Petrology, Geochemistry and Tectonics of the Extrusive Sequence of Fannuj-Maskutan Ophiolite, Southeastern Iran

作者：Moslempour Mohammad Elyas^*; Khalatbari Jafari Morteza; Ghaderi Majid; Yousefi Hamidoddin; Shahdadi Sara

来源：Journal of the Geological Society of India, 2015, 85(5): 604-618.

DOI：10.1007/s12594-015-0255-y

• Makran
• Fannuj-Maskutan
• Extrusive
• Pillow Lava
• BABB
• MORB

The Fannuj-Maskutan ophiolite (FMO) contains all the components of a typical ophiolite sequence: metamorphic tectonites, cumulates, isotropic gabbros, plagiogranites, diabasic sheeted dikes, extrusives and sedimentary cover. The extrusive sequence of FMO comprises of alternate pillow lavas and sheet flows, in which the aphyric types are more abundant than phyric facies. The majority of extrusive rocks are basalt and minor basaltic andesite. The FMO extrusives are similar to back-arc basin basalts (BABB). These rocks show many similarities with mid-ocean ridge basalts (MORB), such as marked Fe, Ti, V enrichment from less fractionated to fairly fractionated rocks, relatively high Ti, P, Y contents, and significant Nb depletion. However, they show higher Th/Ta and LREE/HREE ratios compared to MORBs. In addition, the FMO extrusive rocks are generally more enriched in large ion lithophile elements (Rb, Ba, Sr, and K) than average normal-MORB, which suggests that the mantle beneath the FMO was modified by subducted slab-derived components. So, the Fannuj-Maskutan extrusives can be regarded as representative of back-arc basin located between the Bajgan-Durkan arc and the continental margin of the Lut block. These geochemical features, support the idea that the extrusive sequence of Fannuj-Maskutan ophiolite are formed in an environment related to suprasubduction zone (SSZ).

• 出版日期2015-5