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Physico-chemical conditions of four calc-alkaline granitoid plutons of Chhotanagpur Gneissic Complex, eastern India: Tectonic implications
- Source :
- Journal of Earth System Science. 127
- Publication Year :
- 2018
- Publisher :
- Springer Science and Business Media LLC, 2018.
-
Abstract
- Petrography and mineralogy of four calc-alkaline granitoid plutons Agarpur, Sindurpur, Raghunathpur and Sarpahari located from west to east of northern Purulia of Chhotanagpur Gneissic Complex, eastern India, are investigated. The plutons, as a whole, are composed of varying proportions of Qtz–Pl–Kfs–Bt–Hbl±Px–Ttn–Mag–Ap–Zrn±Ep. The composition of biotite is consistent with those of calc-alkaline granitoids. Hornblende–plagioclase thermometry, aluminium-in-hornblende barometry and the assemblage sphene–magnetite–quartz were used to determine the P, T and $$f_{\mathrm{O}_2}$$ during the crystallisation of the parent magmas in different plutons. The plutons are crystallised under varying pressures (6.2–2.4 kbar) and a wide range of temperatures (896– $$718{^{\circ }}\hbox {C}$$ ) from highly oxidised magmas (log $$f_{\mathrm{O}_2}$$ $$-11.2$$ to $$-15.4$$ bar). The water content of the magma of different plutons varied from 5.0 to 6.5 wt%, consistent with the calc-alkaline nature of the magma. Calc-alkaline nature, high oxygen fugacity and high $$\hbox {H}_{2}\hbox {O}_{{\mathrm{melt}}}$$ suggest that these plutons were emplaced in subduction zone environment. The depths of emplacement of these plutons seem to increase from west to east. Petrologic compositions of these granitoids continuously change from enderbite (opx-tonalite: Sarpahari) in the east to monzogranite (Raghunathpur) to syenogranite (Sindurpur) to alkali feldspar granite (Agarpur) in the west. The water contents of the parental magmas of different plutons also increase systematically from east to west. No substantial increase in the depth of emplacement is found in these plutons lying south and north of the major shear zone passing through the study area suggesting the strike-slip nature of the east–west shear zone.
- Subjects :
- 010504 meteorology & atmospheric sciences
Pluton
Geochemistry
engineering.material
010502 geochemistry & geophysics
01 natural sciences
Petrography
Magma
engineering
General Earth and Planetary Sciences
Fugacity
Syenogranite
Shear zone
Alkali feldspar
Biotite
Geology
0105 earth and related environmental sciences
Subjects
Details
- ISSN :
- 0973774X and 02534126
- Volume :
- 127
- Database :
- OpenAIRE
- Journal :
- Journal of Earth System Science
- Accession number :
- edsair.doi...........6c2430d3a20bf2cbeab11c7c95b1dcc5