The chemical composition deviates somewhat from the average ana-lyses of anorthosite. Jul 6, 2019 - This Pin was discovered by Bernatz. Discover (and save!) your own Pins on Pinterest The Bethampudi layered anorthosite complex at the border zone of Archaean supracrustal rocks of Khammam district, Eastern Ghats shows normal stratification predominantly in the form of rhythmic layering and often exhibits of zebra layering. Graded bedding and cumulate structures are also noticed.

The name is from anorthose, an old name for triclinic feldspars. Anorthosite is often associated with gabbro. Gabbros and norites are found in sills, dikes, stocks, lopoliths, and other bodies. The mineralogy and texture of gabbros, norites, diabases, and basalts indicates that they are probably The textures of naturally deformed rocks present fingerprints of the earth's history and provide information on deformation and recrystallization processes during tectonometamorphic events.

Apollo 12 rocldet 12037,174 is a lightly breccieted norite (average There are two striking features of Archean anorthosites: Their texture and sills and dikes of plagioclase megacrysts of the same texture and composition as in Such rocks are characterized by a porphyritic texture in which large crystals ( phenocrysts) of dark, iron-magnesium (mafic) minerals are enclosed in a fine- grained Alkali suite anorthosites and norites are the second most common plutonic rock have equilibration temperatures of 950–1100 °C, relict igneous textures and, 7 grade into small bodies of leucotroctolite and olivine-bearing anorthosite towards the margin. 1 of the KIC. Cumulate textures are relatively widespread on a Lens-shaped aggre- gates of mafic minerals, up to 10 cm in size, commonly appear as well developed corona textures. Primary olivine reacted with plagioclase, with more homogeneous textures.

THE LAC-ST-JEAN ANORTHOSITE Elsewhere on this outcrop other textures are present. 1998-07-01 TEXTURE • Anorthosite are leucocratic, coarse grained and hypidiomorphic. Some crystals have euhedral form, some have poorly developed faces and others have no crystal form at all. 4. 2010-01-01 2000-03-01 Quantitative texture analysis of an anorthite (polycrystalline plagioclase feldspar) has been under taken using an optical microscope equipped with a universal stage. The microstructure was studied on three orthogonal sections. The microstructural shape analysis suggests an axial fabric which is confirmed by texture analysis.

Typical samples sizes are generally 1-2 inches in length or width but can vary based on availability and natural formation. Abstract. Lunar anorthosite 15415 consists almost entirely of anorthite (homogeneous anorthite 96.6 molecule percent), with accessory diopsidic augite and traces of hypersthene, ilmenite, and a The dominant texture is ‘Nodular’ troctolite, in which amoeboid olivine oikocrysts 10–20 cm in diameter are spaced 20–30 cm apart within a matrix of anorthosite ( Woussen et al., 1988; Figs 1 and 2 ). The oikocrysts consist of a single or possibly a few olivine crystals with abundant chadocrysts of plagioclase. Both plagioclase and olivine are 5–10 mm long. The Layered Troctolite terminates abruptly along sinuous boundaries against Massive Anorthosite, which has a texture similar to anorthositic patches in both types of troctolite. Massive anorthosite Olivine oikocrysts - plagioclase chadocryst orientations indicated schematically where visible 20 cm Fig. 2.
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The texture reflects at least two episodes of shearing (followed by intense and partial recrystallization, respectively), one episode of cataclastic deformation, and one or more episodes of shattering and fragmentation. TEXTURE • Anorthosite are leucocratic, coarse- grained and hypidiomorphic. Some crystals have euhedral form, some have poorly developed faces and others have no crystal form at all. 6. Massive anorthosite has adcumulate texture comprising tightly packed cumulus plagioclase with accessory (<10 vol%) abundances of intercumulus pyroxene and Fe-Ti oxide.

Typical texture of Archean anorthosite. From theFiskenæsset complex, W. Greenland. Myers (1985) Stratigraphy and structure of the Fiskenæsset complex, West Greenland.Grønl.
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Thus age, composition and magmatic texture distinguish Proterozoic massif-type from Archean megacrystic anorthosites. Aside from anorthosite, the dominant rock types of anorthosites massif, include leucogabbro, leuconorite and leucotroctolite, with minor gabbroic rocks. The rock type is anorthosite, a cumulate rock made mostly of plagioclase. Cumulate rocks typically have the same minerals about the same size. In this case, grain textures look somewhat annealed, possibly because of deformation and annealing when it was still very hot.

Such textures have been quantiﬁed in a troctolite–anorthosite from the Proterozoic Lac-St-Jeananorthosite complex,Canada. Crystalsize distributions Here you can know more about texture of Gneiss and Anorthosite.

The texture reflects at least two episodes of shearing (followed by intense and partial recrystallization, respectively), one episode of cataclastic 2017-06-18 Figure 20-1a.