Spatial Origin Research Articles

MiR-17∼92 exerts stage-specific effects in adult V-SVZ neural stem cell lineages.

Neural stem cells (NSCs) in the adult ventricular-subventricular zone (V-SVZ) generate neurons and glia throughout life. MicroRNAs are important post-transcriptional regulators frequently acting in a context-dependent manner. Here, microRNA profiling defines cohorts of miRNAs in quiescent and activated NSCs, with miR-17∼92 highly upregulated in activated NSCs and transit amplifying cells (TACs) versus quiescent NSCs. Conditional miR-17∼92 deletion in the adult V-SVZ results in stage-specific effects. In NSCs, it reduces proliferation invitro and invivo, whereas in TACs, it selectively shifts neurogenic OLIG2- DLX2+ toward oligodendrogenic OLIG2+ DLX2- TACs, due to de-repression of an oligodendrogenic program, leading to increased oligodendrogenesis invivo. This differential regulation of TAC subpopulations highlights the importance of TAC heterogeneity. Finally, in the NSC lineage for intraventricular oligodendrocyte progenitors, miR-17∼92 deletion decreases proliferation and maturation. Together, these findings reveal multiple stage-specific functions of the miR-17∼92 cluster within different adult V-SVZ lineages.

Maser Activity of Large Molecules toward Sgr B2 North

AbstractSingle-dish observations at centimeter wavelengths have suggested that the Sgr B2 molecular cloud at the Galactic Center hosts weak maser emission from several large molecules. Here, we present the interferometric observations of the Class I methanol (CH3OH) maser at 84 GHz, the methanimine (CH2NH) maser at 5.29 GHz, and the methylamine (CH2NH2) maser at 4.36 GHz toward Sgr B2 North (N). We use a Bayesian approach to quantitatively assess the observed masing spectral profiles and the excitation conditions. By comparing the spatial origin and extent of maser emission from several molecular species, we find that the new maser transitions have a close spatial relationship with the Class I masers, which suggests a similar collisional pumping mechanism.

Auroral Field‐Aligned Current Signatures in Jupiter's Magnetosphere: Juno Magnetic Field Observations and Physical Modeling

AbstractWe analyze magnetic data obtained during northern high‐altitude traversals of Jovian middle magnetosphere (MM) field lines during the first 10 inbound data‐taking passes of the Juno spacecraft for azimuthal field perturbations associated with magnetosphere‐ionosphere coupling currents. Full traversals across the MM region occur on all 10 passes at radial distances ∼7 to 16 RJ (T1 traversals), followed in four cases by reversed traversals (T2) at ∼4 to 7 RJ. Signatures of upward field‐aligned currents were observed in all cases, closely collocated with the statistical main auroral oval when mapped along field lines to the ionosphere. Two T1 sheets carry currents ∼10 MA per radian of azimuth in ionospheric colatitudinal layers ∼1.2°, closely comparable with the ∼8.5 MA rad−1 theoretical model value of Cowley et al. (2008, https://doi.org/10.5194/angeo-26-4051-2008). The other T1 sheets typically carry half this current ∼5.1 MA rad−1 in layers half the width ∼0.56°, thus with comparable current densities ∼425 nA m−2. The T2 currents are smaller ∼3.4 MA rad−1 with current densities ∼120 nA m−2, a difference that may relate to locations on opposite sides of the main oval as reflected in near‐contemporaneous ultraviolet observations, though ionospheric field strengths are not greatly different. Comparison with northern near‐periapsis currents observed inside ∼2 RJ on the same passes by Kotsiaros et al. (2019, https://doi.org/10.1038/s41550-019-0819-7) yields a cross‐correlation coefficient ∼0.7 with our T1 currents, though Kotsiaros et al.’s mean current value of ∼3.8 MA rad−1 is somewhat less than our overall mean T1 value ∼6.2 MA rad−1. The differences may have spatial, temporal, or methodological origins.

Potentially toxic elements in the soils of Campi Flegrei (south Italy) and the immediate surroundings: Spatial distribution, origin and probabilistic human health risk

Campi Flegrei is an active volcanic field in south Italy where the potentially toxic elements (PTEs) are of growing concern because the intensive anthropogenic and volcanic activities might pose adverse human health effects. In this article, 394 topsoils (0–15 cm) are collected for instrumental analysis of the <2 mm fraction. The geochemical maps indicate that higher concentrations of Pb, Zn, Cd, Cr, Hg, Ni and Sb are related to the urban area, but greater levels of As, Tl, Co, Cu, Se and V are observed in the other parts. A robust principal component analysis detected: (1) the Pb–Zn–Hg–Cd–Sb–Cr–Ni association that probably highlights anthropogenic activities such as heavy traffic load and fossil fuel combustion in the urbanized area; (2) the Al–Fe–Mn–Ti–Tl–V–Co–As–U–Th association that mostly reveals the contribution of pyroclastic deposits; and (3) the Na–K–B association that feasibly indicates the weathering degree. The probabilistic health risk modeling for the children under 6 years old shows negligible Pb and Zn non-carcinogenic risk and unexpected Pb carcinogenic risk for exposure through soil ingestion. However, for the inhalation pathway, the children aged <1 year old have the highest chance (90%) of acceptable (i.e. between 1E-6 and 1E-4) Pb carcinogenic health risk. This should not be overlooked because Naples is under high environmental pressure and previous studies reported the increased Pb and Zn quantities in soil over a 26-year timespan. Overall, the results of geostatistical interpolation, compositional data analysis and probabilistic health risk modeling potentially uncover the link between soil geochemistry and human health.

The development of the amnion in mice and other amniotes.

The amnion is an extraembryonic tissue that evolutionarily allowed embryos of all amniotes to develop in a transient and local aquatic environment. Despite the importance of this tissue, very little is known about its formation and its molecular characteristics. In this review, we have compared the basic organization of the extraembryonic membranes in amniotes and describe the two types of amniogenesis, folding and cavitation. We then zoom in on the atypical development of the amnion in mice that occurs via the formation of a single posterior amniochorionic fold. Moreover, we consolidate lineage tracing data to better understand the spatial and temporal origin of the progenitors of amniotic ectoderm, and visualize the behaviour of their descendants in the extraembryonic–embryonic junctional region. This analysis provides new insight on amnion development and expansion. Finally, using an online-available dataset of single-cell transcriptomics during the gastrulation period in mice, we provide bioinformatic analysis of the molecular signature of amniotic ectoderm and amniotic mesoderm. The amnion is a tissue with unique biomechanical properties that deserves to be better understood.This article is part of the theme issue ‘Extraembryonic tissues: exploring concepts, definitions and functions across the animal kingdom’.

Fiber-optical analysis of weak knock and pressure oscillations in a single cylinder research engine

The effect of characteristic cycle-to-cycle variations on knock in gasoline engines is not yet fully understood. The analysis requires the use of experimental techniques to characterize weak knock events on a cycle-individual basis. To this end, a novel processing method is presented that focuses on characterizing weak knock events using data from a fiber optic spark plug linked to a high-resolution (400 kHz) photo-multiplier array. The method was applied to a single cylinder research engine. By combining signal and image processing and reconstruction methods, it is shown that reliable automated detection of spatial knock origin is possible for Knock-Peak-Peak pressure values as low as 0.7 bar. Furthermore, the fiber optic spark plug data are used to accurately localize and characterize the pressure oscillations induced by auto-ignition which are shown to be closely related to the number, intensity, and relative location of individual knock events.

Multi-Harmonic Electrothermal Spectroscopy (METS), a New Technique for Spatially Resolved Electrochemical Measurements

In this work, we introduce a new electrochemical technique, Multi-harmonic ElectroThermal Spectroscopy (METS) based on frequency dependent temperature sensing. We show that the thermal signatures generated at different harmonics when an Alternating Current (AC) is passed through an electrochemical cell can be used to extract thermodynamic (entropic), kinetic (charge transfer rate) and transport (charge and mass transport) properties associated with the electrochemical cell. From the frequency dependence of the thermal penetration depth, the spatial origin of the effect can be located within a resolution of a few microns, thereby enabling the attribution of the effect to a particular electrode. A four-point probe RTD sensor acting as a METS sensor is employed on the exterior of the current collector, which non-invasively provides spatially resolved information about the electrochemical processes in the cell. Through this work, we are able to, for the first time, determine the entropy change of a single charge transfer reaction in an electrode and spatially resolve the heat generation in a single Li-ion cell, with a length-scale resolution of a microns.

Time-dependent exchange creates the time-frustrated state of matter

Magnetic systems governed by exchange interactions between magnetic moments harbor frustration that leads to ground state degeneracy and results in the new topological state often referred to as a frustrated state of matter (FSM). The frustration in the commonly discussed magnetic systems has a spatial origin. Here we demonstrate that an array of nanomagnets coupled by the real retarded exchange interactions develops a new state of matter, time frustrated matter (TFM). In a spin system with the time-dependent retarded exchange interaction, a single spin-flip influences other spins not instantly but after some delay. This implies that the sign of the exchange interaction changes, leading to either ferro- or antiferromagnetic interaction, depends on time. As a result, the system’s temporal evolution is essentially non-Markovian. The emerging competition between different magnetic orders leads to a new kind of time-core frustration. To establish this paradigmatic shift, we focus on the exemplary system, a granular multiferroic, where the exchange transferring medium has a pronounced frequency dispersion and hence develops the TFM.

Sōþes ne wanda. The Avoidance is Separation Metaphor in West-Germanic Argument Structure

Abstract In this paper I reconstruct two separative argument structure constructions for West Germanic: one involving a genitive of origin and one involving an instrumental in the process of being subsumed under the dative. Although neither genitives nor instrumentals/datives are typically used to refer to literal origins in space in any of the languages under consideration, a number of verbs attested with genitives and instrumentals/datives can be semantically related to each other as expressing different metaphorical extensions from the concept of separation. The fact that the expression of spatial origin itself is not a function of the genitive or the instrumental/dative can be explained diachronically with reference to a common evolutionary scenario in which adpositional phrases replace bare-case constructions in their concrete, spatial functions before they take over their derived, more abstract senses. The alternation between genitives, instrumentals/datives and separative prepositions is best modelled as a constructeme, a schema with various allostructions.

Spatial origin analysis on atmospheric bulk deposition of polycyclic aromatic hydrocarbons in Shanghai

Atmospheric deposition of polycyclic aromatic hydrocarbons (PAHs) onto soil threatens terrestrial ecosystem. To locate potential source areas geographically, a total of 139 atmospheric bulk deposition samples were collected during 2012–2019 at eight sites in Shanghai and its surrounding areas. A multisite joint location method was developed for the first time to locate potential source areas of atmospheric PAHs based on an enhanced three dimensional concentration weighted trajectory model. The method considered spatial and temporal variations of atmospheric boundary layer height and homogenized all results over the eight sites via geometric mean. Regional transport was an important contributor of PAH atmospheric deposition while massive local emissions may disturb the identification of potential source areas. Northwesterly winds were associated with elevated deposition fluxes. Potential source areas were identified by the multisite joint location method and included Hebei, Tianjin, Shandong and Jiangsu to the north, and Anhui to the west of Shanghai. PM and SO2 data from the national ground monitoring stations confirmed the identified source areas of deposited PAHs in Shanghai.

FAUST

Aims. Methanol is a ubiquitous species commonly found in the molecular interstellar medium. It is also a crucial seed species for the build-up of chemical complexity in star forming regions. Thus, understanding how its abundance evolves during the star formation process and whether it enriches the emerging planetary system is of paramount importance. Methods. We used new data from the ALMA Large Program FAUST (Fifty AU STudy of the chemistry in the disc/envelope system of solar protostars) to study the methanol line emission towards the [BHB2007] 11 protobinary system (sources A and B), where a complex structure of filaments connecting the two sources with a larger circumbinary disc has previously been detected. Results. Twelve methanol lines have been detected with upper energies in the [45–537] K range along with one 13CH3OH transition and one methyl formate (CH3OCHO) line blended with one of the methanol transitions. The methanol emission is compact (FWHM ~ 0.5″) and encompasses both protostars, which are separated by only 0.2″ (28 au). In addition, the overall methanol line emission presents three velocity components, which are not spatially resolved by our observations. Nonetheless, a detailed analysis of the spatial origin of these three components suggests that they are associated with three different spatial regions, with two of them close to 11B and the third one associated with 11A. A radiative transfer analysis of the methanol lines gives a kinetic temperature of [100–140] K, an H2 volume density of 106–107 cm−3 and column density of a few 1018 cm−2 in all three components with a source size of ~0.15″. Thus, this hot and dense gas is highly enriched in methanol with an abundance as high as 10−5. Using previous continuum data, we show that dust opacity can potentially completely absorb the methanol line emission from the two binary objects. Conclusions. Although we cannot firmly exclude other possibilities, we suggest that the detected hot methanol is resulting from the shocked gas from the incoming filaments streaming towards [BHB2007] 11A and B, respectively. Higher spatial resolution observations are necessary to confirm this hypothesis.

Sedimentary Record of Polycyclic Aromatic Hydrocarbons in the Gulf of Trieste (Northern Adriatic Sea) - Distribution, Origin and Temporal Trends

A mid-term study (2003-2013) of polycyclic aromatic hydrocarbons in Gulf of Trieste sediments was conducted at seven sampling sites. The PAH spatial and temporal distribution and origin were determined. The sediments were sampled with a gravity core sampler. After extraction of PAH, their concentrations were determined by gas chromatography. The results of the study show PAH spatial and temporal variability. The highest mean concentration was measured in the marina of Portoroz (1168 ng/g dw), and the lowest at an offshore site (320 ng/g dw). The results show higher concentrations of PAH in coastal areas and a decreasing trend towards the central part of the Gulf of Trieste. The interannual differences in the concentrations of PAH showed a significant downward trend in the marina of Portorož, in the port of Koper and in the offshore site off Piran. No trend was observed at all other sites. Various evaluation indices showed that PAH are predominantly of pyrolytic origin, with a lower proportion of petrogenic origin, especially in the Bay of Koper. The ecological risk assessment found that concentrations of PAH are well below levels associated with adverse biological effects. According to the presented results, this area can be considered as only moderately contaminated with PAH. However, the applied measures to reduce pollution should be continued and intensified.

Spatial origin of the extracellular ATP-induced cytosolic calcium signature in Arabidopsis thaliana roots: wave formation and variation with phosphate nutrition.

Extracellular ATP (eATP) increases cytosolic free calcium ([Ca2+ ]cyt ) as a specific second messenger 'signature' through the plasma membrane DORN1/P2K1 receptor. Previous studies revealed a biphasic signature in Arabidopsis thaliana roots that is altered by inorganic phosphate (Pi) deprivation. The relationship between the two phases of the signature and possible wave formation have been tested as a function of Pi nutrition. The bioluminescent aequorin and intensiometric GCaMP3 reporters were used to resolve the spatial origin of the eATP [Ca2+ ]cyt signature in Arabidopsis root tips. Application of eATP only to the root apex allowed [Ca2+ ]cyt wave resolution without the confounding effects of eATP delivery by superfusion. The first apical millimetre of the root generates the first [Ca2+ ]cyt increase by eATP, regardless of nutritional status. The second increase occurs sub-apically in the root hair zone, has some autonomy and is significantly reduced in Pi-starved roots. A significant component of the Pi-replete signature does not require DORN1/P2K1, but Pi-starved roots appear to have an absolute requirement for that receptor. Application of eATP specifically to the root apex provides evidence for cell-to-cell propagation of a [Ca2+ ]cyt wave that diminishes sub-apically. The apex maintains a robust [Ca2+ ]cyt increase (even under Pi starvation) that is the basis of a propagative wave, with implications for the ability of the root's eATP signalling systems to signal systemically. Partial autonomy of the sub-apical region may be relevant to the perception of eATP from microbes. eATP-induced [Ca2+ ]cyt increase may not have always have an obligate requirement for DORN1/P2K1.

Reconstructing an historical pollination syndrome: keel flowers

BackgroundKeel flowers are bilaterally symmetrical, pentamerous flowers with three different petal types and reproductive organs enclosed by keel petals; generally there is also connation of floral parts such as stamens and keel petals. In this study, the evolution of keel flowers within the order Fabales is explored to investigate whether the establishment of this flower type within one of the species-rich families, the Fabaceae (Leguminosae), preceded and could have influenced the evolution of keel flowers in the Polygalaceae. We conducted molecular dating, and ancestral area and ancestral state analyses for a phylogeny constructed for 678 taxa using published matK, rbcL and trnL plastid gene regions.ResultsWe reveal the temporal and spatial origins of keel flowers and traits associated with pollinators, specifically floral symmetry, the presence or absence of a pentamerous corolla and three distinct petal types, the presence or absence of enclosed reproductive organs, androecium types, inflorescence types, inflorescence size, flower size, plant height and habit. Ancestral area reconstructions show that at the time keel flowers appeared in the Polygaleae, subfamily Papilionoideae of the Fabaceae was already distributed almost globally; at least eight clades of the Papilionoideae had keel flowers with a functional morphology broadly similar to the morphology of the first evolving Polygaleae flowers.ConclusionsThe multiple origins of keel flowers within angiosperms likely represent convergence due to bee specialization, and therefore pollinator pressure. In the case of the Fabales, the first evolving keel flowers of Polygaleae have a functional morphology that corresponds with keel flowers of species of the Papilionoideae already present in the environment. These findings are consistent with the keel-flowered Polygaleae exploiting pollinators of keel-flowered Papilionoideae. The current study is the first to use ancestral reconstructions of traits associated with pollination to demonstrate that the multiple evolutionary origins of the keel flower pollinator syndrome in Fabales are consistent with, though do not prove, mimicry.

Spatial distribution, compositional pattern and source apportionment of n-alkanes in surface sediments of the Bohai Sea, Yellow Sea, and East China Sea and implications of carbon sink

China's marginal seas (CMSs, including the Bohai Sea, Yellow Sea, East China Sea) are a significant sink for both terrestrial organic matter (OM) and marine OM, and they play an important role in the global biogeochemical carbon cycle. The spatial distribution and origin of organic matter based on n-alkanes in the surface sediments of CMSs and the implications of carbon sinks were comparatively analyzed. The n-alkane content in surface sediment from the Bohai Sea was higher than that of the Yellow Sea and the East China Sea. The spatial distribution trends of marine and terrestrial organic matter are obviously different in the surface sediments of China's marginal seas. The n-alkanes in the sediments of the Yellow Sea and the East China Sea were mainly derived from terrestrial higher plants, and land-based influence gradually decreased from the near shore to the open sea. Higher concentration of terrigenous OM are concentrated nearshore, especially near estuaries, such as the Yellow River Estuary, the Old Yellow River Estuary and the Yangtze River Estuary. The input of n-alkanes from woody plants in the Bohai Sea area was slightly higher than that of herbaceous plants, and the input of herbaceous plants in the Yellow Sea and East China Sea was slightly dominant. The distribution of marine organic matter is controlled by marine productivity and the sedimentary environment. Due to climate change, the decomposition and enrichment of organic matter also show the climate effect of carbon molecular combinations. As a semiclosed sea area, the Bohai Sea was beneficial to the growth and reproduction of marine phytoplankton. From the perspective of petroleum pollution, the Bohai Sea was the most serious, followed by the Yellow Sea, and the East China Sea was the lightest. The carbon burial amount of terrestrial organic matter accounts for approximately 7% of the terrestrial organic matter burial amount of global marginal sea sediments, indicating that China's marginal sea plays an important role in the global carbon cycle. The result provide a basis for further understanding the source pattern and burial preservation of sedimentary organic matter in this sea area.

Spatial and Temporal Origins of the La Perouse Low Oxygen Pool: A Combined Lagrangian Statistical Approach

AbstractA shortage of dissolved oxygen in seawater can adversely impact marine life and ecosystems. Low oxygen conditions at depth occur in many coastal regions, driven by both local productivity and remote changes in the source waters. A low‐oxygen dense pool of water is observed every summer over the mid‐shelf off southwest Vancouver Island in the Juan de Fuca Eddy region. We trace the dense pool waters back to their source using Lagrangian Particle tracking in an ocean model. The model accuracy is evaluated against a set of dense observations collected in August 2013. Only locations where the model represents water properties well are used as starting locations for the tracking. These locations are selected using a K‐Means clustering algorithm. Tracking particles backwards in time showed that the low oxygen dense pool is primarily composed of water from the California Undercurrent, shallower water from further offshore of the Washington shelf, and offshore water. Waters from the northern shelf were not a primary source even though summer currents are from the north. Correspondingly, the water primarily arrived in the south Vancouver Island region in spring, months before the cruise. A kernel density estimate shows the final water properties of the dense pool are well represented by this mixture. The dense water pathways up and onto the shelf are primarily through coastal submarine canyons in early summer. Combining high spatial resolution observations, a carefully evaluated numerical model, Lagrangian tracking, and statistical techniques reveal detailed answers not obtainable through a single method.

Disparate Seasonal Nitrate Export From Nested Heterogeneous Subcatchments Revealed With StorAge Selection Functions

AbstractUnderstanding catchment controls on catchment solute export is a prerequisite for water quality management. StorAge Selection (SAS) functions encapsulate essential information about catchment functioning in terms of discharge selection preference and solute export dynamics. However, they lack information on the spatial origin of solutes when applied at the catchment scale, thereby limiting our understanding of the internal (subcatchment) functioning. Here, we parameterized SAS functions in a spatially explicit way to understand the internal catchment responses and transport dynamics of reactive dissolved nitrate (N‐NO3). The model was applied in a nested mesoscale catchment (457 km2), consisting of a mountainous partly forested, partly agricultural subcatchment, a middle‐reach forested subcatchment, and a lowland agricultural subcatchment. The model captured flow and nitrate concentration dynamics not only at the catchment outlet but also at internal gauging stations. Results reveal disparate subsurface mixing dynamics and nitrate export among headwater and lowland subcatchments. The headwater subcatchment has high seasonal variation in subsurface mixing schemes and younger water in discharge, while the lowland subcatchment has less pronounced seasonality in subsurface mixing and much older water in discharge. Consequently, nitrate concentration in discharge from the headwater subcatchment shows strong seasonality, whereas that from the lowland subcatchment is stable in time. The temporally varying responses of headwater and lowland subcatchments alternate the dominant contribution to nitrate export in high and low‐flow periods between subcatchments. Overall, our results demonstrate that the spatially explicit SAS modeling provides useful information about internal catchment functioning, helping to develop or evaluate spatial management practices.

Probing the High-energy Gamma-Ray Emission Mechanism in the Vela Pulsar via Phase-resolved Spectral and Energy-dependent Light-curve Modeling

Abstract Recent kinetic simulations sparked a debate regarding the emission mechanism responsible for pulsed GeV γ-ray emission from pulsars. Some models invoke curvature radiation, while other models assume synchrotron radiation in the current sheet. We interpret the curved spectrum of the Vela pulsar as seen by H.E.S.S. II (up to ∼100 GeV) and the Fermi Large Area Telescope to be the result of curvature radiation due to primary particles in the pulsar magnetosphere and current sheet. We present phase-resolved spectra and energy-dependent light curves using an extended slot gap and current-sheet model, invoking a step function for the accelerating electric field as motivated by kinetic simulations. We include a refined calculation of the curvature radius of particle trajectories in the lab frame, impacting the particle transport, predicted light curves, and spectra. Our model reproduces the decrease of the flux of the first peak relative to the second one, evolution of the bridge emission, near-constant phase positions of peaks, and narrowing of pulses with increasing energy. We can explain the first of these trends because we find that the curvature radii of the particle trajectories in regions where the second γ-ray light-curve peak originates are systematically larger than those associated with the first peak, implying that the spectral cutoff of the second peak is correspondingly larger. However, an unknown azimuthal dependence of the E field, as well as uncertainty in the precise spatial origin of the GeV emission, precludes a simplistic discrimination of emission mechanisms.

The crustal structure in the Northwest Atlantic region from receiver function inversion – Implications for basin dynamics and magmatism

The Labrador Sea and Baffin Bay form an extinct Palaeogene oceanic spreading system, divided by a major continental transform, the Davis Strait, with the whole region defined as the Northwest Atlantic. The Davis Strait hosts the Ungava Fault Zone and is the central structural element of the Davis Strait Large Igneous Province (DSIP) that formed broadly coeval with continental breakup to its north and south. While constraints on the crustal structure in this region primarily exist in the offshore, crustal models are limited onshore, which makes an interpretation of regional structures as well as the extent, and therefore origin of the DSIP extremely difficult to ascertain. Here, we have collected all available teleseismic data from the Northwest Atlantic margins and applied a receiver function inversion to retrieve station-wise velocity models of the crust and uppermost mantle. We integrate the outcomes with published controlled-source seismic data and regional crustal models to make inferences about the crustal structure and evolution of the Northwest Atlantic. In particular, we focused on constraining the spatial extent and origin of high velocity lower crust (HVLC), and determining whether it is generically related to the Davis Strait Igneous Province, syn-rift exhumed and serpentinised mantle, or pre-existing lower crustal bodies such as metamorphosed lower crust or older serpentinised mantle rocks. The new results allow us to better spatially constrain the DSIP and show the possible spatial extent of igneous-type HVLC across Southwest Greenland, Northwest Greenland and Southeast Baffin Bay. Similarly, we are able to relate some HVLC bodies to possible fossil collision/subduction zones/terrane boundaries, and in some instances to exhumed and serpentinised mantle.

The Origin and Physico-Chemical Properties of Some Unusual Earth Rock Fragments

In this paper, several researches were undertaken related to a violent phenomenon, characterized by a sonic boom, felt on an area of at least 500 km2, shortly followed by the fall of rock fragments that were then recovered from the ground. These presented different appearance characteristics from those of the materials and rocks specific to the respective area. Spectroscopic and petrographic analyses were performed to identify the composition, morphological and crystallinity characteristics in order to elucidate the nature of the collected rock samples. Using FTIR spectroscopy functional groups, as those reported in the literature for Murchison, Bells and Allende, carbonaceous chondrite meteorites were identified. The fragments evidenced topography and morphology that can be assigned to the chondrules and chondrites of carbonaceous meteorites (CMs). The material in the fragments proved to be as insoluble organic material (IOM), being insoluble in water and organic solvents. Its crystalline structure was also evidenced by XRD analysis and FTIR spectrum. These physico-chemical properties, in relation to the sonic boom perceived in the area from where they were collected, indicate the spatial origin of the fragments of rock as possible meteorite fragments.