Microfacies Analysis and its Implications for Depositional Environment of Margala Hill Limestone from Khaira Gali Road Section, North Eastern Hazara, Pakistan

Stratigraphic section of Margala Hill Limestone exposed in the Khaira Gali road section of the Hazara Basin has been measured, logged and sampled. The 96m thick section of Margala Hill limestone mainly consists of medium to thick bedded nodular limestone with intercalations of shale. The petrographic studies of formation show mainly wackstone to packstone carbonate texture with different assemblages of Larger Benthonic Foraminifera, e.g. (Assilina spinosa, Nummulites globulus, Ranikothalia sindensis, Nummulites mamillatus, Assilina subspinosa, Nummulites atacicus, Assilina granulosa, Operculina patalensis, Assilina laminosa, Ranikothalia nuttalli, Lockhartia conditi, Ranikothalia sahni, Lockhartia tipperi, Discocyclina dispansa, Discocyclina ranikotensis and Quinqueloculina), Bivalve and green algae. Five microfacies types have been interpreted on the basis of carbonate texture and skeletal grains present. These microfacies include Rotaliids-milliolids mud-wackstone, Algal- bioclastic packstone, Nummulitic wack-packstone, Assilinids wack-packstone and Discocyclina- Ranikothalia wackpackstone microfacies. On the basis of microfacies analysis, inner to mid shelf environment has been deduced. Occurrence of age diagnostic foraminiferal assemblage suggest the Early Eocene age for the Margala Hill Limestone.