Petrography, Geochemistry and Petrogenesis of the Basalt Flow at Al Azraq Al Shamali Area, East Jordan ()
ABSTRACT
Al Azraq Al Shamali (AZS) basaltic rocks were
investigated aiming to understand their
mineralogy, petrography and geochemistry features, and to achieve that a
total of sixteen representative rock samples were selected for both geochemical
and petrographic analysis from several sites in the study area. Petrographic
characteristics were analyzed by optical microscopy after preparation thin
sections for representative rock samples, which show that all basalt samples have minerals comprising: olivine,
plagioclase (labradorite), clinopyroxene
(augite), opaque’s and some secondary minerals such as Iddingsite,
however, the proportions of each mineral vary between samples. Normative
mineralogy by using CIPW Norm showed that AZS basalt samples dominated by
olivine, Diopside, and nepheline, and AZS basalt can be normatively classified
as alkali olivine basalt. Some textures that may be evident on microscopic
examination such as porphyritic, glomeroporphyritic, vesicular, intergranular,
and ophitic to sub-ophitic texture. X-Ray Fluorescence was used for whole rock
major elements analysis (SiO2, TiO2, Al2O3,
Fe2O3, MnO, MgO, CaO, Na2O, K2O and
P2O5 in wt%) and trace element (V, Cr, Co, Ni, Rb, Sr, Y, Zr, Nb, Ce, Nd and Ba in ppm). Geochemical
analysis reveal that the basalt is alkaline and includes into Sodic
series. AZS basalt are produced under-saturated within intraplate continental
environment. The normalized trace element
diagrams suggest that the AZS product of the asthenosphere part of the mantle
at >100 km depth. Furthermore, the data of studied
samples suggest that these rocks evolved from a melt formed by low degrees of partial melting. Also the geochemical variation
trends of (AZS) basaltic samples supposing that the
composition of these basalt have been influenced by fractional crystallization,
without clear
evidences for crustal contamination.