ORCID Profile
0000-0002-2944-8736
Current Organisations
Geneva University
,
University of Queensland
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Geology | Ore Deposit Petrology | Geodynamics | Tectonics | Mineralogy and Crystallography | Igneous and metamorphic petrology | Inorganic geochemistry | Volcanology | Resources Engineering and Extractive Metallurgy | Pyrometallurgy | Metals and Alloy Materials | Exploration Geochemistry | Igneous and Metamorphic Petrology | Geochemistry
ANZSRC Socio-Economic Objective (SEO)
Expanding Knowledge in the Earth Sciences | Titanium Minerals, Zircon, and Rare Earth Metal Ore (e.g. Monazite) Exploration | Basic Precious Metal Products | Copper Ore Exploration | Diamond Exploration |
Related Links
Publications
A Branched Magma Feeder System during the 1669 Eruption of Mt Etna: Evidence from a Time-integrated Study of Zoned Olivine Phenocryst Populations
Publisher: Oxford University Press (OUP)
Date: 03-2017
Increased complexity in volcanic architecture along waning hotspots
Publisher: Research Square Platform LLC
Date: 07-06-2022
DOI: 10.21203/RS.3.RS-1690437/V1
Abstract: Mantle plumes are key drivers of intraplate volcanism on Earth. Hotspot flux controls the lifetime of volcanism, yet its impact on magma plumbing architecture, composition of erupted products, and eruptive styles remain poorly constrained. Here, we combine geochemistry and geochronology on Earth's longest continental hotspot chain to assess the effect of waning plume activity on pre-eruptive magma transfer, storage, and differentiation. We identify two groups of age-progressive Cenozoic volcanoes across eastern Australia. The Northern volcanoes are older and "long-lived" (3.5–7 Ma activity) and erupted high volumes ( km3) of magmas with bimodal compositions, including relatively homogeneous basalts with aphyric texture (~3 vol% phenocrysts). In contrast, the southern volcanic chain splits into two parallel tracks, where volcanoes become "short-lived" (~1.5 Ma or less), erupting km3 of more evolved basalts that show greater compositional and textural complexity (~12 vol% zoned phenocrysts). The inflection point coincides with a change in plate motion, suggesting geodynamic controls on plume flux, which in turn controls plumbing system architecture. Our results suggest waning flux leads to increasingly complex feeder systems and enhanced magma differentiation. Similar trends in hotspot tracks globally suggest that hotspot flux plays a crucial role in the evolution of intraplate volcanoes.
Amphetamine pretreatment induces a change in both D2-Receptor density and apparent affinity: A [11C]raclopride positron emission tomography study in cats
Publisher: Elsevier BV
Date: 06-2004
Microanalysis of Cl, Br and I in apatite, scapolite and silicate glass by LA-ICP-MS
Publisher: Elsevier BV
Date: 12-2020
New Reference Materials, Analytical Procedures and Data Reduction Strategies for Sr Isotope Measurements in Geological Materials by LA‐MC‐ICP‐MS
Publisher: Wiley
Date: 10-03-2023
DOI: 10.1111/GGR.12480
Abstract: Laser ablation multi‐collector mass spectrometry (LA‐MC‐ICP‐MS) has emerged as the technique of choice for in situ measurements of Sr isotopes in geological minerals. However, the method poses analytical challenges and there is no widely adopted standardised approach to collecting these data or correcting the numerous potential isobaric inferences. Here, we outline practical analytical procedures and data reduction strategies to help establish a consistent framework for collecting and correcting Sr isotope measurements in geological materials by LA‐MC‐ICP‐MS. We characterise a new set of plagioclase reference materials, which are available for distribution to the community, and present a new data reduction scheme for the Iolite software package to correct isobaric interferences for different materials and analytical conditions. Our tests show that a combination of Kr‐baseline subtraction, Rb‐peak‐stripping using βRb derived from a bracketing glass reference material, and a CaCa or CaAr correction for plagioclase and CaCa or CaAr + REE 2+ correction for rock glasses, yields the most accurate and precise 87 Sr/ 86 Sr measurements for these materials. Using the analytical and correction procedures outlined herein, spot analyses using a beam diameter of 100 μm or rastering with a 50–65 μm diameter beam can readily achieve 100 ppm 2SE repeatability ("internal") precision for 87 Sr/ 86 Sr measurements for materials with 1000 μg g ‐1 Sr.
Editorial: Crystal Archives of Magmatic Processes
Publisher: Frontiers Media SA
Date: 20-08-2021
Hydrothermal macroscopic Fe-sepiolite from Oujda Mounts (Middle Atlas, Eastern Morocco)
Publisher: Elsevier BV
Date: 10-2008
First Human Evidence of d-Amphetamine Induced Displacement of a D2/3 Agonist Radioligand: A [11C]-(+)-PHNO Positron Emission Tomography Study
Publisher: Springer Science and Business Media LLC
Date: 04-04-2007
Abstract: Imaging the competition between D(2/3) radioligands and endogenous dopamine is so far the only way to measure dopamine release in the living human brain. The dopamine D(2) receptor exists in a high (D(2)(high)) and a low-affinity state for dopamine. Under physiological conditions, dopamine is expected to bind to D(2)(high) only. [(11)C]-(+)-4-propyl-9-hydroxynaphthoxazine ((+)-PHNO) is the first D(2/3) agonist radioligand for positron emission tomography (PET) imaging in humans. Since [(11)C]-(+)-PHNO is expected to bind preferentially to D(2)(high), it should be particularly vulnerable to competition with endogenous dopamine. Nine healthy subjects participated in two PET scans, one after administration of d- hetamine and one after placebo. [(11)C]-(+)-PHNO PET test re-test variability was determined in 11 healthy subjects. Binding potentials (BPs) were calculated for caudate, putamen, ventral striatum, and globus pallidus. d-Amphetamine led to a significant decrease of [(11)C]-(+)-PHNO BPs in caudate (-13.2%), putamen (-20.8%), and ventral striatum (-24.9%), but not in globus pallidus (-6.5%). d-Amphetamine-induced displacement correlated with serum d- hetamine levels in all regions but caudate. This is the first report on competition between endogenous dopamine and a D(2/3) agonist radioligand in humans. [(11)C]-(+)-PHNO PET might be a superior measure for release of endogenous dopamine than PET employing conventional D(2/3) antagonist radioligands.
The Permian mafic dyke swarm of the Panticosa pluton (Pyrenean Axial Zone, Spain): simultaneous emplacement with the late-Variscan extension
Publisher: Elsevier BV
Date: 09-2012
Striatal vs extrastriatal dopamine D2 receptors in antipsychotic response - A double-blind PET study in schizophrenia
Publisher: Springer Science and Business Media LLC
Date: 11-2007
Abstract: Blockade of dopamine D2 receptors remains a common feature of all antipsychotics. It has been hypothesized that the extrastriatal (cortical, thalamic) dopamine D2 receptors may be more critical to antipsychotic response than the striatal dopamine D2 receptors. This is the first double-blind controlled study to examine the relationship between striatal and extrastriatal D2 occupancy and clinical effects. Fourteen patients with recent onset psychosis were assigned to low or high doses of risperidone (1 mg vs 4 mg/day) or olanzapine (2.5 mg vs 15 mg/day) in order to achieve a broad range of D2 occupancy levels across subjects. Clinical response, side effects, striatal ([11C]-raclopride-positron emission tomography (PET)), and extrastriatal ([11C]-FLB 457-PET) D2 receptors were evaluated after treatment. The measured D2 occupancies ranged from 50 to 92% in striatal and 4 to 95% in the different extrastriatal (frontal, temporal, thalamic) regions. Striatal and extrastriatal occupancies were correlated with dose, drug plasma levels, and with each other. Striatal D2 occupancy predicted response in positive psychotic symptoms (r=0.62, p=0.01), but not for negative symptoms (r=0.2, p=0.5). Extrastriatal D2 occupancy did not predict response in positive or negative symptoms. The two subjects who experienced motor side effects had the highest striatal occupancies in the cohort. Striatal D2 blockade predicted antipsychotic response better than frontal, temporal, and thalamic occupancy. These results, when combined with the preclinical data implicating the mesolimbic striatum in antipsychotic response, suggest that dopamine D2 blockade within specific regions of the striatum may be most critical for ameliorating psychosis in schizophrenia.
Supplemental Material: Volcanic plumbing filters on ocean-island basalt geochemistry
Publisher: Geological Society of America
Date: 20-08-2021
Abstract: Data (Tables S1–S8), methods, and Figures S1–S3. br
Binding characteristics and sensitivity to endogenous dopamine of [11C]‐(+)‐PHNO, a new agonist radiotracer for imaging the high‐affinity state of D2 receptors in vivo usi
Publisher: Wiley
Date: 05-04-2006
DOI: 10.1111/J.1471-4159.2006.03840.X
Abstract: [11C]-(+)-PHNO (4-propyl-9-hydroxynaphthoxazine) is a new agonist radioligand that provides a unique opportunity to measure the high-affinity states of the D2 receptors (D2-high) using positron emission tomography (PET). Here we report on the distribution, displaceablity, specificity and modeling of [11C]-(+)-PHNO and compare it with the well characterized antagonist D2 radioligand, [11C]raclopride, in cat. [11C]-(+)-PHNO displayed high uptake in striatum with a mean striatal binding potential (BP) of 3.95 +/- 0.85. Pre-treatment with specific D1 (SCH23390), D2 (raclopride, haloperidol) and D3 receptor (SB-277011) antagonists indicated that [11C]-(+)-PHNO binding in striatum is specific to D2 receptors. Within-subject comparisons showed that [11C]-(+)-PHNO BP in striatum was almost 2.5-fold higher than that measured with [11C]-(-)-NPA ([11C]-(-)-N-propyl-norapomorphine). Comparison of the dose-effect of hetamine (0.1, 0.5 and 2 mg/kg i.v.) showed that [11C]-(+)-PHNO was more sensitive to the dopamine releasing effect of hetamine than [11C]raclopride. Amphetamine induced up to 83 +/- 4% inhibition of [11C]-(+)-PHNO BP and only up to 56 +/- 8% inhibition of [11C]raclopride BP. Scatchard analyses of [11C]-(+)-PHNO and [11C]raclopride bindings in two cats showed that the Bmax obtained with the agonist (29.6 and 32.9 pmol/mL) equalled that obtained with the antagonist (30.6 and 33.4 pmol/mL). The high penetration of [11C]-(+)-PHNO in brain, its high signal-to-noise ratio, its favorable in vivo kinetics and its high sensitivity to hetamine shows that [11C]-(+)-PHNO has highly suitable characteristics for probing the D2-high with PET.
Geochronology of mafic magmatism and hydrothermal alteration during early stages of South Atlantic opening
Publisher: Elsevier BV
Date: 12-2021
Recognising spatially and geochemically anomalous arc magmatism (SGAM) and implications for plate tectonic reconstructions
Publisher: Copernicus GmbH
Date: 04-03-2021
DOI: 10.5194/EGUSPHERE-EGU21-6932
Abstract: & & Subduction zones generate volcanic arcs, but there are many ex les where magmatism in convergent plate boundaries occurs in unexpected locations relative to the subducting slab. These magmas are commonly also geochemically anomalous relative to the composition of neighbouring typical subduction-related rocks. The origin of such Spatially and Geochemically Anomalous arc Magmatism (SGAM) may correspond to local variations in subduction parameters, the presence of crustal and lithospheric heterogeneities, or the potential contribution of melts generated by slab tearing and slab edge effects. Using the Holocene volcanoes in South America as a case study, we investigated spatial and geochemical patterns of volcanism along the Andean volcanic belt. Based on a series of geochemical indices, we developed a scoring system for the composition of volcanic rocks, with the lowest and highest scores indicating & #8216 typical& #8217 and & #8216 anomalous& #8217 arc melting processes, respectively. The results show that a number of Holocene volcanoes in South America can be unambiguously defined as SGAM. Volcanism in these localities may correspond to disruptions in the geometry of the subducting slab, or to areas affected by mantle flow in the proximity of the slab edge. To test the potential applicability of this method for plate tectonic reconstructions, we calculated geochemical anomaly scores for whole-rock analyses of volcanic rocks from other convergent boundary settings. The results show that high geochemical anomaly scores are obtained in areas where slab tearing has been documented or postulated, such as in Mount Etna (Sicily). The occurrence of anomalous magmatic rocks in older convergent plate boundary settings (e.g., Neogene rocks from the Gibraltar area) corroborates plate tectonic reconstructions that incorporated processes such as subduction segmentation, slab tearing, and the development of asthenospheric windows. Accordingly, we suggest that the recognition of SGAM from other modern and ancient arc settings may inform on similar types of processes, even in cases where the three-dimensional slab structure is no longer detectable.& &
Magmatic Processes and the Role of Antecrysts in the Genesis of Corvo Island (Azores Archipelago, Portugal)
Publisher: Oxford University Press (OUP)
Date: 30-11-2012
Radiosynthesis and Evaluation of [11C]-(+)-4-Propyl-3,4,4a,5,6,10b-hexahydro-2H-naphtho[1,2-b][1,4]oxazin-9-ol as a Potential Radiotracer for in Vivo Imaging of the Dopamine D
Publisher: American Chemical Society (ACS)
Date: 19-05-2005
DOI: 10.1021/JM050155N
Abstract: In vivo imaging of dopamine D2 receptors with agonist (as opposed to the more commonly employed antagonist) radiotracers could provide important information on the high-affinity (functional) state of the D2 receptor in illnesses such as schizophrenia, movement disorders, and addictions. We report here the radiosynthesis and evaluation of the potent D2 agonist (+)-4-propyl-3,4,4a,5,6,10b-hexahydro-2H-naphtho[1,2-b][1,4]oxazin-9-ol, (+)-3, labeled with carbon-11, as a potential radiotracer for imaging the high-affinity state of dopamine D2 receptors with positron emission tomography (PET). [(11)C]-(+)-3 was reliably synthesized in the quantities and at the specific activities and radiochemical purities required for human PET studies. Ex vivo biodistribution studies in rat brain demonstrated that [(11)C]-(+)-3 crossed the blood-brain barrier readily and had an appropriate regional brain distribution for a radiotracer that maps dopamine D2 receptors. The binding of [(11)C]-(+)-3 was saturable and demonstrated an excellent signal-to-noise ratio as measured by its striatum-to-cerebellum ratio of 5.6, 60 min postinjection. The binding was highly stereospecific, and blocking and displacement studies were consistent with selective and specific binding to the dopamine D2 receptors. Further, [(11)C]-(+)-3 showed marked and appropriate sensitivity to both increases and decreases in the levels of endogenous dopamine. Brain radioactive metabolite and physicochemical measurements are in full accord with the desired properties of a neuroreceptor imaging agent for PET. All of the above, coupled with the documented full D2 agonistic properties of (+)-3, strongly indicate that [(11)C]-(+)-3 is a leading candidate radiotracer for the imaging of the dopamine D2 high-affinity state using PET in human subjects.
Magnetic fabric from Quaternary volcanic edifices in the extensional Bransfield Basin: internal structure of Penguin and Bridgeman islands (South Shetlands archipelago, Antarctica)
Publisher: Oxford University Press (OUP)
Date: 05-2021
DOI: 10.1093/GJI/GGAB177
Abstract: Studying the magnetic fabric in volcanic edifices, particularly lava flows from recent eruptions, allows us to understand the orientation distribution of the minerals related to the flow direction and properly characterize older and/or eroded flows. In this work, the magnetic fabric from recent (Quaternary) lava flows (slightly inclined in seven sites and plateau lavas in two sites), pyroclastic deposits (two sites from a scoria cone) and volcanic cones, domes and plugs (three sites) from Penguin and Bridgeman islands, located in the Bransfield backarc basin, are presented. The volcanism in the two islands is related to rifting occurring due to the opening of the Bransfield Strait, between the South Shetlands archipelago and the Antarctic Peninsula. The direction of flow of magmatic material is unknown. Rock magnetic analyses, low temperature measurements and electron microscope observations (back-scattered electron imaging and Energy Dispersive X-ray analyses) reveal a Ti-poor magnetite (and maghemite) as the main carrier of the magnetic fabric. Hematite may be present in some s les. S les from the centre of the lavas reveal a magnetic lineation either parallel or imbricated with respect to the flow plane, whereas in the plateau lavas the magnetic lineation is contained within the subhorizontal plane except in vesicle-rich s les, where imbrication occurs. The magnetic lineation indicates a varied flow direction in Bridgeman Island with respect to the spreading Bransfield Basin axis. The flow direction in the plateau lavas on Penguin Island is deduced from the imbrication of the magnetic fabric in the more vesicular parts, suggesting a SE–NW flow. The volcanic domes are also imbricated with respect to an upward flow, and the bombs show scattered distribution.
The role of undercooling during clinopyroxene growth in trachybasaltic magmas: Insights on magma decompression and cooling at Mt. Etna volcano
Publisher: Elsevier BV
Date: 2020
An automated method for the extraction of regional data from PET images
Publisher: Elsevier BV
Date: 06-2006
DOI: 10.1016/J.PSCYCHRESNS.2006.01.011
Abstract: Manual drawing of regions of interest (ROIs) on brain positron emission tomography (PET) images is labour intensive and subject to intra- and inter-in idual variations. To standardize analysis and improve the reproducibility of PET measures, we have developed image analysis software for automated quantification of PET data. The method is based on the in idualization of a set of standard ROIs using a magnetic resonance (MR) image co-registered with the PET image. To evaluate the performance of this automated method, the software-based quantification has been compared with conventional manual quantification of PET images obtained using three different PET radiotracers: [(11)C]-WAY 100635, [(11)C]-raclopride and [(11)C]-DASB. Our results show that binding potential estimates obtained using the automated method correlate highly with those obtained by trained raters using manual delineation of ROIs for frontal and temporal cortex, thalamus, and striatum (global intraclass correlation coefficient >0.8). For the three radioligands, the software yields time-activity data that are similar (within 8%) to those obtained by manual quantification, eliminates investigator-dependent variability, considerably shortens the time required for analysis and thus provides an alternative method for accurate quantification of PET data.
Clinopyroxene and amphibole crystal populations in a lamprophyre sill from the Catalonian Coastal Ranges (NE Spain): A record of magma history and a window to mineral-melt partitioning
Publisher: Elsevier BV
Date: 2014
High-resolution LA-ICP-MS trace element mapping of igneous minerals: In search of magma histories
Publisher: Elsevier BV
Date: 08-2015
Geochronological constraints on the evolution of El Hierro (Canary Islands)
Publisher: Elsevier BV
Date: 2016
Using high-resolution geochemistry to monitor variations in magma dynamics during eruption
Publisher: Copernicus GmbH
Date: 28-03-2022
DOI: 10.5194/EGUSPHERE-EGU22-9743
Abstract: & & Volcano monitoring makes it possible to indirectly visualise magma plumbing systems and follow the onset and evolution of eruptions. While geophysical data provide real-time information on magma transfer and storage, the petrology of erupted products is crucial to assess magma composition and eruptive style. However, erupted magmas often carry recycled crystals which affect bulk rock compositions, masking variations in erupted melts. Here, we explore the use of high-resolution geochemistry to resolve subtle variations in melt composition on the scale of days to years. We investigate recent basaltic eruptions in a variety of geodynamic settings and with distinct eruptive frequencies, including Mount Etna in Sicily (Italy) and Cumbre Vieja in La Palma (Canary Islands, Spain). We demonstrate that targeted laser ablation mass spectrometry can rapidly determine variations in the chemical composition of melts within the plumbing system, which may add petrological insight to volcano monitoring efforts.& &
Antecrysts and their effect on rock compositions: The Cretaceous lamprophyre suite in the Catalonian Coastal Ranges (NE Spain)
Publisher: Elsevier BV
Date: 10-2014
The influence of crystal settling on the compositional zoning of a thin lamprophyre sill: A multi-method approach
Publisher: Elsevier BV
Date: 02-2012
Tracking the Transition From a Gondwana LIP to the South Atlantic Ocean With Geochronological and Geochemical Indicators
Publisher: American Geophysical Union (AGU)
Date: 05-2023
DOI: 10.1029/2022JB025816
Abstract: Evidence of early oceanization during transition from large igneous provinces (LIPs) to new ocean crust is mostly missing in the geological record. Mafic dykes geochemically akin to mid‐ocean ridge basalts (MORBs) occur in late stages of LIPs, but their tectonic role during margin evolution remains poorly constrained. Here we use whole‐rock and high‐resolution clinopyroxene chemistry of two distinct types of mafic dykes from the southeastern Brazilian margin to show that a MORB‐like plumbing system became magmatically active in the central South Atlantic ∼2 Ma after the volcanic peak of the Paraná‐Etendeka Magmatic Province. The LIP basaltic dyke compositions resulted from the mixing between a highly metasomatized lithospheric mantle comprising enriched DMM and Archean contributions. The lack of elemental oscillatory zoning in clinopyroxene crystals suggests that they were produced by a single magma pulse, consistent with the strong magma fluxes in LIPs. In contrast, the MORB‐like dykes, which exhibit strong similarities with South Atlantic MORBs, are interpreted to represent early stages of oceanization deriving from the mixing of enriched asthenospheric melts either with ancient SCLM contributions or small crustal assimilation. The MORB‐like intrusions ascended and cooled rapidly along faults and were fed by numerous magma injections that suggest episodic decompression of the asthenospheric source ∼20 Ma before the birth of central South Atlantic. The combination of subduction‐influenced and MORB‐like dykes is recurrent in ancient and modern rifts globally, suggesting that thinned lithospheric blocks affected by ancient subduction events may become more susceptible to early oceanization in rifted margins.
D2-receptor upregulation is dependent upon temporal course of D2-occupancy: A longitudinal [11C]-raclopride PET study in cats
Publisher: Springer Science and Business Media LLC
Date: 06-08-2009
DOI: 10.1038/NPP.2008.116
Abstract: Long-term occupancy of dopamine D(2)-receptors, as achieved by chronic treatment with antipsychotics, leads to D(2)-receptor upregulation, and this upregulation is thought to be responsible for loss of efficacy and development of tar e dyskinesia. However, little is known about the parameters of D(2)-receptor blockade (duration and percentage of blockade) that lead to upregulation. In this study, we investigated the effects of different degrees (60 vs >80%) and durations (a transient peak vs 24 h/day) of D(2)-receptor blockade on inducing this upregulation. These different patterns of D(2)-receptor occupancy kinetics were produced in cats using bolus vs constant infusion of haloperidol for 4 weeks. D(2)-receptors were measured using positron emission tomography and Scatchard analyses of [(11)C]raclopride binding, before and after withdrawal of treatment. Continuously high (80% for 24 h/day) D(2)-receptor blockade led to a robust upregulation of striatal D(2)-receptors that was maximal at 1-week withdrawal (35+/-5%) and still detectable at 2-week withdrawal (20+/-3%). This pattern of D(2)-receptor blockade also induced behavioral tolerance to the effect of haloperidol on spontaneous locomotor activity. Continuously moderate (60% for 24 h/day) or transiently high (80% for a few hours/day) D(2)-receptor blockade did not produce any of these effects. The long-term effect of haloperidol on D(2)-receptor density and behavioral tolerance thus appears to be dependent not only on a critical threshold of D(2)-receptor blockade but also on the daily duration of D(2)-receptors blockade. This suggests that as far as antipsychotics are concerned, not only dose but disbursment throughout the day have an impact on eventual pharmacodynamic and behavioral outcomes.
40Ar/39Ar constraints on the temporal evolution of Graciosa Island, Azores (Portugal)
Publisher: Springer Science and Business Media LLC
Date: 25-01-2014
Quantitative Validation of an Intracerebral β-Sensitive Microprobe System to Determine in Vivo Drug-Induced Receptor Occupancy Using [ 11C]Raclopride in Rats
Publisher: Wiley
Date: 2004
DOI: 10.1002/SYN.20010
Abstract: In this study, we evaluated the potential of using a new beta-sensitive microprobe system for in vivo quantification of [11C]raclopride binding and for in vivo determination of drug-induced receptor occupancy in the rat striatum. To validate this system, an ex vivo tissue dissection method was used to corroborate in vivo beta-microprobe measurements. Our data showed that the beta-microprobe-derived [11C]raclopride binding kinetics in striatum could be quantified using a tissue compartmental model with a cerebellar reference region. Haloperidol (0.001-0.1 mg/kg i.v.) induced a dose-dependent decrease in [11C]raclopride binding in striatum as measured using the beta-microprobe with an ED50 value of 0.013 mg/kg. Highly significant relationships (P < 0.0001) were observed, within the same animals, between in vivo and ex vivo measures of haloperidol-induced D2-receptor occupancy (r = 0.98) as well as between in vivo and ex vivo measures of [11C]raclopride binding potentials (r = 0.99). Results from pretreatment and displacement studies with unlabeled raclopride and hetamine conformed to the effect of these drugs as observed in humans using [11C]raclopride and PET and allowed estimation of the in vivo k(off) value of raclopride to 0.025 +/- 0.004 min(-1). However, allowing the system to stabilize before measurements and shielding the photomultiplier tubes were critical for obtaining these consistent results. This study demonstrates that the beta-microprobe provides reliable measurements of [11C]raclopride binding kinetics in rodents, allows for quantitative in vivo measurements of antipsychotic drug action in brain, and represents a valid and cost-effective alternative to positron emission tomography imaging in small animals.
New lithostratigraphy for the Cantabrian Mountains: A common tectono-stratigraphic evolution for the onset of the Alpine cycle in the W Pyrenean realm, N Spain
Publisher: Elsevier BV
Date: 2019
AERYN: A simple standalone application for visualizing and enhancing elemental maps
Publisher: Elsevier BV
Date: 12-2016
Kinetic partitioning of trace cations between zoned clinopyroxene and a variably cooled-decompressed alkali basalt: Thermodynamic considerations on lattice strain and electrostatic energies of substit
Publisher: Elsevier BV
Date: 11-2023
Quantitative Data Extraction from Orthopyroxene Trace Element Maps and Its Potential to Examine the Formation of the UG2 Unit, Bushveld Complex
Publisher: MDPI AG
Date: 27-01-2019
DOI: 10.3390/MIN9020073
Abstract: We present a mineral chemical stratigraphy across the UG2 Unit, situated in the Upper Critical Zone of the Bushveld Complex. The magmatic evolution of the rocks hosting this world-class ore deposit for chromium and platinum group elements (PGEs) is still under debate. Orthopyroxene is a common phase across the magmatic stratigraphy of the unit. It hosts trace metals, whose relative contents can record information about magmatic processes. This study determined laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) trace element data for orthopyroxene and spot LA multi-collector ICP-MS Sr-isotope data for plagioclase. Mapping of trace element distributions revealed internal zoning in Cr, V, Y, and Th. Unlike in conventional spot analysis, quantitative trace element concentrations were extracted post-analysis from two-dimensional LA-ICP-MS maps. This approach offered advantages over spot analysis. The maps revealed internal complexities (e.g., inclusions, exsolved phases, zonations and diffusion halos) that could be avoided with suitable thresholds for chemical filter elements (i.e., 100 ppm Cr 4000 ppm, Y 6 ppm), permitting fast, automated extraction of pure orthopyroxene data pixels from elemental maps covering noritic, troctolitic, anorthositic and chromititic mineral assemblages. Diffusive equilibration in orthopyroxene was evaluated by comparing zonations in elements with different known diffusivities. Magnesium and Ni are homogenously distributed, indicative of rapid diffusive processes, while Cr and V show zonations, interpreted to largely reflect primary distribution. Thorium and Y apparently diffused along discrete pathways, indicated by concentration anomalies following orthopyroxene lamellae. A systematic study of the trace element inventory of orthopyroxene across the succession of the UG2 Unit, complemented with Sr isotope signatures of plagioclase, revealed clear evidence for open-system processes: compatible elements (Cr, Ni) are decoupled from Mg# variations in orthopyroxene from specific UG2 subunits distinct Mg# peaks coincide with negative V excursions in orthopyroxene from chromite-bearing subunits towards the top of the unit, plagioclase shows a distinct 87Sr/86Srinitial peak and orthopyroxene shows Cr-depleted and Th-enriched rims. These chemical features cannot be explained by crystal mixing alone and argue for the involvement of at least two chemically distinct melts in the formation of the studied UG2 section.
The Relevance of Crystal Transfer to Magma Mixing: a Case Study in Composite Dykes from the Central Pyrenees
Publisher: Oxford University Press (OUP)
Date: 02-07-2014
In vivo characterization of the pharmacokinetics and pharmacological properties of [11C]-(+)-PHNO in rats using an intracerebral beta-sensitive system
Publisher: Wiley
Date: 2006
DOI: 10.1002/SYN.20290
Abstract: This study reports on the binding kinetics and pharmacological characterization of [11C]-(+)-PHNO ((+)-4-propyl-3,4,4a,5,6,10b-hexahydro-2H-naphtho[1,2-b][1,4]oxazin-9-ol), a promising agonist radiotracer for in vivo evaluation of the D2-receptor. Its in vivo kinetics were monitored in rat striatum and cerebellum using a beta-sensitive Microprobe system. Control studies showed that [11C]-(+)-PHNO binding was reversible and reached a peak time equilibrium of specific binding in striatum 30 min after radiotracer injection. The binding potential (BP) calculated by the simplified reference tissue model was 3-fold higher than that measured with [11C]-(-)-NPA (2.14 +/- 0.50 vs. 0.66 +/- 0.01, respectively). In contrast, the methyl analog of (+)-PHNO, [11C]-(+)-MHNO, which displayed promising D2-agonist properties in vitro, showed no specific binding in the striatum in vivo. [11C]-(+)-PHNO binding was totally blocked by raclopride (1 mg/kg i.v.) and 97% displaced by NPA (2 mg/kg i.v.) suggesting that [11C]-(+)-PHNO was specific for the high affinity states of D2/D3-receptors. However, (+)-PHNO (1 mg/kg i.v.) totally blocked and displaced [11C]-raclopride binding in striatum. Thus, (+)-PHNO at high concentrations might be able to bind to the low affinity states of D2/D3-receptors. After an hetamine pretreatment (2 mg/kg i.v.), a 69% decrease in BP value (P < 0.05) was observed for [11C]-(+)-PHNO indicating that its binding was highly sensitive to variations of endogenous DA. These results substantiate the use of [11C]-(+)-PHNO as an agonist radiotracer for D2-imaging. The sensitivity of its binding to competition with endogenous DA suggests an association with the subset of high affinity state D2-receptors.
The Lead-up to Mount Etna’s Most Destructive Historic Eruption (1669). Cryptic Recharge Recorded in Clinopyroxene
Publisher: Oxford University Press (OUP)
Date: 2020
DOI: 10.1093/PETROLOGY/EGAA025
Abstract: An understanding of destructive historic eruptions has important implications for the assessment of active plumbing systems and the processes that might precede future hazardous eruptions. At Mount Etna (Sicily, Italy), magma production and eruption frequency have increased dramatically since 1970, however, the recent eruptions are considerably less voluminous than those of the 17th century, which occurred at greater intervals. Seventeenth century activity culminated in the 1669 flank eruption, the most voluminous and destructive in Etna’s recorded history, marking the beginning of a new eruptive period. In this study, we examine trace element zoning patterns recorded in clinopyroxene (lava hosted microcrysts: 0·5–1 mm, lava hosted macrocrysts: 1–5 mm and scoria hosted megacrysts: & mm) to reconstruct magma dynamics leading up to the 1669 eruption. The clinopyroxene data are considered alongside previous studies of olivine and plagioclase to present an updated conceptual model for the plumbing system, providing a better understanding of magmatic processes in the lead up to hazardous volcanism. Petrological observations in combination with laser ablation ICP-MS mapping reveal sharp compositional zoning of clinopyroxene, not seen in major element transects. Trace element data, including Cr, Zr, Ni and rare earth elements, show that core, mantle and rim regions originated in distinct magmatic environments. Chromium-rich cores (up to 1080 ppm Cr) are in disequilibrium with the glassy-microcrystalline host groundmass and indicate crystal inheritance from a primitive magma source. Oscillatory zoning in the mantle of the crystals suggests a sustained period of magma replenishment and crystallization. Finally, ubiquitous Cr-rich (170–220 ppm) rims host many large melt inclusions, suggesting a final recharge event inducing relatively rapid crystal growth and eruption. Temperatures of 1120–1160 ± 27°C and pressures of 300–600 ± 200 MPa calculated for the three magmatic environments based on clinopyroxene composition at 2 wt % H2O place most of the clinopyroxene crystallization at more than 10 km depth. Measuring the consistent thickness of crystal rims (219 ± 33 µm) and assuming growth at a low degree of undercooling (10−8 cm/s), we calculate that the eruption triggering magma recharge invaded the plumbing system less than a month before eruption onset, in agreement with historical accounts of pre-eruptive seismicity. Notably, Cr enrichment in the recharge magma was not coupled with increases in MgO content. We therefore propose that a cryptic recharge with similar composition to the resident melt may have tipped the system to erupt, and that the volume of recharge rather than composition or temperature acted as the primary trigger. Finally, LA-ICP-MS maps of clinopyroxene from the previous eruption of Mount Etna (1651–53) revealed strikingly similar compositional zonation to that of 1669, supporting the notion that magmatic storage environments, associated with voluminous 17th century activity, were long-lived.
Evidence of a common source component for east Australian Cenozoic mafic magmatism
Publisher: Elsevier BV
Date: 02-2020
Magmatic Evolution of Graciosa (Azores, Portugal)
Publisher: Oxford University Press (OUP)
Date: 28-10-2014
New reference materials, analytical procedures, and data reduction strategies for Sr isotope measurements in geological materials by LA-MC-ICP-MS
Publisher: California Digital Library (CDL)
Date: 19-10-2022
DOI: 10.31223/X5364X
Abstract: Laser ablation multi-collector mass spectrometry (LA-MC-ICP-MS) has emerged as the technique of choice for in situ measurements of Sr isotopes in geological minerals. However, the method poses analytical challenges and there is no widely adopted standardised approach to collecting these data or correcting the numerous potential isobaric inferences. Here, we outline practical analytical procedures and data reduction strategies to help establish a consistent framework for collecting and correcting Sr isotope measurements in geological materials by LA-MC-ICP-MS. We characterise a new set of plagioclase reference materials, which are available for distribution to the community, and present a new data reduction scheme for the Iolite software package to correct isobaric interferences for different materials and analytical conditions. Our tests show that a combination of Kr-baseline subtraction, Rb-peakstripping using βRb derived from a bracketing glass standard, and a CaCa/CaAr correction for plagioclase and CaCa/CaAr + REE2+ correction for rock glasses, yields the most accurate and precise 87Sr/86Sr measurements for these materials. Using the analytical and correction procedures outlined herein, spot analyses using a beam diameter of 100 μm or rastering with a 50—65 μm diameter beam can readily achieve ppm 2SE internal precision for 87Sr/86Sr measurements for materials with ppm Sr.
Deep Magma Storage Revealed by Multi-Method Elemental Mapping of Clinopyroxene Megacrysts at Stromboli Volcano
Publisher: Frontiers Media SA
Date: 24-09-2019
Plagioclase as a witness of syn-eruptive degassing in rhyolitic magmas
Publisher: Copernicus GmbH
Date: 23-03-2020
DOI: 10.5194/EGUSPHERE-EGU2020-8886
Abstract: & & Lithium (Li) is one of the fastest diffusing elements in most geological media and so has the potential to provide information about processes occurring on timescales too short to be captured by other proxies. & These processes may be of fundamental importance both in terms of understanding what happens during explosive volcanism and for defining where lithium, an element of increasing economic importance, ends up. & To investigate the fate of Li, we studied in detail the 1.30 Ma Mesa Falls Tuff (MFT) from the Yellowstone volcanic field (USA). & MFT is a typical rhyolite of the Yellowstone system containing an anhydrous mineral assemblage of sanidine, quartz, plagioclase, clinopyroxene, fayalite, orthopyroxene and accessory phases. & We focussed on plagioclase crystals that have a strong gradient in Li contents from cores at ~25 ppm to rims with ~ 5 ppm. & This notable decrease in Li abundance is decoupled from changes in other major and trace elements. & & #948 & sup& & /sup& Li values measured by fs-LA-MC-ICPMS in the plagioclase crystals reveal that cores are about 5 & #8240 lower than rims. & Taken together, the Li abundance and isotopic data make a compelling case for the plagioclase attempting to react to a sudden change in Li abundance in the surrounding melt. & Diffusion modelling of these gradients indicates that this sudden Li drop in the melt occurred over timescales of tens of minutes prior to quenching. & The volatile behaviour of Li implied by this result finds support in Li concentrations measured in quartz-hosted melt inclusions that reach 400 ppm while groundmass glass Li contents are much lower (36-55 ppm). & While equilibrium fractionation of stable isotopes is minimised at high temperatures, the large-magnitude, rapid loss of lithium from the melt phase may allow kinetic isotopic fractionation to occur, as recorded in the plagioclase crystals. & With glass / groundmass both volumetrically dominant and the main repository of Li in virtually all volcanic deposits, further consideration of how syn-eruptive processes may affect the bulk Li identity of a s le is warranted. & & & & & & & & & & &
Diffusion chronometry and the timescales of magmatic processes
Publisher: Springer Science and Business Media LLC
Date: 04-2020
Brain region binding of the D2/3 agonist [11C]‐(+)‐PHNO and the D2/3 antagonist [11C]raclopride in healthy humans
Publisher: Wiley
Date: 11-05-2007
DOI: 10.1002/HBM.20392
From Explosive Vent Opening to Effusive Outpouring: Mineral Constraints on Magma Dynamics and Timescales at Paricutin Monogenetic Volcano
Publisher: Oxford University Press (OUP)
Date: 06-01-2021
DOI: 10.1093/PETROLOGY/EGAA112
Abstract: Paricutin volcano is the youngest monogenetic cone of the Michoacán–Guanajuato volcanic field (Mexico), with an excellent historical eruption record from February 1943 to March 1952. The magma emitted during the 9 years of activity was compositionally zoned from basaltic andesite to andesite. This eruption has been considered a classic ex le of magma differentiation controlled by crustal assimilation combined with fractional crystallization. However, a recent geochemical study of the eruption products points to mantle source heterogeneity and fractional crystallization as the key processes involved in the compositional variability of the magmas. Here we present a detailed petrological characterization of the minerals [olivine, plagioclase, pyroxene, Cr-spinel, and (Ti-)magnetite] to shed light on the processes that led to the chemical evolution of the eruptive products. Our s le set includes the early tephra from the first weeks or months of eruption and the whole sequence of lava flows that followed. The mineral assemblage, their texture, and chemical composition show a systematic evolution between the products from the opening of the explosive vent to the effusive stage. The early tephra are basaltic andesites with oscillatory-zoned olivine and plagioclase, zoned Cr-spinel, and rare pyroxene xenocrysts. In contrast, later erupted tephra and post-January 1944 lavas are basaltic andesites and andesites with normally zoned olivine, Cr-spinel inclusions in equilibrium with the host olivine, and frequent orthopyroxene (after December 1947) with minor chemical zoning. Mineral chemistry data and olivine diffusion timescales, together with whole-rock geochemistry, suggest a convective magma regime with large temperature and oxygen fugacity gradients characterized by short timescales (few days) during the opening stage, followed by a steadier magma regime with longer timescales (few months) and including periodic magma recharge, mixing, and fractional crystallization. In addition, the mineralogical evidence we have gathered does not support considerable crustal assimilation at Paricutin. This study shows that monogenetic eruptions are far from being geochemically simple, and instead involve multiple magma batches with complex storage and mixing stages before eruption.
Volcanic plumbing filters on ocean-island basalt geochemistry
Publisher: Geological Society of America
Date: 2022
DOI: 10.1130/G49224.1
Abstract: Ocean-island basalts (OIBs) are considered to be messengers from the deep mantle, yet the filtering effect of the plumbing systems that bring OIB melts to the surface remains poorly assessed. We investigated volcanic products from El Hierro island (Canary Islands) from textural and chemical perspectives. The majority of geochemical data cluster at relatively fractionated basaltic compositions of 5 wt% MgO. Compositions ≥10 wt% MgO are porphyritic whole rocks that accumulate mafic minerals. Near-primary melts do not erupt. Instead, we show that carrier melts (crystal-free whole rocks, glasses, and melt inclusions) are consistently buffered to low-MgO compositions during passage through the plumbing system. We tested our model of melt fractionation and crystal accumulation on a global compilation of OIBs. Similar to El Hierro, the majority of data cluster at evolved compositions of 5 wt% MgO (alkaline) to 7 wt% MgO (tholeiitic). Modeling the fractionation of OIB parental melts, we show that with 50% crystallization, OIB melts reach 5 wt% MgO with reduced density, increased volatile content, and overall low viscosity, becoming positively buoyant relative to wall rocks and highly eruptible when reaching volatile saturation at depths around the crust-mantle boundary. Under these conditions, 5 wt% MgO OIB “sweet spot” melts are propelled to the surface and erupt carrying an assortment of recycled crystals. This mechanism is consistent with the petrography and chemistry of erupted products and suggests OIB volcanoes are dominated by low-MgO basaltic melts.
Increasing complexity in magmatic architecture of volcanoes along a waning hotspot
Publisher: Springer Science and Business Media LLC
Date: 23-03-2023
Petrogenesis of the Hoy lava field, a long-lived continental mafic volcanic province in eastern Australia
Publisher: Informa UK Limited
Date: 09-08-2023
High-Affinity States of Human Brain Dopamine D2/3 Receptors Imaged by the Agonist [11C]-(+)-PHNO
Publisher: Elsevier BV
Date: 03-2006
DOI: 10.1016/J.BIOPSYCH.2005.09.017
Abstract: The high-affinity states of dopamine D2-receptors (D2(high)) are postulated to be functionally responsible for signal transduction. At present, no useful in vivo method exists to selectively measure D2(high) in humans, as current D2 radioligands for positron emission tomography (PET) are either not D2-selective or do not differentiate between D2 high- and low-affinity states. The D2-agonist (+)-PHNO [(+)4-propyl-9-hydroxynaphthoxazine] was labeled with carbon-11 and studied with PET. Eight [11C]-(+)-PHNO scans were acquired in four healthy volunteers. We observed greatest [11C]-(+)-PHNO accumulation in caudate, putamen, and globus pallidus [binding potentials (BPs): 3.00 +/- .4, 3.10 +/- .2, and 4.17 +/- 1.2]. Small but detectable binding was identified in the substantia nigra/ventral tegmental area. Preliminary test-retest data in two subjects suggests BP-estimates to be reliable. Pre-treatment with haloperidol reduced BPs in regions showing specific binding with no detectable changes in cerebellum. Parallel imaging with [11C]-raclopride showed substantial differences in the globus pallidus. [11C]-(+)-PHNO proved to be a D2/3-receptor agonist-radioligand with good brain uptake and favorable kinetics for PET in humans. [11C]-(+)-PHNO delineated D2/3-receptor rich brain regions with high signal-to-noise ratio. This is the first demonstration of a viable agonist-radioligand for D2 receptors in humans and opens the door for investigating D2(high) in health and disease.
Spatially and Geochemically Anomalous Arc Magmatism: Insights From the Andean Arc
Publisher: American Geophysical Union (AGU)
Date: 06-2021
DOI: 10.1029/2021GC009688
Abstract: While most volcanic arcs show a distinctive spatial relationship to subducting plates, there are many ex les where volcanoes occur in anomalous locations. These are commonly also geochemically anomalous relative to the composition of more typical subduction‐related rocks. Using Holocene volcanoes in South America as a case study, we document the spatial and geochemical patterns along the Andean volcanic belt. To determine whether spatial variations are also geochemically anomalous, we assess a series of geochemical indices that provide information on the depth and degree of melting, and the role of metasomatic subduction inputs in melt generation. We use these parameters to develop a scoring system, with the lowest and highest scores indicating “typical” and “anomalous” arc melting processes, respectively. Typical arc magmatism is defined as melts generated in the sub‐arc mantle wedge through slab‐derived fluid metasomatism, with or without contributions from subducted sediments. In contrast, we show that anomalous volcanism in South America appears to relate to geometric anomalies in the subducting Nazca plate (e.g., beneath Sumaco, Laguna Blanca and Payun Matru), or to areas affected by variations in mantle flow due to the proximity to the slab edge (Crater Basalt Volcanic Field). By establishing relationships between anomalous magmatism and slab structure, we propose that similar geochemical fingerprints could be used to explore the magmatic response to slab deformation and/or tearing in older arc systems, particularly in cases where the three‐dimensional slab structure is no longer detectable.
Sector-zoned clinopyroxene as a recorder of magma history, eruption triggers, and ascent rates
Publisher: Elsevier BV
Date: 04-2019
Days to weeks of syn-eruptive magma interaction: High-resolution geochemistry of the 2002-03 branched eruption at Mount Etna
Publisher: Elsevier BV
Date: 07-2021
Age of the Cretaceous alkaline magmatism in northeast Iberia: Implications for the Alpine cycle in the Pyrenees
Publisher: American Geophysical Union (AGU)
Date: 07-2014
DOI: 10.1002/2013TC003511
Temporal constraints on magma generation and differentiation in a continental volcano: Buckland, eastern Australia
Publisher: Elsevier BV
Date: 03-2018
Supplemental Material: Volcanic plumbing filters on ocean-island basalt geochemistry
Publisher: Geological Society of America
Date: 20-08-2021
DOI: 10.1130/GEOL.S.15832080.V1
Abstract: Data (Tables S1–S8), methods, and Figures S1–S3. br
Olivine major and trace element compositions coupled with spinel chemistry to unravel the magmatic systems feeding monogenetic basaltic volcanoes
Publisher: Elsevier BV
Date: 2019
Positron Emission Tomography Quantification of [11C]-(+)-PHNO Binding in the Human Brain
Publisher: SAGE Publications
Date: 11-10-2006
Abstract: The kinetic modeling of [ 11 C]-(+)-PHNO binding to the dopamine D 2/3 receptors in six human volunteers using positron emission tomography (PET) is described. [ 11 C]-(+)-PHNO is the first agonist radioligand for the D 2/3 in humans and as expected showed high uptake in caudate, putamen, globus pallidus (GP) and ventral striatum, and low uptake in cerebellum. A two-tissue compartment model (2CM) with four parameters was necessary to adequately fit time—activity data in all regions. Although a 2CM provided an excellent estimation of total distribution volumes, which were highly correlated with those obtained with the invasive Logan approach, it provided a poor identification of the k 3 / k 4 ratios. Coupling K 1 / k 2 between brain regions (Method C) or fixing K 1 / k 2 to the value obtained in cerebellum (Method D) enabled more stable estimates of k 3 / k 4 as compared with an unconstrained 2CM. The k 3 / k 4 obtained with Method D ranged from 0.12 ± 0.03 in cerebellum to 3.93 ± 0.77 in GP and were similar to those obtained when coupling K 1 / k 2 . Binding potentials (BPs) obtained using the simplified reference tissue model ( BP SRTM ) ranged from 2.08 ± 0.34 in caudate to 3.55 ± 0.78 in GP and were highly correlated with k 3 / k 4 estimates obtained with Method D ( r = 0.98). However, BP SRTM were 11% ± 5% lower than values obtained with Method D. BPs derived using the noninvasive Logan approach were slightly lower but not significantly different than BP SRTM . This study demonstrates that [ 11 C]-(+)-PHNO can be used for the quantitative measurement of D 2/3 densities and should enable further studies of potential D 2/3 dysregulation in several important psychiatric and neurologic illnesses.
Discrete magma injections drive the 2021 La Palma eruption
Publisher: American Association for the Advancement of Science (AAAS)
Date: 07-07-2023
Abstract: Understanding the drivers of the onset, evolution, and end of eruptions and their impact on eruption style is critical in eruption forecasting and emergency management. The composition of erupted liquids is a key piece of the volcano puzzle, but untangling subtle melt variations remains an analytical challenge. Here, we apply rapid, high-resolution matrix geochemical analysis on s les of known eruption date spanning the entire 2021 La Palma eruption. Sr isotope signatures reveal distinct pulses of basanite melt driving the onset, restart, and evolution of the eruption. Elemental variations in matrix and microcrysts track progressive invasion, and draining, of a subcrustal crystal mush. Associated variations in lava flow rate, vent development, seismicity, and SO 2 emission demonstrate that volcanic matrix resolves eruption patterns that could be expected in future basaltic eruptions globally.
A single-scan protocol for absolute D2/3 receptor quantification with [123I]IBZM SPECT
Publisher: Elsevier BV
Date: 02-2017
DOI: 10.1016/J.NEUROIMAGE.2016.12.050
Abstract: Molecular imaging of the D Twenty-nine male rats were used. Binding parameters were estimated using the 3T-7k in a multi-injection protocol. A partial saturation protocol was applied at the region- and voxel-level and results were compared to those obtained with the 3T-7k model. The partial saturation protocol was applied after an adenovirus-mediated D The partial saturation experiments gave similar values as the 3T-7k both at the regional and voxel-level. After adenoviral-mediated D A partial saturation protocol permits the non-invasive and time-efficient estimation of B
First report of a middle-upper permian magmatism in the SE Iberian ranges: Characterisation and comparison with coeval magmatisms in the Western Tethys,Primeros datos del magmatismo pérmico medio-superior del SE de la cordillera ibérica: Caracterización y comparación con magmatismos contemporáneos del Tethys occidental
Publisher: Universidad Complutense de Madrid (UCM)
Date: 15-02-2012
Conditions and Dynamics of Magma Storage in the Snæfellsnes Volcanic Zone, Western Iceland: Insights from the Búðahraun and Berserkjahraun Eruptions
Publisher: Oxford University Press (OUP)
Date: 18-06-2021
DOI: 10.1093/PETROLOGY/EGAB054
Abstract: Establishing the conditions and dynamics of pre-eruptive magma storage and transfer within transient transcrustal storage networks is a major focus of quantitative volcanic petrology. In Iceland, the behaviour, conditions and timescales of magmatic processes within on-rift plumbing systems are increasingly well constrained. However, relatively little is known about magma storage and transfer in off-rift zones, despite off-rift volcanoes being able to generate hazardous explosive eruptions after centuries or millennia of dormancy (e.g. 2010 AD Eyjafjallajökull 1362 AD Öræfajökull 3.0 ka, 4.2 ka and 1104 AD Hekla). We present a combined geochemical and geothermobarometric study of magma storage and transfer recorded in the products of the postglacial Búðahraun (∼5.0–8.0 ka) and Berserkjahraun (∼4.0 ka) eruptions within the Snæfellsnes volcanic zone. The eruption products contain erse and compositionally heterogeneous macrocryst cargoes recording complex petrogenetic histories of crystal evolution and inheritance from different parts of the sub-volcanic plumbing systems. Geothermobarometry indicates two compositionally and thermally heterogeneous magma storage regions located in the lower (20 ± 4 km) and upper-mid (11 ± 3 km) crust. Crystallization pressure and depth estimates coincide with comparable data from Vatnafell, a small sub-glacial table mountain (tuya) in the centre of the Snæfellsnes volcanic zone, indicating that the nature and conditions of magma storage have remained unchanged since the Upper Pleistocene. Trace element zoning of clinopyroxene macrocrysts indicates that mafic recharge into the upper-mid-crustal storage zone triggered the eruptions of Búðahraun and Berserkjahraun. Evidence for eruption-triggering mafic recharge and basaltic cannibalism involving the transfer and amalgamation of crystals with different evolutionary histories sets the Búðahraun and Berserkjahraun eruptions apart from other studied eruptions in Iceland. We propose that the compositional and textural ersity preserved within the crystal cargoes are a direct consequence of the reduced heat flow beneath the Snæfellsnes volcanic zone, which favours the formation of isolated melt pockets in which compositionally erse macrocryst populations formed. Periodic flushes of primitive basaltic magma from depth promote widespread mixing with evolved melts, resulting in the assembly of crystals with erse ancestries from different parts of the sub-volcanic systems. Insights gained from the erse macrocryst cargoes of Búðahraun and Berserkjahraun and comparisons with recent off-rift volcanism in Iceland are essential for the development of future monitoring efforts and hazard evaluation. Although volcanism within the Snæfellsnes volcanic zone differs fundamentally from that in rift zones where eruptions are controlled by extensional spreading, magma ascent from depth still appears to follow pre-existing tectonic escape routes. This could result in extremely short advance warning times on the order of a few days.
In Australasia, gender is still on the agenda in geosciences
Publisher: Copernicus GmbH
Date: 24-09-2020
DOI: 10.5194/ADGEO-53-205-2020
Abstract: Abstract. Diversity and inclusion in the workplace optimise performance through the input of a range of perspectives and approaches that drive innovation and invention. However, gender inequity is prevalent throughout society and females remain underrepresented in geoscience careers. This study provides the current status of gender equity in geosciences throughout Australasia within the context of broader gender equity policy, frameworks and initiatives and suggests additional solutions and opportunities to improve gender equity and the retention of women in the geoscience workforce. At an in idual institutional level in academia, females make up between 23 %–52 % of the total geoscience departmental or school staff in Australia, 26 %–39 % of the total staff in New Zealand, 29 % of total staff at the University of Papua New Guinea and 18 % at the University of the South Pacific. Significant gender imbalance exists at more senior levels, with disproportionately more males than females, a pattern typical of many Science Technology Engineering and Maths (STEM) disciplines. Gender inequity is prevalent within the general membership, committee roles and in award recipients of Australasian geoscience professional associations. Within the Geological Society of Australia and Geoscience Society of New Zealand, only 4 % (n=47) and 18 % (n=161), respectively of past award recipients for national and general awards were female. All past awards considered in this study that are named in honour of a person were named in honour of a man (n=9). In recent years, women-focused networks have begun to play an invaluable role to support the retention and promotion of women in geosciences and provide a supportive mentoring environment to discuss challenges and share advice. The improved visibility of women in the geoscientific community is an ongoing issue that can in part be addressed through the development of public databases of women geoscientists. These provide a list of women geoscientists that encourages and supports the achievement of gender balance of invited talks, job shortlisting and on panels, as well as in the media. This work highlights that more must be done to actively reduce and eliminate sexual harassment and assault in university and field environments. We emphasise that particular efforts are required to make geoscience careers more inclusive and safer, through the establishment of specific codes of conduct for field trips. Shared learning of best practices from evidence-based approaches and innovative solutions will also be of value in creating positive change. Greater engagement from the wider geoscientific community, and society in general, is required for the success of gender equity initiatives. Identified solutions and opportunities must target all levels of education and career development. Additional data in future should be collected to look beyond gender to monitor and assess intersectionality. Improved efforts to understand why women leave STEM careers will help to address the “leaky pipeline” and determine the initiatives that will be most effective in creating long term sustainable change.
Protracted volcanism after large impacts: Evidence from the Sudbury impact basin
Publisher: American Geophysical Union (AGU)
Date: 04-2017
DOI: 10.1002/2016JE005085
The Influence of Undercooling and Sector Zoning on Clinopyroxene–Melt Equilibrium and Thermobarometry
Publisher: Oxford University Press (OUP)
Date: 10-2023
Volcanic crystals as time capsules of eruption history
Publisher: Springer Science and Business Media LLC
Date: 23-01-2018
DOI: 10.1038/S41467-017-02274-W
Abstract: Crystals formed prior to a volcanic event can provide evidence of processes leading to and timing of eruptions. Clinopyroxene is common in basaltic to intermediate volcanoes, however, its ability as a recorder of pre-eruptive histories has remained comparatively underexplored. Here we show that novel high-resolution trace element images of clinopyroxene track eruption triggers and timescales at Mount Etna (Sicily, Italy). Chromium (Cr) distribution in clinopyroxene from 1974 to 2014 eruptions reveals punctuated episodes of intrusion of primitive magma at depth. Magma mixing efficiently triggered volcanism (success rate up to 90%), within only 2 weeks of arrival of mafic intrusions. Clinopyroxene zonations distinguish between injections of mafic magma and regular recharges with more evolved magma, which often fail to tip the system to erupt. High Cr zonations can therefore be used to reconstruct past eruptions and inform responses to geophysical signals of volcano unrest, potentially offering an additional approach to volcano hazard monitoring.
How Antipsychotics Work: Linking Receptors to Response
Publisher: Oxford University PressNew York
Date: 16-10-2010
DOI: 10.1093/ACPROF:OSO/9780195373035.003.0038
Abstract: Schizophrenia is a chronic and disabling disease that typically begins during adolescence or early adult life and severely impacts psychosocial functioning. There is no known single cause of schizophrenia. It is hypothesized that genetic factors and early neurodevelopmental abnormalities (including apoptosis, disruption of neuronal migration, or alteration of synaptogenesis) may confer a constitutional vulnerability to the disease. Subsequent environmental factors (including obstetric complications, exposure to viral infection in utero, or exposure to psychosocial stress during childhood) may then trigger the behavioral expression of this vulnerability, perhaps via subtle alterations of brain development. Within this framework, dysregulations of the dopamine (DA) and glutamate neurotransmitter systems have been most intimately associated with the physiopathology of schizophrenia. This chapter focuses on this aspect of the illness, with special attention given to the DA receptors.
In vivo evidence for dopamine-mediated internalization of D2-receptors after amphetamine: Differential findings with [3H]raclopride versus [3H]spiperone
Publisher: American Society for Pharmacology & Experimental Therapeutics (ASPET)
Date: 02-2003
DOI: 10.1124/MOL.63.2.456
Abstract: Competition with endogenous dopamine (DA) is usually invoked to explain changes in [(11)C]raclopride binding observed after hetamine administration in animals and humans. This account has recently been questioned because a number of inconsistencies have been reported that contradict it. In the present study, we investigated whether the decrease in [(3)H]raclopride binding observed in the rat striatum after an hetamine challenge reflects true competition with endogenous DA or agonist-mediated internalization of D(2)-receptors. We found that the hetamine-induced decrease in [(3)H]raclopride binding is caused by a decrease in D(2)-receptor density (B(max)) with no change in affinity (K(d)). In contrast, in the same tissue, neither the B(max) nor the K(d) were affected when measured with [(3)H]spiperone. Challenge with hetamine not only decreased the number of D(2)-receptors but also eliminated the proportion (22%) of receptors usually in the high-affinity state. The addition of Gpp(NH)p had no effect on B(max), suggesting that these receptors were not just noncompetitively bound with dopamine at the cell-surface. Subcellular fractionation studies showed that hetamine treatment led to a decrease in radioligand binding in the cell-surface fraction for both [(3)H]raclopride and [(3)H]spiperone however, in the case of [(3)H]spiperone, this was accompanied by a compensatory increase in binding in the intracellular compartment, whereas no increase was seen with [(3)H]raclopride. These data suggest that hetamine releases dopamine, which binds to the high-affinity state of the D(2)-receptor, leading to its sequestration in some intracellular compartment in this compartment, sequestered receptors are inaccessible to [(3)H]raclopride binding but can still be bound by [(3)H]spiperone.
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