Structural Analysis of Joints Systems in Karbala and Al-Najaf Governorates, Central Iraq

(Ahmed Abbas Hasan Al-Moadhen)

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Abstract

The primary objective of studying the joints in this area is to understand the tectonic history of the Arabian Plate and to identify the direction of the region's major stresses. This research deals with structural analysis of joints systems existing in Injana Formation (Middle Miocene). In the study area, joints form two systems; each system contains two orthogonal sets of vertical joints, fissures, and veins. The general strike direction of the two sets of one system are NE–SW and NW–SE, while the general strike direction of the two sets of the second system are N10E and N85E. The outstanding similarity in strike orientations between joints sets in Tar Al-Sayed and joints sets in Tar Al-Najaf strongly suggest a common origin. Fractures have the same origin, and these fractures are interpreted as extension fractures, which are found parallel to the greatest principle stress (δ1).  From the geometry of fractures, it is possible to envisage the movement history of the Arabian Plate toward the northeast and toward the north. The greatest principle stress is oriented in two main directions: NE–SW and N–S, subsequently. The least principle stresses are oriented in NW–SE and E–W directions, respectively, while the intermediate principle stress is oriented perpendicular to the plane containing (δ1) and (δ3). The greatest stress (δ1) is in the N45E direction, and the least stress (δ3) is in the N45W direction.

KEYWORDS
Arabian plate, major stresses, tectonic history

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References

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