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Authors
Affiliations
1 Department of Geology, University of Delhi, Delhi-110 007, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 54, No 5 (1999), Pagination: 495-499
Abstract
The 'Kubler index' (Δ°2θ) has been extensively used to document degree of metamorphism in very low grade pelitic rocks and to mark the diagenetic-anchizonal and anchizonal-epizonal boundaries. However, variations in sample preparation procedures significantly affect the Δ°2θ measurements. The effect of variation in thickness (mg/cm2) of the clay layer on Δ°2θ measurements has been studied here. The Δ°2θ values drops rapidly for slides with clay loading less than ∼2-3 mg/cm2 and achieve more or less a plateau beyond this thickness. Owing to the rapid change in slope, even minor variation in thickness (which is difficult to constrain) can significantly affect the Δ°2θ measurements. Low X-ray intensities recorded for thin slides also add uncertainty to the Δ°2θ measurements.
Keywords
Mineral Physics, Illite Crystallinity, Kubler Index, Himalaya.
