Using Fe-Ti oxides and trace element analysis to determine


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Bulk compositions ofanorthositic par-ticles, determined by averaging the results of seven to ten randomly placed, defocused-beam, electron microprobe analyses. a, Anorthositic gabbro (9-8); b, anorthosite-gabbroic anortho-site (37-1). Percentage, byweight Oxide* a b SiO2 46.0 45.4 TiO2 0.3 tr A1203 27.3 33.8 Cr203 0.2 tr FeO 6.2 2.8 “Anorthosite is not rare on Earth,” Rickman said. It is rare, however, to find the nearly pure, high-calcium type of anorthosite—anorthite—that closely resembles the chemical composition of anorthosite from the Moon. Rocks found within the Stillwater Complex come very close.

Anorthosite composition

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In Minnesota, anorthosite was intruded into the lowermost lava flows that formed during the opening of the Midcontinent Rift. Apr 21, 2004 The anorthosites are usually referred to as 'ferroan' after the iron-rich compositions of their olivines and pyroxenes, whereas the norites and  cataclastic anorthosite (figure 1). Or, rather, it is a mixture of pieces from a related sequence of anorthosites, because the mafic minerals vary in composition  Figure 3: Pyroxene composition for 15415 (data from James 1972, Hargraves and Hollister 1972). Figure 4: Plagioclase-low-Ca pyroxene diagram showing that  Sep 13, 2014 The Mg-rich composition of coexisting mafic minerals is difficult to explain by the lunar magma ocean model, as anorthite crystallizes only after  Sep 10, 2014 Olivine compositions in PA5 (Fo75-85) are more magnesian than the mafic minerals in the Dhofar 489 pure anorthosites. These pure anorthosite  Assrnacr.

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2700 Ma ago (Nutman 1984). The Tunulik anorthosite is located in an area of Archaean Table 1.

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Anorthosite composition

Outcrops of pure anorthosite principally occur on the Moon in the inner rings of multiring basins, which are structurally uplifted blocks from midcrustal levels, or rarely, as central peaks in some selected craters (Alphonsus, Aristarchus). 2 dagar sedan · Apollo 16 Anorthosite.

Anorthosite composition

Similar in composition to rocks on the moon, anorthosite is a coarse-grained, intrusive igneous rock composed almost entirely of a single mineral—plagioclase feldspar. In Minnesota, anorthosite was intruded into the lowermost lava flows that formed during the opening of the Midcontinent Rift. If the source is the lower crust, the produced anorthosite parental melts are presumed to be monzodioritic (jotunitic) in composition.
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Anorthosite composition

Composition, Calcium aluminum silicate. May contain some sodium replacing the calcium, but that amount must be less than 10 percent to be strictly Anorthite. Apr 23, 2013 Copper and nickel are two metals modern society cannot get enough of, but there is not enough to go around, says Rick Mills, publisher of Ahead  Dec 26, 2020 26.

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However, there is a gradual decrease in plagioclase content, An content ofplagioclase andXMg of orthopyroxene, and an increasein mafic silicates, oxide minerals content, plagioclase incompatible elements and REE from anorthosite– mafic-leucomafic rocks to Fe-rich dioritic rocks. clase feldspar and Ca-poor pyroxene.