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Authors
Affiliations
1 Wadia Institute of Himalayan Geology, 33, Gen Mahadev Singh Road, Dehra Dun 248001, IN
2 Department of Earth Sciences, University of Roorkee, Roorkee 247667, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 34, No 3 (1989), Pagination: 263-276
Abstract
The Pavagarh Hill is made up of a lava suite comprising seventeen horizontal flows. Its geochemical variation provides compelling evidence that there exists genetic relationship among the various flows and hence it offers an interesting case study for crystal fractionation process. In this paper, least squares modelling, using the massbalance relation has been carried out, to determine the most probable phases and their amounts that must be extracted from or added to a flow to obtain the composition of the next younger flow. The stability of the model was tested by performing singular value analysis. The outcome of this modelling supports the hypothesis that the whole series is a result of crystal fractionation in two episodes with first and eleventh flow serving as the parent magma for the two sub-series. However, minor amount of magma mixing was needed to explain the evolution of lower series. Further, on the basis of the estimated phase proportions, that need be subtracted or added, the trace element abundances in derivative magma are computed, using Rayleigh fractionation law, and are found to be comparable with the observed values.
