Study of Joints in Baba Dome - NE Iraq

The present work involves detailed study for joints in Baba dome within the foreland fold belt of north Iraq. It aims to identification and classification of various joint sets and systems, extraction predominant directions of joint sets and systems and estimation stress direction in the study area. The study includes only Injana (Miocene) and Mukdadiya (Pliocene) formations. The field work has been executed by means of nine traverses, each of them includes mainly two stations, as a result, 719 measurements of joint planes were extracted. The study comprises several categories: carefully scanning the joint plane for any shear movement, measuring the attitude, classification of joints according to tectonic axes a, b and c, determining the predominant direction, calculation of causative stress, estimation the structural history of Baba Dome .The types of joint which distinguished are (ab, bc, ac, hko system acute about a, hko set acute about b, hol system acute about a and hkl set).All measured joints have no visible shear displacement on their planes. The hko system and hol system appeared as single set and as conjugate system. The predominant direction of the joints is determined to be nearly along the strike of exposed beds. The mean causative stress direction is calculated to be: 046° from hko system and 315° from hol system. Trend of measured joints ( ab = 315° , ac = 045° , bc = 315° , hko1 a = 058° , hko2 a = 033° , hko3 b = 336° , hol1 a = 316° , hol2 a = 312° and hkl = 257° ). An attempt to put the measured joints in order according to timing sequence and from older to younger: hko system acute about a ac set, hol system acute about a and hko system acute about b bc set.