Harrat Kishb

The 5,900 km3 Harrat Kishb volcanic field, located E of a N-S-trending line of volcanic fields in central Saudi Arabia, is comprised of basaltic scoria cones, tuff rings and maars, and phonolitic lava domes and flows. Most of it is of Pleistocene age; Holocene flows are restricted to three areas in the western half of the field. Jabal Aslaj cone and its associated lava flows contain abundant granitic blocks from basement rocks and ultramafic nodules. Jabal Hil is a large scoria cone with a 300-m-wide crater that was filled and overtopped by a lava lake. Among the several tuff rings and maars is the 800 x 600 m wide Al Wabah maar in the west-central portion of the field. The most recent products, including the scoria cones and lava flows of Jabal Aslaj and Jabal Hil and the Jabal Shalman lava-dome, lava-flow, and scoria-cone complex, are stratigraphically younger than a pluvial period dated about 6500-4000 years before present.