Presence-absence species/sample matrix for the measured sections at the area of Maghara, North Sinai, Egypt

As age-diagnostic fossils are rare in the Middle to Upper Jurassic sedimentary succession of Gebel Maghara, North Sinai, Egypt, and in order to ensure maximal stratigraphic resolution, chronostratigraphic boundaries were determined based on quantitative biostratigraphy. A data matrix comprising 231 macrofaunal taxa in 93 samples from four sections has been processed with the Unitary Association (UA) Method. This led to construction of a sequence of 29 UAs (maximal sets of actually or virtually coexisting taxa), which have been grouped into 14 laterally reproducible association zones. The UA method allowed an in-depth analysis of the stratigraphically conflicting taxa, enabled the biostratigraphic subdivision of the studied interval, and also provided stratigraphic correlation among the measured sections and with the Tethyan ammonite zones.

Geochemistry of basalts from Serocki Volcano

Basalts collected during drilling and diving programs on Serocki Volcano mostly fall within a limited compositional range, and are moderately evolved, normal MORBs with distinctive high MgO contents (averaging 7.60 wt%) and high A1203 concentrations (averaging 16.14 wt% in whole rock samples). However, samples recovered from within the central crater have lower Ti02 and FeO*/MgO, and higher MgO and Al2O3 concentrations, and are most similar to glasses recovered at Site 649 about 45 km to the north. Comparison of the observed geochemical variations with low-pressure experimental work and other samples from the region suggests that the Serocki Volcano and Site 649 data are compatible with crystal-liquid fractionation involving both olivine and early-stage clinopyroxene, as well as plagioclase, and that the sources may be similar even though Sites 648 and 649 are located in different, but adjacent, spreading cells. Consideration of the stratigraphy and morphology of Serocki Volcano suggests that this feature is more properly described as a megatumulus or lava delta, associated with a steeper, conical peak to the southwest. The evolution of Serocki Volcano involved early construction of a marginal rampart of pillows, followed by doming of this feature and the formation of a perched lava pond. Draining of this pond resulted in collapse and the formation of the central crater.