SEDIMENTATION AND FACIES ANALYSIS OF VOLCANICLASTICUNIT 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.