نتایج جستجو برای: plagioclase
تعداد نتایج: 1579 فیلتر نتایج به سال:
Introduction: According to the canonical lunar magma ocean (LMO) model, ferroan anorthosites (FANs) were part of the lunar anorthosite crust formed via plagioclase flotation and subsequent solidification in a globally distributed LMO [1-4]. The solidification time for a globally distributed LMO is model dependent and ranges from 10 4-10 8 yrs [3,5,6]. At a given time during lunar crust formatio...
Introduction: The non-mare pristine samples are divided into two major suites, the ferroan anorthosites (FAN) and the Mg-suite [1]. FAN is typically characterized by high values of plagiophile interelement ratios, for example, the calcium content of plagioclase, and very high plagioclase content (though more mafic members exist). FAN is well separated from the Mgsuite on a plot of Mg-number vs....
Introduction: High-Ca pyroxene and plagioclase are typically present as minor phases in diogenites [1]. However, although the trace element content of diogenite orthopyroxene has been measured in a number of studies e.g., [2, 3]; almost no trace element data is available for the high-Ca pyroxene and plagioclase with which it routinely coexists in these meteorites. These data could provide insig...
Acid weathering of plagioclase–pyroxene mixtures has been investigated with an open system kinetic dissolution model. The modeling reveals that elevated plagioclase/pyroxene ratios observed in some low-albedo martian regions and atmospheric dust could be partially caused by preferential dissolution of pyroxenes at pHs below ∼3–4. Surface materials with smaller grain sizes, affected by lower pH ...
Remote observation by the reflectance spectrometers onboard the Japanese lunar explorer Kaguya (SELENE) showed the purest anorthosite (PAN) spots (>98% plagioclase) at some large craters. Mineralogical and petrologic investigations on the feldspathic lunar meteorites, Dhofar 489 and Dhofar 911, revealed the presence of several pure anorthosite clasts. A comparison with Apollo nearside samples o...
An undeformed metadolerite dyke cutting foliated pyroxene-granulite facies gneisses in the Jotunhelm, Norway, has almandine rods replacing the cores of plagioclase laths, although garnet is generally absent from the enclosing gneisses, and is not present in reaction zones between peridotites and gneisses. Chemical analyses of the dyke and its garnet, plagioclase, and clinopyroxene are given. Th...
Minerals are defined as naturally occurring, inorganic, solids with a definite chemical composition and a regular, internal crystalline structure. The keys to this definition are the chemical composition and the crystalline structure. Different chemical compositions result in different minerals. A good example is the mineral plagioclase. Plagioclase is a member of the feldspar group, but there ...
Preparations for lunar missions involve the extensive use of simulants of lunar surface materials. Since many planned operations engage the mechanical properties of the regolith, it is of utmost importance to assure that the simulants adequately represent the engineering properties of actual lunar materials. To address this critical issue, we are conducting an experimental and modeling effort t...
The prograde metamorphism of eclogites is typically obscured by chemical equilibration at peak conditions and by partial requilibration during retrograde metamorphism. Eclogites from the Eastern Blue Ridge of North Carolina retain evidence of their prograde path in the form of inclusions preserved in garnet. These eclogites, from the vicinity of Bakersville, North Carolina, USA are primarily co...
Recent advancements in visible to near infrared orbital measurements of the lunar surface have allowed the character and extent of the primary anorthositic crust to be studied at unprecedented spatial and spectral resolutions. Here we assess the lunar primary anorthositic crust in global context using a spectral parameter tool for Moon Mineralogy Mapper data to identify and map Fe-bearing cryst...
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