Geochemistry And Geochronology Of The IKH NART Granite Massive, Eastern Mongolia: Implications For Its Origin Magma
We present new geochemical, geochronological data of the late Mesozoic Ikh Nart massive in the eastern Mongolia. The Ikh Nart massive was intruded to metasedimentary rocks which was emplaced within low grade regional and contact metamorphism along its boundary. The massive are mainly consisted coarse grained porphyritic granite (PCG) and medium grained biotite granite (BMG). In generally, granites were composed by K-feldspar, plagioclase, quartz, biotite, minor amount muscovite and accessory minerals.
The geochemical patterns shown calc-alkaline, I and S-type characteristics which was emplaced in syn to post-collision of tectonic settings. The Eu and Sr anomalies and unfractionated HREE suggest the presence of plagioclase and absent garnet in the source or extensive melting which has resulted in garnet being exhausted from the source. Perhaps the Ikh Nart massive could be described of juvenile material added to the crust from the enriched mantle during Cretaceous extension. The late Mesozoic syn-extensional granites are mainly occurred in the southern and eastern Mongolia. Our U-Pb zircon geochronological data indicates that the Ikh Nart pluton was emplaced in early Cretaceous age 134,5±1.6 Ma.
Keywords: Ikh Nart granite, I and S-type granite, Extension, Crustal material.