Petrogenesis and tectonic implications of Miocene dikes in the southeast of Bam: Constraints on the development of active continental margin

Fudge dikes of diorite and microdiorite are penetrated in the Mio-Pliocene sedimentary-volcanic series in the northeast of Bam. In terms of lithology, these dikes are placed in two categories: gabbro-diorite. The primary minerals of the dikes are plagioclase, amphibole (hornblende), and augite, and secondary minerals such as chlorite, biotite, and sericite. Also, their textures are granular, ophitic, and microgranular. From the geochemical point of view, gabbro-diorites have sub-alkaline and met aluminum with enrichment of LILE and HREE and depletion of Nb and Ta elements. The parental magma of the gabbro-diorites is obtained from the melting of a part of the subcontinental lithospheric mantle affected by the subduction producers and in equilibrium with lherzolite spinel. The characteristics of incompatible element patterns include LILE enrichment and HFSE depletion compared to REE similar to subduction zone igneous rocks. These rocks show the intermediate geochemical characteristics of the volcanic arc magmatism of arc islands and margins, consistent with the formation of these rocks in active continents. Geochemical evidence, as well as the association of igneous rocks with green tuffites and other shallow sea sediments, indicate the occurrence of an extensional basin behind the continental arc.