The Oligo-Miocene deepwater system of the Levant Basin

- 27 -borehole to an unconformity at the top of the upper Miocene Ziqim Formation (at 687 m belowMSL) (Fleischer and Varshavsky, 2002).Throughout the elevated margin of the basin, the Tertiary unconformities were interpreted asonlapping surfaces, where either none or only minor incision is observed. An example is shown in aseismic profile near the Yam Yafo-1 borehole where high-amplitude reflections onlap the red, cyanand purple horizons (Fig. 9). In the Yam Yafo-1 borehole the onlapping surfaces are correlatedrespectively to the base Oligocene unconformity (base of Bet Guvrin Formation at 1,774 m belowMSL), lower Middle Miocene unconformity (top of Bet Guvrin Formation at 1,694 m below MSL)and Late Miocene unconformity (top of Ziqim Formation at 1,557 m below MSL) (Druckman et al.,1994).It is assumed that onlapping and truncation are both related to the same sedimentary process, e.g.the flow of submarine turbidites into the basin. While in some areas these gravity flows resultedwith erosion of the sea floor, in others they were associated with accumulation and filling ofsubmarine relief in structural lows.The seismic profile in Figure 9 shows that the onlapping reflections filled a syncline found west ofthe Yam Yafo fold. The syncline already existed during the Oligocene, as indicated by theonlapping of reflections on the red horizon. A second phase of folding resulted with furthercontraction of the structure (note the curvature of the onlapping reflection on the red horizon),followed by onlapping on the Middle Miocene cyan horizon (Fig. 9). These two phases ofcontraction termed by Gardosh and Druckman (2006) Syrian Arc I and II characterized the SyrianArc folding activity throughout the Levant area (Walley, 1998).It should be noted that the correlation of the Tertiary unconformity surfaces in the seismic profileswere based solely on the onlapping criteria; in areas with no well control it is somewhatproblematic. It is possible that truncation and incision events that are associated with relative sealevelfalls are not contemporaneous with the contractional phases that resulted with the formation ofstructural lows and their filling by gravity flows. In our view, however, on the Levant margin bothrelative sea-level falls and folding are related to the contraction and uplifting associated with theSyrian Arc deformation. Therefore, the application of the two different criteria (truncation andonlapping in structural lows) is justified.