Oxygen Fugacity and Water Activity during Thermal Peak and Retrogression of Granulites around the Sarvapuram Area, Karimnagar Granulite Terrane, Andhra Pradesh, India |
| |
作者姓名: | P. Chandra SINGH D. PRAKASH |
| |
摘 要: | The investigated area around Sarvapuram represents a part of the Karimnagar granulite terrane of the Eastern Dharwar Craton, India. Garnet–bearing gneiss is hosted as enclaves, pods within granite gneiss and charnockite. It is largely made up of garnet, orthopyroxene, cordierite, biotite, plagioclase, K–feldspar, sillimanite and quartz. The peak metamorphic stage is represented by the equilibrium mineral assemblage i.e. garnet, orthopyroxene, cordierite, biotite, plagioclase, sillimanite and quartz. Breakdown of the garnet as well as preservation of the orthopyroxene–cordierite symplectite, formation of cordierite with the consumption of the garnet + sillimanite + quartz represents the decompressional event. The thermobarometric calculations suggest a retrograde P–T path with a substantial decompression of c. 3.0 kbar. The water activity(XH2 O) conditions obtained with the win TWQ program for core and symplectite compositions from garnet–bearing gneiss are 0.07–0.14 and 0.11–0.16 respectively. The quantitative estimation of oxygen fugacity in garnet–bearing gneiss reveal log f O2 values ranging from-11.38 to-14.05. This high oxidation state could be one of the reasons that account for the absence of graphite in these rocks.
|
关 键 词: | metamorphic conditions oxygen fugacity water activity garnet–bearing gneisses Karimnagar granulite terrane India |
收稿时间: | 2018/8/30 0:00:00 |
修稿时间: | 2018/12/5 0:00:00 |
Oxygen Fugacity and Water Activity during Thermal Peak and Retrogression of Granulites around the Sarvapuram Area,Karimnagar Granulite Terrane,Andhra Pradesh,India |
| |
Authors: | P Chandra SINGH and D PRAKASH |
| |
Institution: | 1 Department of Earth Sciences, Indian Institute of Technology, Powai, Mumbai, 400076, India
2 Centre of Advanced Study in Geology, Banaras Hindu University, Varanasi, 221005, India and 2 Centre of Advanced Study in Geology, Banaras Hindu University, Varanasi, 221005, India |
| |
Abstract: | The investigated area around Sarvapuram represents a part of the Karimnagar granulite terrane of the Eastern Dharwar Craton, India. Garnet–bearing gneiss is hosted as enclaves, pods within granite gneiss and charnockite. It is largely made up of garnet, orthopyroxene, cordierite, biotite, plagioclase, K–feldspar, sillimanite and quartz. The peak metamorphic stage is represented by the equilibrium mineral assemblage i.e. garnet, orthopyroxene, cordierite, biotite, plagioclase, sillimanite and quartz. Breakdown of the garnet as well as preservation of the orthopyroxene–cordierite symplectite, formation of cordierite with the consumption of the garnet + sillimanite + quartz represents the decompressional event. The thermobarometric calculations suggest a retrograde P–T path with a substantial decompression of c. 3.0 kbar. The water activity (XH2O) conditions obtained with the winTWQ program for core and symplectite compositions from garnet–bearing gneiss are 0.07–0.14 and 0.11–0.16 respectively. The quantitative estimation of oxygen fugacity in garnet–bearing gneiss reveal log fO2 values ranging from ?11.38 to ?14.05. This high oxidation state could be one of the reasons that account for the absence of graphite in these rocks. |
| |
Keywords: | metamorphic conditions oxygen fugacity water activity garnet–bearing gneisses Karimnagar granulite terrane India |
本文献已被 CNKI 等数据库收录! |
| 点击此处可从《Acta Geologica Sinica》浏览原始摘要信息 |
| 点击此处可从《Acta Geologica Sinica》下载免费的PDF全文 |
|