics more significantly reduced polysomnographically-recorded sleep onset latency [MD = -4.44 min, 95%CI (-7.98, -0.91), p = 0.01] and number of awakenings [MD = -0.89 times, 95%CI (-1.67, -0.10), p = 0.03], and increased total sleep time [MD = 40.72 min, 95%CI (25.14, 56.30), p < 0.01], with fewer adverse events than hypnotics alone. TSA validated the robustness of these quantitative synthesis results. However, the quality of evidence ranged from very low to low. The limited data available for follow-up did not support meta-synthesis. Conclusion: While ZRAS prescription shows promising effectiveness in treating PI, the overall quality of evidence is limited. Rigorously-designed randomized control trials are warranted to confirm the short-term efficacy of ZRAS and explore its medium-to-long-term efficacy. [ABSTRACT FROM AUTHOR]

We present a novel methodology for spatially-resolved high-precision U-Pb geochronology of individual growth domains in complex zircon. Our approach utilizes a combined plasma (Xe+/Ar+) focused ion beam (PFIB)–femtosecond (fs) laser system equipped with a scanning electron microscope (SEM). This system enables micrometer resolution sampling of zircon growth domains with real-time monitoring by cathodoluminescence (CL) SEM imaging. Microsamples are then extracted, chemically abraded, dissolved and analyzed by isotope dilution thermal ionization mass spectrometry (ID-TIMS) to obtain high-precision U-Pb dates. Because of its superior beam precision (~8–20 µm diameter), cleaner cuts, and negligible, nanometer-scale damage imparted on the zircon structure, PFIB machining (30 kV) is preferred for microsamples of sizes expected in most future studies focusing on texturally complex natural zircon (20–120 µm length scales). Femtosecond laser machining is significantly faster and therefore more appropriate for larger microsamples (>120 µm length scales) but it is also coarser (≥20 µm probe size), produces rougher cuts, and creates a minimum of two orders of magnitude wider (micrometer-scale) structurally damaged zone along the laser cuts. Our experiments show that PFIB machining can be conducted on zircon coated with carbon (minor drift of ion beam during machining) and protective metal coatings (no CL signal) as neither offset the U-Pb systematics nor do they introduce trace amounts of common Pb. We used Xe+ PFIB and femtosecond laser to obtain U–Pb dates for Mud Tank and GZ7 zircon microsamples covering a range of sizes (40 × 18 × 40 µm – 100 × 80 × 70 µm) and found that microsampling does not bias the accuracy of the resulting µID-TIMS U-Pb dates. The accuracy and precision of µID-TIMS dates for zircon of any given age and U concentration depend, as for non-microsampled zircon, on Utotal/Ublank and Pb*/Pbc – both a function of sample size. Our accompanying open-source code can aid researchers in estimating the necessary microsample size needed to obtain accurate dates at precision sufficient to resolve the processes under study. µID-TIMS bridges the gap between conventional bulk-grain high-precision dating and high-spatial resolution in situ techniques, enabling the study of the timescales of a variety of processes recorded on the scale of individual growth zones in zircon. This method can be applied to zircon of any age and composition, from terrestrial systems to precious samples from other planetary bodies. [ABSTRACT FROM AUTHOR]

The late‐stage union of Pangea was associated with the convergence of Siberia with Laurussia, but the exact timing remains unclear. The orogenic duration of the Kazakhstan block can provide geochronological constraints as it connects Siberia, Baltica, and Tarim. Zircon petrochronology offers a reliable approach for ascertaining the lifespan of an ancient orogen. In this study, we explore three phases of magmatism recorded in detrital zircons from late Paleozoic and Mesozoic sandstone‐siltstones in Western Tianshan, that is, 400–470 Ma, 320–380 Ma, and 280–320 Ma. Based on their age‐propagated Hf isotopes, melt SiO2 contents, and crustal thicknesses, our findings suggest that the southern limb of Kazakhstan underwent the early Paleozoic amalgamation of microcontinents with arcs, the late Paleozoic maturation of an Andean‐like continental arc, and the late Carboniferous collision of Kazakhstan with the Junggar oceanic basin and the Tarim craton. Such characteristics manifest the long‐term orogenic progression of Kazakhstan. Combining published timelines and paleolatitudes of major orogens and blocks, we propose that the Kazakhstan block welded northeastern Pangea along with the cessation of these orogenic activities around it. Consequently, by docking Kazakhstan with surrounding cratons, the fundamental configuration of Pangea could have been established in the late Carboniferous. Plain Language Summary: Pangea was suggested to have assembled at ca. 250 Ma upon paleogeographic reconstructions. However, the assembling time remains a matter of debate due to low‐quality Permo‐Carboniferous paleomagnetic data on the northeast of Pangea; thus, other geochronological records need to be determined. Here, we employ the method of zircon petrochronology to trace the orogenic processes of Kazakhstan because it serves as a pivot in welding peripheral Siberia, Baltica, and Tarim blocks. Our results demonstrate that episodic variations in melt compositions, crustal thicknesses, and Hf isotopes reveal the long‐lived orogenic progression of the southern limb of Kazakhstan and constrain its incorporation into Pangea to the late Carboniferous. Such an event was almost contemporaneous with the assembly of Baltica and Siberia with the northern limb of Kazakhstan but occurred slightly later than the collision of Laurussia with Gondwana. As such, the fundamental configuration of Pangea could have been established in the late Carboniferous rather than the Permian, as previous paleogeographic reconstructions postulated. Key Points: Detrital zircons in Western Tianshan record three phases of Paleozoic magmatismZircon petrochronology can trace orogenic processes of the southern limb of KazakhstanDocking Kazakhstan with surrounding cratons in the late Carboniferous marked the major assembly of the northeastern Pangea [ABSTRACT FROM AUTHOR]

The amalgamation of Laurentia was initiated along the western margin of the Rae craton. However, the tectonic setting that generated magmatic rocks along this margin has long been debated, with the Thelon tectonic zone in the north having formed in an arc setting, and the Taltson magmatic zone in the south variably attributed to either continental arc or intracratonic magmatism. The magmatic rocks of the Great Slave Lake shear zone (GSLsz) lie between these two tectonic belts and, thus, may be critical to the interpretation of the evolution of the western Rae margin. To understand the origin of the rocks in the GSLsz, we have applied U‐Pb geochronology, trace‐element geochemistry, and O and Hf isotope analyses to zircons from a suite of samples that transect the La Loche River fault (LRf)—a major structure that bisects the GSLsz. Samples collected to the north of the LRf are Neoarchean in age, have mantle‐like δ18O (4.7–5.8‰) and chondritic to juvenile εHf values (0–4.5), whereas those to the south are exclusively Paleoproterozoic in age and have more elevated δ18O (6.3–7‰) and much more evolved εHf values (−12 to −6); these results indicate that the LRf marks a crustal‐scale suture between the Slave craton and the Taltson magmatic zone. Our isotopic data, together with other regional constraints from the area, are most consistent with the Taltson magmatic zone having formed in a continental arc setting emplaced into ca. 2.3 Ga juvenile basement crust. Plain Language Summary: The amalgamation of the Canadian Shield was initiated along the western margin of the Rae craton, one of the principal Archean landmasses. The rocks along the Great Slave Lake shear zone (GSLsz) are situated between the Thelon tectonic zone in the north and the Taltson magmatic zone in the south, two magmatic belts with debated tectonic histories. We use U‐Pb geochronology and oxygen and hafnium isotopes in zircon to understand the origin of rocks along GSLsz. To the north of the La Loche fault, one of the main structures within the GSLsz, rocks are Neoarchean in age with oxygen and hafnium isotopic values similar to that of the Slave craton, while those to the south are exclusively Paleoproterozoic in age with similarities to the Taltson magmatic zone. The La Loche River fault, thus, marks a significant boundary between the Slave craton and the Taltson magmatic zone. The isotope results also suggest that the Taltson magmatic zone formed in an arc setting, providing refinement to the tectonic model invoked for the formation of the Canadian Shield. Key Points: U‐Pb ages together with oxygen and hafnium isotopes are effective at characterizing the contrasting geology across major structuresThe La Loche River Fault is a crustal‐scale structure separating the Slave craton from the Taltson magmatic zoneThe geochronology and isotopic data presented herein are most consistent with the Taltson magmatic zone having formed in an arc setting [ABSTRACT FROM AUTHOR]

While basaltic volcanism is dominant during rifting and continental breakup, felsic magmatism may be a significant component of some rift margins. During International Ocean Discovery Program (IODP) Expedition 396 on the continental margin of Norway, a graphite‐garnet‐cordierite bearing dacitic unit (the Mimir dacite) was recovered in two holes within early Eocene sediments on Mimir High (Site U1570), a marginal high on the Vøring Transform Margin. Here, we present a comprehensive textural, petrological, and geochemical study of the Mimir dacite in order to assess its origin and discuss the geodynamic implications. The major mineral phases (garnet, cordierite, quartz, plagioclase, alkali feldspar) are hosted in a fresh rhyolitic, vesicular, glassy matrix that is locally mingled with sediments. The major element chemistry of garnet and cordierite, the presence of zircon inclusions with inherited cores, and thermobarometric calculations all support an upper crustal metapelitic origin. While most magma‐rich margin models favor crustal anatexis in the lower crust, thermobarometric calculations performed here show that the Mimir dacite was produced at upper‐crustal depths (<5 kbar, 18 km depth) and high temperature (750–800°C) with up to 3 wt% water content. In situ U‐Pb analyses on zircon inclusions give a magmatic crystallization age of 54.6 ± 1.1 Ma, consistent with emplacement that post‐dates the Paleocene‐Eocene Thermal Maximum. Our results suggest that the opening of the Northeast Atlantic was associated with a phase of low‐pressure, high‐temperature crustal anatexis preceding the main phase of magmatism. Plain Language Summary: Fifty‐six million years ago, the continents were beginning the final phase of their journey to their modern‐day locations. This included the rifting and formation of the Northeast Atlantic Ocean, known in particular for producing considerable magmatism during continental break‐up. In summer 2021, Expedition 396 of the International Ocean Discovery Program drilled the oceanic floor off the coast of present‐day Norway to collect volcanic and sedimentary rocks deposited at this time. Their main goal was to investigate the cause of the excess magmatism and its potential implications for the global climate. While sampling sediments on the expedition, an unexpected volcanic unit, a glassy garnet‐cordierite dacite, was recovered. To determine its origin, we combined multiple methods (petrography, stratigraphy, thermodynamic calculations, petrochronology, in situ compositional analyses) and showed that the unit is a product of melting of in the continental crust at shallow depth during the rifting process and likely later emplaced in shallow water. Our results demonstrate that the rifting process in the Northeast Atlantic included a long and intense period of continental crustal thinning. This research provides evidence needed to reconstruct the evolution of the Northeast Atlantic Ocean. Key Points: A dacitic unit was recovered in early Eocene sediments on the Vøring margin during International Ocean Discovery Program Expedition 396The Mimir dacite was formed by upper crustal anatexis at 54.6 ± 1.1 Ma, shortly after the Paleocene‐Eocene Thermal MaximumThe dacite is evidence for a break‐up phase associated with significant continental lithospheric extension [ABSTRACT FROM AUTHOR]

Syn-exhumation and post-collisional mafic magmatism in continental collision orogenic belts may provide insights into the nature of orogenic lithospheric mantle and recycled continental components in continental subduction zones. Lithium and its isotopes have emerged as potentially valuable tools for shedding light on the origin of these magmas, given the contrast Li contents and isotopic compositions between the subducting continental crust and the mantle. Here, we present high-precision Li isotopes data for representative orthogneiss, continental eclogite, syn-exhumation and post-collisional mafic magmatic rocks from the North Qaidam orogen. The syn-exhumation mafic magmatic rocks have relatively higher Li contents (26.5-50.0 ppm) and lower δ7Li values (-1.01%o-1.48%o) than those of the post-collisional mafic magmatic rocks (Li = 11.1-22.7 ppm, δ7ϋ = 1.20%-3.38%), which are comparable to those of orthogneiss and continental eclogite, respectively. Dehydration and melting modelling results show that these mafic magmatic rocks have similar Li contents and δ7Li values to the continental eclogite- and orthogneiss-derived melts but are different from their derived fluids. Monte Carlo simulation for Li-Nd isotopes suggests the syn-exhumation and post-collisional mafic rocks could be derived from an enriched mantle source that contains ~3-8% continental crustal components dominated by the orthogneiss and continental eclogite. The calculated results are consistent with the results from the previous study simulated by trace elements. Therefore, our results highlight Li isotopes as a potential tool to trace the nature of the continental crustal components recycling in continental subduction zones. [ABSTRACT FROM AUTHOR]

Runoff of terrigenous material involved in the structure of Neogene rare metal–Ti placers of the northeastern side of the Dniepr–Donets Basin (DDB) is determined using lithological and mineralogical methods including U–Pb geochronological and chemical study of detrital zircon. The peculiarities of an assemblage of accessory minerals of heavy fraction of placers, the morphology of individual grains, and the depletion of most zircons in U, Th, Y, and Yb indicate that the material was sourced from chemical weathering mantles, which probably developed after Proterozoic (70%) and Neoarchean (15%) metamorphic rocks. The presence of Paleozoic zircon crystals and a higher U, Th, Y, and Yb content are evidence of the erosion of igneous rocks of the Neoproterozoic–Early Paleozoic trap complexes and Devonian intrusive and volcanosedimentary rocks of the DDB. The involvement of clasts of the above rocks in sedimentary recycling was promoted by the evolution of abundant DDB salt tectonics. [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]

In recent years, the maximum age of sedimentation and possible sources of detritus to the sedimentary successions of the Karoo Supergroup has received a lot of interest, with various authors presenting age data from across the main Karoo Basin (MKB). Our paper aims to contribute to this ever-growing geochronological database as we report weighted mean ages for the youngest zircons as well as detrital zircon age distributions for the lower Karoo Supergroup succession sampled from the Centre of Excellence for Integrated Mineral and Energy Resource Analysis (CIMERA)- Karoo Research Initiative (KARIN) drill core KWV-1. A total of 880 near concordant zircon ages were determined using Laser Ablation Quadrupole Inductively Coupled Plasma Mass Spectrometry (LA-Q-ICP-MS) from fifteen samples representing the Dwyka Group, the Collingham-, Ripon-, Fort Brown- and Waterford formations of the Ecca Group and the Koonap Formation of the Beaufort Group as intersected by this ~2 352 m deep research borehole drilled in the southeastern sector of the basin. The weighted mean ages for the youngest zircons calculated for the formations of the Ecca- and Beaufort groups compares with findings reported by other authors and with the ages reported for tuffaceous layers associated with these units. The weighted mean ages for the youngest zircons of the Dwyka Group reflect the age of the youngest source area and do not aid in constraining the maximum age of deposition. A significant change in detrital zircon age distribution was noted between the Dwyka Group and the overlying formations of the Ecca and Beaufort groups, which we interpret as a change in provenance. The major Meso-to Neoproterozoic detrital zircon age fractions present in the Dwyka Group are attributed to source areas located towards the north and northeast of the MKB, in line with regional ice flow directions. A significant late Carboniferous to Permian detrital zircon age fraction is however observed throughout the formations of the Ecca- and Beaufort groups, with a lesser fraction of older zircon ages. The prevailing youngest age fraction reflects ages associated with magmatic source areas in the Gondwanide Orogeny located towards the south of the MKB at the time of deposition, while the recycling of deformed sedimentary strata of the Cape Supergroup contained in the Cape Fold Belt is considered the source of older detritus. The source of detritus to the MKB remained unchanged during the deposition of the respective formations of the Ecca- and Beaufort groups, despite changes in the depositional environment brough on by regional tectonics. [ABSTRACT FROM AUTHOR]

The late Archaean to early Palaeoproterozoic strata of the Transvaal Supergroup of southern Africa is renowned for hosting geological units that preserve some the Earth's most significant geological events. The glaciogenic Makganyene Formation is one such significant unit, given that it has been associated with the Snowball Earth Event. The maximum age of deposition of this formation, and subsequent timing of this event, has come into question, mostly because of concordant detrital zircon ages as young as ~2.2 Ga reported by Beukes et al. (2013). These ages are younger than the recently revised ca. 2.43 Ga baddeleyite age inferred for the overlying Ongeluk Formation and subsequently led to a significant revision of a long-held correlation between the upper Postmasburg- and Pretoria groups of the respective sub-basins of the Transvaal Supergroup. The primary objective of this study is to investigate the mode of occurrence of the ~2.2 Ga zircons in the Makganyene Formation as well as selected formations of the underlying Koegas Subgroup. Here, we report a total of 183 near concordant U-Pb zircon ages for the Koegas Subgroup (Pannetjie- and Naragas formations) and 967 such ages for the Makganyene Formation, extracted from seventeen samples from across the outcrop area for these units. Sensitive High Resolution Ion MicroProbe (SHRIMP) as well as three different Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) techniques were used for U-Pb age measurements. We assessed the quality of the respective data sets and possible shortcomings of the techniques to constrain the maximum age of deposition of the units and to infer possible source areas for the detritus. In contrast to zircon ages determined for the Koegas Subgroup, zircons younger than ~2.4 Ga are a prominent feature of the Makganyene Formation. Upon careful consideration of each data set, we concluded that these so-called young grains have likely suffered significant Pb-loss and that a possible overcorrection for common Pb during data reduction could not be ruled out. Although the age distribution generated using the respective techniques were comparable, none of the four techniques were successful in shedding light on the reliability of the ~2.2 Ga ages. The maximum age of deposition of the Makganyene Formation could not be constrained with confidence and therefore the revised correlation between the Postmasburg- and Pretoria groups is not contested. The detrital zircon age distribution of the Koegas-Makganyene succession was however found to be remarkably similar, with a major ~2.5 Ga age fraction and subordinate fractions at ~2.65 to ~2.9 Ga and older than ~3.0 Ga. The major ~2.5 Ga zircon age fraction points towards a prominent, likely orogenic source of detritus. We assign the origin of the major ~2.5 Ga and older zircon age fractions to a Rae-type craton, which we proposed to have been attached to the north of the Vaalbara Craton at time of deposition of these units and consider a tectono-magmatic event characteristically associated with this family of cratons as the possible cause of alteration and Pb-loss in zircon grains dated at ~2.2 Ga. [ABSTRACT FROM AUTHOR]

The widespread High Arctic Large Igneous Province (HALIP) exhibits prolonged melting over more than 50 Myr, an observation that is difficult to reconcile with the classic view that large igneous provinces (LIPs) originate from melting in plume heads. Hence, the suggested plume‐related origin and classification of HALIP as a LIP have been questioned. Here, we use numerical models that include melting and melt migration to investigate a rising plume interacting with lithosphere of variable thickness, that is, a basin‐to‐craton setting applicable to the Arctic. Models reveal that melt migration introduces significant spatial and temporal variations in melt volumes and pulses of melt production, including protracted melting for at least about 30–40 Myr, because of the dynamic feedback between migrating melt and local lithosphere thinning. For HALIP, plume material deflected from underneath the Greenland craton can re‐activate melting zones below the previously plume‐influenced Sverdrup Basin after a melt‐free period of about 10–15 Myr, even though the plume is already ∼500 km away. Hence, actively melting zones do not necessarily represent the location of the deeper plume stem at a given time, especially for secondary pulses. Additional processes such as (minor) plume flux variations or local lithospheric extension may alter the timing and volume of HALIP pulses, but are to first order not required to reproduce the long‐lived and multi‐pulse magmatism of HALIP. Since melting zones are always plume‐fed, we would expect HALIP magmatism to exhibit plume‐related trace element signatures throughout time, potentially shifting from mostly tholeiitic toward more alkalic compositions. Plain Language Summary: Typically, the arrival of a large mantle upwelling ("mantle plume") is expected to cause catastrophic large‐scale volcanism that lasts a few million years. However, a massive past volcanic event now distributed onshore and offshore across the Arctic (the High Arctic Large Igneous Province—HALIP) defies this definition. This wide‐spread magmatism exhibits dates spanning more than 50 Myr, with several pulses of activity. Based on this prolonged magmatism, it has been questioned whether all of it can be attributed to a mantle plume, despite the geochemistry of basalts indicating a plume source. Here, we show that a plume can cause prolonged and multi‐pulse magmatism if it interacts with an increase in lithosphere thickness. Once the plume moves below the thicker lithosphere, hot plume material is channeled along the base of the lithosphere toward the adjacent thinner part, where it can reactivate previous melting regions. At this time, the active plume can be about 500 km away from the melting region, hence plume‐related melt cannot be used as a proxy for the plume position at the given time. Based on the models, we suggest that the prolonged HALIP magmatism was caused by a plume interacting with the edge of a craton. Key Points: Mantle plumes interacting with changes in lithosphere thickness at craton edges can cause prolonged melting with pulses in the same regionRejuvenated melting happens underneath previously melt‐affected thinned lithosphere several hundred km downstream of the plume stemThe timing and duration of rejuvenated melting in models correspond to and therefore may explain observations of magmatic pulses from High Arctic Large Igneous Province [ABSTRACT FROM AUTHOR]

Sedimentary basins are valuable archives of tectonic processes involved in continental rifting. The northern Rocky Mountains preserve the Belt Supergroup, one of the most complete records of Mesoproterozoic strata on Earth; however, debate remains about its tectonic origin. We investigated a recently identified package of Mesoproterozoic strata at Leaton Gulch near Challis, Idaho, using a combination of traditional and newer sedimentological tools. Results suggest that the Leaton Gulch stratigraphic section was deposited in a fluvial setting ca. 1,380–1,317 Ma, spanning the poorly documented interval between late Belt Supergroup deposition at ∼1,370 Ma and recently characterized Deer Trail Group strata that are less than 1,300 Ma. Detrital zircon age distributions from Leaton Gulch demonstrate a similar provenance signature to Missoula Group rocks of the upper Belt Supergroup; however, Leaton Gulch strata are up to ∼70 Ma younger than most prior age constraints on Belt Supergroup rocks. Regional metabentonites (interpreted as metamorphosed reworked tuffs) found within Leaton Gulch and Missoula Group strata show dominantly radiogenic εHf(t), with a range of −8 to +15, interpreted as a mix of primary mantle and remelted metasedimentary sources. Zircon trace element data of the metabentonite from Leaton Gulch suggest a 1,450–1,300 Ma geochemically consistent and moderate–high silica melt source. Collectively, the strata of Leaton Gulch record basin sedimentation during a critical window of Mesoproterozoic time. We speculate that sedimentation during late‐stage Belt Supergroup deposition thickened and stepped westward, abandoning the main Belt basin, culminating with breakup of the Nuna Supercontinent. Plain Language Summary: Sedimentary basins serve as important records of continental breakup. One of the most complete basin records in North America is the 1470–1370 million year old Belt Supergroup, but its tectonic origin is still poorly understood. We investigated recently identified Mesoproterozoic sedimentary rocks near Challis, Idaho. By measuring the sedimentary rocks and determining the age and chemistry of detrital (transported as ancient sediments) zircons within them, we conclude that the rocks at Leaton Gulch were deposited in a river setting between 1380 and 1317 million years ago. Leaton Gulch rocks therefore span a poorly documented interval between the Belt Supergroup and younger (∼1,300 Ma) Mesoproterozoic rocks of the Deer Trail Group preserved in eastern Washington. Detrital zircons from Leaton Gulch rocks record a sediment provenance similar to that of upper Belt Supergroup rocks. Regionally distributed metabentonites (ancient volcanic ash), found both at Leaton Gulch and in Belt Supergroup rocks, have chemical signatures consistent with continental rifting. Leaton Gulch rocks therefore record the sedimentation and rifting after deposition of the Belt Supergroup predicted by paleogeographic reconstructions. Late‐stage Belt Supergroup rocks thickened and stepped westward through time, ultimately abandoning the main Belt basin, culminating with the breakup of one of Earth's earliest supercontinents, Nuna. Key Points: Fluvial deposition occurred <1,380–1,317 Ma between Belt Supergroup deposition and late‐stage breakup of the Nuna supercontinentLeaton Gulch strata record continued sediment sourcing from the Belt Supergroup or local recycling of Belt Supergroup sedimentary rocksTiming of deposition and detrital zircon results are consistent with westward stepping of rifting after deposition of the Belt Supergroup [ABSTRACT FROM AUTHOR]

The siliciclastics make the major part of the Proterozoic Kumaun Lesser Himalaya region. These share similar appearance, sedimentology, and petrography. In the absence of fossils and any other age constraint, these are named differently in literature, i.e., Nagthat, Bhowali, Lariakantha, and Berinag quartzites, based on their locality, sedimentological and petrographical characteristics. Their stratal disposition and their regional correlation are always debatable. The present work addresses the stratal disposition of these Proterozoic siliciclastics using the detrital zircon (DZ) U–Pb geochronology. The study suggests that the siliciclastics of Bhowali, Lariakantha, Nagthat and Berinag in the Kumaun region are equivalent and show the maximum depositional age (MDA) of ~1850 Ma. However, the Nagthat Formation in Garhwal Lesser Himalaya has a Neoproterozoic DZ depositional age (~850 Ma) and is a different identity. This study suggests that in the Kumaun Lesser region (inner and outer), only Palaeoproterozoic siliciclastic is present. Also, they can be grouped under Berinag with its implications about the inner and outer Lesser Himalayan division and the relationship with younger strata of Blaini Formation. Research highlights: U-Pb Detrital zircon geochronology from siliciclastics, Kumaun Lesser Himalaya (inner and outer) region Only Palaeoproterozoic detrital zircon ages for Kumaun Lesser region (both inner (ILH) and outer (OLH)) Continuous Paleoproterozoic sedimentation in a single basin [ABSTRACT FROM AUTHOR]

The opening of oceans within accretionary orogens is important for understanding the Wilson cycle. The Mongol–Okhotsk Ocean (MOO) began opening within the early Paleozoic accretionary collage of the Central Asian Orogenic Belt (CAOB), representing a world‐class example to constrain the geodynamic history of ocean opening in accretionary orogens, but the kinematics and mechanisms associated to this process are highly debated. We report on a newly‐discovered bimodal volcanic suite and associated volcanic‐sediments that comprise part of the Altay‐Sayan Rift System, which indicate a widespread Early Devonian extensional event within the CAOB. This extension regime is attributed to a Devonian mantle plume, which is thought to have impinged upon and weakened the lithosphere of the Early Paleozoic collage, and drove the opening of the MOO. Opening of the MOO suggests continent breakup in accretionary orogens tends to focus along intervening weak orogenic lithosphere between the rigid microcontinents. Plain Language Summary: The opening of oceans within subduction related accretionary orogens is a process that is common within the geologic record. The tectonic mechanisms involved in this process, however, are not well understood. The Mongol–Okhotsk Ocean began opening within the Early Paleozoic accretionary collage of the Central Asian Orogenic Belt, providing an opportunity to constrain the geodynamic history of ocean opening in accretionary orogens, but the kinematics and mechanisms related to this process are highly debated. We report on newly‐discovered bimodal volcanic suite (410–415 Ma) and associated volcanic‐sedimentary rocks in Northwest Mongolia, which comprise part of the Altay‐Sayan Rift System (also termed Altay‐Sayan Large Igneous Province). This giant rift system represents a widespread Early Devonian extensional event associated with a mantle plume. The ascent of this mantle plume is thought to have impacted and weakened the lithosphere of northern Early Paleozoic collage, ultimately leading to the opening of the Mongol‐Okhotsk Ocean between microcontinents that had earlier accreted to Siberia Craton. Our model suggests continent breakup in accretionary orogens tends to focus along weak orogenic lithosphere between the rigid microcontinents. Key Points: The 415–410 Ma bimodal volcanic suite and associated volcanic‐sediments document a widespread extension regime related to a mantle plumeThe Devonian mantle plume weakened structures within the accretionary orogen and led to the opening of the Mongol‐Okhotsk OceanContinent breakup in accretionary orogens tends to happen along weak orogenic lithosphere between rigid microcontinents [ABSTRACT FROM AUTHOR]

The paper presents isotopic U–Pb zircon data (LA-ICP-MS method) for the main types of high-potassic intrusive rocks of the Chorukh-Dairon W–Mo(–Cu–Au) skarn deposit situated in the Kurama segment of the Middle Tien Shan near the largest porphyry Cu–Mo–Au deposits of the Almalyk mineralized cluster. Together with the other Au, W, Mo and Cu deposits, all these deposits are parts of the extended Late Paleozoic metallogenic belt of Tien Shan. The concordant isotopic U–Pb zircon data obtained for the rocks of successive intrusion phases in the Chorukh-Dairon pluton span from about 298 Ma to 290 Ma. This interval included crystallization of monzodiorite (295.1 ± 3.3 Ma), quartz syenite (294.7 ± 2.3 Ma), quartz monzonite (294.1 ± 2.1 Ma), and monzogranite (293.0 ± 3.0 Ma). These dates correspond to the pluton emplacement at the Late Carboniferous-Early Permian boundary and highlight its younger age compared to the productive high-potassic intrusions of the porphyry Cu–Mo–Au deposits in the Almalyk mineralized cluster, the latter assigned to the Late Carboniferous (about 337–313 Ma and partially to 308–297 Ma). By contrast to the latter, which were intruded in the subduction-related environment, the emplacement of the high-potassic rock of the Chorukh-Dairon pluton occurred in the transitional subduction-related to post-collisional environment or even under an actual post-collisional regime. This allows distinguishing two pulses of ore-bearing Carboniferous-Permian high-potassic calc-alkaline to shoshonitic series magmatism in the Middle Tien Shan. Consistently, there is a metallogenic evolution in the region that was expressed in the transition from porphyry Cu–Mo–Au deposits associated with subduction-related potassic magmatism, and likely evolving toward epithermal Au-Ag deposits, to essentially tungsten (W–Mo–Cu–Au) deposits associated with younger potassic magmatism occurring rather in the post-collisional environment. [ABSTRACT FROM AUTHOR]

The increase in initial Hf isotopes identified in early Mesoarchean detrital zircon is commonly interpreted as a reflection of the geodynamic transition from stagnant‐lid to mobile‐lid tectonics. However, given the lack of petrogenetic context, interpreting detrital zircon may lead to spurious conclusions. In this contribution, we use zircon U‐Pb‐Hf‐O isotopic and bulk rock compositions of newly identified 3.05–2.9 Ga granitoids from the SW Yangtze Block to posit petrogenesis within an isotopically juvenile magmatic system. A statistical analysis of these data with a global igneous zircon Lu‐Hf isotopic compilation reveals an increase in average initial radiogenic Hf isotopes during the Paleoarchean to Mesoarchean transition. We posit that the Earth's continental crust underwent a global rejuvenation across the Paleo‐Mesoarchean transition. This rejuvenation can be explained by an independently observed increase in mantle temperatures resulting from mantle thermal evolution and does not require a change in tectonic style. Plain Language Summary: In this study, we explore the Earth's continental crust evolution before 3.0 billion years ago, a period characterized by limited preserved ancient rocks. We focus on zircon from igneous rocks, which provides a more reliable petrogenetic record than detrital zircon. Our study challenges the widely observed increase in detrital zircon initial Hf isotopes during the Paleo‐to Mesoarchean transition, often interpreted as a shift in tectonic regimes. We present new data from 3.05 to 2.9 billion‐year‐old granitoids in the Yangtze Block, suggesting isotopically juvenile magmatic activity. Statistical analysis of a global database of igneous zircon Hf isotopes reveals a state‐shift increase in εHf(t) across the Paleo‐to Mesoarchean transition, indicating global crustal rejuvenation at that time. Contrary to prevailing theories, we propose that this rejuvenation can be attributed to elevated mantle temperatures, challenging the notion of a significant geodynamic change during this period. Our findings emphasize the need to consider mantle thermal evolution in understanding continental crust growth on early Earth. Key Points: 3.05 and 2.9 Ga granitoids derived from juvenile crust are identified in the SW Yangtze BlockGlobal crust rejuvenation occurred across the Paleo‐to Mesoarchean transitionThis period of rejuvenation resulted from the effects of peak mantle temperatures [ABSTRACT FROM AUTHOR]

It was recognized that two magmatic belts in the Lhasa‐Tengchong terrane formed due to the Mesozoic‐Cenozoic Tethyan evolution. Still, their spatiotemporal variations of magmatic flare‐ups/lulls are rarely discussed. Here we use the new U‐Pb and Lu‐Hf isotopic data of captured zircons and a comprehensive data set to show that the flare‐up of northern magmatic belt has peak ages of 110 Ma in central and northern Lhasa and 120 Ma in eastern Tengchong, possibly related to the tectonic transition from Meso‐ and Neo‐Tethyan double subduction to Neo‐Tethyan single subduction. For the southern magmatic belt, the flare‐ups at 100–85 Ma and 65–45 Ma in eastern southern Lhasa indicate obvious juvenile crustal growth, while flare‐ups at 75–45 Ma in western southern Lhasa and Tengchong record ancient crustal reworking. Such flare‐up variations in the southern magmatic belt possibly resulted from asynchronous changes in the Neo‐Tethyan slab dip. Plain Language Summary: The Tethyan slab subduction and following collision of India and Asia produced two magmatic belts in the Lhasa‐Tengchong terrane. How did the magmatic flare‐ups or high‐flux episodes and sources spatiotemporally vary? We combine the new U‐Pb and Lu‐Hf isotopic data of captured zircons (xenocrystic zircons caught by volcanics from country rocks) and a comprehensive data set to show that the peak ages of early Cretaceous flare‐up of the northern magmatic belt are ca.10 Ma younger in central and northern Lhasa than in eastern Tengchong, possibly related to the diachronous closure of the Meso‐Tethys and flat subduction of the Neo‐Tethys. The southern magmatic belt in Tengchong and western southern Lhasa exhibit 75–45 Ma flare‐ups featured by the reworking of ancient crust, different from the eastern southern Lhasa with the flare‐ups at 100–85 Ma and 65–45 Ma which are dominated by the juvenile crustal growth. Such flare‐up variations may be related to changes of the Neo‐Tethyan slab dip. Key Points: The Neo‐Tethyan arc has asynchronous magmatic flare‐ups and diverse magmatic sourcesThe spatiotemporal changes of slab dip triggered the asynchronous flare‐ups of the Neo‐Tethyan arc [ABSTRACT FROM AUTHOR]

Objective: Our study provides an innovative approach to exploring herbal formulas that contribute to the promotion of sustainability and biodiversity conservation. We employ data mining, integrating keyword extraction, association rules, and LSTM-based generative models to analyze classical Traditional Chinese Medicine (TCM) texts. We systematically decode classical Chinese medical literature, conduct statistical analyses, and link these historical texts with modern pharmacogenomic references to explore potential alternatives. Methods: We present a novel iterative keyword extraction approach for discerning diverse herbs in historical TCM texts from the Pu-Ji Fang copies. Utilizing association rules, we uncover previously unexplored herb pairs. To bridge classical TCM herbal pairs with modern genetic relationships, we conduct gene-herb searches in PubMed and statistically validate this genetic literature as supporting evidence. We have expanded on the present work by developing a generative language model for suggesting innovative TCM formulations based on textual herb combinations. Results: We collected associations with 7,664 PubMed cross-search entries for gene-herb and 934 for Shenqifuzheng Injection as a positive control. We analyzed 16,384 keyword combinations from Pu-Ji Fang's 426 volumes, employing statistical methods to probe gene-herb associations, focusing on examining differences among the target genes and Pu-Ji Fang herbs. Conclusion: Analyzing Pu-Ji Fang reveals a historical focus on flavor over medicinal aspects in TCM. We extend our work on developing a generative model from classical textual keywords to rapidly produces novel herbal compositions or TCM formulations. This integrated approach enhances our comprehension of TCM by merging ancient text analysis, modern genetic research, and generative modeling. [ABSTRACT FROM AUTHOR]

The paper presents the first data on PGE sulfide and selenide mineralization formed in podiform chromitites at different stages of evolution of the Dunzhugur ophiolite massif. The chromite bodies are localized in listvenitized aposerpentinites, which are part of the Dunzhugur ophiolite complex. The forms of occurrence, microstructural features and compositions of platinum-group minerals in chromitites were studied by scanning electron microscopy. The enrichment of chromitites with a refractory platinum group-element (PGE) sulfides and alloys in the Os–Ir–Ru system (IPGE) testify that the formation of magmatic platinum-group minerals (PGMs) occurred under mantle conditions. Primary PGMs were replaced by iridium sulfoarsenides and sulfoantimonides due to the interaction of mantle peridotites and chromitites with As–Sb-bearing fluid generated during dehydration and melting of the subducting slab. Native osmium was formed as a result of desulfurization of magmatic PGE-bearing sulfides with the participation of reduced fluids at the serpentinization stage. The replacement of Ru–Os sulfides by selenides of these metals in chromitites could occur at the stages of subduction or obduction at high oxygen fugacity under the influence of acid hydrothermal/metamorphogenic fluids. A qualitative assessment of physicochemical parameters of the formation of ruthenium selenides was carried out. Oxygen fugacity values estimated from the magnetite–hematite association are log fO2 (–30.5) at 300°C and log fO2 (–40.5) at 200°C. The minimum sulfur fugacity value was determined by the stability line of laurite at 300°C, log fS2 = –20; the maximum sulfur fugacity values—by the stability line of iron and nickel sulfides: log fS2 < –4.5 at 300°C and log fS2 < –10.5 at 200°C. The selenium fugacity at T = 300°C is log fSe2 (–8...–13); at T = 200°C, log fSe2 (–12...–17). Au–Ag selenides were formed at T = 200°C, log fS2 (–9...–10.5); log fSe2 is from –13.5 to –20.5, log fO2 (–40). An important factor for the possibility of replacement of Ru–Os sulfides by selenides is Se occurrence in the ore-forming system. The source of Se may be the substance of the subducting slab—volcanogenic–sedimentary rocks containing fragments of Se-rich hydrothermal–sedimentary sulfide ores. They were involved in the processes of magma genesis and accompanying hydrothermal circulation. [ABSTRACT FROM AUTHOR]

The data of chemical composition and content of trace elements in alkaline-ultrabasic rocks of the northwestern region of the Ukrainian Shield are summarized. The occurrences of alkaline rocks of this composition were discovered as results of drilling in four areas (Horodnytsa, Hlumcha, Bolyarka, Hubkiv). They are presented by small hypabyssal intrusions, stock- and dike-like bodies. The rocks are represented by the jacupirangite-melteigite series, which belong to high-Mg (Mg# 0.7-0.8) varieties. Less common are alkaline and subalkaline gabbroids found in thin apophyses and veins near alkaline-ultrabasic bodies. It is assumed that these gabbroids were formed as a result of crust material contamination of the primary alkaline-ultrabasic melts. The alkaline-ultrabasic rocks of all occurrences have high Cr (233-2737 ppm) and Ni (95-1022 ppm), but are unusually depleted in incompatible elements (Nb, Ta, Zr, Hf, REE, Y), with moderate Ba and Sr. Their geochemical features sharply differ from similar rocks, carbonatite and alkaline complexes known as in the Ukrainian Shield and other regions of the world . Despite the primitive composition of alkaline-ultrabasic rocks and anomalous REE depletion, their chondrite-normalized patterns have negative slopes and are similar to differentiated rocks with a prevailing of LREE (La/Yb = 6-16). The petrogenesis of such primitive and trace-element depleted alkaline-ultrabasic rocks is enigmatic . We suppose that these unusual geochemical features are the result of primary melt(s) generation from mantle source and their evolution by a similar way. For the alkaline rocks of the Horodnytsa, Hlumcha intrusions, and possibly the Hubkiv occurrence, the primary melts arose through partial melting of garnet (with amphibole?) peridotites. At the same time, the primary melt for the Bolyarka intrusion was generated by partial melting of spinel peridotite, probably in a shallower environment. The anomalous depletion at HFSE and REE can be considered as the result of specific conditions of partial melting of depleted mantle source at low temperature and pressure, when refractory minerals concentrating these elements (rutile, amphibole) remained in the restite, or due to early crystallization and fractionation of concentrating minerals (perovskite, apatite). [ABSTRACT FROM AUTHOR]

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Granitic batholiths of the ∼500 Ma Ross Orogen in Antarctica are voluminous in scale, reflecting prolific magmatism along the active early Paleozoic convergent margin of Gondwana. New age and isotopic analysis of zircons from a large suite of Ross granitoids spanning >2,000 km along the orogen provide a wealth of geochronologic, tracer, and inheritance information, enabling us to investigate the pace of magmatism, along‐strike temporal and geochemical trends, magmatic sources, and tectonic modes of convergence. Because granitoids penetrate the crust of the earlier Neoproterozoic rift margin, they also provide insight into the age and composition of the largely ice‐covered East Antarctic craton. Zircon U‐Pb ages from these and other samples indicate that active Ross magmatism spanned 475–590 Ma, much longer than generally regarded. Most samples have heavy zircon δ18O values between 6.5 and 11.5‰ and initial εHf compositions between 0 and −15; their isotopic co‐variations are independent of age, as in other contemporary continental arcs, and reflect largely crustal melt sources. Samples near Shackleton Glacier have distinctly more mantle‐like isotope composition (i.e., radiogenic εHf and low δ18O) and separate two regions with distinctive isotopic properties and inheritance patterns—a more juvenile section of Mesoproterozoic crust underlying the southern TAM and an older, more evolved region of Paleoproterozoic and Archean crust in the central TAM. The isotopic discontinuity separating these regions indicates the presence of a cryptic crustal boundary of Grenvillian or younger age within the East Antarctic shield that may be traceable into the western Laurentian part of the Rodinia supercontinent. Plain Language Summary: Isotopic information obtained from granitic rocks formed during subduction‐zone convergence can help distinguish mantle and crustal sources of melting, evaluate the processes leading to chemical changes in the magmas, and reveal information about the age and composition of rocks in the upper plate. The Neoproterozoic to early Paleozoic Ross Orogen in Antarctica is a significant part of the active Gondwana‐margin convergent plate boundary stretching from present‐day eastern Australia to Argentina, but it is largely obscured by ice and younger sedimentary cover. The Ross Orogen hosts a prolific and widespread continental‐margin magmatic arc dominated by granitoid intrusions that serve as geochemical "samplers" of upper‐plate rocks with which they interact. We report U‐Pb ages and O‐Hf isotopic compositions in zircons from nearly 40 samples of Ross Orogen granitoids covering a large section of the modern Transantarctic Mountains that reveal patterns in magmatism best explained by variations in composition of the cratonic upper plate. They thus help to identify an otherwise hidden lithospheric boundary separating a region of juvenile Mesoproterozoic crust from evolved Paleoproterozoic and Archean crust that may represent a tectonic suture formed during Rodinia amalgamation. Key Points: Subduction‐related granites are effective geochemical samplers of the upper plate lithosphereU‐Pb, O and Hf isotope data from zircons in Ross Orogen granitoids reveal variations in age and magma sourcesContrasting magma compositions distinguish the East Antarctic upper‐plate lithosphere and reveal key boundaries related to Rodinia assembly [ABSTRACT FROM AUTHOR]

The ancient stable continents are up to 250 km deep, with roots extending into the diamond stability field 1 . These cratons owe their mechanical strength to being cool and rigid 2 , features inherited from extensive melt extraction 1,3 . The most prominent model for craton formation anticipates dominant melting at relatively shallow depth (50-100 km) above diamond stability 4-7 , followed by later imbrication to form the deeper roots 8,9 . Here we present results from thermodynamic and geochemical modelling of melting at sufficiently high temperatures to produce the very magnesian olivine of cratonic roots 10 . The new closed-system and open-system modelling reproduces the observed cratonic mantle mineral compositions by deep (about 200 km) and very hot melting (≥1,800 °C), obviating the need for shallow melting and stacking. The modelled highly magnesian liquids (komatiites) evolve to Al-enriched and Ti-depleted forms, as observed in the greenstone belts at the fossil surface of cratons 11 . The paucity of Ti-depleted komatiite 12 implies that advanced closed-system isochemical melting (>1,825 °C) was much less common than open-system interaction between deeper liquids and melting of existing refractory mantle. The highly refractory compositions of diamond inclusion minerals could imply preferential diamond growth in the more reducing parts of the cratonic root, depleted by ultra-hot melting in response to heat plumes from a deeper former boundary layer that vanished at the end of the Archaean 13 ., (© 2023. The Author(s), under exclusive licence to Springer Nature Limited.)

Metasomatized mantle xenoliths containing hydrous minerals, such as amphiboles, serpentine, and phlogopite, likely represent the potential mineralogical compositions of the metasomatized upper mantle, where low seismic velocities are commonly observed. This study presents the first experimentally determined single‐crystal elasticity model of an Fe‐free near Ca, Mg‐endmember amphibole tremolite at high pressure and/or temperature conditions (maximum pressure 7.3(1) GPa, maximum temperature 700 K) using Brillouin spectroscopy. We found that sound velocities of amphiboles strongly depend on the Fe content. We then calculated the sound velocities of 441 hydrous‐mineral‐bearing mantle xenoliths collected around the globe, and quantitatively evaluated the roles that amphiboles, phlogopite and serpentine played in producing the low velocity anomalies in the metasomatized upper mantle. Plain Language Summary: Amphiboles are the most widely distributed hydrous minerals resulting from metasomatism in the upper most mantle. We measured sound velocities of tremolite (Ca, Mg endmember of the amphibole series) at high pressures and high temperatures by Brillouin spectroscopy. Based on global hydrous‐mineral‐bearing mantle xenoliths record, we quantitively evaluated the contributions of amphiboles, serpentine, and phlogopite to low velocity anomalies and water storage in the upper most mantle. We found the existence of hydrous minerals (amphiboles, serpentine, and phlogopite) remains a viable explanation for the low velocity anomalies in the upper most mantle (e.g., mid‐lithosphere discontinuity). Compared to serpentine and phlogopite, although the amount of velocity reduction caused by amphibolization is moderate, the formation of amphiboles does not require K, Al, Si‐rich environments like phlogopite, or exceedingly water‐rich environments like serpentine. Key Points: The single‐crystal elasticity of tremolite is determined by Brillouin spectroscopy up to 7.3 GPa and 700 KSound velocities of uppermost mantle amphiboles mainly depend on Fe contentHydrous minerals (amphiboles, serpentine, phlogopite) are plausible causes of the low velocity anomalies in the uppermost mantle [ABSTRACT FROM AUTHOR]

A promising primary reference material for U-Pb LA-ICP-MS carbonate dating is analysed and reported here. The new RM is a botryoidal cement (C1) from sample RA138. The sample was collected in outcrop strata of mid-Carboniferous (Uppermost Mississippian, upper Serpukhovian) in northern Spain near La Robla, and multiple aliquots have been meticulously prepared for distribution. The RA138 is characterised by variable U/Pb ratios (from ~1 to ~19) and a relatively high and homogeneous U content (~4 ppm). This material exhibits a low age uncertainty (0.2 %, 2s; unanchored, ID-TIMS), allowing for the establishment of a well-defined isochron, particularly when anchored to the initial Pb ratio using LA-ICP-MS. ID-TIMS analyses of micro drilled C1 cement (17 sub-samples) produce a lower intercept age of 321.99 ± 0.65 Ma, an initial 207Pb/206Pb ratio of 0.8495 ± 0.0065, and a Mean Square of Weighted Deviations (MSWD) of 5.1. The systematic uncertainty of 1.5 % observed in repeated LA-ICP-MS analyses challenges previous estimations of 2–2.5 % based on repeated analyses of ASH-15D and JT using WC-1 as primary reference material, underscoring the precision and reliability of RA138 for U-Pb dating applications. [ABSTRACT FROM AUTHOR]

Background. It is currently considered that around 30% of chronic pain patients are totally refractory to medical treatment. Among patients who remain responsive to medical treatment, it is estimated that between 20% and 50% are likely to discontinue treatment due to severe side effects. Given these therapeutic difficulties, a significant number of patients turn to complementary therapies. Objective. The LineQuartz® is a medical device that combines 3 complementary therapies, namely, music therapy, light therapy, and chromotherapy. We propose to evaluate its effectiveness in chronic pain patients. Methods. Between October 2021 and October 2022, 44 patients aged between 23 and 85 years (mean: 55.4 years) were included in a prospective study. All patients had background pain intensity greater than 4/10 on the Numerical Pain Scale (NS). Treatment consisted of 4 half-hour sessions, divided into one session per week for 3 weeks (21 days). Patients were assessed by the Brief Pain Inventory (BPI) and the Hospital Anxiety and Depression scale (HAD) the day before starting treatment (Day 0) and the day after the end of treatment (Day 22). Results. Apart from the BPI item, "relationship with others," all items improved significantly (p < 0.050). Background pain intensity (NS) and frequency of painful attacks improved very significantly (p < 0.001). The HAD anxiety subscore was also significantly improved (p < 0.001). Discussion. This open pilot study supports the idea that LineQuartz® has a place among complementary therapies dedicated to the treatment of chronic pain. However, these results need to be confirmed by a controlled study. [ABSTRACT FROM AUTHOR]

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The possibility that the Proto‐Tethys Ocean may have undergone intra‐oceanic subduction during ocean closure remains poorly constrained due to a lack of geological evidence for a mature intra‐oceanic arc. Here we present new geochemical and geochronological data for potential arc‐related volcanic rocks adjacent to the accretionary complex and forearc basin in the North Qaidam collisional belt, northern Tibetan Plateau. The volcanic rocks are dominated by foliated basalt, andesite, tuff, and minor dacite with zircon U‐Pb ages ranging from 517 to 497 Ma. They show distinctive geochemical characteristics and can be subdivided into three groups: island‐arc intermediate‐basic volcanic rocks, back‐arc basin basalts (BABB), and dacites with intra‐oceanic arc affinity. The island‐arc volcanic rocks have variable εNd(t) values (+1.6 to +7.5) that decrease northward and were generated by partial melting of depleted mantle wedge modified by hydrous fluid and sediment melt. The BABBs have high εNd(t) values (+5.3 to +6.6) and formed through the melting of MORB‐like mantle, whereas the nearby dacites have positive εNd(t) values (+1.9 to +3.6) similar to the surrounding island‐arc volcanic rocks and were derived from partial melting of intra‐oceanic arc crust as a result of BABB underplating. Integrated analysis of the spatial‐temporal distribution of these volcanic rocks and the reconstructed intra‐oceanic arc‐trench system confirms the existence of the earliest Phanerozoic intra‐oceanic arc formed in response to north‐directed intra‐oceanic subduction. This unrecognized subduction of the Proto‐Tethys Ocean in the North Qaidam belt initiated at ca. 530 Ma, matured ca. 520 Ma, and terminated by ca. 480 Ma. Plain Language Summary: Closure of an ocean basin is achieved through subduction of oceanic lithosphere at a continental margin or in an intra‐oceanic setting. Identification and structure of subduction‐related magmatic rocks are critical for fully understanding the complex processes associated with ocean closure and the paleotectonic framework. Geological mapping and geochemical analyses of the Tanjianshan Group in the North Qaidam collisional belt, northern Tibetan Plateau were undertaken. Results demonstrate the presence of relics of the earliest Phanerozoic intra‐oceanic arc and an associated complete arc‐trench system, generated by previously unrecognized intra‐oceanic subduction far from microcontinents that are now adjacent. This study reveals the entire evolution of a missing intra‐oceanic subduction system within the Proto‐Tethys Ocean, which started ca. 530 Ma, matured ca. 520 Ma and ended ca. 480 Ma. Key Points: Relics of the earliest Phanerozoic intra‐oceanic arc discovered in North Qaidam collisional beltProto‐Tethys Ocean in North Qaidam belt experienced north‐directed intra‐oceanic subductionIntra‐oceanic subduction started at ca. 530 Ma and lasted until ca. 480 Ma [ABSTRACT FROM AUTHOR]

Copyright of Journal of Applied & Regional Geology / Zeitschrift der Deutschen Gesellschaft für Geowissenschaften (ZDGG) is the property of E. Schweizerbart'sche Verlagsbuchhandlung and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Haib porphyry copper deposit is situated in the Richtersveld Subprovince and is host to unique Palaeoproterozoic porphyry copper mineralisation in Namibia. Several lines of evidence, including machine-learning geothermobarometry, indicate that the deposit is exposed at mid- to upper-crustal levels, as constrained from average pressure and temperature estimates of 4 kbar and 870°C, respectively. The Haib porphyry copper deposit is associated with, and is in close proximity to, a mafic-ultramafic intrusion named the Kokerboom Intrusion (KI) in this study. Together with several other mafic intrusions in this region, these intrusions are known collectively as the Vuurdood Subsuite of the Richtersveld Subprovince. The purpose of this study is to demonstrate a genetic link between the KI and the Vuurdood Subsuite using lithological characteristics, mineral and alteration assemblages, major and trace element geochemistry and U-Pb geochronology. Pyroxenites from the KI contain magmatic sulphides and have a geochemical affinity with shallow plutonic and volcanic rocks of the Haib porphyry, providing a unique mid-crustal perspective on porphyry copper deposit metallogenesis. [ABSTRACT FROM AUTHOR]

Dehydration reactions within subducted oceanic crust are important for fluid‐mediated element transfer within the subducting plate and potentially to the mantle wedge. The effects of metamorphic reactions and fluid flow on element recycling that occur during retrogression and exhumation of subducted continental crust from mantle depths are poorly understood. We study two metabasite pods with fresh eclogite cores and retrogressed amphibolite‐facies rims and surrounding host gneiss within the Western Gneiss Region (WGR), Norway, to better understand element mobility and mass transfer during exhumation of subducted continental crust. Bulk‐rock data were collected from samples taken across the pod and into the host gneiss. Phengite breakdown in eclogite and epidote recrystallization in veins and/or gneiss within pod cores contributed large ion lithophile elements and REE to retrogressed eclogite closest to the pod cores. In gneiss hosting the pods, phengite and epidote breakdown provided fluid that mediated elemental transfer and redistribution to the pod rim or tail. Compared to the studied pod in the southern WGR, the pod in the northern WGR underwent higher P‐T conditions, partial melting and higher strain rates. This resulted in the infiltration of external fluid farther into the pod interior from the rim and facilitated larger mass gain in trace elements in the amphibolite tail of the pod relative to fresh eclogite in the core. The results show clear evidence for retrogression dehydration reactions driving significant fluid‐mediated element redistribution as observed on the outcrop scale during exhumation following ultrahigh‐pressure metamorphism, which directly impacts element signatures within the exhuming crust. Plain Language Summary: A lot is not known about how fluids and metamorphic reactions recycle elements in continental crust as it is brought to the surface after being subducted to ∼100 km. We study two eclogite pods that are surrounded by gneiss in the Western Gneiss Region, Norway to study how different pressure‐temperatures (P‐T), deformation, and fluids control element movement in deep crust as it is exhumed. The pod cores have eclogite that record the rock conditions at ∼100 km, but the exteriors were altered during exhumation. We sampled transects from the pod cores to ∼20 m into the surrounding gneiss. Bulk‐rock and mineral trace‐element data show two situations of mineral breakdown that generated trace‐element‐rich fluid that reacted with and enriched metabasite in Rb, Sr, Ba, and light rare earth elements: (a) veins or gneiss in pod cores enriched adjacent eclogite, and (b) surrounding gneiss enriched the pod exteriors. As shown by the pod that experienced higher P‐T conditions and deformation than the second pod, larger amounts of elements were transferred into the pod rim, and fluid penetrated the pod, enriching eclogite near the pod rim. Clearly, exhumation conditions and mineral break‐down reactions are important for elemental recycling in crust during exhumation. Key Points: In the Western Gneiss Region, Norway, fluids redistribute elements during retrogression after ultrahigh‐pressure metamorphismRecrystallization of epidote‐group minerals and phengite in metabasite pod interiors facilitate elemental transfer within the podsHost gneiss‐derived fluids infiltrate amphibolite‐facies retrogressed pod rims, driving significant element redistribution and mass transfer [ABSTRACT FROM AUTHOR]

The crustal evolution of the southernmost ∼2000–1800 Ma Trans‐Hudson orogen (THO) is enigmatic due to burial by Phanerozoic sediments. We provide new insights through petrochronologic analysis of a paragneiss drill core sample. Detrital zircon age peaks at 2625, 2340, and 1880 Ma and Hf isotopes suggest Paleoproterozoic arc development proximal to Archean source(s). Phase equilibria modeling and ternary feldspar thermometry suggest peak conditions of ≥1 GPa, ≥900°C, the first recognition of extreme, ultra‐high temperature metamorphism in the THO. The largely isobaric P‐T path, rapid heating rate, and ∼20 Myr duration (1872–1850 Ma) of peak conditions suggest that this metamorphism occurred in a back‐arc tectonic setting. The sample records post‐peak (1850–1815 Ma) mid‐crustal residence, slow cooling, and exhumation. Further retrogression occurred during Proterozoic regional exhumation (1630–1470 Ma) and Phanerozoic (360–220 Ma) reheating and/or fluid influx. Evidence for Paleoproterozoic arc(s) supports geophysical data for Archean cratonic and Paleoproterozoic arc crust in this region. Plain Language Summary: The Trans‐Hudson orogeny was a Himalayan‐scale collisional mountain building event approximately 1.8 billion years ago that formed the core of North America. The southern portion of the Trans‐Hudson orogen (THO) is poorly understood because it is almost entirely buried by younger rocks. It is unknown whether the southern THO is underlain by Archean or Proterozoic crust. The timing, conditions, and setting of high‐grade metamorphism in this region are also poorly known. We carried out petrologic, geochemical, and geochronologic analyses on a metasedimentary rock sample recovered from drill core. Detrital zircon and tracer isotopic data show derivation from both Paleoproterozoic and Archean sources. This suggests that Paleoproterozoic magmatic arc(s) developed on or near Archean crust. The rock sample experienced extreme temperatures (≥900°C, ≥1 GPa) and partial melting between approximately 1870 and 1850 million years ago perhaps in a back‐arc tectonic setting. This marks the first recognition of extreme, ultra‐high temperature metamorphism in the THO. Later retrograde metamorphism occurred in the Mesoproterozoic and Phanerozoic. These constraints provide new understanding of the enigmatic southern THO and highlight the ability of a combined petrologic, geochemical, and geochronologic study to extract a comprehensive record of crustal evolution from a single sample. Key Points: Paleoproterozoic arc(s) buried beneath North Dakota developed proximal to, or on, Archean craton(s)Metamorphic temperatures of >900°C are the first recognition of ultra‐high temperature (UHT) metamorphism in the Trans‐Hudson orogenBack‐arc setting for UHT metamorphism indicated by isobaric P‐T path and short timescales of heating and peak conditions [ABSTRACT FROM AUTHOR]

Inconsistencies between observations from long and short period seismic waves and geochemical data mean craton formation and evolution remains enigmatic. Specifically, internal layering and radial anisotropy are poorly constrained. Here, we show that these inconsistencies can be reconciled by inverting cratonic Rayleigh and Love surface wave dispersion curves for shear‐wave velocity and radial anisotropy using a flexible Bayesian scheme. This approach requires no explicit vertical smoothing and only adds anisotropy to layers where required by the data. We show that all cratonic lithospheres are comprised of a positively radially anisotropic upper layer, best explained by Archean underplating, and an isotropic layer beneath, indicative of two‐stage formation. Within the positively radially anisotropic upper layer, we find a variable amplitude low velocity zone within 9 of 12 cratons studied, that is well correlated with observed Mid‐Lithospheric Discontinuities (MLDs). The MLD is best explained by metasomatism after craton formation. Plain Language Summary: The ancient cores of the continents, or cratons, are a treasure‐trove of >2.5 billion years of Earth's history. However, scientists disagree on the processes that led to their formation, or whether they have evolved significantly through time. This is because the geological and geophysical methods used to investigate cratons often yield conflicting results. By capitalizing on an up‐to‐date global long‐wavelength seismic data set, we image the cores of 12 cratons using an advanced statistical method, Bayesian inference. The flexible method requires few choices to be made a priori, is driven by the quality of the data itself and measures uncertainties on results. By detecting velocity differences between horizontally and vertically vibrating seismic waves, we show that all cratons likely comprise an upper layer formed during the hot early Earth, by a process that strongly aligns the constituent minerals of the rocks in the horizontal plane. Below this ∼125 km thick upper layer, a lower layer (∼150 km thick) shows no clear alignment of minerals and so was likely formed by a different process, at a later time. Variable slow wavespeed zones exist within the upper layer that match previous results from short‐wavelength seismic data. Key Points: Bayesian surface wave inversion reconciles existing differences between seismic images of craton structure from long and short period dataCratons show a shallow low velocity zone (LVZ) within a layer of positive radial anisotropy and a high velocity isotropic layer beneathCratons are formed in two stages shown by anisotropic structure and are later modified producing a LVZ and mid lithosphere discontinuities [ABSTRACT FROM AUTHOR]

The 2021 Tajogaite eruption at La Palma has represented a unique opportunity to investigate the characteristics of the mantle source feeding modern volcanism in the Canary Islands. With the aim of track the fingerprint of carbon in the local oceanic lithosphere-asthenosphere system, we report the isotopic composition of CO2 (δ130 values versus Vienna Pee Dee Belemnite) in olivine- and clinopyroxene-hosted fluid inclusions (FI) from the 2021 Tajogaite lavas and from lavas/ultramafic xenoliths (olivine-clinopyroxenites, clinopyroxenites, dunites and harzburgites) from the nearby 1677 San Antonio eruption cone/lavas, in an attempt to characterize the origin and evolution of carbon within the local mantle source. Our results indicate that the 2021 and 1677 lavas exhibit δ130 values ranging from -4.94%" to -2.71%" and CO2/3He ratios from 3.37 to 6.14 χ 109. Ultramafic xenoliths fall in a comparable range of values despite showing higher CO2 concentrations. Our δ130 values fall within the range of carbon isotope results previously reported for the Dos Aguas cold spring located in the Taburiente Caldera (northern La Palma), suggesting an apparent carbon isotope homogeneity at the scale of the entire island. The (relatively narrow) δ1^ vs. CO2/3He ratio range of La Palma samples is interpreted to reflect either i) variable extents of open-system degassing of a common mantle endmember having δ1^ of -1.7%", or ii) mixing between depleted mantle-like carbon (-6% < δ1^ < -4%) and crustal carbon ^13C = 0%) endmembers. Both models testify a crustal carbon component recycled in the local mantle. This component, also detected in mantle xenoliths from the neighboring island of El Hierro and the easternmost Lanzarote, indicates a regional characteristic of the mantle beneath the Canary Islands, interpreted as a result of infiltration of carbon-rich melts during past metasomatic events in the local mantle. [ABSTRACT FROM AUTHOR]

Petrological and major-trace element mineral chemistry studies have been carried out on pyroxenites from the Pakkanadu alkaline-ultramafic complex from the southern India to understand their origin and nature of magma responsible for ultramafic magmatism in the area. Pyroxenites display cumulus texture and consist of clinopyroxenes (cpx) and amphiboles (amp) as dominant phases with a subordinate amount of apatite, biotite, ilmenite, magnetite, pyrite, sphene, and calcite. Mineral chemistry classifies cpx as augite and diopside, whereas amp falls under tremolite-actinolite and hornblende- actinolite fields. Cpx are alkaline to sub-alkaline in composition and Mg# -- Al2O3 compositions suggest their crystallization under high-pressure conditions. A negative correlation between Mg# and TiO2 in cpx suggests early crystallization of magnetite and pyrite; high Mg# (76-92) suggests its link with the Alaskan- type intrusions, which may be crystallized through fractionation-accumulation Processes. Tectonic discrimination diagrams for cpx argue for the magmatic emplacements underan arc-tholeiitic environment in a subduction zone setting. Amp mineral chemistry (high SiO2 and low TiO2) indicate as the products of hydrothermal alteration of clinopyroxenes. A Low Al/Si ratio in the cpx suggests their derivation from silica-oversaturated magma, whereas low-Ti contents reflect slow cooling rate of the magma. Positive Rb, Ba and U anomalies in the multi-element patterns of the cpx probably signifying varying degrees of hydrothermal alteration in the studied samples. However, consistent Nb-Ta depletion can also be attributed to an enriched mantle source of the magma from which pyroxenites were crystallized. Moreover, single-cpx geothermobarometry yielded a crystallization temperature of 905 to 911°C under moderate to high pressure of 3-9 kbar. [ABSTRACT FROM AUTHOR]

The 40Ar/39Ar age is determined for K-bearing minerals from high-K nepheline syenite (rischorrites), liebenerite and carbonatized nepheline syenite, and pseudoleucite syenite of the Bogdo alkaline massif (Arctic Siberia). The polychronous formation of alkaline complexes of the Tomtor type at the Paleozoic stage is revealed from summarizing and analysis of the 40Ar/39Ar age data on the thermochronological diagram for minerals of rocks of the Tomtor massif, Udachnaya–Vostochnaya kimberlite pipe, and alkaline rocks of the Bogdo massif. The isotopic data indicate a complex three-stage evolution of rocks of the massif with the most productive Late Devonian–Early Carboniferous rare metal–rare earth element mineralization. The Devonian stage of the formation of the Tomtor and Bogdo massifs is related to the impact of the Vilyui plume on the eastern margin of the Siberian Craton. A similar age range is registered during the formation of rocks of the Kola alkaline province. [ABSTRACT FROM AUTHOR]

The Bystrinsky Cu–Au–Fe porphyry–skarn and Shakhtama Mo-porphyry deposits are located in Eastern Transbaikalia, Russia. The host rocks in the deposits are multiphase granitoid plutons of the Middle–Late Jurassic Shakhtama complex. Economical mineralization is genetically related to small bodies of granite porphyries and granodiorite porphyries of late phases. To identify the specifics of fertile magmatic rocks, the composition of volatile components and rare-earth elements in apatite from fertile and barren intrusions was studied. Special attention was paid to the proof of the primary magmatic origin of apatite and the absence of influence of metasomatic alteration processes on their composition. It was shown that fertile intrusions at the Bystrinsky and Shakhtama deposits are characterized by an increased SO3 content in apatite, which indicates their formation from oxidized melts. In addition, it is shown that the presence of sulfate sulfur in the melt is a necessary for the sulfide ore formation. It has been established that a high Cl content (>0.8 wt %) in fertile magmatic rocks, which ensures the transfer of chalcophilic elements, is a characteristic difference between apatites from Cu-porphyry and Mo-porphyry systems. The content of volatile apatite can be used as a sign of fertility for porphyry systems. An analysis of the trace element composition of apatite made it possible to establish that apatites from fertile granitoids of the Shakhtama and Bystrinsky deposits are characterized by Eu/Eu* > 0.4, which indicates the oxidation and high water saturation of the parental melts. The revealed characteristics of apatite from fertile intrusions and their discreteness from barren granitoids can serve as a sign of fertility of igneous rocks for porphyry mineralization. [ABSTRACT FROM AUTHOR]

The southwest Lahad Datu felsic rocks were previously thought to have formed in the late Triassic as part of the microcontinental crystalline basement. Based on U-Pb ages, geochemistry, and the Hf isotopes of zircon from the southeastern Sabah gabbro and granite, in this study, the tectonic properties of the Sabah area during the Triassic were investigated. The weighted average U-Pb zircon ages of the gabbro and granite samples were determined to be (230.9 ± 2.5)Ma and (207.1 ± 3.3)Ma, respectively. The granite had SiO2 contents of 66.54%–79.47%, low TiO2 contents of 0.08%−0.3%, Al2O3 contents of 10.97%–16.22%, Na2O contents of 5.91%–6.39%, and low K2O contents of 0.15%–0.65%. The chondrite-normalized rare earth element (REE) patterns exhibit light REE enrichment, with right-sloping curves. The primitive mantle-normalized trace element spider diagrams exhibit Th, U, La, Sr, and Zr enrichment and Nb, Ta, P and Ti depletions, i.e., the geochemical characteristics of typical island arc igneous rocks. The tectonic discriminant diagram indicates that the granite is a volcanic arc granite. The Hf isotopic analysis of gabbro zircon revealed that the zircons have εHf(t) values of 12.08–16.24 (mean of 14.32) and two-stage model ages (tDM2) of 223–491 Ma (mean of 347 Ma). This indicates that the diagenetic magma of the gabbro was mainly derived from melting of newly formed crustal materials. The ophiolite in southeast Sabah has existed since the early Late Triassic. The crystalline basement granite in southeastern Sabah was emplaced lasted from late Triassic to early Cretaceous. Based on previous studies and global plate reconstruction models, it is speculated that the southeastern Sabah granite may have been formed in an island arc setting, i.e., where the oceanic crust of the Paleo-Tethys Ocean collided with the oceanic crust of the Panthalassa Ocean. [ABSTRACT FROM AUTHOR]

Exhumed serpentinites are fragments of ancient oceanic lithosphere or mantle wedge that record deep fluid‐rock interactions and metasomatic processes. While common in suture zones after closure of ocean basins, in non‐collisional orogens their origin and tectonic significance are not fully understood. We study serpentinite samples from five river basins in a segment of the non‐collisional Andean orogen in Ecuador (Cordillera Real). All samples are fully serpentinized with antigorite as the main polymorph, while spinel is the only relic phase. Watershed delineation analysis and in‐situ B isotope data suggest four serpentinite sources, linked to mantle wedge (δ11B = ∼−10.6 to −0.03‰) and obducted ophiolite (δ11B = −2.51 to +5.73‰) bodies, likely associated with Triassic, Jurassic‐Early Cretaceous, and potentially Late Cretaceous‐Paleocene high‐pressure (HP)–low‐temperature metamorphic sequences. Whole‐rock trace element data and in‐situ B isotopes favor serpentinization by a crust‐derived metamorphic fluid. Thermodynamic modeling in two samples suggests serpentinization at ∼550–500°C and pressures from 2.5 to 2.2 GPa and 1.0–0.6 GPa for two localities. Both samples record a subsequent overprint at ∼1.5–0.5 GPa and 680–660°C. In the Andes, regional phases of slab rollback have been reported since the mid‐Paleozoic to Late Cretaceous. This tectonic scenario favors the extrusion of HP rocks into the forearc and the opening of back‐arc basins. Subsequent compressional phases trigger short‐lived subduction in the back‐arc that culminates with ophiolite obduction and associated metamorphic rock exhumation. Thus, we propose that serpentinites in non‐collisional orogens are sourced from extruded slivers of mantle wedge in the forearc or obducted ophiolite sequences associated with regional back‐arc basins. Plain Language Summary: Serpentinites are metamorphic rock products of fluid‐mediated alteration of the mantle. They occur in the ocean floor and the core of mountain belts resulting from continental collisions after the closure of ancient oceanic basins. However, their origin in non‐collisional mountain belts, such as the Andes, remains unclear. To address this conundrum, we studied serpentinite boulders from five river basins in the Ecuadorian northern Cordillera Real. We found that rocks are composed of the high‐temperature serpentine mineral, while spinel is the only original mineral preserved. River basin analysis and boron stable isotopes indicate four potential sources for the studied rocks, juxtaposed to rocks ranging in age from ∼240 to 55 million. Bulk‐rock chemistry and boron isotopes suggest that the serpentinization was triggered by crustal fluids at depths between 80 and 30 km in a subduction zone environment. Through time, the Andes have been characterized by extensional and compressional tectonic phases. These tectonic scenarios enhance the extraction of rocks at deep sections of the Earth along major faults. We propose that Andean serpentinites are fragments of the Earth's mantle sourced from ancient subduction zones and back‐arc basins. Key Points: Serpentinites associated with HP–LT rocks are common in the Andes, but their origin and tectonic significance are not fully understoodOur results in Cordillera Real serpentinites suggest four sources derived from the mantle wedge and obducted ophiolitesSerpentinites in non‐collisional orogens are exhumed during slab rollback and back‐arc basin closure phases [ABSTRACT FROM AUTHOR]

Atmospheric mineral dust is a poorly constrained yet extremely important component of the climate system. Provenance studies from geologic dust archives are crucial to understand the drivers of the dust cycle over long time scales. Our multi‐technique provenance analysis of a rare Paleogene (35–27 Ma) eolian dust sequence from Ulantatal, ∼400 km northwest of the Chinese Loess Plateau (CLP), shows that Paleogene dust transporting winds generally varied between northwesterly and westerly, the same as those in the late Neogene‐Quaternary bipolar icehouse. We propose that, as today, westerly wind circulation patterns would have been modulated by an Arctic Oscillation (AO)‐like situation, and that the warm Eocene favored a long‐term negative phase of AO, leading to meridional westerly circulation and the dominance of a northwesterly dust transport pathway. After the Eocene‐Oligocene transition (EOT), long‐term positive phase of AO‐like conditions initiated, leading to stronger and more zonal westerlies. The Siberian High (SH) also formed or strengthened at the EOT and started to control dust storm activity along the northwesterly transport pathway. We argue that increased Paleogene Northern Hemisphere (NH) ice volume was the ultimate driver of this modern‐type dust transport regime in the Ulantatal region, possibly also controlling initial Ulantatal dust sequence formation via the development of the SH and modern‐type eolian regime. The similarity between the Ulantatal and late Neogene northern CLP dust provenance signals suggests that the increased NH ice volume, via its control on the northwesterly dust transport, could have promoted increased loess formation also in the late Miocene. Plain Language Summary: Understanding the effects and responses of atmospheric mineral dust to climate changes in the geologic past is crucial for predicting future scenarios. Analysis of the source of dust deposited 35–27 million years ago in Ulantatal, Inner Mongolia, China reveals that the Central‐East Asian atmospheric circulation during this time interval was similar to that of today. Specifically, dust transport was dominated by northwesterly and westerly winds despite a significantly warmer global climate. We also propose that Arctic Oscillation (AO)‐type conditions, stemming from the temperature difference between the high and low latitudes, modulated planetary westerly winds during this period. Our results suggest that during warmer phases, a negative AO type dominated and resulted in wave‐like westerly wind patterns and a northwesterly dust transport pathway to Ulantatal. During cooler phases, the westerly circulation became stronger and more zonal. The Siberian High pressure system was possibly strengthened during increased Northern Hemisphere (NH) ice volume and further affected northwesterly dust transport. Our findings suggest that NH ice volume increase was possibly also responsible for the formation of the Ulantatal dust sequence itself. Our results imply that even under significantly warmer conditions than today, polar ice affects the long‐term dustiness in this highly populated region. Key Points: The provenance of a Paleogene (35–27 Ma) eolian dust sequence in Ulantatal, Inner Mongolia, China, reveals a modern‐type eolian regimeGlobal cooling and possibly expansion of Northern Hemisphere ice volume modulated the dust provenance by strengthening the Siberian HighLong‐term negative (positive) phase of Arctic Oscillation‐like conditions were favored in the warmhouse Eocene (coolhouse Oligocene) [ABSTRACT FROM AUTHOR]