Results 111 to 120 of about 73,435 (259)

Oxygen Isotope Variations of Basaltic Lavas and Upper Mantle Rocks [PDF]

open access: yes, 2001
This chapter summarizes the oxygen isotope geochemistry of terrestrial basalts and their mantle sources, including the conceptual framework for interpreting such data and the phenomenology of known variations.
Eiler, John M.
core  

Petrography and mineral chemistry of Northeast Africa 053—A remnant of Martian crystal mush

open access: yesMeteoritics &Planetary Science, EarlyView.
Abstract In Earth's igneous systems, crystal mushes, crystal‐rich frameworks permeated by silicate melt, represent a common and fundamental stage in the evolution of magma bodies. However, whether crystal mushes occur within Martian igneous systems and play a comparable role is unknown. Here, we present a comprehensive petrography and mineral chemistry
Xhonatan Shehaj   +2 more
wiley   +1 more source

The 10 micron spectral structure in comets [PDF]

open access: yes
The 10 micron spectra of comets Halley (1982i), Wilson (1986l), Kohoutek (1973f) and Bradfield (1987s) are presented and compared. The silicate emission profiles of Halley and Bradfield are seen to be remarkably similar in that both contain a sharp break
Campins, Humberto   +2 more
core   +1 more source

Microspherules Formed by Lightning Strikes

open access: yesMeteoritics &Planetary Science, EarlyView.
Abstract Natural microspherules are formed by high‐temperature processes and are present throughout the geologic record to the present day. We report the discovery of large numbers of microspherules recovered from a rock pavement in the Pilbara region, Western Australia.
M. R. Boyd, M. J. Genge, A. G. Tomkins
wiley   +1 more source

Petrogenetic Implications for Ophiolite Ultramafic Bodies from Lokris and Beotia (Central Greece) Based on Chemistry of Their Cr-spinels

open access: yesGeosciences, 2017
Cr-spinels from ultramafic rocks from Lokris (Megaplatanos and Tragana), and Beotia (Ypato and Alyki) ophiolitic occurrences were studied. These rocks comprise principally harzburgite with minor dunite. Small amounts of clinopyroxene-rich harzburgite and
Panagiotis Pomonis, Andreas Magganas
doaj   +1 more source

Terrestrial ages of meteorites from the Atacama Desert (Chile) and insights into the past meteorite flux to Earth

open access: yesMeteoritics &Planetary Science, EarlyView.
Abstract The Atacama Desert in Chile is characterized by its high meteorite density and old meteorite terrestrial ages. In this work, we present new terrestrial ages derived from measurements of the concentration of cosmogenic 36Cl in the metal fraction of 51 ordinary chondrites collected over a 6.8 km2 area located in the Catalina Dense Collection ...
Carine Sadaka   +13 more
wiley   +1 more source

The making of pure quartzose sand in continental interiors: Paraná River (Brazil and Argentina)

open access: yesSedimentology, EarlyView.
ABSTRACT As part of a comprehensive project on sedimentary processes in South America, this study focuses on sediment generation in the intracratonic Paraná Basin and monitors the evolution of sand composition along the Paraná River from central Brazil to the Río de la Plata estuary in Argentina.
Eduardo Garzanti   +5 more
wiley   +1 more source

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