Karst Investigation and Analysis in An Nuayriyah Area, Kingdom of Saudi Arabia

SGS-TR-2009-6 Yaser Zabrmawi, Hussam Khiyami, Ahmed M. Youssef, Abdullah Sabtan, Saad Al-Harthi, Abdullah Memesh, Adel Al-Sharef, and Khaled Al-Ahmadi
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ABSTRACT


Different types of sinkholes have been recognized in the Kingdom of Saudi Arabia. The sinkholes are of various sizes, shapes and occur at different depths. Their presence may create direct risk to the infrastructural facilities such as urban areas, roads, future development areas, and farmlands. Other types of sinkholes appear barren unhabitated areas.  In the last few decades more than eight sinkholes have collapsed to the west of the Al Khafji and An Nu’ayriyah areas (northern eastern side of the Kingdom). Six of them are located in Al Khafji (along the border with Kuwait) and two are in An Nu’ayriyah, about 50 km west of the Saudi–Kuwait border. This research concentrated on An Nu’ayriyah and the surrounding areas and covers an area of about 16,471 km2. The region is composed of Dammam limestone (Eocene) at the base overlain by Hadrukh limestone, calcareous sandstone, and sandstone (Miocene) and at the top is the Dibdibba Formation (Pleistocene).  The essence of this research is to study the subsurface features and extent of the existing sinkholes, relate the ground surface features to any hidden old sinkholes and to classify the hazardous zones in the area using GIS techniques.  It was found that the deep lithological and geological characteristics of the area indicate that the western part of the study area is underlain by the upper Hadrukh Formation, which consists mainly of freshwater limestone and calcareous sandstone. Its upper surface is characterized by clear ring structures of various sizes that are aligned along a NE direction. The eastern part is underlain by weak feldspathic sandstone of the lower Hadrukh Formation. Although Dammam limestone is not exposed in the area it is encountered in the boreholes located in the eastern part beneath a thin cover of the lower Hadrukh Formation. Both the Miocene fresh-water Hadrukh limestone and the Eocene marine Dammam dolomitised limestone have karst features due to uplift and erosion during the Pliocene and Oligocene respectively. The ground surface (including the old depressions) are formed by the combined effect of a major syncline (in NS direction), and several anticlines and faults. The local structure participated in the creation of the existing sinkholes at the top (or close to) of the anticline axial plane and they are aligned along two directions, NS and EW. The sinkholes are of two types; cover-collapse that are filled by recent sediments, and rejuvenated old cover-collapse. The formation of the recent sinkholes is due to two factors; 1) the rock types and the distinct structure, 2) the agricultural activities. The ring structures were   indicated by the geophysical exploration to be karst phenomena, having complex collapse features that are cemented by fine impermeable material.  The proposed model indicates that most of sinkhole in the study area was formed because of piping of the lower Hadrukh sediments into a solution cavity in the Dammam Formation due to the huge expansion of land use.

 

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Zabrmawi, Y., Khiyami, H., Youssef, A.M., Sabtan, A., Al-Harthi, S., Memesh, A., Al-Sharef, A., and Al-Ahmadi, K., 2010, Karst investigation and analysis in An Nuayriyah area, Kingdom of Saudi Arabia: Saudi Geological Survey Technical Report SGS-TR-2009-6, 56 p., 80 figs., 4 tables