GRAPHIC CORRELATION AND SEQUENCE STRATIGR APHY OF NEOGENE ROCKS IN THE GULF-OF-SUEZ

Graphic correlation of paleontological data from wells and outcrops in the Gulf of Suez reveals that the Neogene section consists of at leas t eight biostratigraphic sequences (S10-S80) separated by graphic terr aces (T00-T70) (geologic lacunae or hiatuses). Field analysis in the S inai of terraces T00 to T30 and their associated fossil assemblages in dicates that they represent widespread regressive or transgressive eve nts. The number of true stratigraphic sequences (those bounded by regr essive erosional surfaces) is therefore less than the number of paleon tological sequences revealed by graphic correlation. Terraces T00 and T20 are sequence boundaries sensu Vail, and geophysical and well log e vidence indicate that T40 is a condensed section and that T50 is an er osional unconformity or sequence boundary. Field observations of lacun a T10 at Wadi Thal in the Sinai region reveal that it consists of two ravinement surfaces and one condensed section in a narrow stratigraphi c interval. Similarly, the T30 lacuna associated with the Markha Anhyd rite at Wadi Feiran is composed of perhaps seven stacked flooding and regressive surfaces. These surfaces at both Wadi Thal and Wadi Feiran are probably associated with minor hiatuses. These minor hiatuses cann ot be individually resolved by graphic correlation, particularly when the paleontological database is derived from well cuttings, but their sum total within a thin rock (hiatal) interval is detectable as a terr ace. Despite this limitation, graphic correlation of paleontological d ata can recognize stratal surfaces and intervals that are critical to sequence stratigraphy. Fieldwork, rock core, well logs, and paleoenvir onmental analysis are necessary for their interpretation and integrati on into sequence stratigraphy.