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The metamorphic conditions of the Natal Metamorphic Province (NMP) have been the focus of previous studies to assist with Rodinia reconstructions but there are limited constraints on the age of metamorphism. We use a combination of modern techniques to provide new constraints on the conditions and timing of metamorphism in the two southernmost terranes: the Mzumbe and Margate. Metamorphism reached granulite facies, 780–834°C at 3.9–7.8 kbar in the Mzumbe Terrane and 850–892°C at 5.7–6.1 kbar in the Margate Terrane. The new pressure and temperature constraints are supportive of isobaric cooling in the Margate Terrane as previously proposed. Peak metamorphism of the two terranes is shown to have occurred c. 40 myr apart, which contrasts strongly with previous assumptions of coeval metamorphism. While the age of peak metamorphism of the Margate Terrane (1032.7 ± 4.7 Ma) coincides with the tectonism and magmatism associated with the emplacement of the Oribi Gorge Suite ( c. 1050–1030 Ma), the age of metamorphism of the Mzumbe Terrane (987.4 ± 8.1 Ma) occurs c. 30–40 myr after tectonism is previously thought to have finished. We propose that models of advective cooling during transcurrent shearing can explain the metamorphic conditions and timing of the NMP.

Bibliometric and survey-based data are used to evaluate and compare the productivity of Earth scientists. Work-from-home initiatives have led to disproportionate impact among different genders. An individual’s perception of their own productivity is significant in understanding how equity-deserving groups are affected by disruptions to normal routines. Additionally, peer-reviewed publications are a key metric of academic productivity, as they are a vital component of career advancement. Using sex- (female vs. male) and gender-based (women vs. men) methods, this study investigates how both the perceived and measured productivity of women and men was impacted by global COVID-19 work-from-home initiatives. Here we show that in a normal year females publish proportionally to males, and that the proportion of female first authors increased between the 2019-2020 (“pre-pandemic”) and 2020-2021 (“during pandemic”) years. This finding is contrary to the perceived productivity between women and men and indicates that our perceptions may not always match reality. Although women and men are publishing at nearly identical rates based on their proportions within our field, women are harder on themselves. Support structures should be focused on women and early-career researchers as their more negative perception of self-productivity can lead to mental health issues and a lack of confidence.

The mechanism and timing of crustal growth and differentiation on early Earth are debated. Evidence of crustal differentiation is detectable as deviations from Earth’s assumed chondritic uniform reservoir (CHUR) as crust is extracted from the mantle leading to a melt-depleted reservoir. For the long-lived zircon Lu-Hf system, no incontrovertible evidence of significant mantle depletion >3.8 Ga exists. We conduct combined U-Pb and Lu-Hf isotopic analyses for the detrital zircon from the Caozhuang supracrustal sequence in North China. The zircon Hf isotopic compositions are broadly scattered along the CHUR evolution line. However, given the possibility of potential systematic biases in zircon petrogenesis and the unique tectonic setting of early Earth, we posit that magmatism controlled by the nascent forms of plate tectonics during the Eoarchean could have likely hidden the degree of ancient crust-mantle differentiation. The non-depleted zircon Hf isotopes observed in North China and globally during early Earth may in verity imply the existence of ubiquitous depleted mantle domains at that time.

The timing of the emergence of subaerial landmasses is equivocally constrained as post-Archean and continues to be a much-debated issue. In this study, we document exceptionally 18O-depleted (δ18O < 4.7‰) Mesoarchean to early Neoarchean magmatism in India that shows a similarity with the coeval low-δ18O magmas reported from Australia, South America, and northern China. Such global-scale low-δ18O magmatism would require high-temperature meteoric water–rock interaction in the uppermost crust synchronous with magma generation, necessitating the emergence of a substantial volume of the continental crust. The timing of this low-δ18O magmatism coincides with the development of extensive, subaerial large igneous provinces, a downward shift in δ18O and Δ17O values in pelitic rocks, the rise of normalized 87Sr/86Sr in seawater, and an intermittent upsurge in the proportion of atmospheric oxygen. We propose that the emergence of substantial volumes of continental crust initiated at ca. 3.2 Ga and peaked at 2.8–2.6 Ga, facilitating the generation of globally distributed low-δ18O magmas, and this event can be linked to the first appearance of atmospheric oxygen.

How serpentinites in the forearc mantle and subducted lithosphere become involved in enriching the subarc mantle source of arc magmas is controversial. Here we report molybdenum isotopes for primitive submarine lavas and serpentinites from active volcanoes and serpentinite mud volcanoes in the Mariana arc. These data, in combination with radiogenic isotopes and elemental ratios, allow development of a model whereby shallow, partially serpentinized and subducted forearc mantle transfers fluid and melt from the subducted slab into the subarc mantle. These entrained forearc mantle fragments are further metasomatized by slab fluids/melts derived from the dehydration of serpentinites in the subducted lithospheric slab. Multistage breakdown of serpentinites in the subduction channel ultimately releases fluids/melts that trigger Mariana volcanic front volcanism. Serpentinites dragged down from the forearc mantle are likely exhausted at >200 km depth, after which slab-derived serpentinites are responsible for generating slab melts., How the subducted oceanic lithosphere provides fluids and melts to flux the subarc mantle source of arc magmas is controversial. Here the authors use Mo and other isotopes to show serpentinites formed in both the forearc mantle and the subducted lithosphere contribute to generating arc magmas.

The Archean-Proterozoic transition marks a time of fundamental geologic, biologic, and atmospheric changes to the Earth system, including oxygenation of the atmosphere (termed the Great Oxygenation Event; GOE), and the emergence of continents above sea level. The impacts of the GOE on Earth’s surface environment are imprinted on the geologic record, including the disappearance of mass-independent fractionation of sulfur isotopes (S-MIF). Temporally overlapping geologic and geochemical observations (e.g. a change in oxygen isotope ratio of sediments and an increase in subaerial volcanism) imply the widespread subaerial emergence of continents was coeval with atmospheric oxygenation. Here we present triple sulfur isotope ratios in pyrite and oxygen isotope ratios in garnet and zircon in a global suite of Archean and Proterozoic granitoids derived from the partial melting of sedimentary protoliths. These crustal melts record an increase in average garnet and zircon δ18O from 7.2‰ before 2.3 Ga to 10.0‰ post-2.3 Ga. Pre-2.3 Ga granitoids show small S-MIF signatures with Δ33S ranging from −0.29‰ to 0.13‰, whereas post-2.3 Ga granitoids record S-MDF (i.e. Δ33S = 0‰). The combination of sulfur and oxygen isotope signatures in the same sample with zircon U-Pb geochronology provides new insights on a potential causal link between the emergence of continents and Paleoproterozoic atmospheric oxygenation.

Supercontinents signify self-organization in plate tectonics. Over the past ~2 billion years, three major supercontinents have been identified, with increasing age: Pangaea, Rodinia and Columbia. In a prototypal form, a cyclic pattern of continental assembly and breakup likely extends back to ~3 billion years ago, albeit on the smaller scale of Archaean supercratons, which, unlike global supercontinents, were tectonically segregated. In this Review, we discuss how the emergence of supercontinents provides a minimum age for the onset of the modern global plate tectonic network, whereas Archaean supercratons might reflect an earlier geodynamic and nascent tectonic regime. The assembly and breakup of Pangaea attests that the supercontinent cycle is intimately linked with whole-mantle convection. The supercontinent cycle is, consequently, interpreted as both an effect and a cause of mantle convection, emphasizing the importance of both top-down and bottom-up geodynamics, and the coupling between them. However, the nature of this coupling and how it has evolved remains controversial, resulting in contrasting models of supercontinent formation, which can be tested by quantitative geodynamic modelling and geochemical proxies. Specifically, which oceans close to create a supercontinent, and how such predictions are linked to mantle convection, are directions for future research. Repeated amalgamation and dispersal of continents over Earth history is known as the supercontinent cycle; however, the geodynamic processes driving this cyclicity remain debated. This Review synthesizes observations, plate reconstructions and geodynamic models of supercontinent, and older Archaean supercraton, cycles.

Background To identify factors predictive of developing symptomatic radiation necrosis (sRN) among patients with either intact or resected brain metastases undergoing five-fraction stereotactic radiosurgery (5fSRS). Methods Multi-institutional retrospective review of 117 brain metastases from 83 patients treated with 5fSRS. The cumulative incidence of sRN and predictors of sRN were calculated using Gray’s competing risks and Cox regression. Results The median dose of 5fSRS was 30 Gy (range: 25–40), and 21 lesions (18%) had prior SRS. After a median follow-up of 10.3 months (range: 3–52), the cumulative sRN incidence was 15%, with a median time to sRN of 6.9 months (range: 1.8–31.7). sRN incidence was significantly higher among the lesions treated with prior SRS: hazard ratio (HR): 7.48 [95% confidence interval: 2.57–21.8]. Among lesions without prior SRS, higher volume of uninvolved brain receiving 25 Gy (BrainV25; HR: 1.07 [1.02–1.12]) and 30 Gy (BrainV30; HR: 1.07 [1.01–1.33]) were the most significant factors associated with sRN. Similar results were also observed among the patients with prior SRS. For lesions without prior SRS, BrainV25 > 16 cm3 (HR: 11.7 [1.47–93.3]) and BrainV30 > 10 cm3 (HR: 7.08 [1.52–33.0]) were associated with significantly higher risk of sRN. At two years, the sRN incidence was 21% if violating either dosimetric threshold and 2% if violating neither (p = .007). Conclusion BrainV25 and BrainV30 are significant dosimetric predictors of sRN of brain metastases treated with 5fSRS. In the absence of prior SRS, maintaining BrainV25Gy

The Earth is unique in the Solar System due to significant volumes of granite in the lithosphere. However, the origins of granites are still highly debated, especially sediment-derived granites, which are often treated as a geochemical end-member of the continental crust. In the Yunnan region of South China, we identify the occurrence of pure sediment-derived granite in a subduction system. The suite of strongly peraluminous granite reported herein is interpreted to represent pure metasedimentary melts based on their whole-rock elemental and Sr-Nd-B and zircon Hf-O isotopic compositions. These Late Permian–Early Triassic (ca. 254–248 Ma) granites are characterized by radiogenically enriched Sr, Nd, and Hf isotopic signatures. They show δ11B and δ18O signatures akin to those of continental shales. Geochemical modeling indicates no contributions from the mantle that can be detected. Considering the regional tectonic evolution, these granites are suggested to be formed in a subduction zone by decompression melting of rapidly exhumed back-arc sediments. We posit that decompression melting was triggered by widespread extension and thinning of the crust prompted by rollback of the subducting oceanic crust. These granites thus provide evidence that granite formation in subduction zones does not necessarily contribute to crustal growth. These subduction-related pure sediment-derived granites have different elemental ratios and contents (e.g., Al2O3/TiO2 and Yb) from the Himalayan leucogranites. Considering their source compositions (e.g., pelitic rocks), which are similar to those of the Himalayan leucogranites, these differences are likely due to their higher formation temperature and lower pressure despite a great similarity in isotopic compositions. Identification of pure sediment-derived, strongly peraluminous granites (SPGs) in subduction systems provides an important geodynamic mechanism for crustal anatexis, which can both geochemically and tectonically complement their collisional counterparts identified in the Himalayas.

We explore the effects of health and healthcare utilization on household saving and financial portfolios using data from the Japanese Household Panel Survey and the Keio Household Panel Survey. Poor psychological well-being is found to be associated with lower levels of savings and smaller financial portfolios, whereas associations with poor physical health are largely absent. Significantly, our findings do not support the hypothesis that poorer physical health is associated with savings accumulation. In contrast, healthcare utilization in the form of hospital visits, hospitalization, and health screening is associated with greater savings and larger financial portfolios. This suggests that healthcare-based incentives to accumulate savings and financial wealth are related to channels associated with investment in health.

Supercontinent Pangea was preceded by the formation of Gondwana, a “megacontinent” about half the size of Pangea. There is much debate, however, over what role the assembly of the precursor megacontinent played in the Pangean supercontinent cycle. Here we demonstrate that the past three cycles of supercontinent amalgamation were each preceded by ∼200 m.y. by the assembly of a megacontinent akin to Gondwana, and that the building of a megacontinent is a geodynamically important precursor to supercontinent amalgamation. The recent assembly of Eurasia is considered as a fourth megacontinent associated with future supercontinent Amasia. We use constraints from seismology of the deep mantle for Eurasia and paleogeography for Gondwana to develop a geodynamic model for megacontinent assembly and subsequent supercontinent amalgamation. As a supercontinent breaks up, a megacontinent assembles along the subduction girdle that encircled it, at a specific location where the downwelling is most intense. The megacontinent then migrates along the girdle where it collides with other continents to form a supercontinent. The geometry of this model is consistent with the kinematic transitions from Rodinia to Gondwana to Pangea.

The status of Pannotia as an Ediacaran supercontinent, or even its mere existence as a coherent large landmass, is controversial. The effect of its hypothesized amalgamation is generally ignored in mantle convection models claiming the transition from Rodinia to Pangaea represents a single supercontinent cycle. We apply three geodynamic scenarios to Pannotia amalgamation that are tested using regional geology. Scenarios involving quasi-stationary mantle convection patterns are not supported by the geological record. A scenario involving feedback between the supercontinent cycle and global mantle convection patterns predicts upwellings beneath the Gondwanan portion of Pannotia and the arrival of plumes along the entire Gondwanan (but not Laurentian) margin beginning at c. 0.6 Ga. Such a scenario is compatible with regional geology, but the candidates for plume magmatism we propose require testing by detailed geochemical and isotopic studies. If verified, this scenario could provide geodynamic explanations for the origins of the late Neoproterozoic and Early Palaeozoic Iapetus and Rheic oceans and the terranes that were repeatedly detached from their margins.

The Earth’s mantle is currently divided into the African and Pacific domains, separated by the circum-Pacific subduction girdle, and each domain features a large low shear-wave velocity province (LLSVP) in the lower mantle. However, it remains controversial as to whether the LLSVPs have been stationary through time or dynamic, changing in response to changes in global subduction geometry. Here we compile radiogenic isotope data on plume-induced basalts from ocean islands and oceanic plateaus above the two LLSVPs that show distinct lead, neodymium and strontium isotopic compositions for the two mantle domains. The African domain shows enrichment by subducted continental material during the assembly and breakup of the supercontinent Pangaea, whereas no such feature is found in the Pacific domain. This deep-mantle geochemical dichotomy reflects the different evolutionary histories of the two domains during the Rodinia and Pangaea supercontinent cycles and thus supports a dynamic relationship between plate tectonics and deep-mantle structures. Earth’s deep-mantle domains are geochemically distinct. The African domain is enriched in subducted material, which suggests a different history from the Pacific domain and a dynamic relationship between plate tectonics and deep-mantle structures.

There is no question that rural patients face a number of healthcare-related obstacles; however, rural healthcare challenges may also place a significant burden on healthcare professionals who treat these patients. Cancer care is already complex and challenging, but oncology professionals in rural settings may face additional challenges as a result of unique issues their patients face. Very little research has specifically assessed how distinct characteristics of the rural setting and patient population may impact rural oncology professionals’ work experience. The purpose of this study was to better understand the impact of the rural setting on oncology professionals’ work experience in hopes to identify future areas to target for recruitment and retention purposes. We utilized a qualitative case study design. Multiple healthcare professionals, including oncologists, nurses, social workers, and administrators, were interviewed, and a number of challenges and benefits to providing rural healthcare were identified. Overall, we provide a holistic, interdisciplinary approach to understanding positive and negative work experiences associated with providing rural care. We also provide a foundation for future research to better understand direct connections between rural healthcare, and challenges and benefits faced as part of oncology professionals’ work experience.

Electrostatic charging of hospital personnel and patients during various activities increases the risk of electrostatic discharge (ESD) malfunctions of medical devices and the likelihood of patients’ adverse events. Therefore, the test level for ESD immunity of medical devices, specified in the IEC 60601-1-2 standard needs to reflect the reasonably maximum electrostatic voltages during usage. This study investigated the effects of material combinations and relative humidity on the body voltage while performing two routine clinical activities of lying down on a hospital bed and transferring to a bed using a sliding board. The peak body voltages in nearly 50% of the lying down experiments and 40% of sliding tests exceeded the test voltage level in the IEC 60601-1-2 standard (i.e., 15 kV). Using cotton blankets in lying down experiments and nylon sheets during sliding experiments resulted in 50% and 40% larger median than the median including all combinations, respectively. Sliding boards with antistatic coating reduced the peak body voltage by 24% on average, however, 33% of the tests still exceeded 15 kV. Based on the findings, recommendations are provided for healthcare facilities and medical device manufacturers to mitigate the risks of ESD malfunctions.

Analysis of a database of ∼600,000 detrital zircon ages constrained by the depositional ages of the respective sedimentary units reveals a dynamic evolution of zircon age peaks through time. This analysis demonstrates that zircon age peaks from ancient sedimentary successions are often out of phase with the detrital zircon record obtained from modern sediments. The growth and diminishment of the zircon age peaks through time implies the presence of continental crust whose age is not proportionately represented in the modern record, and therefore that the current crustal archive is biased. However, when the detrital zircon record is viewed in terms of its evolution through time, that is taken as a time-lapse view of continental growth, it appears there never was a time in Earth history without an associated zircon age peak. The analysis of detrital zircon age peaks presented herein also reveals an evolution that can be broadly divided into three temporal groupings that broadly correspond with phases of Earth9s tectonic evolution, namely pre-supercontinent continental growth (pre-2.1 Ga), Earth9s middle age (2.1–0.8 Ga), and post-onset of modern-day plate tectonics (post-0.8 Ga). These three groupings each display increasing degrees of zircon age diversification with time, and are a likely result of a net increase of preserved continental crust through time. The presence of these three tectonic states in multiple geologic proxies (detrital zircon ages, changing styles of metamorphism, paleogeography/supercontinents) suggests that while the growth of the continental crust is continuous, the tectonic processes that shape the long-term preservation of the crust have evolved over geologic time.

Forearc basins preserve the geologic record relating strictly to arc magmatism. The provenance of forearc sediment can be used to differentiate periods of crustal growth, accretion, and destruction, enhanced magmatism, advancing and retreating subduction slabs, delamination, etc. All these tectonic events systems predict differing degrees of sedimentary reworking of the older forearc units. Additionally, Hf isotopes of zircon can be used to evaluate the degree of continental reworking that occurs in the arc system. In this paper, we evaluate the changes in a long-lived subduction system using detrital zircon U-Pb and Hf data from forearc units in northern Honshu, Japan that span in age from the Silurian Period to the present from the forearc provenance of the Japanese subduction system. Our data demonstrate a series of dominant age peaks (430 ± 20, 360 ± 10, 270 ± 20, 184 ± 12, 112 ± 22, and 7 ± 7 Ma) and a progressive loss of the older zircon populations. Zircon Hf data reveal three discrete shifts that correspond to differing degrees of isotopic enrichment and correlate with changes in the dominant zircon age peaks. Additionally, each temporal isotopic shift is associated with isolation of the older sedimentary packages wherein no detrital zircon from the previous stages are observed in subsequent stages. We propose these shifts provide evidence for rapid shifts in arc tectonics including: magmatic flare-ups, producing the dominant peaks; protracted tectonic erosion progressively removing older sources of zircons reveals; a late Carboniferous event triggering the complete removal of the Precambrian crust; and the Cretaceous melting of the entire Permian arc crust, likely related with the subduction of the mid-oceanic ridge separating the Izanagi and Pacific plates.

Global-scale cycling of silicon through the biosphere, atmosphere, and hydrosphere has received much attention although, silicon cycling in the Earth’s lithosphere remains poorly understood. As the products of internal heat and material exchange, igneous rocks preserve significant information of silicon migration through the lithosphere. Here we report silicon isotopic compositions of nine peraluminous granites from the Chinese Altai, which forms part of the Central Asian Orogenic Belt. These rocks are characterized by the heaviest δ30Si values (−0.13 ± 0.03‰ to +0.78 ± 0.05‰) compared to global granites, with a linear variation in the silicon isotopic values against silica content, with high silica-rich granites displaying more depleted isotopic compositions. In conjunction with the whole rock weakly negative ɛNd(t) and uniform δ26Mg values, as well as high δ18O values, we suggest that the δ30Si values of these granites were mainly inherited from the magma source, rather than produced by magmatic fractionation. In addition, the wide range of initial 87Sr/86Sr ratios and high Ba content of the samples suggest the role of aqueous fluids. The Chinese Altai is considered to have formed through accretion of volcanic arcs associated with subduction of the Paleo-Asian oceanic lithosphere. The magma derived through partial melting of metasomatic mantle scavenges the heavy 30Si isotopes derived through fluids released from oceanic sediments and transfers to the upper crust where partial melting of crustal sedimentary rocks occur. Mixing of these two melts generated the peraluminous granites. Our study offers a novel insight into a potentially important mechanism of silicon cycling in the lithosphere.

Diamonds are erupted at Earth’s surface in volatile-rich magmas called kimberlites1,2,3. These enigmatic magmas, originating from depths exceeding 150 kilometres in Earth’s mantle1, occur in stable cratons and in pulses broadly synchronous with supercontinent cyclicity4. Whether their mobilization is driven by mantle plumes5 or mechanical weakening of cratonic lithosphere4,6 remains unclear. Here we show that most kimberlites spanning the past billion years erupted approximately 25 million years after the onset of continental fragmentation, suggesting an association with rifting processes. Our dynamic models show that physically steep lithosphere-asthenosphere boundaries formed during terminal rifting (necking) generate convective instabilities in the asthenosphere that slowly migrate many hundreds of kilometres inboard of the rift, causing destabilization of cratonic mantle keel tens of kilometres thick. Displaced lithosphere is replaced by hot, upwelling asthenosphere in the return flow, causing partial melting of carbonated mantle and variable assimilation of lithospheric material. The resulting small-volume kimberlite magmas ascend rapidly and adiabatically, exsolving amounts of carbon dioxide (CO2) that are consistent with independent constraints7. Our model reconciles diagnostic kimberlite features including association with cratons and geochemical characteristics that implicate a common asthenospheric mantle source contaminated by cratonic lithosphere8. Together, these results provide a quantitative and mechanistic link between kimberlite episodicity and supercontinent cycles via progressive disruption of cratonic keels.

Subduction is a major process cycling material through Earth’s geochemical reservoirs. Although trends in chemical composition of arc magmas imply assimilation of metasediment, the degree of such assimilation and the loci of that metasediment contamination (whether via subducted sediment or country rock assimilation) are poorly understood. To address these issues, we explore compositional data of oceanic and continental arc systems from circum-Pacific subduction zones. We find that high-silica continental arc rocks of the circum-Pacific are associated with higher aluminium saturation indices interpreted to reflect higher degrees of metasediment assimilation, with Sr/Y suggestive of shallow emplacement levels within the crust. In contrast, high-silica oceanic rocks of the circum-Pacific display lower aluminosity and equilibrated at deeper levels within the crust. Continental arc basalts are often assumed to be the source of high-silica continental arc rocks. However, phase equilibrium modelling of partial melting and crystal fractionation of continental arc basalts yield results that question this assumption. Furthermore, continental arc rock compositions show that the assimilated metasediments have protoliths that are most probably felsic greywacke and pelite rather than mafic greywacke. These findings are consistent with the hypothesis that high-silica rocks in continental arcs are directly influenced by anatexis of metasediment at shallow crustal levels (

The Archean‐Proterozoic transition heralded a number of fundamental changes on Earth, including the oxygenation of the atmosphere, a marked emergence of continents above sea‐level, and an increase in δ¹⁸O of felsic magmas. The potential drivers for the latter are changes in the composition of supracrustal material or increased crustal reworking. Although the onset of subduction‐induced continental collision and associated enhanced crustal recycling could produce high‐δ¹⁸O felsic magmas, temporally constrained zircon δ¹⁸O reveals an increase in δ¹⁸O at ~2.35 Ga that predates the oldest widely recognized supercontinent. In this work, we use the O and Hf isotope ratios of magmatic zircon crystals in Archean and Proterozoic sediment‐derived granitoids of the North China Craton to track the incorporation of supracrustal material into magmas. The results are consistent with a Paleoproterozoic increase of continental freeboard producing sedimentary reservoirs with comparatively elevated δ¹⁸O that subsequently partially melted to generate the granitoids.

Analysing the Panel Study of Income Dynamics and the Health and Retirement Study, we investigate the extent to which US households reduce their financial risk exposure when confronted with background risk. Our novel modelling approach – termed a deflated ordered fractional model – quantifies how the overall composition of a household portfolio with three asset classes adjusts with background risk, and is unique in recovering for any given risky asset class the shares that are reallocated to each safer asset category. Background risk exerts a significant impact on household portfolios, inducing a ‘flight from risk’ from riskier to safer assets.

Supplemental Digital Content is available in the text., Introduction: Patients receiving cyclophosphamide or ifosfamide chemotherapy require intravenous fluid hydration to prevent hemorrhagic cystitis. In selected patients without medical contraindications (ie, excess nausea/vomiting), this hydration may be completed after discharge. We aimed to reduce the time to discharge after completing mesna in patients receiving cyclophosphamide or ifosfamide therapy on an inpatient chemotherapy service. Methods: The quality improvement team performed a medical record review to capture the time to discharge after mesna therapy and the readmission rate and used quality improvement methods to redesign discharge workflow and increase patient involvement with the discharge process. Results: From August 2017 through July 2018, there were 160 admission encounters (73 patients) for cyclophosphamide or ifosfamide on a dedicated chemotherapy service. Of those encounters, 89 (55.6%) were appropriate for outpatient hydration; 48 (53.9%) of these encounters involved a patient who elected to receive outpatient hydration. Although the median time to discharge for the whole cohort did not change, in encounters where patients chose intravenous outpatient hydration, the median time to discharge was reduced from 2.82 to 0.66 hours (76.6% reduction) after implementing the new discharge workflow. No patients experienced readmission within 48 hours. Conclusions: Discharge workflow redesign and standardization reduced the time to discharge after chemotherapy in patients who chose outpatient hydration. Outpatient intravenous hydration after cyclophosphamide or ifosfamide appears safe and feasible in selected patient populations.

The Southern Great Xing'an Range (SGXR) which forms part of the eastern segment of the Central Asian Orogenic Belt (CAOB) is known as one of the most important Cu-Mo-Pb-Zn-Ag-Au metallogenic belts in China, hosting a number of porphyry Mo (Cu), skarn Fe (Sn), epithermal Au-Ag, and hydrothermal vein-type Ag-Pb-Zn ore deposits. Here we investigate the Bianjiadayuan hydrothermal vein-type Ag-Pb-Zn ore deposit in the southern part of the SGXR. Porphyry Sn ± Cu ± Mo mineralization is also developed to the west of the Ag-Pb-Zn veins in the ore field. We identify a five-stage mineralization process based on field and petrologic studies including (i) the early porphyry mineralization stage, (ii) main porphyry mineralization stage, (iii) transition mineralization stage, (iv) vein-type mineralization stage and (v) late mineralization stage. Pyrite is the predominant sulfide mineral in all stages except in the late mineralization stage, and we identify corresponding four types of pyrites: Py1 is medium-grained subhedral to euhedral occurring in the early barren quartz vein; Py2 is medium- to fine-grained euhedral pyrite mainly coexisting with molybdenite, chalcopyrite, minor sphalerite and galena; Py3 is fine-grained, subhedral to irregular pyrite and displays cataclastic textures with micro-fractures; Py4 occurs as euhedral microcrystals and forms irregularly shaped aggregate with sphalerite and galena. LA-ICP-MS trace element analyses of pyrite show that Cu, Pb, Zn, Ag, Sn, Cd and Sb are partitioned into pyrite as structurally bound metals or mineral micro/nano-inclusions, whereas Co, Ni, As and Se enter the lattice via isomorphism in all types of pyrite. The Cu, Zn, Ag, Cd concentrations gradually increase from Py1 to Py4, which we correlate with cooling and mixing of ore-forming fluid with meteoric water. Py2 contains the highest contents of Co, Ni, Se, Te and Bi, suggesting high temperature conditions for the porphyry mineralization stage. Ratios of Co/Ni (0.03–10.79, average 2.13) and sulphur isotope composition of sulfide indicate typical hydrothermal origin for pyrites. The δ34SCDT values of Py1 (0.42‰–1.61‰, average 1.16‰), Py2 (–1.23‰ to 0.82‰, average 0.35‰), Py3 (–0.36‰ to 2.47‰, average 0.97‰), Py4 (2.51‰–3.72‰, average 3.06‰), and other sulfides are consistent with those of typical porphyry deposit (–5‰ to 5‰), indicating that the Pb-Zn polymetallic mineralization in the Bianjiadayuan deposit is genetically linked to the Yanshanian (Jurassic–Cretaceous) magmatic-hydrothermal events. Variations of δ34S values are ascribed to the changes in physical and chemical conditions during the evolution and migration of the ore-forming fluid. We propose that the high Sn content of pyrite in the Bianjiadayuan hydrothermal vein-type Pb–Zn polymetallic deposit can be used as a possible pathfinder to prospect for Sn mineralization in the surrounding area or deeper level of the ore field in this region. Keywords: Trace elements, In-situ sulfur isotope, Pyrite, Bianjiadayuan deposit, Southern Great Xing'an range

The Scourie dyke swarm has long been important to unravelling the geological history of the Lewisian Gneiss Complex (LGC) and the North Atlantic Craton. Recent dating has documented that the majority of those dykes were emplaced between c. 2418–2375 Ma. Here we show that a quartz dolerite dyke in the Rona Terrane of the LGC has a U-Pb zircon age of 1989.08 +4.3/−0.99 Ma. This is the first mafic dyke to be dated from the Rona terrane, the southernmost of those proposed for the terrane model of the LGC. Our new age also overlaps with the c. 1992 Ma age of a previously dated olivine gabbro dyke in the Northern region of the LGC and shows that the LGC contains at least three, and possibly four, temporally discrete episodes of Palaeoproterozoic mafic magmatism: The Scourie dyke swarm ‘sensu stricto’ at c. 2.4 Ga; a suite of younger dykes at c. 1.99 Ga, referred to here as the Strathan dyke swarm; and the c. 1.99–1.90 Ga mafic rocks that are part of the Palaeoproterozoic Loch Maree Group. A c. 2.04 Ga dyke in the Assynt terrain may be part of the younger suite of dykes or perhaps records a temporally separate event. Crucially, our new age data demonstrate that suites of mafic dykes emplaced across the mainland LGC are similar in age and supports the correlation of structural and metamorphic features across that Complex.

Numerous geologic proxies for Earth system processes track dramatic changes at the atmosphere-lithosphere or atmosphere-ocean interface during the early Paleoproterozoic Era. The presence of a geodynamic driver for these changes and how this might have affected the deeper lithosphere is more cryptic. Here we present temporally constrained δ18O and eHf in detrital zircon from Paleoproterozoic sedimentary successions in Western Australia and Canada that chart a rapid change in the oxygen isotopic composition from

The proto-Andean margin of Argentina consists of several suspect terranes, the origins of which are disputed. The Cuyania (greater Precordillera) suspect terrane was originally interpreted to be of southeast Laurentian affinity, but more recently a southwestern Gondwanan provenance has been argued. Both potential source regions comprise Mesoproterozoic rocks, but we show they are isotopically distinct, using previously published zircon Lu-Hf data. Detrital zircon εHf data from southwestern Gondwana (Namaqua-Natal belt) show no correlation with new zircon U-Pb and Lu-Hf data from Cuyania, suggesting that Gondwana was not the source of these sediments. Rather, detrital zircons from Cambrian strata in Cuyania yield Mesoproterozoic zircons with depleted εHf that correlate to the Grenville margin of Laurentia, and a ca. 535 Ma zircon population sourced directly from rift-related rocks of the Ouachita Embayment, thus recording rifting and drifting of Cuyania from Laurentia. By contrast, zircons from Middle to Late Ordovician strata of Cuyania record a larger range of εHf values, correlated with Western Sierras Pampeanas Mesoproterozoic basement inliers of Argentina. These synorogenic clastic deposits record the Ordovician arrival of Cuyania at the proto-Andean margin of Gondwana. The new data require the terrane boundaries of Cuyania to be redefined, thereby excluding Western Sierras Pampeanas basement inliers. The results verify the Laurentian microcontinent model for the origin of Cuyania.

The metamorphic core of the Himalaya is composed of Indian cratonic rocks with two distinct crustal affinities that are defined by radiogenic isotopic geochemistry and detrital zircon age spectra. One is derived predominantly from the Paleoproterozoic and Archean rocks of the Indian cratonic interior and is either represented as metamorphosed sedimentary rocks of the Lesser Himalayan Sequence (LHS) or as slices of the distal cratonic margin. The other is the Greater Himalayan Sequence (GHS) whose provenance is less clear and has an enigmatic affinity. Here we present new detrital zircon Hf analyses from LHS and GHS samples spanning over 1000 km along the orogen that respectively show a striking similarity in age spectra and Hf isotope ratios. Within the GHS, the zircon age populations at 2800–2500 Ma, 1800 Ma, 1000 Ma and 500 Ma can be ascribed to various Gondwanan source regions; however, a pervasive and dominant Tonianage population (∼860–800 Ma) with a variably enriched radiogenic Hf isotope signature (εHf = 10 to −20) has not been identified from Gondwana or peripheral accreted terranes. We suggest this detrital zircon age population was derived from a crustal province that was subsequently removed by tectonic erosion. Substantial geologic evidence exists from previous studies across the Himalaya supporting the Cambro-Ordovician Kurgiakh Orogeny. We propose the tectonic removal of Tonian lithosphere occurred prior to or during this Cambro-Ordovician episode of orogenesis in a similar scenario as is seen in the modern Andean and Indonesian orogenies, wherein tectonic processes have removed significant portions of the continental lithosphere in a relatively short amount of time. This model described herein of the pre-Himalayan northern margin of Greater India highlights the paucity of the geologic record associated with the growth of continental crust. Although the continental crust is the archive of Earth history, it is vital to recognize the ways in which preservation bias and destruction of continental crust informs geologic models. Keywords: Himalaya, Gondwana, Zircon, Subduction erosion