ANATOMY OF CARBONATE BRECCIAS, TURBIDITE FACIES AND DEPOSITIONAL SYSTEMS OF GERCUS FORMATION IN DOKAN AREA, NORTHERN IRAQ

Abstract

Four facies associations are classified based on facies types, sedimentary structures and facies successions, these are; distal slope apron siliciclasticcalciturbidites (siliciclastic/ carbonate dominated), proximal marine siliciclasticcalciturbidites (carbonate/ siliciclastic dominated), distal basinal fan siliciclastic turbidites (siliciclastic dominated) and proximal basinal fan siliciclasticcalciturbidites (carbonate/ siliciclastic dominated). The most important characteristic representative facies types are; ball and pillows dolomite (reported here for the first time), thick fissile shale, slump/ slide limestone, slump/ slide sandstone, channeled sandstone, ball and pillow sandstone, slump sandstone, convolute sandstone, crossbedded sandstone, sigmoidal channeled sandstone, disturbed sandstones, red argillaceous mudstone, gray massive claystone, flute scoured sandstone with slump carbonate breccias types. The carbonate breccias are the most important characteristic facies types observed in the formation and reported here for the first time and it is strong indication for marine environment. Examinations and anatomy of facies types and associations suggest developed marine environment, effected mainly by gravity flows and turbidity currents, forming sequences of submarine fans including high density turbidity currents in deeper margins.