Results 31 to 40 of about 5,310 (122)

Delivery of Dark Material to Vesta via Carbonaceous Chondritic Impacts [PDF]

, 2012
NASA's Dawn spacecraft observations of asteroid (4) Vesta reveal a surface with the highest albedo and color variation of any asteroid we have observed so far. Terrains rich in low albedo dark material (DM) have been identified using Dawn Framing Camera (FC) 0.75 {\mu}m filter images in several geologic settings: associated with impact craters (in the ...
arxiv   +1 more source

Strengths and Weaknesses of the Analytical Techniques Used for Measuring Low Mercury Mass Fractions (< 10 ng g‐1) in Crystalline Rocks: Direct Mercury Analyser Versus Cold Vapour‐Atomic Fluorescence Spectroscopy

Geostandards and Geoanalytical Research, EarlyView.
Key Points DMA‐80 analyses are inaccurate and imprecise when crystalline rocks have Hg < 10 ng g‐1. DMA‐80 cannot desorb all Hg from mafic‐ultramafic rocks. CV‐AFS analyses are more accurate and precise, even at ultra‐low Hg mass fractions (< 1 pg g‐1).
Francesco Narduzzi, Stefano Covelli, Federico Floreani, Elena Pavoni, Elisa Petranich, Sarah C. Jantzi, Mattia Pistone, Ana Černok, Marco Venier, Matteo Crosera, Luca Ziberna   +10 more
wiley   +1 more source

Phase Equilibria Analysis for Metacarbonate With Applications to Zoned Calc‐Silicate Aureoles

Journal of Metamorphic Geology, EarlyView.
ABSTRACT Carbonate rocks react with infiltrating hydrothermal fluids to produce zoned calcsilicate assemblages in contact aureoles. Petrogenetic grids provide valuable insights into phase relations, metamorphic temperature (T) and the fluid composition (X) of the metacarbonate systems, as well as semi‐quantification of the prograde decarbonation at ...
Zhenhao Zhou, Xu Chu
wiley   +1 more source

A Volcanological Paradox in a Thin-Section: Large Explosive Eruptions of High-Mg Magmas Explained Through a Vein of Silicate Glass in a Serpentinized Peridotite Xenolith (Hyblean Area, Sicily)

Geosciences, 2019
Ultramafic magmas (MgO ≥ 18 wt%) are generally thought to be primary mantle melts formed at temperatures in excess of 1600 °C. Volatile contents are expected to be low, and accordingly, high-Mg magmas generally do not yield large explosive ...
Alessandra Correale, Vittorio Scribano, Antonio Paonita   +2 more
doaj   +1 more source

Multi‐isotope (N, O, Ti, and Cr) study of C1 and CM‐like clasts—Probing unsampled C1 material

Meteoritics &Planetary Science, EarlyView.
Abstract A multi‐element isotope (N, O, Ti, and Cr) study was conducted on C1 and CM‐like clasts hosted in achondrites and chondrite breccias to understand the genesis of these chondritic clasts. The mineralogy, O, and N isotopes confirm that CM‐like clasts in howardites and polymict eucrites closely resemble CM chondrite‐like material.
Markus Patzek, Yogita Kadlag, Miriam Rüfenacht, Evelyn Füri, Andreas Pack, Addi Bischoff, Harry Becker, Robbin Visser, Timm John, Maria Schönbächler   +9 more
wiley   +1 more source

Hydrous Asthenosphere Underneath the Northern Pannonian Basin

Terra Nova, EarlyView.
ABSTRACT This study reveals the structural hydroxyl content in clinopyroxenes of three cumulate xenoliths from the Nógrád‐Gömör/Novohrad‐Gemer Volcanic Field (northern Pannonian Basin), with values ranging from 275 to 384 ppm. Based on these data, the water content of the equilibrium parental alkali basaltic melt was estimated to be between 1.5 and 2.1 
Levente Patkó, Ákos Kővágó, Monika Huraiová, Szilvia Kövér, Szilveszter Gergely, Patrik Konečný, Vratislav Hurai   +6 more
wiley   +1 more source

Thinning and Heating of Laramide Continental Lower Crust Recorded by Zircon Petrochronology

Geochemistry, Geophysics, Geosystems
Zircon grains from the metasedimentary lower crust of the Rio Grande Rift, New Mexico, preserve a metamorphic record of the transition from Laramide compression to Eocene extension.
J. H. Cipar, A. J. Smye, J. M. Garber, J. R. Reimink, A. R. C. Kylander‐Clark   +4 more
doaj   +1 more source

Spinel crystals in mantle ultramafic xenoliths as the source of P-T conditions of alteration above the magma chamber beneath the Avacha Volcano (Kamchatka)

Journal of Asian Earth Sciences: X, 2022
This study focuses on the ability of spinel crystals in ultramafic xenoliths, like zircon, to store the primary composition and structure when exposed to magma fluid flows or the thermal heating of ultramafic fragments in magma flows during volcanic ...
Viktor Sharapov, Yuri Semenov, Grigory Kuznetsov, Anatoly Boguslavsky   +3 more
doaj  

Extensive Magmatic Heating of the Lithosphere Beneath the Hawaiian Islands Inferred From Salt Lake Crater Mantle Xenoliths

Geochemistry, Geophysics, Geosystems, 2020
An ongoing challenge in studies of the oceanic upper mantle is how intraplate hotspots impact the thermal structure of the lithosphere. To address this issue at the Hawaiian hotspot, we analyze mineral compositions for a petrographically diverse suite of
Imani Guest, Garrett Ito, Michael O. Garcia, Eric Hellebrand   +3 more
doaj   +1 more source

Synchronous Emplacement of the Anorthosite Xenolith‐Bearing Beaver River Diabase and One of the Largest Lava Flows on Earth

Geochemistry, Geophysics, Geosystems, 2021
New geochronologic and paleomagnetic data from the North American Midcontinent Rift (MCR) reveal the synchronous emplacement of the Beaver River diabase, the anorthosite xenoliths within it, and the Greenstone Flow—one of the largest lava flows on Earth.
Yiming Zhang, Nicholas L. Swanson‐Hysell, Mark D. Schmitz, James D. Miller, Margaret S. Avery   +4 more
doaj   +1 more source