Scientific Quarterly Journal of Geosciences

Scientific Quarterly Journal of Geosciences

Petrologic and Tectonomagmatic Aspects of Cenozoic Basalts in East Iran (Khorasan)

Document Type : Original Research Paper

Author
Mansur Vosughi Abedini
Department of Geology, Faculty of Earth Sciences, Shahid Beheshti University, Tehran, Iran
Abstract
In order to determine the petrological characteristics, recent volcanic rocks in east Iran have been sampled and studied. In previously published geological maps, these rocks are known as " Quaternary basalts" although by using different petrological methods they seem to be andesite and dacite rather than basalt. In east Iran, is basalt only found in two restricted regions: one near Mud village, southeast of Birjand, the other in Ferdows area. This paper deals with the petrographic, petrologic and tectonomagmatic aspects of these two localities.
Petrographic and geochemical studies show that, these rocks have an alkaline nature and normative nepheline is present in most of the samples. From the geochemical point of view the samples has a genetic relation and derived from the same parental magma.
In some cases, the chemical composition is very similar to a basaltic parental magma, however, in other ones fractional crystallization is the major process of magma evolution. In diagrams, these basalts, in spite of their alkaline nature; plotting in calcalkaline fields tectonomagmatic. Probably because of a distinctive mode of magma evolution, of course this evolution had not enough intensity to remove the alkaline nature completely. In general consideration a rifting origin seems to be acceptable and for the better deduction, isotopic study is needed.
Keywords
Tectonomagmatic investigation, Khorasan

Subjects

 
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Scientific Quarterly Journal of Geosciences
Volume 6, 23-24
Spring & Summer 1998, Vol. 6, No. 23-24
Autumn 1998
Pages 16-31