نتایج جستجو برای: pyroxene group
تعداد نتایج: 980267 فیلتر نتایج به سال:
Mafic Mound” is a distinctive and enigmatic feature 75 km across and 1km high near the center of the vast South Pole-Aitken Basin (SPA). Using several modern data sets, we characterize the composition, morphology, and gravity signature of the structure in order to assess its origin. Mafic Mound is found to exhibit a perched circular depression and a homogeneous high-Ca pyroxene-bearing composit...
New mapping, geochronology, and geochemistry of the supracrustal enclave and associated orthogneisses at Akilia, West Greenland, support a >3825 6 Ma age for the sequence and a chemical sedimentary origin for the controversial Fe-rich quartz-pyroxene gneisses. Lithologies of the enclave comprise laterally continuous, mappable units of mafic amphibolite, ultramafic rocks, and two Fe-rich quartzp...
Petrology and Mineral Compositions: The fresh, pale gray interior of this specimen has multiple shock fractures (with very minor calcite coatings) and some thin glass veinlets (Figure 2). This rock is a poikiloblastic recrystallized breccia, with larger grains of plagioclase (~70%) enclosing much smaller grains (less than 100 microns across) of pyroxene (~20%), olivine (~10%) and accessory Ti-c...
Introduction: Telescopic spectra of Vesta, ves-toids and HED meteorites show a 506 nm absorption feature whose wavelength position varies for different Vestoids, howardites vs eucrites vs diogenites, and across the surface of Vesta [1, 2, 3]. [1] believe that the shift is due to the change in composition of pyrox-enes, specifically that increases in calcium content are correlated with increases...
The nakhlites experienced a fluid alteration event on Mars leading to the rapid crystallization at low temperature (e.g. 25-150C) of siderite, clay and other salts in fractures within olivine and interstitial sites [1-2]. In order to help constrain the origin and evolution of the brine we present new Li-isotopic, C and Thermal Gas Analysis data for Nakhla and Lafayette samples. Techniques: Whol...
Ab&m+--The. petrology and geochemistry of twenty-three chondritic dust particles with masses of l47 pg (sizes 100-400 pm) were recovered from blue ice near Cap Prudhomme, Antarctica, and studied by INAA, ASEM, EMPA, and optical microscopy. Sample selection criteria were irregular shape and (for a subsample) black color, with the aim of stud~ng as many unmelted micrometeo~~s (MI&) as possible. O...
abstract the present study tried to investigate the effect of visual aids (films) on the development of the speech act of disagreement among iranian efl intermediate learners. to this end, the researcher selected 40 homogeneous intermediate learners based on their scores on oxford placement test. .the subjects then divided into control group and experimental group. both classes were tested by ...
[1] Water played a major role in the formation and alteration of rocks and soils in the Columbia Hills. The extent of alteration ranges from moderate to extensive. Five distinct rock compositional classes were identified; the order for degree of alteration is Watchtower ffi Clovis > Wishstone ffi Peace > Backstay. The rover’s wheels uncovered one unusual soil (Paso Robles) that is the most S-ri...
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