Studying the genesis of igneous rocks in Zarin-Kamar Region (Shahrood, Northeastern Iran) by rare earth elements

AutorEbrahim Nazemi - Mohammad-Ali Arian - Abdolreza Jafarian - Mohsen Pourkermani - Abdollah Yazdi
CargoDepartment of Geology, North Tehran Branch, Islamic Azad University, Tehran, Iran. - Department of Geology, North Tehran Branch, Islamic Azad University, Tehran, Iran. Corresponding author: maa1361@yahoo.com - Department of Geology, Shahrood Branch, Islamic Azad University, Shahrood, Iran. - Department of Geology, North Tehran Branch, Islamic ...
Páginas446-466
Periódico do Núcleo de Estudos e Pesquisas sobre Gênero e Direito
Centro de Ciências Jurídicas - Universidade Federal da Paraíba
V. 8 - Nº 04 - Ano 2019 Special Edition
ISSN | 2179-7137 | http://periodicos.ufpb.br/ojs2/index.php/ged/index
446
STUDYING THE GENESIS OF IGNEOUS ROCKS IN ZARIN-
KAMAR REGION (SHAHROOD, NORTHEASTERN IRAN) BY
RARE EARTH ELEMENTS
Ebrahim Nazemi1
Mohammad-Ali Arian2
Abdolreza Jafarian3
Mohsen Pourkermani4
Abdollah Yazdi5
Abstract: Zarin-Kamar region is located
north east of Shahrood (36o37’-36o42’N,
55007’-55012’E). Plutonic rocks in this
area belongs to syenite group and their
texture is intergranular hypidiomorphic.
Volcanic rocks in the area have
porphyritic, amygdale intersertal texture.
which quartz is also seen among their
cavities and porosities. Total
concentration of REEs (REE) in the
study igneous rocks varies between 450
and 683 ppm. Diagram of Eu/Eu* versus
Sr and Eu/Eu* versus Ba show negative
anomalies of Eu. This phenomenon as
well as Ba and Sr trends show that
plagioclase removal has happened
during the magma evolution. These
1 Department of Geology, North Tehran Branch, Islamic Azad University, Tehran, Iran.
2 Department of Geology, North Tehran Branch, Islamic Azad University, Tehran, Iran.
Corresponding author: maa1361@yahoo.com
3 Department of Geology, Shahrood Branch, Islamic Azad University, Shahrood, Iran.
4 Department of Geology, North Tehran Branch, Islamic Azad University, Tehran, Iran
5 Department of Geology, Kahnooj Branch, Islamic Azad University, Kahnooj, Iran
rocks have rock has originated from an
enriched mantle source. The rate of
Dy/Yb in the igneous rocks of the region
varies between 1.32 and 2.62. it shows
that it stemmed from a garnet lherzolitic
source. The rate of (Tb /Yb )N was
between 0.97 to 2.25 showing a garnet
source. Also other related figures
showed that the samples belonged to
OIB (Oceanic Island Basalt). The rate of
La/Ta was between 6.6 to 14.01. It also
showed that they had a source from
asthenosphere. The rate of La/Nb was
0.5 to 0.91. It also shows a less crustal
contamination among these samples.
Periódico do Núcleo de Estudos e Pesquisas sobre Gênero e Direito
Centro de Ciências Jurídicas - Universidade Federal da Paraíba
V. 8 - Nº 04 - Ano 2019 Special Edition
ISSN | 2179-7137 | http://periodicos.ufpb.br/ojs2/index.php/ged/index
447
Keywords: plutonic, intergranular,
hypidiomorphic, volcanic, porphyritic,
asthenosphere, crustal contamination.
Introduction
The study rocks involve two
types of igneous rocks, intrusive and
volcanic. The intrusive ones are alkali
aegirine syenite and alkali feldspar
aegirine quartz syenite. The volcanic
ones are aegirine trachyte types. The
minerals detected in XRD were as same
as those minerals highlighted in thin
section. There is no plagioclase in thin
sections of Zarin-Kamar igneous rocks
which confirmed the negative anomaly
of Eu (Nazemi et al, 2017; Yazdi et al.,
2017). Dominate process in the
evaluation of the study rocks was
fractional crystallization (Nazemi, 2017)
. Ti, P, and Sr are deplated while Rb, Th,
and U are enriched in the study samples.
The ratio of La/Ta was 7.13 to 14.01.
Crustal contamination played no
significant role on evolving the rocks in
the region. However, this little
contamination showed that speed of
magma rise from magma could be
significantly high.
Alkali feldspar quartz aegirine syenite
(A3)
Alkali feldspar crystals are seen
in different shape in this sample. Some
of them has been getting dusty color. The
feldspars has cut each other and their
abundance is 80 to 95 percent. Quartz
among the minerals Located has 5 to 10
percent of the total abundance. Pyroxene
crystals are coarse and subhedral with
dark green color and they also have
zoning. Pyroxene is considered as one of
the keys of fractional crystallization
phase in alkaline magmatic systems. It is
also considered as a potential for
enriching the rare earth elements during
the crystallization (Charlie Beard et al.,
2017; Mobashergarmi et al., 2018).
Amphibole crystals have also parallel
cleavage and they are elongated and
amorphous. Their color is green to
brown. (Figure 1)
In the XRD analysis report Major phases are microcline and acmite .(figure 2)

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