Filtering by Subject: Geochemistry

Upper mantle mush zones beneath low melt flux ocean island volcanoes: insights from Isla Floreana, Galápagos

Matthew Gleeson, Sally A Gibson, Michael J. Stock

Published: 2020-05-25
Subjects: Earth Sciences, Geochemistry, Physical Sciences and Mathematics, Volcanology

The physicochemical characteristics of sub-volcanic magma storage regions have important implications for magma system dynamics and pre-eruptive behaviour. The architecture of magma storage regions located directly above high buoyancy flux mantle plumes (such as Kīlauea, Hawai’i and Fernandina, Galápagos) are relatively well understood. However, far fewer constraints exist on the nature of magma [...]

Holocene tephrochronology of Kerguelen Archipelago, Subantarctic Indian Ocean

Fabien Arnaud, Pierre Sabatier, Anouk Leloup, Aymerick Servettaz, Bertrand Moine, Anne-Lise Develle, Stéphane Guédron, Vincent Perrot, Cécile Pignol, Jérôme Poulenard

Published: 2020-05-20
Subjects: Earth Sciences, Geochemistry, Physical Sciences and Mathematics, Sedimentology, Stratigraphy, Volcanology

Up to now, no geochemical or geochronological data has been published about Holocene volcanic activity on the Kerguelen Archipelago. Here we present the first continuous Holocene chronology of volcanic eruptions on the archipelago. We compared sedimentological, geochronological and geochemical data from two lake sediment cores taken in two different depocenters of Lake Armor, located ca. 70 km [...]

Jarosite formation in deep Antarctic ice provides a window into acidic, water-limited weathering on Mars

Giovanni Baccolo, Barbara Delmonte, Paul B. Niles, Giannantonio Cibin, Elena Di Stefano, Dariush Hampai, Lindsay Keller, Valter Maggi, Augusto Marcelli, Joseph Michalski

Published: 2020-05-20
Subjects: Cosmochemistry, Earth Sciences, Geochemistry, Physical Sciences and Mathematics, Planetary Geochemistry, Planetary Glaciology, Planetary Sciences

Many interpretations have been proposed to explain the presence of jarosite within Martian surficial sediments, including the possibility that it precipitated within paleo-ice deposits owing to englacial weathering of dust. But until now a similar mechanism was not observed on Earth nor in other planetary settings. We report the first multi-analytical indication of jarosite formation within deep [...]

Constraining crustal silica on ancient Earth

C. Brenhin Keller, T. Mark Harrison

Published: 2020-05-07
Subjects: Earth Sciences, Geochemistry, Geology, Physical Sciences and Mathematics

Accurately quantifying the composition of continental crust on Hadean and Archean Earth is critical to our understanding of the physiography, tectonics, and climate of our planet at the dawn of life. One longstanding paradigm involves the growth of a relatively mafic planetary crust over the first 1-2 billion years of Earth history, implying a lack of modern plate tectonics, a paucity of [...]

Do olivine crystallization temperatures faithfully record mantle temperature variability?

Simon Matthews, Kevin Wong, Oliver Shorttle, Marie Edmonds, John Maclennan

Published: 2020-05-07
Subjects: Earth Sciences, Geochemistry, Physical Sciences and Mathematics

Crystallization temperatures of primitive olivine crystals have been widely used as both a proxy for, or an intermediate step in calculating, mantle temperatures. The olivine-spinel aluminum-exchange thermometer has been applied to samples from mid-ocean ridges and large igneous provinces, yielding considerable variability in olivine crystallization temperatures. We supplement the existing data [...]

Lateral variations in lower crustal strength control the temporal evolution of mountain ranges: examples from south-east Tibet

Camilla Penney, Alex Copley

Published: 2020-04-17
Subjects: Earth Sciences, Geochemistry, Geomorphology, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure

Controversy surrounds the rheology of the continental lithosphere, and how it controls the evolution and behaviour of mountain ranges. In this study, we investigate the effect of lateral contrasts in the strength of the lower crust, such as those between cratonic continental interiors and weaker rocks in the adjacent deforming regions, on the evolution of topography. We combine numerical [...]

Rethinking Groundwater Age

Grant Ferguson, Mark Cuthbert, Kevin M. Befus, Tom Gleeson, Jennifer C. McIntosh

Published: 2020-04-03
Subjects: Earth Sciences, Geochemistry, Hydrology, Physical Sciences and Mathematics

The ideas that old or “fossil” groundwater cannot be pumped sustainably, or that recently recharged groundwater is inherently sustainable are both mistaken. Both old and young groundwaters can be used in physically sustainable or unsustainable ways.

International disparities in open access practices of the Earth Sciences community

Olivier Pourret, David William Hedding, Dasapta Erwin Irawan, Haiyan Liu, Jonathan Tennant

Published: 2020-03-31
Subjects: Biogeochemistry, Cosmochemistry, Earth Sciences, Geochemistry, Geology, Geomorphology, Geophysics and Seismology, Glaciology, Hydrology, Library and Information Science, Mineral Physics, Other Earth Sciences, Paleobiology, Paleontology, Physical Sciences and Mathematics, Sedimentology, Social and Behavioral Sciences, Soil Science, Speleology, Stratigraphy, Tectonics and Structure, Volcanology

Short communication on international disparities in open access practices of the Earth Sciences community

On the potential of preprints in geochemistry: the good, the bad and the ugly

Olivier Pourret, Dasapta Erwin Irawan, Jonathan Tennant

Published: 2020-03-21
Subjects: Biogeochemistry, Cosmochemistry, Earth Sciences, Geochemistry, Library and Information Science, Physical Sciences and Mathematics, Social and Behavioral Sciences

Short communication on the use of preprint in geochemistry

Mechanistic insights into sulfur rich oil formation, relevant to geological carbon storage routes. A study using (+) APPI FTICR-MS analysis

Renzo C. Silva, Calista Yim, Jagos Radovic, Melisa Brown, Priyanthi Weerawardhena, Haiping Huang, Lloyd Snowdon, Oldenburg , Steve Larter

Published: 2020-03-03
Subjects: Earth Sciences, Geochemistry, Physical Sciences and Mathematics

Sulfur incorporation into sedimentary organic matter has a key role in carbon preservation in the geosphere. Such processes can inform strategies for human timescale carbon storage to mitigate climate change impacts and thus more detailed knowledge of sulfur incorporation into biomass species is needed. Until recently, detailed chemical characterization of sulfurized organic matter was only [...]

Magma diversity reflects recharge regime and thermal structure of the crust

Gregor Weber, Guy Simpson, Luca Caricchi

Published: 2020-03-03
Subjects: Earth Sciences, Geochemistry, Geology, Physical Sciences and Mathematics, Volcanology

The chemistry of magmas erupted by volcanoes is a message from deep within the Earth’s crust, which if decrypted, can provide essential information on magmatic processes occurring at inaccessible depths. While some volcanoes are prone to erupt magmas of a wide compositional variety, others sample rather monotonous chemistries through time. Whether such differences are a consequence of physical [...]

Constraining mechanisms of quartz precipitation during silicification and chemical sedimentation in the in the ~2.7 Ga Abitibi Greenstone Belt, Canada

Latisha Ashley Brengman, Christopher M. Fedo, Martin J. Whitehouse, Neil R. Banerjee, Iffat Jabeen

Published: 2020-03-03
Subjects: Earth Sciences, Geochemistry, Physical Sciences and Mathematics

Silica-rich Precambrian rocks often preserve geochemical information and microfossil remnants from the early biosphere. Because these rocks are such critical geochemical and paleontological archives, we need robust tools to identify the chemical and physical conditions under which siliceous Precambrian rocks form, and determine how such information links to the specific depositional environment. [...]

Using computer-aided image processing to estimate chemical composition of igneous rocks: A potential tool for large-scale compositional mapping

Julin Zhang, Cin-Ty A. Lee, Michael Farner

Published: 2020-02-20
Subjects: Earth Sciences, Geochemistry, Geology, Physical Sciences and Mathematics

Digital cameras, particularly on smartphones, have led to the proliferation of amateur photographers. Of interest here is the use of smartphone cameras to conduct rapid, low-cost compositional mapping of geologic bedrock, such as plutons and batholiths, in combination with chemical analyses of rocks in the laboratory. This paper discusses some of the challenges in geochemical mapping using image [...]

Chalcophile elements track the fate of sulfur at Kīlauea Volcano, Hawai’i

Penny E Wieser, Frances Jenner, Marie Edmonds, John Maclennan, Barbara Kunz

Published: 2020-02-08
Subjects: Earth Sciences, Geochemistry, Geology, Physical Sciences and Mathematics, Volcanology

Chalcophile element concentrations in melt inclusions and matrix glasses may be used to investigate low pressure degassing processes, as well as sulfide saturation during crustal fractionation, and mantle melting. Erupted products from Kīlauea Volcano, Hawaiʻi, record three stages of sulfide saturation (in the mantle, crust, and within lava lakes), separated by episodes of sulfide resorption [...]

Novel insights from Fe-isotopes into the lithological heterogeneity of Ocean Island Basalts and plume-influenced MORBs

Matthew Gleeson, Sally A Gibson, Helen Wiliams

Published: 2020-02-02
Subjects: Earth Sciences, Geochemistry, Physical Sciences and Mathematics, Volcanology

The extent of lithological heterogeneity in the Earth’s convecting mantle is highly debated. Whilst the presence of pyroxenite in the mantle source regions of Ocean Island Basalts (OIBs) has traditionally been constrained using the minor-element chemistry of olivine phenocrysts, recent studies have shown that the Ni and Mn contents of primitive olivines are influenced by the conditions of mantle [...]


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