نتایج جستجو برای: plagioclase

تعداد نتایج: 1579  

2016
Patrick N. Peplowski Andrew W. Beck David J. Lawrence

Thermal neutron emissions from the lunar surface provide a direct measure of bulk elemental composition that can be used to constrain the chemical properties of near-surface (depth <1 m) lunar materials. We present a new calibration of the Lunar Prospector thermal neutron map, providing a direct link between measured count rates and bulk elemental composition. The data are used to examine the c...

Journal: :Geochimica et Cosmochimica Acta 2020

Journal: :Journal of Geophysical Research: Solid Earth 2016

2017
Diane R. Smith William P. Leeman

Smith, D. R. and Leeman, W. P., 1993. The origin of Mount St. Helens andesites. J. Volcanol. Geotherm. Res., 55: 271-303. Mount St. Helens volcano has intermittently produced mainly dacitic products but occasionally erupted a more diverse suite of lavas including basalts and andesites. Petrogenetic relations between these magmas provide insight into the dynamics of the subjacent magma system. M...

2013
L. C. Cheek K. L. Donaldson Hanna C. M. Pieters J. W. Head J. L. Whitten

[1] The Orientale basin is a multiring impact structure on the western limb of the Moon that provides a clear view of the primary lunar crust exposed during basin formation. Previously, near-infrared reflectance spectra suggested that Orientale’s Inner Rook Ring (IRR) is very poor in mafic minerals and may represent anorthosite excavated from the Moon’s upper crust. However, detailed assessment...

2000
Guochun Zhao Peter A. Cawood Simon A. Wilde Min Sun Liangzhao Lu

Lithological, structural, metamorphic and geochronological data for the North China Craton enable its division into the Western and Eastern Blocks of Archean to Paleoproterozoic age separated by a north–south trending Paleoproterozoic orogenic belt: the Central Zone. The Central Zone is divisible into a series of lowto medium-grade granite–greenstone belts and high-grade metamorphic terrains co...

Journal: :Frontiers in Earth Science 2021

Study of melt inclusions (MIs) is a commonly applied method for defining the composition magmas present at depth prior to mixing, fractionation, and degassing. Our ability use data from MIs complicated by post-entrapment processes (PEP) that can modify their during transport eruption. Many PEP be reversed heating temperatures near those which MI its host were formed. However, process reversing ...

1998
T. J. DEMPSTER R. J. PRESTON

Plagioclase-rich reaction zones occur around numerous aluminous crustal xenoliths within a suite of Palaeogene sub-volcanic basic sheets on the Isle of Mull, NW Scotland. The xenoliths consist of a glassy core, containing mullite needles, generated from the melting of pelitic source rocks. Thick plagioclase mantles grew at the interface between the aluminous liquid and the enclosing basaltic ma...

2004
S. A. MORSE J. B. BRADY B. A. SPORLEDER

The inferred crystallization history of the troctolitic Lower Zone of the Kiglapait Intrusion in Labrador is tested by melting mineral mixtures from the intrusion, made to yield the observed crystal compositions on the cotectic trace of liquid, plagioclase, and olivine. Melting experiments were made in a piston-cylinder apparatus, using graphite capsules at 5 kbar. Lower Zone assemblages crysta...

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