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The Kyzylkum Desert, as a transition area of different dust source in Central Asia, provides and reserves a large amount of dust transported by different atmospheric circulation systems, affecting Uzbekistan and downwind East Asia. However, there remains very few investigations about sediment sources and control factors of the desert. We hereby first present a provenance study on the Kyzylkum Desert, utilizing detrital zircon U‐Pb ages of samples composed of desert sand, alluvial sediments from Amu Darya River and piedmont of Southwest Tianshan Mountains. The results reveal that the Southwest Tianshan Mountains contribute the majority of the Kyzylkum desert sand, and the river system, dominated by Syr Darya, controls the sediment provenance of the desert. Moreover, little contribution from the Kyzylkum and Nurata segments indicates that wind erosion on the bedrocks is weak. However, the aeolian process is still crucial but deposit and storage of dust are determined by local topography. Plain Language Summary: The Arid Central Asia is commonly considered one of the most important dust sources in the world. The Kyzylkum Desert, located in the center of the multiple dust sources in Central Asia, provides and receives a large amount of dust, affecting Uzbekistan and downwind East Asia. However, research on sediment sources and control factors in the area is under debate. We investigate the potential provenance, spatial variability, and transport patterns of sand in the Kyzylkum Desert using detrital zircon U–Pb geochronology on 10 sediment samples. The results reveal that the Southwest Tianshan Mountains contribute the majority of the Kyzylkum desert sand, however, the proximal provenances also have a significant influence on the formation of the desert. The geomorphologic history shows that, the river system, dominated by Syr Darya, controls the sediment provenance of the Kyzylkum Desert. The wind displays little influence on the rework and recycle process of Kyzylkum Desert, indicated by inhomogeneous composition between northwest and southeast desert. The unmixing model results show evidence of sediments from the Kyzylkum Desert transported to the piedmont areas, but the transport and deposition of dust are primarily controlled by topography. Key Points: Detrital zircon U‐Pb dating indicates that the Southwest Tianshan Mountains are the primary sediment source of the Kyzylkum DesertThe river system controls the sediment provenance of the Kyzylkum DesertTopography determines reserve positions of the aeolian sand and dust from Central Asian deserts [ABSTRACT FROM AUTHOR]

Eruptive dynamics is influenced by gas escape from the ascending magma. Gas pathways form in the magma via bubble coalescence, leading to gas channeling. Magmatic crystals play a key role in gas channel formation. This work constrains experimentally decompression‐induced coalescence in high‐crystallinity silicic magmas without external deformation, focusing on low gas content and bimodal crystal size (microlites and phenocrysts). All percolating samples have permeabilities of 10−14 m2 at bulk porosities of 7–10 vol% and bulk crystallinities up to 75 vol%. Our results demonstrate the possibility of coalescence‐related outgassing at high pressure (120–350 MPa) and without external strain, which corresponds to magma stagnating deep in a volcanic conduit. Channeling at such low gas content implies that bimodal crystallinity favors effusive over explosive volcanic behavior. It may also be the missing physical mechanism explaining gas transfer across magmatic systems despite high melt viscosity and low or absent magma extrusion. Plain Language Summary: The way volcanoes erupt is mainly controlled by the ability of gases to escape from the magma (outgassing). An efficient way to outgas is to connect bubbles together (coalescence) up to the point where channels form in the magma (channeling) in which gas can circulate toward the surface. We investigate experimentally how coalescence and channeling happen in immobile, crystal‐rich viscous magma in conditions (pressure and temperature) similar to those found in deep volcanic conduit, where only a small amount of gas (<10%) is present. Our experiments demonstrate that bubble connections are possible thanks to a large amount of crystals on which bubbles can lean, deform, and join each other. That gas can escape from magma at depth could favor effusive eruption over volcanic explosions and even bring new insights on degassing in immobile magma. Key Points: Gas permeability in silicic magma is possible with gas volumes below 10% thanks to high crystallinityOutgassing at low gas content can happen without external deformation nor fracturation of the magmaVolcanic outgassing in stagnant magmas is explained by deep conduit bubble channeling that may be a key mechanism in eruptive transition [ABSTRACT FROM AUTHOR]

FeO is an important component in both mantle silicates and core iron alloys. Understanding its melting behavior and physical properties is crucial for exploring the chemistry and physics of our planet. Here we report the melting curve of FeO up to 186 GPa from laser‐heating experiments in a diamond‐anvil cell coupled with synchrotron X‐ray diffraction (XRD) techniques. In‐situ observations of both temperature plateau and changes in XRD patterns were used as primary melting criteria. The ex‐situ examination of a recovered sample shows consistent melting temperatures of FeO with in‐situ determinations. Our melting curve of FeO agrees with existing low‐pressure data within uncertainties and is much lower than earlier experimental results above 100 GPa including those extrapolated by Lindemann's law. Our results indicate that FeO‐rich materials could be present as melts coexisting with surrounding solids in the lowermost mantle, providing plausible explanations to the seismically observed ultra‐low velocity zones. Plain Language Summary: As an endmember of mantle silicates, the melting behavior of FeO is critical to understand the early magma ocean crystallization as well as present mantle signatures. However, the question on the high‐pressure melting curve of FeO remains because of the use of different melting criteria in earlier experiments. In this study, we conducted melting experiments on FeO up to 186 GPa in a laser‐heated diamond‐anvil cell using both in‐situ synchrotron X‐ray diffraction techniques and supplementary ex‐situ analyses of a recovered sample. Our results show that the melting temperature of FeO is 3,440 ± 250 K at 135 GPa, the Earth's core‐mantle boundary (CMB) pressure. The MgO‐FeO‐SiO2 melting phase diagram shows that fractional crystallization of mantle silicate melts would end up with a cotectic ternary minimum containing up to 95 mol% FeO, which would have a similar or slightly lower melting temperature than FeO. Considering the temperature at present‐day CMB, we anticipate that FeO‐rich materials, possible products of late‐stage magma ocean crystallization, would still exist as melts with surrounding solids at the bottom of the mantle. Due to its liquid nature and high density, the existence of FeO‐rich melts above the CMB could provide important insights for explaining the seismologically observed ultra‐low velocity zones. Key Points: The melting curve of FeO was determined up to 186 GPa based on in‐situ observations with supplementary ex‐situ examinationsOur determined melting temperature of FeO is much lower than earlier experimental results above 100 GPaAt the late magma ocean crystallization, the residual FeO‐rich materials could exist as melts in the lowermost mantle and explain ultra‐low velocity zones [ABSTRACT FROM AUTHOR]

The kinematics and deformation pattern along the Altyn Tagh fault (ATF), one of the largest strike‐slip faults on Earth is of great significance for understanding the growth of the Tibetan Plateau. However, the initial rupture along the ATF remains debated given the limited constraints on the depositional age of associated Cenozoic syntectonic strata. Here we investigated the syntectonic Cenozoic strata in the Xorkol Basin, associated with the strike‐slip faulting along the ATF. New uranium‐lead analyses of the carbonate deposits in the Paleogene strata yield dates of 58.9 ± 1.29 Ma, representing the initial rupture of the ATF. This first documented radioisotopic age coincides with the ca. 60 Ma onset timing of India‐Asia collision, highlighting its far‐field effect at the northern edge of the Tibetan Plateau. We infer that the deformation of the entire Tibetan Plateau started synchronously with the India‐Asia collision. Plain Language Summary: Carbonate U‐Pb dating techniques applied to rocks associated with the Altyn Tagh fault, a major fault in North Tibet, reveal that the fault started slipping about 58.9 million years ago, coinciding with the time when India collided with Asia. This finding provides new constraints on when and where this fault formed and suggests that the northern Tibetan Plateau started deformation earlier than previously thought. This result emphasizes that the entire Tibetan Plateau deformed simultaneously in the early Cenozoic. Key Points: Calcite U‐Pb dating yields ca. 59 Ma age for carbonate strata in the East Xorkol BasinXorkol Basin was a pull‐apart basin during the Paleocene due to the left‐lateral strike‐slip faulting along the Altyn Tagh faultWidespread Paleocene‐Eocene tectonism in Northern Tibet highlights the far‐field effect of the India‐Asia collision [ABSTRACT FROM AUTHOR]

The tonalite–trondhjemite–granodiorite suites (TTGs) are key components of the Archean continental crust and therefore crucial to the understanding of the evolution of the early Earth. Here, we present in situ zircon Si–O isotope data of TTGs from Barberton. Results show that the 3.45–3.42 Ga (Group 1) and 3.24–3.23 Ga TTGs (Group 2) have elevated δ30Simelt values but mantle‐like δ18Ozrc values, whereas the 3.23–3.22 Ga TTGs (Group 3) have coupled elevated δ30Simelt and δ18Ozrc values relative to mantle‐derived rocks. We suggest that the Group 1 and 2 TTGs had a silicified source that was affected by low‐δ18O fluid released from the komatiitic rocks. The low‐δ18O fluid decreased the δ18Ozrc values of Group 1 and 2 TTGs but had negligible influence on their δ30Simelt values. The Group 3 TTGs were generated solely from the silicified source, as the low‐δ18O fluid had become exhausted at that time. Plain Language Summary: The Archean granitic continents are dominated by tonalite–trondhjemite–granodiorite suites (TTGs) that are generated from the partial melting of hydrous basaltic rocks. The genesis of TTGs is controversial, as the source of water is unclear. Si and O isotopes are effective indicators of the water source and should be covariant. However, in this study, we discovered both decoupled enriched Si but mantle‐like O isotopic compositions, and coupled enriched Si–O isotopic compositions of TTGs from the Barberton region. We suggest that the decoupled Si–O isotope compositions resulted from the involvement of both supracrustal silicified materials and fluid released from komatiitic rocks, and that the coupled Si–O isotopic compositions were produced by the silicified materials only. The results indicate that TTGs have more variable sources than previously thought. Key Points: Elevated δ30Si and δ18O values of Archean granitic continental rocks indicate the involvement of a supracrustal silicified sourceMantle‐like δ18O values of Archean granitic continental rocks may have been caused by low‐δ18O fluid released from komatiitic rocksMantle‐like δ18O values of Archean granitoids might not reflect the absence of supracrustal materials [ABSTRACT FROM AUTHOR]

The composition of basaltic melts in equilibrium with the mantle can be determined for several Martian meteorites and in‐situ rover analyses. We use the melting model MAGMARS to reproduce these primary melts and estimate the bulk composition and temperature of the mantle regions from which they originated. We find that most mantle sources are depleted in CaO and Al2O3 relative to models of the bulk silicate Mars and likely represent melting residues or magma ocean cumulates. The concentrations of Na2O, K2O, P2O5, and TiO2 are variable and often less depleted, pointing to the re‐fertilization of the sources by fluids and low‐degree melts, or the incorporation of residual trapped melts during the crystallization of the magma ocean. The mantle potential temperatures of the sources are 1400–1500°C, regardless of the time at which they melted and within the range of the most recent predictions from thermochemical evolution models. Plain Language Summary: Martian meteorites and rocks analyzed by rovers are witnesses of magmatic processes on Mars. Some of the basaltic specimens among them have been classified as "primitive" as they are closely related to the melts that form in the mantle and feature high MgO/FeO. They record important properties of the mantle of Mars. We use the mantle melting model MAGMARS to constrain the temperature and composition of the mantle source regions from which primitive basalts originated. We find that the mantle compositions were low in CaO and Al2O3, either because they melted on several occasions, or because these components were locked in deeper layers of the mantle when it solidified from the bottom up (early magma ocean). Several mantle sources are comparatively rich in Na2O, K2O, P2O5, and TiO2. These components were either subsequently added to the mantle sources by fluids and low‐degree melts or can be explained by the trapping of melts during the progressive crystallization of the magma ocean. The temperature of the mantle sources projected to surface conditions for easier comparison (potential temperature) was 1400–1500°C, regardless of the time at which they melted, and is within the range of recent predictions from planetary‐scale models of interior dynamics. Key Points: Basalts that sampled discrete mantle regions throughout Mars's history provide information about the mantle composition and temperatureThe mantle potential temperature of primitive basalts appears constant (1400–1500ºC), yet is likely not representative of the average mantleIncompatible element concentrations in the mantle vary due to magma ocean crystallization, partial melting, and metasomatism [ABSTRACT FROM AUTHOR]

The genesis of intermediate intrusions is highly controversial, and one of the hot topics is whether they represent frozen melts or cumulates in the evolution of magmatic systems. Distinguishing accumulation from crystallization melt differentiated along the liquid line of descent is the key issue. The Paleoproterozoic intermediate intrusions in southern North China Craton provide an excellent case to decipher this issue. Multiple lines of evidence, including mineral textures, geochemistry as well as alphaMELTS modeling, indicate disequilibrium between whole‐rock and minerals, with melt extraction occurring at temperatures of 760°–820°C and with 10–40 wt.% of trapped melts. Effective water storage, revealed by amphibole and clinopyroxene hygrometers, plays a crucial role in promoting crystal‐melt segregation in pluton‐sized reservoirs in the upper crust. This study demonstrates that the accumulation in intermediate magmas can be identified even without evident complementary initial and extracted melts and provides deep insights into the genesis of intermediate continental crust. Plain Language Summary: The genesis of intermediate rocks has long been controversial since they are analogs of the average composition of continental upper crust. The key topic is whether intermediate rocks represent frozen melts of intermediate magmas or crystal residues after melt extraction in the evolution of felsic magmatic systems. Here we carried out a comprehensive study on the Paleoproterozoic intermediate intrusions in the southern North China Craton, which is considered to have recorded the process of crystal accumulation and melt segregation in the shallow crust. Upon mineral texture, geochronologic, whole‐rock and mineral geochemical, and thermodynamic investigation, we propose that crystal accumulation and crystal‐melt segregation processes can be identified in intermediate magmas with the melt extraction temperatures and proportions of trapped melts recorded by zircon trace elements. Amphibole and clinopyroxene hygrometers revealed high water content of the melts, which likely decreased the viscosity of melts and facilitated effective cumulate‐melt segregation. This study provides a powerful reference to see through the accumulation in intermediate magmas, record the processes of crystal‐melt segregation, and definitively resolve the debate concerning the genesis of intermediate intrusions. Key Points: Crystal accumulation in intermediate magmas can be identified by mineral texture and geochemistryThe effective water storage system in the reservoirs is key to promoting crystal‐melt segregationCrystal‐melt segregation and accumulation are fundamental processes to form evolved continental upper crust [ABSTRACT FROM AUTHOR]

We have simultaneously measured thermal conductivity (λ) and thermal diffusivity (κ) for polycrystalline ferropericlase with different Fe contents (Fp3, Fp5, Fp10, Fp20, Fp30 and Fp50) up to 23 GPa and 1100 K by a pulse heating method. Experiment results reveals that even small amounts of Fe in ferropericlase can strongly reduce the thermal conductivity by several times at low temperature compared with MgO periclase. With increasing Fe in ferropericlase, both their pressure and temperature dependence decrease. λ of Fe‐bearing ferropericlase is not sensitive to temperature compared with silicates and shows a tendency of first increasing and then decreasing with increasing temperature. A universal equation was derived to estimate λ of ferropericlase with arbitrary composition under mantle conditions. The low λ values of Fe‐rich ferropericlase can explain one possible origin of ultralow velocity zones. This study suggests that Fe content in ferropericlase is an important factor controlling the cooling history of terrestrial planets. Plain Language Summary: To understand different roles of ferropericlase in heat transport during the evolution of terrestrial planet, pressure, temperature, and compositional dependence of thermal conductivity (λ) of ferropericlase need to be well constrained. We measured thermal conductivity and thermal diffusivity of ferropericlase with different Fe content simultaneously under high pressure and high temperature. The measurement results revealed a dramatic effect of Fe: a small addition of Fe causes a decrease in the absolute value and pressure dependence of ferropericlase by several times compared with end member MgO. Fe substitution also reduces the temperature sensitivity of thermal conductivity of ferropericlase, leading to nonmonotonic temperature dependence. Based on the systematic measurement data, we derive a universal equation as an applicable tool to estimate thermal conductivity of ferropericlase with variable compositions as functions of temperature and pressure. The results suggest that Fe‐poor ferropericlase (XFe < 0.1) is a thermal conductor while Fe‐rich ferropericlase (XFe ≥ 0.3) is likely to work as a thermal insulator under terrestrial planet mantle conditions. The highly composition‐dependent λ of ferropericlase suggests that the crystallization sequence of ferropericlase may influence the magma ocean cooling of terrestrial planets and result in thermal heterogeneity in the deep mantle. Key Points: We simultaneously measured the thermal conductivity and diffusivity of ferropericlase with different Fe contents by pulse heating methodA dramatic effect of Fe on pressure and temperature dependence of thermal conductivity of ferropericlase was foundThe low λ of Fe‐rich ferropericlase at the bottom of the mantle supports patches of Fe‐rich materials as an origin for ultralow velocity zones [ABSTRACT FROM AUTHOR]

Here we report the first set of thallium (Tl) isotope data in alkaline rocks from the North China Craton to constrain the nature of recycled materials in the metasomatized subcontinental lithospheric mantle. Samples from the Hekanzi and Saima alkaline complexes display Tl isotope compositions (ε205Tl) identical to the present‐day upper mantle and continental crust, suggesting that neither the recycled low‐temperature altered oceanic crust nor the pelagic sediments were involved in their sources. The volcanic rocks from the Liaodong‐Jinan region, whose source was previously proposed to contain recycled low‐temperature altered oceanic crust, also display modern mantle‐like Tl isotope composition, suggesting a significant Tl‐loss in the recycled oceanic crust during the subduction due to the dehydration process. Our Tl isotope data provide complementary constraints to the Sr‐Nd‐Hf‐O isotopes on the nature of metasomatic agent in the subcontinental lithospheric mantle. Plain Language Summary: Recycling of crustal materials into Earth's mantle by subduction causes mantle heterogeneities. The sources of some alkaline rocks contain recycled crustal materials. Pelagic sediments, low‐temperature altered oceanic crust, and continental crust have sharp differences in thallium isotope compositions. Combined with Sr‐Nd‐Hf‐O isotopes, whole‐rock Tl isotopes place a better constraint on the metasomatic sources. Key Points: Thallium isotope compositions of the alkaline rocks were analyzed to track crustal recycling in the subcontinental lithospheric mantleThallium isotope suggested that low‐temperature altered oceanic crust and pelagic sediments were not involved in the investigated sourcesThe O‐Nd‐Hf‐Tl isotope data for the Liaodong‐Jinan volcanics reveal a significant Tl‐loss in the subducted slab during dehydration process [ABSTRACT FROM AUTHOR]

Solubility of oxygen and silicon in the iron‐alloying liquids is important for constraining the core composition over the Earth's history. In this study, we systematically simulated the free energies of Fe‐O‐Si ternary liquids from 3000 K, 55 GPa to 6000 K, and 330 GPa. We found that temperature and pressure have remarkable influences on the free energies, and the nonideality of mixing is important for the chemical potentials even at high temperatures. Equilibrating with SiO2 phase, Fe‐O‐Si liquids significantly enhance the solubility of Si and O simultaneously with increasing temperature. Considering the secular cooling of the Earth's core, this leads to high precipitation rates of SiO2 once it was saturated, which would efficiently drive ancient geodynamo. If the evolution of Earth's core started from an oxygen‐poor composition, later incorporations of oxygen seem to be needed to reach a core composition compatible with geophysical observations. Plain Language Summary: According to planetary formation models, the Earth's core experienced two stages in its history: during the early stage of accretion, the iron‐rich core gained light elements from the silicate mantle at high temperatures; in the subsequent stage of evolution, the core gradually cooled down and this might have led to changes in core composition. During these two stages, solubility of light elements in liquid iron determines their gain and loss limits and thus is of fundamental importance. In this study, we obtained the free energies of Fe‐O‐Si liquids and predicted the exsolution boundaries of SiO2. The derived data show that Si and O would be precipitated out of the core as SiO2 crystals at the core‐mantle boundary with the secular cooling of the Earth's core, because the temperature effects are more significant than previous empirical extrapolations. With the predicted exsolution boundaries at various temperatures, we were able to provide new constraints on how the Earth's core evolved from the previous accretion stage to the present‐day status. Key Points: Free energies of Fe‐O‐Si ternary liquids have been predicted under Earth's core conditionsTemperature effects on the solubility of SiO2 in Fe‐O‐Si liquids are significantPrecipitation rate of SiO2 is high and efficient to drive magnetic field's dynamo [ABSTRACT FROM AUTHOR]

Long‐distance lateral magma propagation may reflect the complex interaction between regional tectonics and crustal uplift. Here, we report observations on the Taxkorgan intrusive complex (TIC) of the Central Pamir. TIC is a 70 km long, 10–18 km wide, north‐northwest–elongated body intruded into mid‐upper crust in parallel with, and close to, the Kongur Shan Extensional System. New zircon U‐Pb dating shows that syenite samples exhibit a clear younging pattern from south to north along the pluton axis within an interval between 11.5 and 10.3 Ma, which is interpreted as lateral magma propagation from a single feeder zone at its northwestern margin. The lateral magma propagation was caused by a combination of crustal rigidity differences, and a topography‐induced pressure gradient that is nearly orthogonal to the least compressive stress. We propose that long‐distance lateral magma propagation plays an important role in plateau expansion, restraining the thickness and elevation of the Pamir Plateau. Plain Language Summary: Long‐distance lateral magma propagation within the crust has been documented for diverse magmatic systems. The Miocene Taxkorgan intrusive complex was formed during India‐Asia collision in the Central Pamir Plateau, and it consists of a syenite pluton and several discrete lobes of monzogranites. New SIMS zircon U‐Pb dating results shows that monzogranites across TIC have overlapping ages between 12.4 and 12.2 Ma, indicating they were emplaced from a series of synchronous and independent magma feeder zones. In contrast, syenite samples exhibit a clear younging pattern from south to north within an interval between 11.5 and 10.3 Ma. The pattern of decreasing ages along the pluton axis is interpreted as lateral magma propagation from a single feeder zone at its northwestern margin. It is inferred that long‐distance lateral magma propagation, such as documented for the Taxkorgan intrusive complex, played a key role in plateau expansion, restraining the thickness and elevation of the Pamir Plateau. Key Points: Taxkorgan intrusive complex (TIC) syenite pluton shows a clear younging pattern from south to north within an interval between 11.5 and 10.3 MaTIC syenite pluton formed by lateral magma propagation from a single feeder zone at its northwestern marginLong‐distance lateral magma propagation plays an important role in plateau expansion, restraining the thickness and elevation of Plateau [ABSTRACT FROM AUTHOR]

The production of H2O during metamorphism along active plate boundaries is inferred to contribute to low‐frequency tectonic tremor. This study combines predictions from phase equilibria and mechanical modeling of coincident volume changes to investigate links of tremor with hydrofracturing and fluid migration under the actively forming Southern Alps, New Zealand. The posited location of metamorphic fluid production correlates with published geophysical images of inferred permeability enhancement, fluid accumulation and potential fluid flow. As the hanging‐wall rocks are translated toward the surface by motion along the Alpine Fault, they can undergo metamorphic reactions that involve positive volume changes. Production of metamorphic fluids leads to hydrofracturing and the development of tremor hypocenters in regions along, and above deep reflectors of the Alpine Fault. The capacity of metamorphic rocks to generate or consume fluid along portions of the pressure–temperature path exerts a fundamental control on the distribution of stresses in the crust. Plain Language Summary: As continents collide, rocks traverse through the mountain belt and undergo prograde metamorphism. This releases water that has been bound in minerals in the rocks because of the effects of both heating and decompression. The production of water from these rocks contributes to the generation of low‐frequency and low‐energy earthquakes. This study is the first to couple mineral phase equilibria of dehydration processes with mechanical modeling of the resulting volume changes to investigate the potential links between hydrofracturing and seismicity under the Southern Alps of New Zealand. The positive volume changes that accompany dehydration during exhumation can induce hydrofracturing and the development of low frequency earthquakes at mid‐crustal depths. Key Points: Links between metamorphic dehydration and hydrofracturing are investigated in the Southern Alps of New ZealandMetamorphic fluid production leads to the development of tremor hypocenters in regions along, and above deep reflectors of the Alpine FaultThe capacity of metamorphic rocks to generate or consume fluid along portions of the P–T path exerts a control on stresses in the crust [ABSTRACT FROM AUTHOR]

The tectonic evolution of the Paleo‐Jinshajiang Ocean, and in particular the time of its closure, is debated. Here we present new constraints on the evolution of this region from an integrated paleomagnetic and geochronologic study of the Late Triassic Batang Group volcanic rocks in Qamdo, Eastern Qiangtang Terrane (EQT). Two zircon U‐Pb ages indicate that the volcanic rocks erupted at ∼227–222 Ma. New paleomagnetic results yield a robust Late Triassic paleopole of 57.6°N, 176.4°E (A95 = 7.8°), corresponding to a paleolatitude of 32.5 ± 7.8°N for the study area. Integrated with other lines of paleomagnetic and geological evidence, we show that the northward drift of the EQT placed it at the same paleolatitude as the Tarim Block by ∼227–222 Ma, which suggests that the Paleo‐Jinshajiang Ocean in the Qamdo region closed before that time, and likely around ∼230 Ma. Plain Language Summary: The closure of the Paleo‐Jinshajiang Ocean, which was one of the most important ancient oceans of Asia, closed when the Qiangtang Terrane (QT) collided with the terranes now located to the north of it. However, the evolution of this ocean, and especially the timing of its closure, are still debated. The drift history of the QT is a key to understanding the evolution of the Paleo‐Jinshajiang Ocean. We present here new constraints on the evolution of this region from an integrated paleomagnetic and zircon U‐Pb geochronologic study of Late Triassic volcanic rocks in Qamdo, Eastern QT. Two zircon U‐Pb geochronologic results indicate that the volcanic rocks erupted at ∼227–222 Ma. New paleomagnetic results yield a robust Late Triassic paleopole of 57.6°N and 176.4°E, and indicate that the study area was then located at a paleolatitude of 32.5 ± 7.8°N. In integrating these data with other lines of evidence, we show that a northward drift of the EQT since the early Permian brought it to the same paleolatitude as the Tarim Block by ∼227–222 Ma. This implies that the closure of the Paleo‐Jinshajiang Ocean in the Qamdo region occurred before 227–222 Ma, and likely around ∼230 Ma. Key Points: Volcanic rocks of the Late Triassic Batang Group are dated by U‐Pb on zircon to ∼227–222 MaPaleomagnetic data from these rocks yield a robust Late Triassic paleopole of 57.6°N, 176.4°E(A95 = 7.8°)Closure of the Paleo‐Jinshajiang Ocean occurred before 227–222 Ma, and likely around ∼230 Ma [ABSTRACT FROM AUTHOR]

Classical fractional crystallization scenarios of early lunar evolution suggest crustal formation by the flotation of light anorthite minerals from a liquid magma ocean. However, this model is challenged by the >200 $ > 200$ Myr age range of primitive ferroan anorthosites, their concordance with Mg‐suite magmatism and by the compositional diversity observed in lunar anorthosites. Here, we propose a new model of slushy magma ocean crystallization in which crystals remain suspended in the lunar interior and crust formation only begins once a critical crystal content is reached. Thereafter crustal formation occurs by buoyant melt extraction and magmatism. The mixture viscosity strongly depends on temperature and solid fraction driving the development of a surface stagnant lid where enhanced solidification and buoyant ascent of melt lead to an anorthite‐enriched crust. This model explains lunar anorthosites heterogeneity and suggests a crustal formation timescale of 100s Ma, reconciling anorthosite ages with an early age of the Moon. Plain Language Summary: The discovery of primitive lunar anorthosites by the Apollo 11 mission was surprising. Their global distribution and purity suggested flotation of anorthite crystals over a liquid magma ocean. Flotation theory elegantly explains early formation of the Highlands and the Procellarum KREEP terrane composition, interpreted as the residual liquid from crystallization, enriched in incompatible elements. Since then, many lunar meteorites have been analyzed and the lunar surface has been studied remotely. Lunar anorthosites appear more heterogenous in composition than suggested by ferroan anorthosite samples only, contradicting the classical flotation scenario where the liquid ocean is the common source of all anorthosites. The ∼300 Ma age range for ferroan anorthosites also appears difficult to reconcile with a mostly liquid ocean. A reevaluation of the magma ocean solidification history thus seems necessary. In the low lunar gravity, efficient crystal‐liquid separation may be difficult to achieve. Here, we investigate the case where a slushy crystal suspension persists throughout magma ocean solidification and the crust instead forms by extraction of melts enriched in an anorthite component. Crustal magmatism then produced the lunar anorthosites, explaining their observed diversity. The crust formation timescale is several hundreds of million years, matching the observed age range of lunar anorthosites. Key Points: We consider the cooling of a slushy lunar magma oceanCrust formation occurs by liquid extraction over hundreds of millions of yearsThis model can explain both the chronology and diversity of lunar crustal rocks [ABSTRACT FROM AUTHOR]

The tectonic evolution of the eastern Paleo‐Tethys in the Three‐Rivers headwater region remains uncertain, especially because of the lack of quality paleomagnetic data from the east Eastern Qiangtang Terrane (EQT). Here, we present an integrated paleomagnetic and zircon U‐Pb geochronologic study of the Gadikao Formation (Fm.) volcanic rocks in the EQT. This previously assumed Carboniferous or Permian rock unit is now zircon U‐Pb dated to ∼254–248 Ma. Our new high quality (29 sites and 257 samples) inferred primary paleomagnetic results yield a robust Permo‐Triassic boundary paleopole of 59.7°N and 228.2°E (A95 = 3.3°), with a paleolatitude of 10.0 ± 3.3°N for the study area. Integrated with other reliable Permo‐Triassic paleomagnetic data of the EQT and the Tarim Block and other lines of geologic evidence, we propose that the EQT drifted continuously northward during 300–200 Ma and the Paleo‐Tethys Ocean probably closed at ∼232–220 Ma around the Qamdo region, most likely at 230 Ma. Plain Language Summary: The drift history of the Qiangtang Terrane is the key to understand the evolution of the "Proto‐Tibet" and the Paleo‐/Meso‐Tethys Oceans, which is still under debate. In this work, we provide U‐Pb zircon data to constrain (254–248 Ma) a high quality paleomagnetic pole (59.7°N, and 228.2°E, with A95 = 3.3°) for the EQT, which was located at ∼10.0°N during ∼254–248 Ma. Integrated with other available lines of evidence, we propose that the EQT drifted continuously northward during the Permian and Triassic and collided with the Songpan‐Ganzi/Tarim Terrane, resulting in the closure of the Paleo‐Tethys Ocean around the Qamdo region during ∼232–220 Ma, most likely at about 230 Ma. Key Points: The previous upper Paleozoic Gadikao Formation yields high precision Zircon U‐Pb dates from ∼254 to 248 MaThe volcanic rocks yield a robust Permo‐Triassic boundary paleopole of 59.7°N and 228.2°E (A95 = 3.3°)The closure of the Paleo‐Tethys Ocean around Qamdo is best estimated at ∼232–220 Ma, mostly likely at ∼230 Ma [ABSTRACT FROM AUTHOR]

The relative importance of global cooling and Tibetan Plateau uplift in driving the aridification of Asia during the late Cenozoic is debated, largely due to the lack of appropriate proxy indicators. Here we address this problem by investigating changes in the source of Chinese loess and Red Clay, which is directly controlled by changes in the extent and distribution of the arid zone of Asia and the intensity of the East Asian winter monsoon, using zircon U‐Pb dating of 27 levels in a near‐continuous eolian sedimentary sequence in southern Chinese Loess Plateau. The results show that source regions expanded stepwise at ~7.2, ~2.6, 1.2–0.9 Ma, and at the Last Glacial Maximum. These changes were synchronous with global cooling and ice cover expansion in the Northern Hemisphere, suggesting that the drivers of aridification of the Asian interior were intimately related to global cooling in the late Cenozoic. Plain Language Summary: The arid and semiarid regions of Central Asia are one of the most important dust sources on Earth. Dust emitted from these regions is deposited in the Chinese Loess Plateau, the North Pacific Ocean, and even in Greenland, with broad environmental impacts. Although there is evidence that the drying of the Asian interior occurred gradually over several tens of million years, the driving factor remains unclear. Here we investigate the evolution of the sediment sources of the Chinese Loess Plateau and find that the changes in the source regions of wind‐blown sediment were synchronous with global cooling since ~7.2 Ma. This indicates that the long‐term aridification of the Asian interior was most likely driven by global cooling. Key Points: Dust source areas of the Chinese Loess Plateau expanded at ~7.2, 2.6, 1.2–0.9 Ma, and at the Last Glacial MaximumExpansion of dust source areas since ~7.2 Ma was mainly controlled by the aridification of the Asian interior and the strengthening of the East Asian Winter MonsoonAridification of the Asian interior and strengthening of the East Asian Winter Monsoon were mainly driven by global cooling [ABSTRACT FROM AUTHOR]