PETROLOGY OF THE INJANA FORMATION (UPPER MIOCENE)AT ZAWITA, AMADIYA AND ZAKHO AREA, NORTHERN IRAQ

Abstract

This study deals with the petrology of Injana Formation (Upper Miocene) at
Zawita, Amadia and Zakho areas. The sandstone of Injana Formation is of two
typesnamely, litharenite and feldspathiclitharenite. The rock fragments of Injana
Formation are mostly sedimentary and hence the sandstones are classified as
sedarenite and more specifically chertarenite owing to the predominance of chert
rock fragments. The sandstone is mineralogicallysubmature rangingfrom
mechanically and chemically stable tounstable. The petrographic studies reveal
nearness of source area with arid to semi-arid climate. The source rocks are
sedimentary, low- to medium-grade metamorphic and basic volcanic rocks. They are
mostly supplied from the rising mountain farther north and east (Taurus and Zagros
Ranges) during the Alpine Orogeny induced by the continent-continent collision
between Arabia and Eurasia.The mudstone consists of mixture of clay and silt with
variable percentages. The major clay minerals are chlorite, kaolinite and mixed-layer
illite-smectite. The non-clay minerals are calcite, quartz and subordinate feldspars.