Rate, Temporal Distribution and Geochemical Variation of Volcanism from the North-Central Part of the Lut Block

Central-eastern Iran, as a micro-continent, occurs within the convergent orogen between the Arabian, Eurasian and Indian plates. Within the central, eastern, and western Lut block the surface areas have covered by volcanic rocks have varied with time. The data were grouped according to age reported in geological maps suggests that the maximum volcanic activities took place during Eocene time, and then it dramatically decreased to present. Based on samples were collected from this area, there is significant variation in lava chemistry between samples from the central Lut block and those from western and eastern margins of the Lut block. Volcanic units of the central Lut block follow both calcalkaline and alkaline trend on alkali versus SiO2 diagram. Mafic volcanic rocks erupted along western and eastern margin of the Lut block are very similar in trace element abundance patterns to the average composition of oceanic island basalt. In contrast, depletions in Nb relative to LILE (Ba, Sr.) and other characteristics, such as low TiO2, high Ba/Nb and La/Nb ratios for basalts and andesitic samples from the central Lut block, suggest affinities at least for some of these samples, with other convergent plate boundary arc magmas around the world. The geochemical data presented in this study shows LILE/HFSE variations as an indication of subduction signature decreases to the northnortheast of the central Lut block, where Neotethyan oceanic crust was subducted beneath Iran from approximately Late Triassic to Late Oligocene time.

کلیدواژه ها:

Central-eastern Iran ، subduction ، geochemical variation ، Lut block