Geochemical Relations in Cores from Nile Delta, Egypt

Frederic R. Siegel, Christopher D. Gerber, Neeraj Gupta, Daniel J. Stanley

The < 2-µm size fraction of 124 samples from seven eastern Nile delta cores were analyzed for 30 metals. These include elements that may react to physiochemical conditions of depositional environments and be useful as geochemical markers. Means and standard deviations of several of these are given.

Strong correlations were found for Ca-Sr, which suggests a biogenic influence on the population, and between the elements Fe, Cr, Ni, and Co, which suggests either a primary association or a similar response of related elements to depositional conditions. Statistical analysis showed that a cluster with Fe-Ni-Co-Cr at least one standard deviation below the mean and Cu above the mean marked the bottom of a transition from delta front into marsh and the top of a transition from swamp into delta front. Sediment representing the main marsh environment is characterized by a cluster with above-mean values for Fe-Cr-Ni and below-mean values for Co-Cu. Factor analysis indicated 8 of 17 factors explained 84% of the total variation. The dominant factor was Fe-Ni-Co-Cr-Cu-Mn which accounted for 2 % of the total variation. Boron had significantly different mean values for three defined environments, probably reflecting salinity differences. Multielement analyses can be useful in aiding facies definition in eastern Nile delta cores.

AAPG Search and Discovery Article #91030©1988 AAPG Annual Convention, Houston, Texas, 20-23 March 1988.