Characterization and Origin of Selected Basaltic Outcrops in Harrat Irbid (HI), Northern Jordan

This research is conducted to investigate the mineralogy, geochemistry and the petrology of Harrat Irbid (HI), in northern Jordan. Petrographic, mineralogical, and geochemical data were obtained from twenty representative samples selected from the studied HI outcrops. Mineralogical data show that HI consists of plagioclase, olivine, pyroxene, Feldspathoids, alkali feldspar, opaques, carbonates, iddingsite and chlorite minerals. The petrographical data show that the basalt is mesocratic and has hypocrystalline minerals. Modally, three petro-types are recognized, olivine-plagioclase- pyroxene phyric (23 %), olivine-pyroxene phyric (53 %) and olivine phyric basalt (24 %). The HI minerals are arranged mainly according to the porphyritic, glomeroporphyritic, paliotaxitic, vesicular, radiate and intergranular textures. Geochemically, all of the inspected samples of HI are located within plate alkaline basalt. They belong to the sodic series and are produced from undersaturated magma which resulted from a primitive mantle source. The rare-earth elements showed a depletion in the heavy rare earth elements and a strong negative Europium anomaly and enrichments in some lithophile elements, suggesting that the basalt resulted from a partial melting of a slightly differentiated pattern later. Magmas, which are analyzed for petrogensis modeling, may have been derived from low degrees (about 10 %) of partial melting of an enriched deeper garnet peridotite mantle source ( 100km) with a limited crustal contamination.