75-9 Understanding Mantle Xenolith Origin in Northern Morocco

Session: Mineralogy, Geochemistry, Petrology, and Volcanology Student Session (Posters)

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The Middle Atlas Volcanic Field (MAVF) in Northern Morocco comprises 100s of Quaternary-age monogenetic cones derived from magmas of uncertain derivation. We focus on understanding the origin and creation of magmas from the Ouest Hébri volcanic crater in the MAVF. Ouest Hébri is a cone-maar, and its formation yielded basalt scoria with copious xenoliths, presumed to be of mantle origin. Backscatter electron images obtained via SEM detail features of the xenoliths’ history such as mineral zonation and variable stages of mineral-melt reactions. We also analyzed olivine, pyroxene (ortho- and clino-), and spinel crystals from the Ouest Hébri xenoliths via electron microprobe. Olivine composition ranges from Fo86 to Fo89; spinel has Cr#s ranging from 10 to 20; orthopyroxene compositions range from En~84–89 and the composition of clinopyroxene is predictably magnesian (Fs<~6). Geothermobarometry calculations were then performed for olivine-spinel pairs and equilibrium orthopyroxene-clinopyroxene pairs in order to assess mantle source conditions. Comparison of these values with those from other MAVF xenoliths will enable further characterization of the mantle underlying the MAVF and lend insight into the nature of these magmas and their relationship to other regional magmatic systems, including assessment of the MAVF and its relationship to the nearby Canary hot spot.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

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