TITLE:
Petrology, Geochemistry and Tectonomagmatic Setting of Neshveh Intrusion (NW Saveh)
AUTHORS:
Reza Keshavarzi, Dariush Esmaili, Mehdi Rezaei Kahkhaei, Mir Ali Asghar Mokhtari, Reza Jabari
KEYWORDS:
Petrology, Geochemistry, Intrusion, Granitoid, Neshveh, Saveh
JOURNAL NAME:
Open Journal of Geology,
Vol.4 No.5,
May
2,
2014
ABSTRACT: Neshveh intrusion is
located in the NW of Saveh City and is a part of Orumieh-Dokhtar magmatic arc.
This intrusion consists of quartz monzodiorite, granodiorite and granite that
have intruded into the Eocene volcano-sedimentary rocks. This intrusion is
high-K calk-alkaline and metaluminous and is classified as I-type granitoids.
Field investigations along with petrographic and geochemical studies indicate
that all phases of Neshveh intrusion are derived from a common magma source as
a result of mineral differentiation. Different phases of this intrusion have
low Mg#, Ni, Cr, Co and V which are indicative for higher evolution of magma
during the magma ascent and before complete crystallization. All phases of
Neshveh granitoid are characterized by LREE-rich patterns with high LREE/HREE
ratio and negative Eu anomalies. Similarity of the mentioned patterns suggests
a comagmatic source for these rocks and demonstrates the role of magmatic
differentiation in their evolution. There are negative anomalies in the Nb and
Ti along with positive anomalies of Rb, Ba, K and Pb on the spider diagrams.
These anomalies are indicative for a subduction setting for magma source of
these rocks. Geochemical studies indicate that the Neshveh granitoid is formed
in a volcanic arc and active continental margin. In this base, it is assumed
that this intrusion is formed as a result of Neo-Tethys oceanic lithosphere
subduction beneath the Central Iran zone which is replaced in the
Orumieh-Dokhtar magmatic arc.