Background/Aims: Recent studies have indicated that exosomes secreted from adipose-derived stem cells (ADSCs) have important effects in the treatment of ischemic injury. However, the treatment ...mechanism is unclear. This study aimed to investigate whether ADSC-derived exosomes enriched with microRNA (miR)-30d-5p have a protective effect on acute ischemic stroke (AIS). Methods: In the current study, inflammatory factors and miR-30d-5p expression were assessed in 70 subjects with AIS and 35 healthy controls. Exosomes were characterized by transmission electron microscopy and further examined using nanoparticle tracking analyses. A rat model of AIS and an in vitro model of oxygen- and glucose-deprived (OGD) primary microglia were established to study the protective mechanism of exosomes from miR-30d-5p-overexpressing ADSCs in ischemia-induced nerve injury. Results: The results showed that following AIS, the expression of inflammatory cytokines increased, while the anti-inflammatory cytokines IL-4, IL-10, and miR-30d-5p decreased both in patients and in animal models. Moreover, in vitro studies demonstrated that suppression of autophagy significantly reduced the OGD-induced inflammatory response. In addition, exosome treatment was more effective in suppressing the inflammatory response by reversing OGD-induced and autophagy-mediated microglial polarization to M1. Furthermore, in vivo studies showed that exosomes derived from ADSCs significantly decreased the cerebral injury area of infarction by suppressing autophagy and promoting M2 microglia/macrophage polarization. Conclusions: Our results suggest that miR-30d-5p-enhanced ADSC-derived exosomes prevent cerebral injury by inhibiting autophagy-mediated microglial polarization to M1.
•The sub-PAO mantle has a typical Pacific MORB-like Pb isotopic compositions.•The Pacific-type mantle domain can be traced back to early Paleozoic.•The Pacific-type mantle domain is a long-lived low ...Th/U secular mantle domain.•Plate tectonic-driven material circulation produces long-term mantle heterogeneity.
The presence of Pacific-type and Indian-type mid-ocean ridge (MORB) isotopic source domains in the upper mantle is a clear manifestation of global-scale mantle compositional heterogeneities. The Indian-type mantle domain is a long-lived feature that can be traced back to, at least, the Palaeozoic Tethyan mantle domain. Few temporal constraints currently exist, however, regarding the longevity of Pacific-type mantle domain. The extinct Paleo-Asia Ocean (PAO), a subsidiary ocean of the Panthalassic Ocean that formed during the breakup of the Rodinia supercontinent in Mesoproterozoic to Neoproterozoic, can provide a solution to this dilemma. Here, we report the first complete geochemical and Sr, Nd and high-precision Pb isotopic data set for representative mafic rock samples from ophiolites representing remnants of the PAO basement ranging in age from 275 to 624 Ma to constrain the composition of their mantle provenance. Data suggest that the sub-PAO mantle has a similar long time-integrated, high Sm/Nd ratio as the global depleted upper mantle, but also shows typical Pacific MORB-like Pb isotopic compositions with lower 207Pb/204Pb(t) and 208Pb/204Pb(t) for given 206Pb/204Pb(t) ratios, and low radiogenic 208Pb*/206Pb*, indicating a long time-integrated, low Th/U ratio. Thus, the Pacific-type mantle domain, like the Indian-type mantle domain, is a long-lived secular mantle domain that can be traced back to early Paleozoic or even to the Neoproterozoic. Data further indicate that the Nd and Pb isotopic distinction between such two large-scale and long-term mantle domains is due to the different evolutionary and tectonic histories of the circum-Pacific (PAO, Paleo- and modern Pacific) and sub-Tethys-Indian oceanic mantle realms. Our results indicate that the high Sm/Nd and low Th/U ratio of Pacific-type mantle domain most likely are an inherited, long-standing intrinsic feature of the depleted upper mantle derived from the Earth's primordial mantle with less contamination of continental materials. In contrast, the large-scale and long-lived Indian-type mantle heterogeneity is produced by plate tectonic-driven continental material circulation in the upper mantle. Such a genetic link between plate tectonics and mantle chemical geodynamics is crucial to our understanding of how the Earth system works.
Abstract
Carlin-type gold deposits are among the largest hydrothermal gold deposits in the world. However, direct dating the metallogenic age of these deposits is difficult, because not all deposits ...provide material suitable for conventional radiometric methods. Syn-mineralization stage quartz veins from these deposits usually contain abundant fluid inclusions, which allow fluid inclusion
40
Ar/
39
Ar dating. In this study, progressive crushing
40
Ar/
39
Ar dating has been performed on a gold-bearing quartz vein from the Liaotun Carlin-type gold deposit in northwestern Guangxi, China. Argon isotopes liberated from the later steps yielded an isochron age of 200.7 ± 2.1 Ma. We infer that Ar-bearing gas was extracted from the primary fluid inclusions, and that the age of ca. 200.7 Ma reflects the timing of gold mineralization. The initial
40
Ar/
36
Ar ratio corresponding to the isochron is 298.0 ± 4.3, which is statistically indistinguishable from the value for air, indicating that the ore-forming fluids probably mainly derived from gravitational pressure flow in the basin of air-saturated water. Our preliminary study shows the feasibility and great potential of
40
Ar/
39
Ar dating of gases from fluid inclusions by progressive crushing of quartz veins to date the mineralization age and decipher the fluid origins of Carlin-type gold deposits.
Cerebral ischemic injury is a complicated pathological process. Adipose-derived stromal cells (ADSCs) have been used as a therapeutic strategy, with their therapeutic effects chiefly attributed to ...paracrine action rather than
differentiation. Studies have shown that circAkap7 was found to be downregulated in a mouse model of transient middle cerebral artery occlusion (tMCAO).
To explore whether exosomes derived from circAkap7-modified ADSCs (exo-circAkap7) have therapeutic effects on cerebral ischemic injury, a mouse model of tMCAO, as well as an
model of oxygen and glucose deprivation-reoxygenation (OGD-R) in primary astrocytes, were used.
Results showed that treatment with exo-circAkap7 protected against tMCAO in mice, and
experiments confirmed that co-culture with exo-circAkap7 attenuated OGD-R-induced cellular injury by absorbing miR-155-5p, promoting ATG12-mediated autophagy, and inhibiting NRF2-mediated oxidative stress.
We demonstrate here that exo-circAkap7 protected against cerebral ischemic injury by promoting autophagy and ameliorating oxidative stress.
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•Report two new U-Pb zircon ages for the Paoshuiling and Yucai granites.•Report five new 40Ar-39Ar muscovite ages for the quartz-vein-type deposits.•Establish a geochronological ...framework of granitic emplacement and mineralization.
The Limu mining district is located in the Nanling Polymetallic Belt in South China. The district contains a number of W-Sn-Nb-Ta deposits and a number of exposed and unexposed granitic stocks that are connected as a single pluton at depth, referred to as Limu composite pluton. The deposits occur either within or above the stocks of the pluton, bearing a close mutual spatial relationship. Two types of W-Sn-Nb-Ta mineralization or ores exist in the district: the predominant quartz-vein type and the lesser albite-granite type. Extensive high-precision U-Pb zircon (SHRIMP and LA-ICP-MS) and Ar-Ar muscovite geochronological analyses on the granite stocks and the ores were performed in recent years, with exception only for the quartz-vein-type ores. This study applied Ar-Ar muscovite dating method for the quartz-vein-type ores at five quartz-vein-type deposits and obtained five new 40Ar/39Ar plateau ages ranging from 210 ± 1.5 Ma to 205.5 ± 1.6 Ma. New U-Pb zircon dating with LA-ICP-MS method was also performed for the non-mineralized Paoshuiling and mineralized Yucai stocks, which yielded weighted mean ages of 230.8 ± 0.63 Ma and 222.7 ± 1.2 Ma, respectively. With reliable geochronological data available for all the granites and mineralization types, combining field and petrographic observations, this study attempts to establish a high-resolution geochronological framework for three episodic granitic stocks and two mineralization types of the Limu district. The first episode is represented by Paoshuiling annite-lepidolite granite aged at 230.8 ± 0.63 Ma; the second-episode granite was emplaced at 224.8 ± 1.6–222.7 ± 1.2 Ma; and the third at 218.3 ± 2.4–212.3 ± 1.8 Ma. The high-temperature albite-granite-type mineralization began in the second episode of granitic emplacement and lasted into the third episode. The quartz-vein-type mineralization was subsequent to the albite-granite-type mineralization and immediately dominated the post-third-episode hydrothermal ore-forming process at 210 ± 1.5–205.5 ± 1.6 Ma as revealed by new muscovite Ar-Ar ages obtained in this study.
Introduction:
The North Qilian orogenic belt, as the Northern branch of the original Tethys tectonic domain, is important for reconstructing the tectonic evolution of the ancient Tethys. However, the ...tectonic history of the North Qilian orogenic belt remains controversial. This study addresses this issue from a geochemical perspective.
Methods:
In this study, a comprehensive analysis of the geochronology, whole-rock geochemistry, clinopyroxene mineral geochemistry, zircon Ti crystallization temperature, and gabbromagma temperature and pressure in the Yushigou ophiolite of the North Qilian orogenic belt was conducted to provide constraints on its tectonic evolution.
Results and Discussion:
Laser ablation inductively coupled plasma mass spectrometry zircon U-Pb dating results reveal that the gabbros have ages of 519 ± 3 Ma and 495 ± 4 Ma, belonging to the Cambrian period. Most of the studied gabbros exhibited geochemical characteristics of tholeiitic basaltic rocks with normal mid-ocean ridge basalt and island arc tholeiite dual geochemical affinities. The gabbros are interpreted to have formed by a high degree of partial melting of the depleted mantle spinel lherzolite. These results suggest that the back-arc basin of the North Qilian tectonic belt may have evolved to a relatively mature stage from 519 to 495 Ma. Overall, this study contributes to our understanding of the tectonic evolution of the North Qilian orogenic belt through geochemical analyses.
Many types of hydrothermal deposits (e.g. W, Bi, Pb, Zn, Ag) are confined by faults and hidden granodiorite in the Luowei Orefield in Xidamingshan, Guangxi, China. The orebodies in the Luowei W–Bi ...deposit are predominantly layered and distributed along bedding in sandstones of the Cambrian Xiaoneichong Formation. The orebodies in the Lujing Pb–Zn deposit are controlled mainly by west‐south‐west (WSW)‐trending faults, and those in the Fenghuangshan Ag deposit are controlled mainly by west‐north‐west (WNW)‐trending faults, which were reverse faults during mineralization and were later reactivated as sinistral strike‐slip faults. The Luowei fault was formed postmineralization and resulted in sinistral displacement of the subsurface granodiorite and the Cambrian strata. A tectonomagmatic mineralization model of the Luowei Orefield is proposed, and the following conclusions were made. (i) Under a regional N–S compressive stress regime, WSW‐ and WNW‐trending reverse faults and N–S‐trending tensional fractures were formed. (ii) Magma intruded along the tensional fractures. Under the force of magmatic thermodynamics, mineralizing fluid migrated along bedding planes in sandstones and formed W–Bi orebodies at favorable sites. Some fluid migrated along WSW‐ and WNW‐trending faults to sites farther from the magma source, forming vein‐type Pb–Zn and Ag orebodies. (iii) After mineralization, under ~E–W compression, a NW‐trending left‐lateral slip fault was formed, cutting the subsurface granodiorite and orebodies. Concurrently, sinistral shear slip occurred on WNW‐trending ore‐controlling faults. However, the small displacement on these faults did not change the overall distributions of the rock mass and orebodies.
The Luowei W–Bi deposit is dominated by bedding in Cambrian sandstone, and the Pb–Zn and Ag deposits are dominated by ∼E–W‐trending fault zones.Three deposits are located around the hidden granodiorite. WNW‐trending ore‐controlling faults were reverse faults during mineralization, and NW and WNW‐trending faults occurred sinistral shear slip after mineralization.
West Junggar is a key area for understanding intra-oceanic plate subduction and the final closure of the Junggar Ocean. Knowledge of the Carboniferous tectonic evolution of the Junggar Ocean region ...is required for understanding the tectonic framework and accretionary processes in West Junggar, Central Asian Orogenic Belt. A series of Early Carboniferous volcanic and intrusive rocks, namely, basaltic andesite, andesite, dacite, and diorite, occur in the Mayile area of southern West Junggar, northwestern China. Our new LA-ICPMS zircon U-Pb geochronological data reveal that diorite intruded at 334 (±1) Ma, and that basaltic andesite was erupted at 334 (±4) Ma. These intrusive and volcanic rocks are calc-alkaline, display moderate MgO (1.62%–4.18%) contents and Mg# values (40–59), and low Cr (14.5×10
−6
–47.2×10
−6
) and Ni (7.5×10
−6
–34.6×10
−6
) contents, and are characterized by enrichment in light rare-earth elements and large-ion lithophile elements and depletion in heavy rare-earth elements and high-field-strength elements, meaning that they belong to typical subduction-zone island-arc magma. The samples show low initial
87
Sr/
86
Sr ratios (range of 0.703649–0.705008), positive ε
Nd(t)
values (range of 4.8–6.2 and mean of 5.4), and young T
DM
Nd model ages ranging from 1016 to 616 Ma, indicating a magmatic origin from depleted mantle involving partial melting of 10%–25% garnet and spinel lherzolite. Combining our results with those of previous studies, we suggest that these rocks were formed as a result of northwestward subduction of the Junggar oceanic plate, which caused partial melting of sub-arc mantle. We conclude that intra-oceanic arc magmatism was extensive in West Junggar during the Early Carboniferous.
The Central Tianshan Block is one of numerous microcontinental blocks within the Central Asian Orogenic Belt (CAOB) that overlies Precambrian basement rocks. Constraining the evolution of these ...ancient basement rocks is central to understanding the accretionary and collisional tectonics of the CAOB, and their place within the Rodinia supercontinent. However, to date, the timing and tectonic settings in which the basement rocks in the Central Tianshan Block formed are poorly constrained, with only sparse geochemical and geochronological data from granitic rocks within the northern segment of the block. Here, we present a systematic study combining U-Pb geochronology, whole-rock geochemistry, and the Sr-Nd isotopic compositions of newly-identified granitic gneisses from the Bingdaban area of Central Tianshan Block. The analyzed samples yield a weighted mean Neoproterozoic
206
Pb/
238
U ages of 975–911 Ma. These weakly-peraluminous granitic rocks show a common geochemical I-type granite affinity. The granitic gneisses are calc-alkaline and enriched in large ion lithophile elements (LILEs) and light rare earth elements (LREEs), but they are depleted in high field strength elements (HFSEs); these characteristics are similar to those of typical subduction-related magmatism. All samples show initial (
87
Sr/
86
Sr)
(
t
)
ratios between 0.705136 and 0.706745. Values for
Ɛ
Nd(
t
)
in the granitic gneisses are in the range from −5.7 to −1.2, which correspond to Nd model ages of 2.0–1.7 Ga, indicating a role for Mesoproterozoic to Paleoproterozoic rocks in the generation of the granitic protoliths. The documented geochemical features indicate that the protoliths for the gneisses have a similar petrogenesis and magmatic source, which may reflect partial melting of thickened crust with the addition of small amounts of mantle-derived material. The Central Tianshan Block probably constitute part of an exterior orogen that developed along the margin of the Rodinian supercontinent during the Early Neoproterozoic and underwent a transition from subduction to syn-collision compression at 975–911 Ma.
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