Stable isotope of some selected Egyptian pectinids and their paleoenvironmental implications

► The calcitic pectinid shells can yield faithful records of their paleoenvironments. ► Their shell has high preservation potential and relatively immune to dissolution. ► δ 18O and δ 13C analysis of their shells is used to track the paleoenvironment. ► Scalerochronological profile of the shell reveals the seasonal changes. Eight pectinid shells were collected and subjected to quantitative study using δ 18O and δ 13C isotopic analysis in order to study the paleoenvironment which prevailed during their calcification. The scalerochronological variations in δ 18O and δ 13C values, among these shells are also discussed. The Early Miocene pectinid shells display highly depleted δ 18O and δ 13C signature as a result of paleo-meteoric water with heavy rainfall that was produced by Tropical Cyclones when the Mediterranean Sea was open. The Early Pliocene pectinid shells reveal depleted δ 18O values, related to the influx of fresh water influenced by monsoonal activity following the formation of the Tibetan Plateau. Their enrichment in the δ 13C isotopic excursion is referred to high productivity of the Indian Ocean, which was the main source of the Red Sea water. The Pleistocene pectinid shell shows highly depleted δ 18O and δ 13C signature with obvious diagenetic shell structure, indicating that a wetter humid climate prevailed during the Early–Middle Pleistocene and long sub-arial exposure of the shell. The Recent Mediterranean pectinid shell displays slight enrichment in δ 18O and δ 13C values referring to deeper inhabitation of this species with a low temperature and high salinity environment. The scalerochronological variations in both δ 18O and δ 13C values, along these shells is referred to seasonal variations or kinetic effects.