THE HAMADYA BOMB-RICH AGGLOMERATE - A CASE-STUDY OF EXPLOSIVE PLIOSENE VOLCANISM IN THE JORDAN VALLEY, ISRAEL

A pyroclastic deposit rich in basaltic bombs, lapilli and scoria is ex posed near Hamadya along the western margin of the Jordan Rift Valley, Israel. The deposit is a basaltic agglomerate interlayered with basal t flows of Pliocene age. The agglomerate consists of bombs (some of th em 50-70 cm in length), juvenile fragments of lapilli-sized scoriaceou s porphyritic basalt and scoria weakly cemented by basaltic ash and sa nd. Fumarolic features are present in the area. The bombs are commonly unipolar, rotational, cylindrical, or cylindrical to spindle-shaped. The abundance of bombs and lapilli within the agglomerate suggests a n earby vent. From the size and abundance of the bombs, and the geomorph ology of the area, the eruption centre is assumed to be a few hundred metres east of the northern agglomerate exposure. The Hamadya basaltic agglomerate may be indicative of an explosive pulse separating two ef fusive phases of Pliocene volcanism. (C) 1997 Elsevier Science Limited .