SITE SELECTION PROBLEMS IN GYPSUM-BEARING FORMATIONS. A CASE STUDY FROM NORTH OF IRAQ

Abstract

Gypsum is a well known problematic rock for engineering constructions. The Fatha Formation (Middle Miocene) is a widely spread formation in Iraq. One of its main lithological constituents is gypsum, beside marl and limestone, which occur in cyclic repetition within the formation. Due to high dissolving ability of the gypsum by water, different karst features are developed within the formation. These features, especially when are below surface, may cause severe damages to the constructions which are built on them. Detailed geological mapping of a site, north of Iraq, revealed many surface indications for detecting subsurface karst features that have caused true problems during excavation of the site.