The Ordovician Sorkhband ultramafic complex lies in the southern Kerman Province of Iran. The wedge shape complex is divided into lower and upper parts. The former comprises of dunite, podiform chromitite deposits, massive and dyke like olivine clinopyroxenite, wehrlite (as bands with width of 0.5-5m and a few meters long) and olivine websterite dykes. The upper part consist of foliated porphyroclastic diopsidic harzburgite with subordinate lenses and dykes of dunite, massive and dyke like olivine clinopyroxenite and minor orthopyroxenite dykes with no significant chromitite mineralization.
Mineral chemistry of olivine, clinopyroxene, orthopyroxene, and chromites in wehrlites are similar to olivine clinopyroxenites and reveal a mantle origin for the Sorkhband ultramafic complex. Moreover, chondrite normalized rare-earth element (REE) patterns of wehrlites show flat medium REE (MREE) and heavy REE (HREE) patterns, [(Gd/Yb)N~1], and highly light REE (LREE) depletions similar to olivine clinopyroxenite patterns. Furthermore, platinum group element (PGE) show highly differentiated pattern in wehrlites with a positive slope (similar to olivine clinopyroxenites) and high Pd/Ir ratio (36-59).
According to Nicolas and Prinzhofer (1983), wehrlite may be formed by the passage of a melt through dunite bodies where by the process of impregnation and melt-rock interaction clinopyroxene crystallize in dunite. Such impregnated clinopyroxenes are allotriomorphic and interstitially filled between olivine crystals and due to poikilitic crystallization may contain spinel and olivine inclusions. Other evidences of melt-rock interaction in the Sorkhband ultramafic complex have been reporetd before (Najafzadeh et al., 2009, 2010).
So, regarding the mineral chemistry; REE, PGE and transition elements (TE) patterns similarity in between wehrlites and olivine clinopyroxenites in the Sorkhband ultramafic complex it can be concluded that wehrlites are most likely formed by interaction of pyroxenite melt with dunites as a result of impregnation and melt-rock interaction.