Geochemistry and nature of protolith of quartz sillimanite schist from Sonapahar area, West Khasi Hills district of Meghalaya
- DOI
- 10.2991/msc-18.2018.19How to use a DOI?
- Keywords
- Quartz sillimanite schists, Sonapahar, geochemistry, sediment, rock
- Abstract
The Precambrian terrain of the Sonapahar area is characterised by the presence of a thin, long, discontinuous band of quartz-sillimanite schist which hosts the massive sillimanite-corundum deposits. The quartz sillimanite schists are generally siliceous, SiO2 (60.59-76.82 wt %) and are characterized by high Al2O3 content with average value (27.22 wt %), low P2O5, Fe2O3 and MgO, MnO Na2O, K2O and TiO2. Average MgO, CaO, K2O and Na2O values are generally less than 0.15 wt %. TiO2 values range from 0.13-0.35 wt %. Compared with the post-Archean metasediments, the Sonapahar schists are richer in SiO2 and Al2O3 but depleted in other oxides. In Harkers variation diagram, SiO2 shows a linear inverse correlation with Al2O3 and TiO2, but there are no significant correlations observed with other oxides. In general, Al2O3 and SiO2 constitute more than 97 wt % in most of the samples. Among trace elements, Zr, Hf and Pb are characterized by high concentration and low La/Th and Th/U. The schistose rocks are generally low in Sr/Ba ratios (< 0.88 %) and relatively high content of Rb in contrast to Ba. Chondrite normalize REE patterns of the schists reveals a strongly fractionated patterns with enriched LREE and low HREE values [(La/Yb)N = 27.38-43.98] with prominent negative Eu-anomaly. The concentration of V (10.28-51.49) shows the apparent mobility in these quartz sillimanite schists and the oxidizing conditions prevailed during weathering. Geochemical characteristics suggested that quartz sillimanite schists from Sonapahar area are derived from post-Archean recycled upper crust sources and the precursor sediments are possibly derived from felsic rocks and probably not mafic rocks.
- Copyright
- © 2018, the Authors. Published by Atlantis Press.
- Open Access
- This is an open access article distributed under the CC BY-NC license (http://creativecommons.org/licenses/by-nc/4.0/).
Cite this article
TY - CONF AU - V. Vanthangliana AU - Jimmy Lalnunmawia AU - Laldinpuia AU - Lalhmingsangi PY - 2018/12 DA - 2018/12 TI - Geochemistry and nature of protolith of quartz sillimanite schist from Sonapahar area, West Khasi Hills district of Meghalaya BT - Proceedings of the Mizoram Science Congress 2018 (MSC 2018) - Perspective and Trends in the Development of Science Education and Research PB - Atlantis Press SP - 116 EP - 122 SN - 2352-5401 UR - https://doi.org/10.2991/msc-18.2018.19 DO - 10.2991/msc-18.2018.19 ID - Vanthangliana2018/12 ER -