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Abstract
The mineralogy, chemical composition, and physical properties of cratonic mantle eclogites with oceanic crustal protoliths can be modified by secondary processes involving interaction with fluids and melts, generated in various slab lithologies upon subduction (auto‐metasomatism) or mantle metasomatism after emplacement into the cratonic lithosphere. Here we combine new and published data to isolate these signatures and evaluate their effects on the chemical and physical properties of eclogite. Mantle metasomatism involving kimberlite‐like, ultramafic carbonated melts (UM carbonated melts) is ubiquitous though not pervasive, and affected between ~20% and 40% of the eclogite population at the various localities investigated here, predominantly at ~60–150 km depth, overlapping cratonic midlithospheric seismic discontinuities. Its hallmarks include lower jadeite component in clinopyroxene and grossular component in garnet, an increase in bulk‐rock MgO ± SiO2, and decrease in FeO and Al2O3 contents, and LREE‐enrichment accompanied by higher Sr, Pb, Th, U, and in part Zr and Nb, as well as lower Li, Cu ± Zn. This is mediated by addition of a high‐temperature pyroxene from a UM carbonated melt, followed by redistribution of this component into garnet and clinopyroxene. As clinopyroxene‐garnet trace‐element distribution coefficients increase with decreasing garnet grossular component, clinopyroxene is the main carrier of the metasomatic signatures. UM carbonated melt‐metasomatism at >130–150 km has destroyed the diamond inventory at some localities. These mineralogical and chemical changes contribute to low densities, with implications for eclogite gravitational stability, but negligible changes in shear‐wave velocities, and, if accompanied by H2O‐enrichment, will enhance electrical conductivities compared to unenriched eclogites.
Plain Language Summary
Oceanic crust formed at spreading ridges is recycled in subduction zones and undergoes metamorphism to eclogite. Some of this material is captured in the overlying lithospheric mantle, where it is exhumed by passing magmas. Having formed in spreading ridges, these eclogites have proven invaluable archives for the onset of plate tectonics, for the construction of cratons during subduction/collision, as probes of the convecting mantle from which their precursors formed, and as generators of heterogeneity upon recycling into Earth's convecting mantle. During subduction and until exhumation, interaction with fluids and melts (called metasomatism) can change the mineralogy, chemical composition, and physical properties of mantle eclogites, complicating their interpretation, but a comprehensive study of these effects is lacking so far. We investigated mantle eclogites from ancient continents (cratons) around the globe in order to define hallmarks of metasomatism by subduction‐related fluids and small‐volume ultramafic carbonated mantle melts. We find that the latter is pervasive and occurs predominantly at midlithospheric depths where seismic discontinuities are detected, typically causing diamond destruction and a reduction in density. This has consequences for their gravitational stability and for the interpretation of shearwave velocities in cratons.
Primary determinants of communities in deadwood vary among taxa but are regionally consistent
(2020)
The evolutionary split between gymnosperms and angiosperms has far‐reaching implications for the current communities colonizing trees. The inherent characteristics of dead wood include its role as a spatially scattered habitat of plant tissue, transient in time. Thus, local assemblages in deadwood forming a food web in a necrobiome should be affected not only by dispersal ability but also by host tree identity, the decay stage and local abiotic conditions. However, experiments simultaneously manipulating these potential community drivers in deadwood are lacking. To disentangle the importance of spatial distance and microclimate, as well as host identity and decay stage as drivers of local assemblages, we conducted two consecutive experiments, a 2‐tree species and 6‐tree species experiment with 80 and 72 tree logs, respectively, located in canopy openings and under closed canopies of a montane and a lowland forest. We sampled saproxylic beetles, spiders, fungi and bacterial assemblages from logs. Variation partitioning for community metrics based on a unified framework of Hill numbers showed consistent results for both studies: host identity was most important for sporocarp‐detected fungal assemblages, decay stage and host tree for DNA‐detected fungal assemblages, microclimate and decay stage for beetles and spiders and decay stage for bacteria. Spatial distance was of minor importance for most taxa but showed the strongest effects for arthropods. The contrasting patterns among the taxa highlight the need for multi‐taxon analyses in identifying the importance of abiotic and biotic drivers of community composition. Moreover, the consistent finding of microclimate as the primary driver for saproxylic beetles compared to host identity shows, for the first time that existing evolutionary host adaptions can be outcompeted by local climate conditions in deadwood.
Background: Conditions during blood product storage and transportation should maintain quality. The aim of this in vitro study was to investigate the effect of interruption of agitation, temporary cooling (TC), and pneumatic tube system transportation (PTST) on the aggregation ability (AA) and mitochondrial function (MF) of platelet concentrates (PC).
Study Design and Methods: A PC was divided equally into four subunits and then allocated to four test groups. The control group (I) was stored as recommended (continuous agitation, 22 ± 2°C) for 4 days. The test groups were stored without agitation (II), stored as recommended, albeit 4°C for 60 minutes on day (d)2 (III) and PTST (IV). Aggregometry was measured using Multiplate (RocheAG; ADPtest, ASPItest, TRAPtest, COLtest) and MF using Oxygraph‐2k (Oroboros Instruments). The basal and maximum mitochondrial respiratory rate (MMRR) were determined. AA and MF were measured daily in I and II and AA in III and IV on d2 after TC/PTST. Statistical analysis was performed using tests for matched observations.
Results: Eleven PCs were used. TRAP‐6 induced AA was significantly lower in II when compared to I on d4 (P = 0.015*). In III the ASPItest was significantly lower (P = 0.032*). IV showed no significant differences. The basal and MMRR were significantly reduced over 4 days in I and II (for both rates in both groups: P = <0.0001*). No significant differences occurred on d4 (P = 0.495).
Conclusion: Our results indicate that ex vivo AA and MF of PCs are unaffected, even in no‐ideal storage and transport circumstances with respect to agitation, temperature, and force.
We analyze limit order book resiliency following liquidity shocks initiated by large market orders. Based on a unique data set, we investigate whether high‐frequency traders are involved in replenishing the order book. Therefore, we relate the net liquidity provision of high‐frequency traders, algorithmic traders, and human traders around these market impact events to order book resiliency. Although all groups of traders react, our results show that only high‐frequency traders reduce the spread within the first seconds after the market impact event. Order book depth replenishment, however, takes significantly longer and is mainly accomplished by human traders’ liquidity provision.
Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder that is accompanied by neurodevelopmental differences in regional cortical volume (CV), and a potential layer‐specific pathology. Conventional measures of CV, however, do not indicate how volume is distributed across cortical layers. In a sample of 92 typically developing (TD) controls and 92 adult individuals with ASD (aged 18–52 years), we examined volumetric gradients by quantifying the degree to which CV is weighted from the pial to the white surface of the brain. Overall, the spatial distribution of Frustum Surface Ratio (FSR) followed the gyral and sulcal pattern of the cortex and approximated a bimodal Gaussian distribution caused by a linear mixture of vertices on gyri and sulci. Measures of FSR were highly correlated with vertex‐wise estimates of mean curvature, sulcal depth, and pial surface area, although none of these features explained more than 76% variability in FSR on their own. Moreover, in ASD, we observed a pattern of predominant increases in the degree of FSR relative to TD controls, with an atypical neurodevelopmental trajectory. Our findings suggest a more outward‐weighted gradient of CV in ASD, which may indicate a larger contribution of supragranular layers to regional differences in CV.
We show that financial advisors recommend more costly products to female clients, based on minutes from about 27,000 real-world advisory meetings and client portfolio data. Funds recommended to women have higher expense ratios controlling for risk, and women less often receive rebates on upfront fees for any given fund. We develop a model relating these findings to client stereotyping, and empirically verify an additional prediction: Women (but not men) with higher financial aptitude reject recommendations more frequently. Women state a preference for delegating financial decisions, but appear unaware of associated higher costs. Evidence of stereotyping is stronger for male advisors.
Three leptostracan species (Crustacea: Phyllocarida) are reported from mud volcanoes at the Moroccan margin of the Gulf of Cadiz (NE Atlantic). Nebalia strausi Risso, 1826 and N. abyssicola Fage, 1929 were found in experimentally deployed organic substrates in Mercator, Meknès and Darwin mud volcanoes; N. abyssicola was also found among bathymodiolin bivalves and is recorded for the first time in the Atlantic Ocean. The third species was collected from the Gemini mud volcanoes and is described herein as Sarsinebalia ledoyeri sp. nov. The new species is characterised by having the eyes provided with ommatidia and lacking pigment, the ventral margin of the eye is concave along distal half, the antennular scale is more than twice as long as wide, the second article of the mandibular palp bears one seta on lateral surface about 0.5 times as long as the article and one subterminal seta longer than the third article, the distal article of the maxilla II endopod is about 1.8 times as long as the proximal article, the maxilla II exopod is clearly longer than the endopod proximal article, the lateral margin of the pleopod I exopod lacks setae and the posterodorsal border of pleonites VI–VII is provided with rounded to pointed denticles.
Bopopia, a new monotypic genus of Gesneriaceae (Gesnerioideae, Coronanthereae) from New Caledonia
(2021)
A new genus of Gesneriaceae, Bopopia Munzinger & J.R.Morel gen. nov., is described from New Caledonia. The genus is based on B. parviflora Munzinger & J.R.Morel gen. et sp. nov., a new species collected during an expedition on Mt Katalupaik, in the North Province of New Caledonia’s main island. Originally considered as a species of Coronanthera, our phylogenetic analysis – including 19 species within Coronanthereae and two individuals of B. parviflora gen. et sp. nov., and using three molecular markers (nuclear rDNA ITS, and chloroplast regions trnL-trnF and trnE-trnT) – showed that the new species is not close to Coronanthera in subtribe Coronantherinae, but belongs to subtribe Negriinae where it is sister to Depanthus. From that genus Bopopia gen. nov. differs in floral symmetry (zygomorphic vs actinomorphic) and the number of stamens (4 vs 5). From the other genera of Negriinae the new genus differs in the white corolla and its indeterminate thyrse with 3 to 5 levels of branching. The morphological circumscription of the subtribe Negriinae is amended to include Bopopia gen. nov. Two keys are provided, one to the subtribes in the tribe Coronanthereae, and one to the genera in subtribe Negriinae. Following the IUCN Red List categories and criteria, the conservation status of B. parviflora gen. et sp. nov. is provisionally assessed as Endangered (EN).
Eight species of Ophryotrocha and one of Parougia were identified from organic substrata (wood and alfalfa) sampled at the Gulf of Cadiz and Western Iberian Margin (NE Atlantic). Morphological examination and molecular phylogenetic analyses, based on the nuclear gene H3 and the mitochondrial gene 16S, indicate the presence of four species new to science: Ophryotrocha chemecoli sp. nov., O. nunezi sp. nov., O. geoffreadi sp. nov. and Parougia ougi sp. nov. The geographic and/or bathymetric distribution is extended for four previously known species: O. cantabrica, O. hartmanni, O. mammillata and O. scutellus. Another species may also have its distribution extended, pending the molecular confirmation of its identity: O. lipscombae. Full descriptions and figures are given for all the new species and, when justified, also for the previously known ones. The original description of O. scutellus is amended. New DNA sequences are given for eight of the nine species studied here. The ecology and geographic distribution of the reported species is discussed.
Polycladida (Platyhelminthes, Rhabditophora) from Cape Verde and related regions of Macaronesia
(2021)
The systematics and distribution of the order Polycladida within the Macaronesian archipelagos are analysed. New species (Marcusia alba sp. nov., Prostheceraeus crisostomum sp. nov., Parviplana sodade sp. nov., Euplana claridade sp. nov., Stylochus salis sp. nov. and Distylochus fundae sp. nov.), new variety (Pseudoceros rawlinsonae var. galaxy), new records and records of shared species among different archipelagos are studied to compare the marine flatworm biodiversity of each island. The complex of archipelagos known as Macaronesia (including Madeira, Selvagens Islands, Canary Islands, Azores and Cape Verde) share a volcanic origin and European political influence. The five archipelagos are located along the eastern coast of the Atlantic Ocean and are subject to similar trade winds, streams (like the Gulf Stream) and cold currents. The term Macaronesia has suffered several changes throughout the years and it still is a topic of discussion in present times. The new delimitation of Macaronesia is mainly based on systematic studies on the invertebrate fauna of the islands. The resulting analyses shed new light on the differences and similarities among these archipelagos. In addition, molecular analyses employing 28S nuclear gene sequences are compared to verify relationships among anatomically similar species of marine polyclads.