ausblenden:
Schlagwörter:
deep sand deposition, source to sink systems, the Levant Basin, the Nile Delta, wavelength
analysis
Zusammenfassung:
Sand transport and its deposition in deep marine basins are controlled by diverse
climatic, tectonic, physiographic and oceanographic processes. Disentangling
the impact of each of these drivers on the sedimentary record is a fundamen-
tal challenge in the study of source to sink systems. In this study, we investi-
gate seismic and borehole data by combining statistical and spectral analyses to
identify the factors controlling sand deposition in the deep Levant Basin (Eastern
Mediterranean) during the Pliocene–Quaternary (PQ). We interpret the sand
content in boreholes from gamma ray (GR) logs and identify two major trends in
sand/shale ratios. On a million-year scale, we demonstrate that since the Early
Pliocene (5.3 Ma), sand content gradually increased until it formed a ca. 100 m
thick and widespread sheet of sand at the top of the section. On a shorter time
scale, we identify oscillations in sand content depicting significant power of pe-
riodic components at the 350–450 ky, 90–150 ky and 10s ky bands. The long-term
increase in sand content reaching the deep Levant Basin is interpreted as a result
of the Nile Delta propagation, which had continuously shortened the distance
between the edge of the Nile delta that is the source of sand, and the deep Levant
Basin. The superimposed short-term oscillations are interpreted as Milanković
cycles, reflecting hydroclimatic oscillations of water and sediment discharge into
the Eastern Mediterranean Sea by the Nile River. This demonstrates the hydrocli-
matic control on sand deposition in the deep Levant Basin. Our observations are
consistent with the development of a submarine channel system along with the
accretion of the Nile delta, which may have served as a pathway for sand delivery
via high-energy turbidity currents that reached the Levant Basin.
