Preprints
Filtering by Subject: Mineral Physics
The sensitivity of lowermost mantle anisotropy to past mantle convection
Published: 2024-06-20
Subjects: Geophysics and Seismology, Mineral Physics
It is widely believed that seismic anisotropy in the lowermost mantle is caused by the flow-induced alignment of anisotropic crystals such as post-perovskite. What is unclear, however, is whether the anisotropy observations in the lowermost mantle hold information about past mantle flow, or if they only inform us about the present-day flow field. To investigate this, we compare the general and [...]
Theoretical infrared signature of OH defects in Fe3+, Cr3+ and Al3+-doped enstatite
Published: 2024-06-08
Subjects: Mineral Physics
The infrared spectroscopic properties of selected defects involving one proton and one nearby M3+ (M=Al, Cr, Fe) substitution in orthoenstatite are investigated by first- principles calculations. Based on the theoretical results, the absorption bands experimentally observed on synthetic samples with high crystalline quality and low doping levels can be assigned to specific defect configurations. [...]
Synchrotron radiation reveals transient weakening during mineral phase transformations
Published: 2024-05-13
Subjects: Earth Sciences, Geology, Mineral Physics, Tectonics and Structure
Phase transformations are widely invoked as a source of rheological weakening during subduction, continental collision, mantle convection, and various other geodynamic phenomena. However, the likelihood and magnitude of such weakening in nature remains undetermined. Here, experiments performed on a synchrotron beamline reveal dramatic weakening across the polymorphic quartz↔coesite phase [...]
Grüneisen parameter formalism in the study of the Earth's core formation: a sensitivity study
Published: 2024-03-21
Subjects: Condensed Matter Physics, Earth Sciences, Geochemistry, Geology, Mineral Physics, Other Earth Sciences, Planetary Geophysics and Seismology, Planetary Mineral Physics, Planetary Sciences
The Grüneisen parameter is an important parameter for the thermal state and evolution of the core, but its uncertainties and their implications are sometimes overlooked . Several formalisms using different parameters values have been used in different studies, making comparison between studies difficult. In this paper, we use previously published datasets to test the sensitivity of modeling the [...]
Three-dimensional mineral dendrites reveal a non-classical crystallization pathway
Published: 2024-03-04
Subjects: Earth Sciences, Fluid Dynamics, Geochemistry, Mineral Physics, Physical Sciences and Mathematics, Physics
Manganese (Mn) dendrites are a common type of mineral dendrite that typically forms two-dimensional structures on rock surfaces. Three-dimensional (3D) Mn dendrites in rocks have rarely been reported, hence their growth implications have largely escaped attention. Here, we combine high-resolution X-ray and electron-based data with numerical modelling to give the first detailed description of [...]
Excited state lifetime of electron trapping centres in alkali feldspars
Published: 2023-11-02
Subjects: Earth Sciences, Mineral Physics, Other Earth Sciences, Physical Sciences and Mathematics, Physics
The development of the infrared photoluminescence (IRPL) signal enables the direct non-destructive probing of the trapped electron population in feldspars. Whilst IRPL offers new perspectives for luminescence dating, it also enables detailed, site-selective measurements of the dosimetric defects emitting IRPL at 880 nm (IRPL880) and 955 nm (IRPL955), allowing improved understanding of [...]
A key role for diffusion creep in eclogites: Omphacite deformation in the Zermatt-Saas Unit, Italian Alps
Published: 2023-04-18
Subjects: Earth Sciences, Geochemistry, Geology, Mineral Physics, Tectonics and Structure
Eclogites are important components of subduction-collision zones, with the mineral omphacite acting as the supporting framework mineral that accommodates the majority of any accumulated strain. As such it is important to determine which deformation mechanisms operate in omphacite during and after its formation to understand the rheology of deforming subducted crust. Such information is key to [...]
Examining the power supplied to Earth's dynamo by magnesium precipitation and radiogenic heat production
Published: 2023-04-05
Subjects: Earth Sciences, Geophysics and Seismology, Mineral Physics, Physical Sciences and Mathematics, Planetary Sciences
We examine magnesium and potassium solubility in liquid Fe mixtures, representative of Earth’s core composition, in equilibrium with liquid silicate mixtures representative of an early magma ocean. Our study is based on the calculation of the chemical potentials of MgO and K2O in both phases, using density functional theory. For MgO, we also study stability against precipitation of the solid [...]
Compressibility of ferropericlase at high-temperature: evidence for the iron spin crossover in seismic tomography
Published: 2023-04-05
Subjects: Earth Sciences, Geophysics and Seismology, Mineral Physics
The iron spin crossover in ferropericlase, the second most abundant mineral in Earth’s lower mantle, causes changes in a range of physical properties, including seismic wave velocities. Understanding the effect of temperature on the spin crossover is essential to detect its signature in seismic observations and constrain its occurrence in the mantle. Here, we report the first experimental results [...]
DiadFit: An Open-Source Python3 Tool for Peak fitting of Raman Data from silicate melts and CO2 fluids
Published: 2023-04-04
Subjects: Earth Sciences, Geology, Mineral Physics, Physical Sciences and Mathematics, Volcanology
We present DiadFit - an open-source Python3 tool for efficient processing of Raman spectroscopy data collected from fluidinclusions, melt inclusions and silicate melts. DiadFit is optimized to fit the characteristic peaks from CO2 fluids (Fermi diads,hot bands, 13C), gas species such as SO2, N2, solid precipitates (e.g., carbonates), and Ne emission lines with easily tweakablebackground positions [...]
Can homogeneous nucleation resolve the inner core nucleation paradox?
Published: 2023-03-24
Subjects: Condensed Matter Physics, Earth Sciences, Geophysics and Seismology, Mineral Physics, Planetary Geophysics and Seismology, Planetary Mineral Physics
Barometers behaving badly: Assessing the influence of analytical and experimental uncertainty on clinopyroxene thermobarometry calculations at crustal conditions
Published: 2022-12-01
Subjects: Earth Sciences, Geochemistry, Geology, Mineral Physics, Volcanology
The composition of clinopyroxene and Clinopyroxene-Liquid (Cpx-Liq) pairs are frequently used to calculate crystallization/equilibration pressures in igneous systems. While canonical uncertainties are often assigned to calculated pressures based on fits to calibration or test datasets, the sources of these uncertainties (and thus ways to reduce them) have not been rigorously assessed. We show [...]
Comparative study of alteration sequences in pegmatitic aluminium phosphates
Published: 2022-09-29
Subjects: Earth Sciences, Geochemistry, Geology, Mineral Physics, Other Earth Sciences
Aluminium phosphates are mineral phases commonly occurring in rare-element pegmatites that record initial magmatic crystallization, metasomatic and hydrothermal replacements and precipitation and low-temperature alteration. Here we perform a comparative mineralogical study between several localities to assess similarities and variations in these parageneses and establish a general alteration [...]
Characterisation of phosphate mineralogy in Montebras-en-Soumans Pegmatite, Massif Central, France
Published: 2022-09-22
Subjects: Earth Sciences, Geochemistry, Geology, Mineral Physics
Montebras-en-Soumans pegmatitic cupola hosts large pods of phosphate composed of primary amblygonite-montebrasite. These aluminium phosphate masses are considerably altered by post-magmatic processes producing a number of secondary metasomatic hydrothermal phosphates (lacroixite, wardite, morinite, viitaniemiite, apatite, triplite, eosphorite) and low-temperature phosphates (apatite, crandallite, [...]
Time-resolved infrared stimulated luminescence of the blue and yellow-green emissions – insights into charge recombination in chemically and structurally different alkali feldspars
Published: 2022-08-23
Subjects: Earth Sciences, Mineral Physics
Time-resolved luminescence measurements can be used to explore luminescence processes in minerals and the defects involved. It has also been applied to feldspars and knowledge has been gained regarding potential crystal defects associated with luminescence productions in these minerals, but also regarding processes governing electron-hole recombination leading to luminescence emission. Here we [...]