Fragments of ancient lunar crust: Ferroan noritic anorthosites from the descartes region of the Moon

Other

Scientific paper

Rate now

  [ 0.00 ] – not rated yet Voters 0   Comments 0

Details

Anorthosite, Breccia, Crystallization, Lunar Composition, Lunar Crust, Lunar Geology, Lunar Rocks, Lunar Soil, Metamorphism (Geology), Meteoritic Composition, Minerals, Recrystallization, Chromites, Degassing, Feldspars, Igneous Rocks, Ilmenite, Iron, Olivine, Phosphates, Pyroxenes, Sulfides, Troilite

Scientific paper

Noritic anorthosite clasts from breccia 67016 have bulk compositions similar to that of the upper crust of the Moon and petrogenetic affinities with pristine ferroan anorthosites. Rb-Sr and Sm-Nd isotopic compositions of mineral separates from one of these clasts suggest very old (greater than or = 4.4 Ga) ages, but interpretation of these data is complicated by the multi-stage history of the clasts which involved magmatic crystallization, brecciation, subsolidus recrystallization, and sulfide metasomatism. These clasts record some of the earliest events on the Moon, including early crust formation, accretionary bombardment, and degassing of the lunar interior. Modal analyses of these clasts show they are now composed of about 70 percent plagioclase, 28 percent pyroxene, 2 percent troilite, and minor amounts of ilmenite and chromite. No metallic iron, phosphates, or other trace phases were observed. Olivine is very rare, occurring only as relicts within secondary troilite+pyroxene intergrowths which may reflect reaction of olivine with sulfurous vapors. PIXE proton microprobe analyses of the sulfides show that the metasomatism was accompanied by enrichments of Cu, Zn, Ni, Se, and Sb. The clasts have been only mildly shocked since the observed texture was established. Major and minor element mineral compositions are very homogeneous and strikingly similar to those of pristine ferroan anorthosites. Pyroxene compositions indicate equilibration temperatures of 850-900 C. Except for the sulfide and chalcophile element metasomatism, these clasts appear to be essentially monomict and probably represent a noritic member of the ferroan anorthosite suite. Their low Ni contents and Ni/Co ratios are consistent with the interpretation of these clasts as igneous rocks which have escaped mixing with meteoritic material.

No associations

LandOfFree

Say what you really think

Search LandOfFree.com for scientists and scientific papers. Rate them and share your experience with other people.

Rating

Fragments of ancient lunar crust: Ferroan noritic anorthosites from the descartes region of the Moon does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Fragments of ancient lunar crust: Ferroan noritic anorthosites from the descartes region of the Moon, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Fragments of ancient lunar crust: Ferroan noritic anorthosites from the descartes region of the Moon will most certainly appreciate the feedback.

Rate now

     

Profile ID: LFWR-SCP-O-1450083

  Search
All data on this website is collected from public sources. Our data reflects the most accurate information available at the time of publication.