Petrology
S. M. Tabatabaei Manesh; M. A. Mackizadeh; saeideh ranjbar; R. Gholinezhad
Abstract
Javinan skarn is located at 115 km north west of Isfahan (40 km south of Kashan and east of Ghohrud), is included in Central Iran structural zone and spread in contact with Ghohrud granitoid (Middle Miocene age) with shale, sandstone and limestone succession of the Jurassic age known ...
Read More
Javinan skarn is located at 115 km north west of Isfahan (40 km south of Kashan and east of Ghohrud), is included in Central Iran structural zone and spread in contact with Ghohrud granitoid (Middle Miocene age) with shale, sandstone and limestone succession of the Jurassic age known as Shemshak Formation. Skarnification is made up of endo- and exoskarn subzones. Wide mineralization in these skarns hasn’t observed. Endoskarn subzone has limited occurence (from a few millimeters to a few centimeters) and exoskarn has the greatest development (from 1 meter to more than 10 meters). Endoskarn with the formation of the skarn minerals garnet, pyroxene, plagioclase, epidote and sphene, is formed in the intrusive host rock and is in the vicinity of the carbonate part. In its immediate neighborhood, exoskarn subzone starts with the formation of minerals garnet, pyroxene, idocrase, epidote, phlogopite, chlorite, quartz and calcite in the carbonate section. Mineralogical studies and textural relationship of minerals have shown that the metamorphic facies اhas reached to pyroxene hornfels in skarn rocks of this area.
S Ranjbar; S.M Tabatabaei manesh; M.A Mackizadeh
Abstract
The Khuni skarn has been developed in the contact between small tongues of the Late Eocene-Oligocene I-type Kal-e kafi granitoidic intrusive body and the Precambrian Lakh marble-dolomite unit, Located 220 km northeast of Esfahan in the Central Iran structural zone. Skarnification could be divided into ...
Read More
The Khuni skarn has been developed in the contact between small tongues of the Late Eocene-Oligocene I-type Kal-e kafi granitoidic intrusive body and the Precambrian Lakh marble-dolomite unit, Located 220 km northeast of Esfahan in the Central Iran structural zone. Skarnification could be divided into two subzones: endoskarn and exoskarn. There is no significant mineralization in relation to this skarn system. The extent of the endoskarn subzone is very limited (often from 2 mm to 2 cm), but the exoskarn has the most extension across the contact. The endoskarn subzone can be recognized by formation of euhedral garnets adjacent to the carbonate part. In the immediate vicinity of the endoskarn, the exoskarn subzone initiates with formation of garnet and clinopyroxene in the carbonates and is extended far away from the contact as represented by vesuvianite and phlogopite minerals. Garnet is one of the most abundant minerals in this skarn system and is found in different sizes and forms. In this paper, the zonation pattern of garnet crystals in the exoskarn subzone in the immediate vicinity of intrusive body is investigated. These garnets are mainly euhedral and isotropic and in some cases anhedral and anisotropic. They are commonly cored by a grossular-rich inner part, and a sharp considerable increase in their andradite content is found toward the rim in most cases. Most studies on skarn systems consider boiling to be the most important cause for this phenomenon. This means that boiling increases the Fe content and oxygen fugacity in the final stages of the system evolution, which consequently increases the andradite content of garnet in its solid solution
S. Zandifar; M.V. Valizadeh; M. A. Barghi; M. R. Foroodijahromi
Abstract
The crystallization history of a rock is recorded by the size and the distribution of its minerals. The porphyroblast crystal size in metamorphic rocks can give notable information about its growing medium. Considering the varieties of mineralogy in the Hassan-Abad's skarn and high frequency of garnet ...
Read More
The crystallization history of a rock is recorded by the size and the distribution of its minerals. The porphyroblast crystal size in metamorphic rocks can give notable information about its growing medium. Considering the varieties of mineralogy in the Hassan-Abad's skarn and high frequency of garnet porphyroblasts in different metamorphic zones and special different sizes in the first metamorphic zone of the NE skarn, the crystal size distributions of this mineral is studied. With regard to this, digital photos of cutting surface were provided and analyzed by JMicrovision software. It has been expected, two different slopes can show three suspections: 1- parent rock composition effect; 2- crystal growing time; 3- fluid flow around plutonic rock. According to the presence of clintonite, vesuvianite and garnet and as many as joints in the region, the role of fluid in growing the size of garnet porphyroblast in part of the first metamorphic zone seem to be noticeable.
