Authors

1 M.Sc., Research Institute for Earth Sciences, Geological Survey of Iran, Tehran, Iran

2 Associate Professor, Islamic Azad University, Islamshahr Branch, Islamshahr; Research Institute for Earth Sciences, Geological Survey of Iran, Tehran, Iran

3 Assistant Professor, Research Institute for Earth Sciences, Geological Survey of Iran, Tehran, Iran

Abstract

The post Eocene rhyolitic rocks of the Kahak area are located in SE of the Qom quadrangle map in scale of 1:250,000 and in the Kahak sheet in scale of 1:100,000. This area is situated at the marginal part of SW Central Iran, in the Urmia- Dokhtar magmatic belt. The rhyolitic rocks outcrop as endogenous domes and due to the presence of these rhyolitic masses along the Meyem strike-slip fault, it can be resulted that this fault has probably played an effective role in emplacement of magma ascending. The rhyolitic rocks are calc-alkaline and on the base of chemical composition of them and the chemistry of the present garnet and mica, the rhyolitic magma is S-type and peraluminus, which, belongs to the collision geotectonic environment and suggesting the role of continental crust in generation of these rocks. Since garnet is phenocrystal and seen individually in rhyolitic rocks and it could not be crystallized in most of the basic magmas, therefore the rhyolitic rocks  could not derived from the fractional crystallization of basic magma.

Keywords

آقانباتی، ع.، 1383- زمین‌شناسی ایران، سازمان زمین‌شناسی و اکتشافات معدنی کشور، 608 ص.
امامی، م. ه.،1370- شرح نقشه زمین‌شناسی چهار‌گوش قم 1:250000، سازمان زمین‌شناسی و اکتشافات معدنی کشور، 200 ص.
بهاری‌فر، ع. ا.، 1385-  گزارش پایانی عملیات اکتشافی معدن خاک صنعتی دستگرد قم، شرکت رنگین پودر غدیر (منتشر نشده).
بهاری‌فر، ع. ا.، 1388- شیمی میکا در ریولیت‌های منطقه کهک، قم و کاربرد آن در بررسی خاستگاه سنگ‌های منطقه، سومین همایش تخصصی زمین‌شناسی دانشگاه پیام‌نور.
عسکری، ن.، امامی، م. ه.، خیرخواه، م. و خداییان چگنی، ز.،‌ 1389- مینرال شیمی و منشأ گارنت در ریولیت‌های کهک (جنوب خاور قم)، بیست و نهمین گردهمایی علوم زمین، سازمان زمین‌شناسی و اکتشافات معدنی کشور، تهران.
قلمقاش، ج.، بحرودى، ع.، فنودى، م.، باباخانى، ع. ر. و امامى، م. ه.، 1374- نقشه 1:100000کهک، سازمان زمین‌شناسی و اکتشافات معدنی کشور.
 
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