Distinguishing between Apollo 14 impact melt and pristine mare basalt samples by geochemical and textural analyses of olivine

Distinguishing between basalts produced by endogenic volcanism and impact processes: A non-destructive method using quantitative petrography of lunar basaltic samples

“…For olivine, the impact melts appear to have steeper CSDs than those from mare basalts (see Fig. 5a where the impact melts are represented by the A-14 Olivine Vitrophyres; Fagan et al, 2013a). However, it is difficult to differentiate all sample types when CSDs are presented in this way.…”

“…5. (a) Olivine CSDs from basalts returned by the Apollo 12, 14, and 17 missions as well as two basaltic samples from Apollo 16 (Zeigler et al, 2006) and Apollo 14 olivine vitrophyres (impact melts) (Fagan et al, 2013a); (b) CSD for basaltic sample 71597, an olivine cumulate including Population Density errors. Table 1 Samples where plagioclase crystal size distributions have been determined for this study.…”

“…None of these samples exhibit an alignment of crystals indicating they represent a random sampling of crystals that exhibit no flow texture. Complementing the work of Fagan et al (2013a), olivine CSDs (Table 2) have also been constructed for additional Apollo 12 (N = 5), Apollo 14 (N = 3), Apollo 16 (N = 2) and Apollo 17 (N = 7) basalts as well as for known Apollo 14 impact melts (olivine vitrophyres N = 4; described as impact melts by Allen et al, 1979;Shervais et al, 1988). The mare basalts used in this study represent samples from the Apollo 12 pigeonite and ilmenite basalt suites plus the one feldspathic basalt (12038) (Neal et al, 1994a,b); each geochemical group of the Apollo 14 high-Al basalts (Neal and Kramer, 2006) excluding the very high potassium basalts ("VHK"- Shervais et al, 1985a;Neal et al, 1988aNeal et al, , 1989a; three Apollo 16 basalts (Zeigler et al, 2006;Fagan and Neal, 2012); and each geochemical group from the Apollo 17 mare basalts (Rhodes et al, 1977;Neal et al, 1990;Ryder, 1990).…”

“…Comparison of the slopes and y-axis intercepts of these CSDs allows the distinction to be made between the two petrogeneses and builds upon the work of several recent contributions (Oshrin, 2009;Oshrin and Neal, 2009;Hui et al, 2011;Fagan, 2012;O'Sullivan, 2012;Fagan et al, 2013a;and Fagan and Neal, 2012;Donohue, 2013). During these studies, it has been demonstrated that phenocrysts can be distinguished from xenocrysts in impact melts by texture and composition (e.g., Figs.…”

Basaltic diversity at the Apollo 12 landing site: Inferences from petrologic examinations of the soil sample 12003

“…Fagan et al. () have identified a relationship involving the ratio of Ti/V contents in olivine phases that appears to distinguish between ilmenite and olivine basalts. However, despite a large number of previous studies reporting major and minor element mineral chemistries of the Apollo 12 basalts (e.g., Bence et al.…”