Field evidence, microscopic and geochemical data to determine the origin of magmatic enclaves in the Jebale Barez plutonic complex (eastand northeast Jiroft)


1 Department of Geology, Faculty of Earth Sciences, Shahid Beheshti University, Tehran, Iran

2 Department of Geology, Payame Noor University, 19395-3697 Tehran, I. R. of Iran


The Jebale-Barez plutonic complex is composed of granitoid intrusive bodies and is located in the east and northeast of Jiroft and south of the Kerman province. The plutonic complex is composed of granodiorite, quartz diorite, syenogranite and mostly granite. This plutonic complex includes abundant rounded and ellipsoid magmatic enclaves ranging in size from a few millimeters to 30 centimeters and varying in composition from quartz diorite, monzodiorite to quartz monzodiorite. These enclaves are very fine-grained and show chilled margin and their crystal size gradually decreases from center to the margin. The chilled margin is an evidence of rapid magma cooling once the enclaves were surrounded by host felsic magma. The mingling of two magmas is testified by presence of the disequilibrium textures such as: poikilitic and antipertite textures in the K-feldspar megacrysts, rounded, corroded and altered plagioclases, mafic clots, acicular apatites, small lath-shaped plagioclases in the large plagioclases as well as the occurrence of mafic microgranular enclaves with crenated and cuspate contact with the felsic -host rocks. Also, the plagioclase crystals display essentially normal and occasionally oscillatory zoning. The enclaves and their host rocks, geochemically is different. The former is Na-enriched whilst the latter is enriched in K. Furthermore, the enclaves are depleted in LREE and LILE while are enriched in HREE and Ti in analogy to their host granodiorites. Therefore, it seems that the enclaves and granodiorites have been originated from two different magmas which were placed adjacent to each other by magma mingling and mixing process.