PETROGRAPHIC AND CHEMICAL CHARACTERISTICS OF GLAUCONITIC AND PHOSPHATIC SEDIMENTS OF THE KUSSAK FORMATION, KHEWRA GORGE, SALT RANGE, PAKISTAN··
Keywords:
Glauconitic and phosphatic sediments, Kussak fornation, Khewra Gorge salt range.Abstract
The Kussak formation is a sequence of glauconitic sandstone, shales and dolomite. Quartz, feldspar, dolomite, glauconite,
apatite, illite, calcite, goethite, chlorite and montmorillonite were identified by XRD and microscopy. Quartz,
feldspar and dolomite are predominant. Glauconite occurs as medium to coarse rounded pellets. Goethite occurs mostly
as stain around grains. Apatite occurs as small pellets or as matrix. The green and rounded nature of the glauconitic
pellets with approx. 6% KzO and high percentage of major elements like Si, Al and Fe in most of the samples from
Khewra Gorge suggest marine authigenic origin for the glauconite. Field and laboratory data suggest that glauconitic
sandstones were deposited in deep and semiconfined conditions followed at the top by shallow sea conditions. The
phosphatization may succeed glauconitization in a normal evaluation of an epicontinental basin but low concentration
of PZ05 in the Kussak sediments was perhaps due to lack of organic compounds.
