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New data and interpretations on geological relationships of igneous rocks at Mokka Fiord, Axel Heiberg Island, Nunavut, provide insight into the timing and nature of magmatism associated with the Sverdrup Basin and High Arctic Large Igneous Province (HALIP). Field relationships indicate that the igneous rocks, previously interpreted to be volcanic flows, are most likely an intrusive unit discordant to regional bedding. An intrusive origin helps resolve chronostratigraphic inconsistencies in previous work. The host rocks are palynologically constrained to be late Barremian to late Aptian in age and are interpreted to be Paterson Island or Walker Island member of the Isachsen Formation. If the igneous body is intrusive, it's previously reported Ar–Ar age (102.5 ± 2.6 Ma) is no longer in conflict with accepted stratigraphic interpretations and probably reflects the emplacement age of the intrusion. Lingering uncertainties in interpreting the normal and reverse magnetic polarities determined in the previous work remain, and both are considered viable. Although this uncertainty precludes definitive conclusions on the significance of paleomagnetic data at Mokka Fiord, examination of the stratigraphic, paleomagnetic, and geochronologic relationships there highlight potential for the study of excursions, or reversed magnetic polarity subchrons, in the Cretaceous Normal Superchron elsewhere in the HALIP. [ABSTRACT FROM AUTHOR]

[Display omitted] • Garnet-hosted xenotime and gold are dated at ca. 1827 Ma • Early gold veins are metamorphosed to amphibolite facies (505–689 °C) • New ages for gold mineralization also post-date metamorphism by up to 80 Myr • Post-orogenic gold mineralization is coeval with biotite cooling ages (ca. 1746 Ma) • Exhumation of the Trans-Hudson orogen triggered gold mineralization Metamorphic devolatilization is thought to be the critical process that can liberate gold from amphibolite facies source rocks to form orogenic gold deposits. However, a growing number of studies demonstrate that orogenic gold deposits are the product of multiple hydrothermal stages over 10 s to 100 s of Myr rather than one metallogenic event. Herein we report new geochronology results for orogenic gold deposits hosted within the Paleoproterozoic Lynn Lake greenstone belt (Manitoba, Canada) to address the knowledge gap. Garnet-hosted xenotime crystals, which occur in a folded pyrite veinlet with gold, yield a weighted average 207Pb/206Pb date at 1827 ± 8 Ma. This new and more precise age demonstrates that the earliest auriferous fluids at the MacLellan gold deposit coincided with the rapid burial of ca. 1836 Ma sedimentary rocks before regional metamorphism. New garnet-biotite geothermometry results further demonstrate that the earliest auriferous veins were preserved despite being metamorphosed to amphibolite facies conditions (505–689 °C). The peak metamorphic mineral assemblage is overprinted by: (1) the main xenotime- and gold-bearing deformation fabric (S 2 ; 1790–1827 Ma); (2) an overprinting xenotime- and monazite-bearing S 3 fabric that is also associated with gold-rich arsenopyrite (1769–1790 Ma); and (3) chlorite-hosted xenotime and gold (1747 ± 12 Ma) that are coeval with the oldest U-Pb apatite dates (1691–1740 Ma) and a prominent mode of 40Ar/39Ar biotite dates at ca. 1746 Ma. We suggest that the post-orogenic gold events are incompatible with the standard devolatilization model because they post-date subduction and peak-metamorphism by up to 80 Myr. Instead, the new geochronological results suggest that gold deposition at the MacLellan deposit was linked to burial and the subsequent exhumation of chemically reactive trap rocks through favourable temperature windows that allowed gold transport as sulphide complexes. Exhumation and far-field tectonics are interpreted as the most likely drivers of post-orogenic auriferous fluids rather than regional metamorphism and active subduction. This revised mineral systems model provides an explanation for the high prospectivity of high- and low-temperature mineral assemblages and suggests that mineral exploration should focus on the earliest ore-forming structures that are reactivated during multiple stages of orogenesis. [ABSTRACT FROM AUTHOR]

Highlights: [•] We identify a ca. 830–810Ma back-arc basin in the southeastern Yangtze Block. [•] The basalts of Shaojiwa Formation might have been derived from a slightly depleted mantle source metasomatized by fluid. [•] The rhyolites of Shaojiwa Formation can be explained by fractional crystallization of the basaltic magma. [•] The precursor magma of the amphibolites might have been originated from an N-MORB source modified by slab-derived fluids. [•] Widespread Neoproterozoic igneous rocks (850–810Ma) in the Jiangnan Orogen most likely occurred in back-arc environment. [Copyright &y& Elsevier]

Highlights: [•] A back-arc basin developed along the southeastern Yangtze Block at 842–825Ma. [•] Neoproterozoic juvenile crustal growth in the southeastern Yangtze Block. [•] Orogen-parallel motion played a significant role in amalgamation of South China. [ABSTRACT FROM AUTHOR]

Abstract: A SHRIMP U–Pb zircon age along with geochemical and Nd–Hf isotopic results are reported for the Tieshajie volcanic rocks in the southeastern Yangtze Block, South China. The Tieshajie volcanic rocks are bimodal in composition and are dominantly transitional alkaline basalts and alkaline rhyolites, with an eruption age of 1159±8Ma. The basaltic samples have high TiO2 (2.14–3.12%) and relatively low Mg# (36–49) with variable ɛ Nd(t) values (−2.2 to +1.2), and display OIB-like incompatible elemental patterns, similar to many alkali basalts in continental rifts. These geochemical characteristics indicate that the primary magma of these basalts was probably derived from a moderately depleted asthenospheric mantle source and underwent fractional crystallization plus minor crustal contamination. The rhyolitic rocks are highly enriched in Th, Ta, Nb, REE, Zr, Hf and Y and depleted in Sr, P, Eu and Ti, showing affinity to A1-type granites. Combined with their slightly positive ɛ Nd(t) values (+1.3 to +1.6) and negative ɛ Hf(t) values (−2.45 to −12.7), the Tieshajie rhyolites were most likely generated by partial melting of mafic lower crust induced by basaltic underplating following asthenospheric ascent. The Tieshajie alkaline bimodal volcanic sequence is proposed to have developed within a continental rift setting on a passive continental margin. Combined with documented rift events in Yangtze Block during the late Mesoproterozoic, they may indicate onset of the amalgamation of Yangtze Block with other blocks within the Rodinia supercontinent. Integrating our data with the oldest arc-related igneous events in eastern Zhejiang, the transition of the regional tectonic regime from intracontinental rifting to interplate convergence occurred between ca. 1159Ma and 970Ma in the southeastern Yangtze Block. [Copyright &y& Elsevier]

Abstract: The reconstruction of the paleocontinental configuration involving ancestral North America (Laurentia) at the Paleoproterozoic–Mesoproterozoic boundary has been developed in the last 30 years with different scenarios being proposed and different combinations of landmasses assembled together. However, the lack of information for the northwestern side of the North American craton has so far been an obstacle for the complete paleocontinental reconstruction and its tectonic history. Here we provide new age determinations on rocks of the Wernecke Supergroup and of the Wernecke Breccia of the Wernecke Mountains in Yukon to provide a more complete picture of the entire North American craton and its possible conterminous at 1600Ma. The six youngest U–Pb ages of the detrital zircon from quartz sandstones of the Wernecke Supergroup suggest that the sedimentary succession is as old as 1640Ma. Lu–Hf garnet ages on garnet bearing schists of the Fairchild Lake Group (lower Wernecke Supergroup) give a bimodal population of ages of approximately 1600Ma and 1370Ma: the first age is related to the Racklan Orogeny, and the younger event is likely attributable to a reheating episode (Hart River Sills emplacement). The younger age of the Wernecke Supergroup puts into question the previous model concerning the emplacement of the Bonnet Plume River Intrusions, and requires the development of a new tectonic model for the northwestern margin of Laurentia. This new model involves obduction of an exotic terrane on top of the Wernecke Supergroup during the latest phases of the Racklan Orogeny (ca. 1600Ma). This exotic terrane, herein called Bonnetia, contains rocks of the Bonnet Plume River intrusions and of the Slab volcanics. During the hydrothermal event that led to the emplacement of the Wernecke Breccia, clasts and megaclasts of the overlying Bonnetia foundered down to the breccia pipes to the level of the Wernecke Supergroup, and this dynamic explains the existence of older rocks engulfed within a younger sedimentary succession. The Racklan Orogeny is now interpreted as a northwestern expression of the Mazatzal Orogeny of southwestern United States, and of the Labradorian Orogeny of eastern Canada which was in turn connected with the Gothian Orogeny of Scandinavia. The connection among these orogenic events makes plausible the hypothesis of a circum-Laurentian orogenic belt with possible extensions in other landmasses (Australia, Antarctica, Siberia, or China) where coeval deformation belts are present. [Copyright &y& Elsevier]

Abstract: U–Pb zircon SHRIMP geochronology and Lu–Hf zircon LA–MC–ICPMS isotope geochemistry are used to constrain the ages of Paleoproterozoic felsic magmatism and their crustal sources in the Aillik Group, Makkovik Province of Labrador. This information is important for understanding the extent of crustal reworking vs. juvenile crustal growth in subduction-related magmatism during the Paleoproterozoic and improves framework knowledge for uranium exploration in the Central Mineral Belt of Labrador. U–Pb SHRIMP zircon geochronology from four felsic tuff samples collected from two different areas of the Aillik Group yield magmatic 207Pb/206Pb ages of 1852±7Ma (2σ), 1854±7Ma (2σ), 1861±7Ma (2σ), and 1862±7Ma (2σ). The ages fall within the range of previous U–Pb zircon dates reported for felsic volcanic rocks of the Aillik Group. Altogether these dates indicate that felsic volcanism spanned at least 30m.y. and was perhaps most intense during the last 10m.y. of that interval. A foliated syn-deformational monzogranite in the Aillik Group (Cross Lake granite) yields a 207Pb/206Pb zircon date of 1805±6Ma (2σ), which indicates that development of a pervasive planar fabric associated with northwestward thrusting of the Aillik Group continued after this time. Initial values for magmatic zircons from the four felsic tuffs (−4.8 to −1.9, −1.7 to +2.2, −11.8 to +3.8, −9.0 to −4.6) and monzogranite (−4.8 to −1.5) exhibit significant variability, which indicates heterogeneous sources. Most of the zircon grains have negative initial values and calculated crust formation Hf-isotope T DM model ages point to substantial contributions from melts of ancient crust, ranging in age from ca. 2200 to 2900m.y. and clustering at ca. 2500m.y. Inherited zircon grains in the felsic tuffs and monzogranite, mainly have U–Pb ages of ca. 1880–1920Ma, though others are older, up to ca. 2743Ma. Hf-isotope T DM model ages for the inherited zircons are similar to those of the magmatic zircons. The Hf-isotope results indicate that subduction-related felsic magmatism in the Makkovik Orogen involved significant crustal reworking (∼80%) during formation of the Aillik Group. [Copyright &y& Elsevier]

• Provenance of Meall Dearg Formation (Torridonian succession) investigated in detail. • Detrital-zircon U-Pb ages compared to compilation from Lewisian Gneiss Complex. • Provenance from Lewisian Gneiss Complex resolved at the terrane scale. • Fluvial-aeolian sediment mixing investigated by detrital-zircon age distributions. • Meall Dearg Formation represents late stage of a rift basin within Laurentia. The Meall Dearg Formation is a 1.2 Ga fluvial-aeolian sandstone exposed in the northwestern Highlands of Scotland, and represents one of the least studied rock units in the Torridonian succession, especially in terms of sedimentary provenance. Three hundred and nine detrital zircon grains were analysed from four samples of the Meall Dearg Formation using sensitive high-resolution ion microprobe, allowing for its provenance to be resolved at the terrane scale. Ages range from c. 3,100 to c. 1,750 Ma, with dominant proportions between c. 2,900 and c. 2,650 Ma, and subordinate fractions of c. 2,500 Ma and c. 1,900 Ma. U-Pb protolith-zircon ages from eight previous studies across the Lewisian Gneiss Complex were compiled and compared to detrital-age distributions of the Meall Dearg Formation. Strong similarities in age trends and palaeocurrent data corroborates the hypothesis of sedimentary provenance from the Lewisian Gneiss Complex. Detritus was prevalently derived from the Rhiconich and Gruinard terranes, and subordinately from the Assynt, Gairloch (including the Loch Maree Group and Ard Gneiss), and Ialltaig terranes. Age distributions from the fluvial and aeolian samples show near-matching distributions, indicating sediment transfer between adjacent depositional environments, and possibly derivation from similar source regions. The Meall Dearg Formation, part of the Stoer Group, is postulated to record the overfilling stage of a rift basin near the eastern flank of the Columbia Supercontinent at c. 1.2 Ga. Critical comparisons can be drawn between the Stoer Group and Gardar Rift of southern Greenland, based on their age, palaeogeography, and patterns of rift-basin development. [ABSTRACT FROM AUTHOR]

Lung cancer patients treated with targeted therapies frequently respond well but invariably relapse due to the development of drug resistance. Drug resistance is in part mediated by a subset of cancer cells termed "drug-tolerant persisters" (DTPs), which enter a dormant, slow-cycling state that enables them to survive drug exposure. DTPs also exhibit stem cell-like characteristics, broad epigenetic reprogramming, altered metabolism, and a mutagenic phenotype mediated by adaptive mutability. While several studies have characterised the transcriptional changes that lead to the altered phenotypes exhibited in DTPs, these studies have focused predominantly on protein coding changes. As long non-coding RNAs (lncRNAs) are also implicated in the phenotypes altered in DTPs, it is likely that they play a role in the biology of drug tolerance. In this review, we outline how lncRNAs may contribute to the key characteristics of DTPs, their potential roles in tolerance to targeted therapies, and the emergence of genetic resistance in lung adenocarcinoma.

Plate tectonics is a fundamental factor in the sustained habitability of Earth, but its time of onset is unknown, with ages ranging from the Hadaean to Proterozoic eons 1-3 . Plate motion is a key diagnostic to distinguish between plate and stagnant-lid tectonics, but palaeomagnetic tests have been thwarted because the planet's oldest extant rocks have been metamorphosed and/or deformed 4 . Herein, we report palaeointensity data from Hadaean-age to Mesoarchaean-age single detrital zircons bearing primary magnetite inclusions from the Barberton Greenstone Belt of South Africa 5 . These reveal a pattern of palaeointensities from the Eoarchaean (about 3.9 billion years ago (Ga)) to Mesoarchaean (about 3.3 Ga) eras that is nearly identical to that defined by primary magnetizations from the Jack Hills (JH; Western Australia) 6,7 , further demonstrating the recording fidelity of select detrital zircons. Moreover, palaeofield values are nearly constant between about 3.9 Ga and about 3.4 Ga. This indicates unvarying latitudes, an observation distinct from plate tectonics of the past 600 million years (Myr) but predicted by stagnant-lid convection. If life originated by the Eoarchaean 8 , and persisted to the occurrence of stromatolites half a billion years later 9 , it did so when Earth was in a stagnant-lid regime, without plate-tectonics-driven geochemical cycling., (© 2023. The Author(s).)

Most of the described species in kingdom Fungi are contained in two phyla, the Ascomycota and the Basidiomycota (subkingdom Dikarya). As a result, our understanding of the biology of the kingdom is heavily influenced by traits observed in Dikarya, such as aerial spore dispersal and life cycles dominated by mitosis of haploid nuclei. We now appreciate that Fungi comprises numerous phylum-level lineages in addition to those of Dikarya, but the phylogeny and genetic characteristics of most of these lineages are poorly understood due to limited genome sampling. Here, we addressed major evolutionary trends in the non-Dikarya fungi by phylogenomic analysis of 69 newly generated draft genome sequences of the zoosporic (flagellated) lineages of true fungi. Our phylogeny indicated five lineages of zoosporic fungi and placed Blastocladiomycota, which has an alternation of haploid and diploid generations, as branching closer to the Dikarya than to the Chytridiomyceta. Our estimates of heterozygosity based on genome sequence data indicate that the zoosporic lineages plus the Zoopagomycota are frequently characterized by diploid-dominant life cycles. We mapped additional traits, such as ancestral cell-cycle regulators, cell-membrane- and cell-wall-associated genes, and the use of the amino acid selenocysteine on the phylogeny and found that these ancestral traits that are shared with Metazoa have been subject to extensive parallel loss across zoosporic lineages. Together, our results indicate a gradual transition in the genetics and cell biology of fungi from their ancestor and caution against assuming that traits measured in Dikarya are typical of other fungal lineages.

Plantago princeps var. princeps is an endangered native Hawaiian plant, and part of the recovery plan includes repopulation using plants grown in a nursery. However, disease pressure from downy mildew is hindering repopulation efforts. The organism associated with the downy mildew was determined to be a Peronospora species with brown, ellipsoid conidia measuring 21 by 16 µm on average, which was morphologically different from validly described species of Peronospora that infect Plantago species, but it was morphologically similar to the invalidly published species Peronospora lanceolatae (Art. 40.1). Comparison of mitochondrial cytochrome oxidase subunit I ( cox 1), mitochondrial cytochrome oxidase subunit II ( cox 2), nuclear internal transcribed spacer (ITS), and nuclear 28S rRNA D1-D2 (28S) loci revealed the unknown Peronospora to be molecularly divergent from Peronospora alta and Peronsopora plantaginis , but very similar to Peronospora from Plantago lanceolata , the type host of P. lanceolatae . Phylogenetic trees inferred with maximum likelihood and Bayesian inference from a concatenated alignmaent and individual gene trees confirmed the divergence of the unknown Peronospora from P. alta and P. plantaginis and its similarity to P. lanceolatae . However, attempts to inoculate Plantago lanceolata with the strain from Plantago princeps var. princeps were unsuccessful, which, in conjunction with divergence in ITS, suggests that the unknown Peronospora is specific to Plantago princeps var. princeps . Herein, the Peronospora strain on Plantago princeps var. princeps is described as the new species Peronospora kuewa based on morphology, molecular phylogenetics, and host specificity. In addition, Peronospora gaponenkoae is described here to honor Nina Ivanova Gaponenko on the basis of her description of P. lanceolatae .

Background: Devastating transient and permanent postoperative neurocognitive complications in previously healthy, low-risk patients have been observed after elective shoulder arthroscopy in the beach chair position (BCP). Continuous monitoring of cerebral oxygen saturation has been recommended to identify cerebral desaturation events (CDEs) and improve patient safety. However, the relatively high cost and limited availability of monitoring may not be cost-effective. More cost-effective and available measures, including the use of thigh-high compression stockings (CS), have been investigated. However, efficacy data of CS usage is limited, especially for obese patients, who have been shown to be at increased risk for CDEs. The purpose of this was study was to determine if the intraoperative addition of thigh-high compression stockings decreases the incidence, frequency, and magnitude of CDEs in obese patients undergoing shoulder arthroscopy in the BCP., Methods: Thirty-three patients in the treatment group wore both thigh-high compression stockings (CS) and sequential compression devices (SCDs), and the remaining 33 patients in the control group wore SCDs alone. Cerebral oximetry was monitored during surgery using near-infrared spectroscopy., Results: The incidence of CDEs was equal between groups, with 9 patients (27%) in each experiencing desaturation events. The median number of CDEs per patient was 3 for the control group and 1 for patients wearing CS (P = .29). There was no difference between groups in terms of median time from induction of anesthesia to onset of CDE (P = .79), median time from upright positioning to onset of CDE (P = .60), mean CDE duration per patient (P = .22), and median cumulative CDE duration (P = .19). The median maximal desaturation from baseline was also not different between groups: 27.6% in the control group and 24.3% in the treatment group (P = .35)., Conclusion: The combination of thigh-high CS and SCDs did not decrease the incidence, frequency, or magnitude of CDEs in patients undergoing shoulder arthroscopy in the BCP. Twenty-seven percent of patients undergoing shoulder arthroscopy in the BCP demonstrated CDEs with or without the use of CS. Therefore, further research is required to identify cost-effective, minimally invasive, and universally available methods of decreasing the incidence of CDEs during this common surgical procedure., (Copyright © 2020 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

The beach chair position (BCP) is commonly used position in upper extremity surgery. Although there are many advantages to surgery in this position, there are also potential drawbacks and described complications including devastating neurologic outcomes. The etiology of these complications is postulated to be due to the gravitational effects of the seated position leading to cerebral hypoperfusion. We review the current literature on intraoperative cerebral monitoring and neurocognitive complications with shoulder surgery performed in the BCP. A previous systematic review estimated the incidence of neurocognitive complications after surgery in the BCP to be 0.004%. However, the true incidence is unknown and is likely much more common. Reports of neurologic complications have revealed a need for heightened vigilance, alternative anesthesia techniques, and improved monitoring. Methods for monitoring have included near-infrared spectroscopy, a measurement of cerebral oximetry shown to reliably detect cerebral hypoperfusion. In this literature review, we sought to update the incidence of intraoperative cerebral desaturation events (CDEs) to investigate the relationship of CDEs to neurocognitive complications and to review recent reported cases of neurocognitive complications. Existing literature suggest that accurate intraoperative monitoring of cerebral perfusion may improve patient safety., (Copyright © 2019 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Orthopaedic Surgeons.)

Food webs in temporary forest ponds are driven by decomposition of terrestrial inputs. Chytrid fungi are important components of the fungal community, degrading leaf litter in streams reliant on terrestrial inputs and in lake ecosystems where they may stabilize the food web. However, little is known about chytrid fungi in temporary forest ponds. We inventoried the chytrid diversity present in two temporary forest ponds via light microscopy of baited samples and ion semiconductor (Ion Torrent) sequencing of environmental DNA. We quantified trends of chytrid alpha and beta diversity as a function of spatial and temporal factors. A total of 59 chytrid taxa were detected throughout the study. Beta diversity exhibited variation across the sampled months for both the entire fungal community as well as for chytrids alone. Shifts in community composition were also apparent, although diversity metrics and composition patterns did not meet adjusted P values. The results of this study highlight the diversity of chytrid fungi in temporary forest ponds and the need for further studies on the spatial and temporal dynamics of chytrid species.

Knowing when the geodynamo started is important for understanding the evolution of the core, the atmosphere, and life on Earth. We report full-vector paleointensity measurements of Archean to Hadean zircons bearing magnetic inclusions from the Jack Hills conglomerate (Western Australia) to reconstruct the early geodynamo history. Data from zircons between 3.3 billion and 4.2 billion years old record magnetic fields varying between 1.0 and 0.12 times recent equatorial field strengths. A Hadean geomagnetic field requires a core-mantle heat flow exceeding the adiabatic value and is suggestive of plate tectonics and/or advective magmatic heat transport. The existence of a terrestrial magnetic field before the Late Heavy Bombardment is supported by terrestrial nitrogen isotopic evidence and implies that early atmospheric evolution on both Earth and Mars was regulated by dynamo behavior., (Copyright © 2015, American Association for the Advancement of Science.)