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Abstract: Magnetostratigraphic Correlation and Dating of the Early to Middle Miocene Stratigraphy Within the Suez Rift

Peter A. Bentham, William A. Wescott, William N. Krebs, Steven P. Lund

As part of an extensive regional study of the Gulf of Suez synrift stratigraphy, a paleomagnetic analysis of early to middle Miocene sediments was undertaken to establish the suitability of the stratigraphic sequence for magnetostratigraphic correlation. During an initial field program, multiple hand-oriented samples were collected at key stratigraphic localities along the western Sinai Peninsula within the onshore rift sequence. All important clastic lithofacies were sampled for test analysis, although finer-grained lithologies were preferentially collected due to their usually lower susceptibility to remagnetization. Initial rock magnetic studies indicate that although they are weakly magnetized, the samples do preserve a primary paleomagnetic signature. Thermal and alternating-field demagnetization studies suggest that detrital titano-magnetite is the likely primary magnetic carrier. Results suggest that a stable remnant magnetization can be accurately measured if we use low-temperature thermal demagnetization to remove a pervasive normal-polarity overprint. Detailed stratigraphic sampling was performed during a subsequent field program and a total of 138 oriented samples were collected from eight stratigraphic sections. Two long sections were measured and sampled to establish a local standard stratigraphy and the other shorter sections were correlated with these reference sequences.

Multidisiplinary biostratigraphic studies have shown the importance of regionally-extensive unconformities with in the Miocene section of the Suez Rift. Such erosion and/or omission surfaces severely inhibit the use of magnetostratigraphy as an absolute age-dating method as the tool demands continuous sedimentary sequences be sampled, or that breaks in sedimentation be known. However, the technique can be used as an additional correlation tool within paleontologically-defined, time-equivalent stratigraphic packages. Results indicate that the integration of the two different data sets yields significantly better correlative resolution than applying biostratigraphy alone.

AAPG Search and Discovery Article #90956©1995 AAPG International Convention and Exposition Meeting, Nice, France