Stylolite Structures and Faults in the Bandwaya Area at the Western Plunge of the Alqosh Anticline in Northern Iraq
The current study is conducted on the stylolite structures and faults appearing in the Bandwaya resort, where the overlapping area of Alqosh and Dehqan anticlines occurred. Two locations are selected for investigation: one at Injana Formation, and the other at the contact zone between Fatha and Pilaspi formations. This is due to the abundance of tectonic stylolite especially at the contact zone between Fatha and Pilaspi formations. The stylolites are associated with minor faults represented by slicken lines. The occurrence of both structures is linked to the presence of the basal sinistral strike-slip fault that affected the area as seen in satellite images. (ẟ1) direction refers to (N-S), (NE-SW) and (NW-SE) and little stylolite were formed by vertical stresses. It has been also noted that the two structures appear independently in some layers, as there are layers containing only stylolite, and others containing only sheet of slicken lines. This has prompted the author to investigate the reasons behind their occurrences by studying the mechanical relationship between layers containing only stylolite and others of only slicken lines by measuring the Schmidt rebound of each of these layers. Also, by studying the mineral components and extracting the ratio of insoluble components versus carbonate mineral (acid dissolution method). The study shows a relationship between the mechanical and brittle deformation behavior with insoluble contents and carbonate content in the layers containing only slicken lines and others having only stylolite, where the rock layers containing only stylolite exhibit lower Schmidt rebound and contain slightly higher insoluble residue than the layers containing only slicken lines, which contain lower percentage of dissolved residue and give higher Schmidt rebound.
