SEDIMENTATION AND FACIES ANALYSIS OF VOLCANICLASTIC UNIT WITHIN MAQDADIA FORMATION,INJANA AREA, SOUTHERN HEMRIN, NE IRAQ

Abstract

Field observations revealed the occurrence of volcaniclstic units (pyroclastic units) within the Muqdadyia Formation (Pliocene) in Injana area, southern Hemrin anticline; these rock-units located along Tayawi, Magrin and Zarloukh sections and has been called as a volcaniclastic unit of Muqdadyia Formation.the facies analysis for the volcaniclastic units is part of succession which was deposited in a fluvio-laucustrine environment. This succession is divided into eight facies on the basis of deposition and transportion settings into:- 1-Primary tuff rock (non-reworking), this represent the surge facies (A1) and fallout facies (¬A2) which deposited in a quiet environment (lake or marsh) near Zarloukh area; 2-Secondary tuff rock these represent the sandy tuffstone (B1), mudy tuffstone (B2) and clayey tuffstone (B3) which deposited in meander active channel environment during high concentration supply. And tuffaceous sand (C1), tuffaceous mudstone (C2) and tuffaceous claystone (C3) which were deposited in the same environment but during low concentration volcaniclasts supply. Accordingly, the rock unit deposited by two stages of the supplying in volcaniclasts during three deposition cycles.