Characteristics of lava-sediments interactions during emplacement of mid-Tertiary volcanism, Northeastern Desert, Egypt: field geology and geochemistry approach

El Desoky, Hatem M.; Shahin, Taher M. ✉

Angol nyelvű Tudományos Szakcikk (Folyóiratcikk)
Megjelent: ARABIAN JOURNAL OF GEOSCIENCES 1866-7511 1866-7538 13 (9) Paper: 328 , 15 p. 2020
  • SJR Scopus - Earth and Planetary Sciences (miscellaneous): Q2
    Mid-Tertiary volcanism in the Northeastern Desert of Egypt was associated with the African-Arabian plate rifting and opening of the Red Sea, a period of 30 Ma (Late Oligocene). The resulted lava flows, predominately basaltic sheets, have mingled with the underlying sediments, forming peperite along the contact between them. Field geology, petrography, and geochemistry methods have been used to identify the behavior of the lava-sediment interaction which produced peperite. Two types of peperite have been recognized, fluidal at Naqb Ghul and El-Yahmum areas, and blocky at El-Qattamiya area. Sometimes, the two types are represented together at the El-Qattamiya area. Fluidal peperite is characterized by globular and equant juvenile clasts and with irregular or ragged margins suggesting low viscosity, ductile fragmentation, and sediment fluidization. Blocky peperites are characterized by angular, polyhedral, platy juvenile clasts and a jigsaw-crack texture, resulted from quenching of magma in a brittle regime. The coexistence of fluidal and blocky clasts together reflects progressive disintegration and suggests decreasing temperature and increasing viscosity during fragmentation. The presence of sediments in vesicles and in fractures in the peperite zone indicates a non-explosive phase of interaction. Geochemical data suggests that different composition across the magma/sediment boundary is a result of silicification and sediment fluidization.
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    2021-05-13 12:15