Quaternary alluvial deposits of Wadi Gaza in the middle of the Gaza Strip (Palestine): Facies, granulometric characteristics, and their paleoflow direction

Abstract

The Quaternary rocks of the Gaza Strip mainly consist of clastic sedimentary rocks. In Wadi Gaza, the outcropping rocks consist of brownish fine-grained deposits, sandstones, and conglomerates. The deposits have been studied from a genetic point of view, and six facies have been described: (i) graded clast-supported conglomerates, (ii) cross-bedded clast-supported conglomerates, (iii) sandy matrix conglomerates, (iv) cross-laminated medium-grained sandstones, (v) graded coarse-grained sandstones, and (vi) massive sandstones. The field work observations and granulometric analysis show that the sphericity of the grains increase toward the west, where its value ranges from ∼0.64 in the east to ∼0.70 in the west. In addition, the grain forms tend to be disc shape in the east, whereas they tend to be disc-to spheroid shape in the west, and they become well rounded to well sorted toward the west. Moreover, the features, geometry, and spatial relationship among these facies suggest that the Wadi Gaza was meandering wadi fed from Beir Sheva and the Northern Negev in the southeast of Gaza Strip through Wadi Al Shallala and Wadi Sheneq and from Hebron mountains in the West Bank at the east through Wadi Al Shari'a alluvials. Within the Gaza Strip, paleocurrent data ranges from 210° to 310°, indicating a mean a paleoflow direction to the W (276°) and a median value about 275°. The sedimentary rocks in the Wadi Gaza are considered to be deposited in two periods of climate conditions: the coarse-grained rocks were deposited during the period of wet condition before 12.4 ka age, whereas the eolinite fine-grained rocks were deposited during semiarid climate conditions which are younger in age than 12.4 ka.