Filtering by Subject: Geochemistry

Linking the core heat content to Earth's accretion history

Vincent Clesi, Renaud Deguen

Published: 2023-03-25
Subjects: Earth Sciences, Geochemistry, Geophysics and Seismology, Planetary Geochemistry, Planetary Geophysics and Seismology

In this study we use a parameterized model of differentiation in a magma ocean setting, in which the magma ocean depth evolves during accretion, to predict the composition of the primordial core. We couple this chemical model to a thermal evolution model of the accreting metal to estimate the Earth's core heat content at the end of its formation. We find geochemically consistent models. All these [...]

Single Column REE Separation and Radiogenic 143Nd/144Nd Analysis in TIMS

Bidisha Dey, Tomoyuki Shibata, Masako Yoshikawa

Published: 2023-03-10
Subjects: Analytical Chemistry, Geochemistry

We use 145Nd/146Nd for instrumental mass fractionation correction to accurately determine radiogenic 143Nd/144Nd for natural samples without requiring Sm elimination from Nd fraction. Conventionally, radiogenic Nd isotope ratios are expressed relative to the non-radiogenic 144Nd which is an isobar of 144Sm. To mitigate this problem, traditional analysis methods eliminate Sm entirely from the [...]

Steady decline in mean annual air temperatures in the first 30 ka after the Cretaceous-Paleogene boundary

Lauren O'Connor, Emily Dearing Crampton-Flood, Rhodri Jerrett, et al.

Published: 2023-03-06
Subjects: Climate, Earth Sciences, Geochemistry, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics, Stratigraphy

The Cretaceous-Paleogene (K-Pg) boundary marks one of the five major mass extinctions of the Phanerozoic. How the climate system responded to a bolide impact and extensive volcanism at this time over different timescales is highly debated. Here we use the distribution of branched tetraether lipids (brGDGT) from fossil peats at two sites in Saskatchewan, Canada (paleolatitude ~55°N), to generate a [...]

The applicability of G-BASE stream sediment geochemistry as a combined geological mapping, and prospective exploration tool for As-Co-Cu-Ni mineralisation across Cumbria, UK.

Adam Eskdale, Sean Johnson, Amy Gough

Published: 2023-01-18
Subjects: Earth Sciences, Geochemistry, Geology, Multivariate Analysis, Physical Sciences and Mathematics, Statistics and Probability

Stream sediment geochemistry is a useful tool to analyse the geochemistry of the local geology within the source catchment area. This has significant applicability within the field of mineral exploration where understanding regional lithological geochemistry is needed, facilitating the identification of critical metal deposits. Successful identification of these deposits is essential to help [...]

A multi-siderophile element connection between volcanic hotspots and Earth’s core

Bradley Peters, Andrea Mundl-Petermeier, Valerie Finlayson

Published: 2023-01-18
Subjects: Geochemistry

The existence of resolvable 182W/184W deficits in modern ocean island basalts (OIB) relative to the bulk silicate Earth has raised questions about the relationship of these rocks to Earth’s core. However, because the core is expected to host high abundances of highly siderophile elements (HSE), it would be expected that such heterogeneity is accompanied by correlating variability in HSE [...]

Diffusion of halogens (F, Cl, Br, I) in silicic melt

Yves Feisel, Jonathan M. Castro, Christoph Helo, et al.

Published: 2023-01-10
Subjects: Earth Sciences, Geochemistry, Volcanology

Chemical diffusion of the halogens F, Cl, Br, and I in silica-rich natural melts was experimentally investigated by the diffusion couple technique. Experiments were conducted under anhydrous conditions at atmospheric pressure and hydrous conditions (~1.5 wt.% H2O) at 160 MPa, over a temperature range of 750–1000 °C and 1000–1200 °C, respectively. Quenched trachytic melt samples were analyzed [...]

Are marl-limestone alternations mainly driven by CaCO3 variations at the astronomical timescale? New insights from extraterrestrial 3He

Pierre-Henri BLARD, Baptiste SUCHERAS-MARX, Guillaume SUAN, et al.

Published: 2023-01-07
Subjects: Biogeochemistry, Earth Sciences, Geochemistry, Geology, Sedimentology, Stratigraphy

Marl-limestone alternations are rhythmical inter-bedded deposits that commonly occur in many sedimentological environments. It is quite well established that these lithological variations originate from astronomically-driven climatic variations paced by the Milankovitch cycles of main periods 19, 23, 41, 100 and 405 ka. However, the sedimentological mechanisms involved are not clear: some models [...]

Tracing timing of growth in cultured mollusks using strontium spiking

Niels J. de Winter, Sterre van Sikkeleras, Barbara Goudsmit-Hazevoort, et al.

Published: 2022-12-23
Subjects: Aquaculture and Fisheries Life Sciences, Biogeochemistry, Geochemistry, Paleontology

Growth experiments present a powerful tool for determining the effect of environmental parameters on growth and carbonate composition in biogenic calcifiers. For successful proxy calibration and biomineralization studies, it is vital to exactly identify volumes of carbonate precipitated at precise intervals during the experiment. Here, we investigate the use of strontium labelling in mollusk [...]

Rates and Products of Oxidation of Ferrous Iron in Trioctahedral Smectites

Robert J Kupper, Nanqing Zhou, Clara S Chan, et al.

Published: 2022-12-16
Subjects: Biogeochemistry, Geochemistry, Other Earth Sciences, Planetary Biogeochemistry, Planetary Geochemistry

Iron(II)-bearing trioctahedral smectites (saponites) form during anoxic alteration of basaltic rock. They are predicted to have been widespread on the early Earth and are observed in the oceanic subsurface today. Smectite structures, including the occupancy of sites in the octahedral sheet, affect iron redox behavior but the rates and products of trioctahedral smectite oxidation have been largely [...]

Barometers behaving badly II: A critical evaluation of Cpx-only and Cpx-Liq thermobarometry in variably-hydrous arc magmas

Penny Wieser, Adam J Kent, Christy Till

Published: 2022-12-14
Subjects: Earth Sciences, Geochemistry, Geology, Volcanology

The chemistry of erupted clinopyroxene crystals (±equilibrium liquids) have been widely used to deduce the pressures and temperatures of magma storage in volcanic arcs. However, the wide variety of different equations parametrizing the relationship between mineral and melt compositions and intensive variables such as pressure and temperature yield vastly different results, with implications for [...]

Barometers behaving badly: Assessing the influence of analytical and experimental uncertainty on clinopyroxene thermobarometry calculations at crustal conditions

Penny E Wieser, Adam J Kent, Christy Till, et al.

Published: 2022-11-30
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 [...]

Lithospheric structure and melting processes in southeast Australia: new constraints from joint probabilistic inversions of 3D magnetotelluric and seismic data

Maria Constanza Manassero, Sinan Özaydin, Juan Carlos Afonso, et al.

Published: 2022-11-18
Subjects: Geochemistry, Geophysics and Seismology, Volcanology

The thermochemical structure of the lithosphere exerts control on melting mechanisms in the mantle as well as the location of volcanism and ore deposits. Imaging the complex interactions between the lithosphere and asthenospheric mantle requires the joint inversion of multiple data sets and their uncertainties. In particular, the combination of seismic velocity and electrical conductivity with [...]

Community recommendations for geochemical data, services and analytical capabilities in the 21st century

Marthe Klöcking, Lesley Wyborn, Kerstin Lehnert, et al.

Published: 2022-11-17
Subjects: Biogeochemistry, Cosmochemistry, Earth Sciences, Geochemistry

The majority of geochemical and cosmochemical research is based upon observations and, in particular, upon the acquisition, processing and interpretation of analytical data from physical samples. The exponential increase in volumes and rates of data acquisition over the last century, combined with advances in instruments, analytical methods and an increasing variety of data types analysed, has [...]

PREPRINT: A global platform solution for Big Data in low-temperature thermochronology

Samuel C Boone, Fabian Kohlmann, Wayne Noble, et al.

Published: 2022-11-12
Subjects: Earth Sciences, Geochemistry, Physical Sciences and Mathematics

Low-temperature thermochronology is a powerful tool for constraining the thermal evolution of geological materials at temperatures (< ~300 °C) common in the upper crust in relation to geodynamics, continental crustal evolution, landscape evolution, and natural resource formation and preservation. However, complexities inherent to these analytical techniques can make interpreting the significance [...]

The missing carbon budget puzzle piece: shallow-water hydrothermal vents contribution to global CO2 fluxes

Alessia Bastianoni, Martina Cascone, Joost M de Moor, et al.

Published: 2022-11-08
Subjects: Earth Sciences, Geochemistry, Geology, Planetary Biogeochemistry, Volcanology

The release of CO2 gases from volcanoes and their secondary geothermal manifestations are an important contributor to the global carbon budget. While degassing from mid ocean ridges is relatively well-constrained, the contribution of shallow submarine volcanic degassing to the atmosphere is less clear. Shallow-water hydrothermal vents are common seafloor features present at depths shallower than [...]


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