. The change of the ratio of feldspar to clay minerals is reflected in the CIA values. CIA increases
from 57.2 (CIA values of feldspar and biotite = 50) to 93.0 (CIA values of illite = 80 and kaolinite = 100). Obviously the highest degree
of alteration (in terms of CIA) is compatible with the sediments
having maximum kaolinite and less feldspar content. CIA values
correlate well (r= 0.58) with kaolinite content (Fig. 2); increasing
upwards with increase in kaolinite and decrease in feldspar