RESEARCH POSTER PRESENTATION DESIGN © 2015 www.PosterPresentations.com NWA 7397 • Poikilitic shergottite • Discovered in Morocco in June, 2012 [1] • 2.13 kg, partially covered in fusion crust • 3 rd REE-enriched permafic (after RBT 04262 and GRV 020090) [2] • Crystallization age: ?? • Comprised of 2 lithologies [2] : Poikilitic: olivine, pyroxene, chromite Non-poikilitic: olivine, pyroxene, maskelynite, minor spinel, phosphate, sulfide, Fe-oxide • Olivine of both lithologies contain melt inclusions (MIs) Introduction • Determine the melt inclusion (MI)-source magmas and their progressive differentiation using textural observations • Understand the evolution of shergottite magmatic systems Objectives 7 MIs of a thick section of NWA 7397 (Fig. 3) were studied by- • EDX-elemental maps and BSE-images JEOL-SEM 7600F @ NASA-JSC • Major oxide analysis of host olivines and MIs Cameca SX-100 electron microprobe @ NASA-JSC • Modal composition (in wt.%) calculation of MIs ImageJ software • Post-entrapment Fe-Mg re-equilibration correction PETROLOG3 software Methods Melt Inclusions (MIs) References [1] Meteoritical Bulletin Database. [2] Howarth et al. (2014) MAPS, 49, 1812-1830. [3] Danyushevsky et al. (2002) Chem Geo, 183, 5-24. [4] Potter et al. (2015) LPSC XLVI, Abstr. #2945. [5] Basu Sarbadhikari et al. (2011) GCA, 75, 6803-6820. [6] Basu Sarbadhikari et al. (2016) MAPS, 1-17. [7] Agee et al. (2013) Science, 339, 780-785. [8] Filiberto & Dasgupta (2011) EPSL, 304, 527-537. [9] McSween et al. (2009) Science, 324, 736-739. [10] McSween et al. (2006) JGR, 111, E02S10. [11] Schmidt et al. (2014) JGR, 119, 64-81. Compared to RBT 04262 1 University of Houston, Houston TX 77204, USA, [email protected], 2 Jacobs, NASA-Johnson Space Center, Mail Code X13, Houston TX 77058, USA J. Ferdous 1 , A. D. Brandon 1 and A. H. Peslier 2 Magma Evolution of Poikilitic Shergottite NWA 7397 from its Olivine-hosted Melt Inclusions Figure 1: NWA 7397. block is 1 cm. Source: www.meteoritemarket.com Figure 3: Energy Dispersive X-ray (EDX) map of NWA 7397 thick section showing major phases with the poikilitic (P) and non-poikilitic (nP) lithologies outlined by the black line. The analyzed melt inclusion (MI) locations are marked by red boxes. Figure 5: Compositional diagram of primary pyroxenes [2] and MI-pyroxenes (MI PX) of NWA 7397. Melt Compositions Figure 2: Major phases and modal abundances of NWA 7397 [2]. Host Olivine MI Ca-poor PX MI Ca-rich PX a) Host Olivine MI Ca-poor PX MI Ca-rich PX b) Host Olivine MI-1 Mg-rich PX rim MI-1,2 K-Na-rich Glass MI-2 Ca-rich PX rim c) MI-1 MI-2 Host Olivine MI-1,2 PX MI-1,2 K-Na-rich Glass d) MI-1 MI-2 Host Olivine MI Mg-rich PX rim MI Ca-rich PX rim MI Plag-rich Glass MI K-feld-rich Glass e) f) Host Olivine MI Ca-P-rich PX MI Plag-rich Glass Figure 4: Compositional maps of NWA 7397 melt inclusions generated using ImageJ software. Poikilitic MIs (a-b) and Non-poikilitc MIs (c-g). PX= pyroxene, Plag= plagioclase, K-feld= K-feldspar. Host Olivine MI Plag-rich Glass MI K-feld-rich Glass MI Sulfide MI Phosphate g) Primary PX MI PX Figure 6: MgO/FeO ratios of NWA 7397 MIs and corrected for Fe-Mg exchange with host olivine vs. forsterite content (Fo) of host olivine. Black arrow= equilibrium conditions between olivine and basaltic melt [3]. Figure 8: SiO 2 vs. (a) FeO/MgO ratio and (b) Na 2 O+K 2 O- diagrams of MI-trapped magma compositions (MC) of NWA 7397, RBT 04262 [4], LAR 06319 [5] and Tissint [6] with other Martian surface rocks [7,8] and Martian mantle average [8]. Blue arrows= fractionation trends in terrestrial magmas [9]. Blue shaded area= SNC-bulk composition field, Pink shaded area= Gusev crater rock composition field [10], Green shaded area= Gale crater rock composition field [11]. Figure 7: Molar Mg# vs. (a) SiO 2 , (b) Al 2 O 3 , (c) CaO and (d) CaO/Al 2 O 3 contents of MIs of NWA 7397 and another olivine-phyric shergottite RBT 04262 [4] before and after the post-entrapment corrections [3]. P= Poikilitic MI, nP= Non-poikilitic MI, PBC= Present Bulk Composition, MC= Trapped Magma Composition. Compared to Other Meteorites and Rover data 0 5 10 15 20 25 0 10 20 30 40 50 60 70 80 Al 2 O 3 (wt %) (b) 0 5 10 15 20 25 0 10 20 30 40 50 60 70 80 CaO (wt %) Molar Mg# (c) 0 0.4 0.8 1.2 1.6 2 0 10 20 30 40 50 60 70 80 CaO/Al 2 O 3 Molar Mg# (d) (a) (b) Conclusions • MI of NWA 7397 and RBT 04262 have higher SiO 2 and distinct alkali-contents compared to SNC bulk-rock and Bounce rock. Their compositions can be linked by fractional crystallization processes. • Some MI of NWA 7397 and RBT 04262 have compositions resembling that of rocks analyzed by the Pathfinder rover. • One MI from NWA 7397 has a composition similar to those of Gale crater rocks. 45 55 65 75 0 10 20 30 40 50 60 70 80 SiO 2 (wt%) NWA-P-PBC NWA-P-MC NWA-nP-PBC NWA-nP-MC RBT-P-PBC RBT-P-MC RBT-nP-PBC RBT-nP-MC (a)