Petrogenesis of the alkaline basalts, west Shalatein, Egypt: Evidence from clinopyroxene chemistry

Abdel Abdel-Karim, G. Dobosi

Research output: Contribution to journalArticle

Abstract

The Paleogene volcanic and subvolcanic alkaline basalt rocks of the west Shalatein comprise mainly Olivine-rich and olivine dolerite and/or basalt and normal basalt. The pyroxenes of the ultrabasic and basic rocks follow the augite-diopside-hedenbergite fractionation trend which is significant for the undersaturated rock suites with low silica activity. The studied basalts are characterized by the presence of very peculiar zoned clinopyroxenes of megacrysts and groundmass grains. This pyroxene exhibit a clear decrease of Si, Mg, Ca and Cr from cores to rims. The Ti and Al content increases in pyroxenes with crystallization, but the coprecipitation of other Ti- and Al-bearing phases deplete the pyroxenes of outer rims as well as the groundmass in these elements in the later stage of fractionation. The incorportion of both Ti and Al into the pyroxene lattice is indicative of non-equilibrium crytallization (e.g. sector zoning). The clinopyroxenes exhibit a trend of fractionation analogous to that of the non-orogenic, intraplate-type basalts from undersaturated alkaline suites. Cr-bearing cores of clinopyroxene reveal that the present basalt were derived from deep-seated mantle source magma under early high pressure and low fO2 conditions.

Original languageEnglish
Pages (from-to)33-43
Number of pages11
JournalArab Gulf Journal of Scientific Research
Volume20
Issue number1
Publication statusPublished - Mar 2002

Fingerprint

basalt
petrogenesis
Egypt
clinopyroxene
chemistry
fractionation
rocks
pyroxene
olivine
rock
hedenbergite
coprecipitation
zoning
augite
diopside
crystallization
diabase
mantle source
silica
Paleogene

Keywords

  • Basalts
  • Chemistry
  • Clinopyroxene
  • Egypt
  • Pertogenesis
  • West Shalatein

ASJC Scopus subject areas

  • Aquatic Science
  • Plant Science
  • Ecology

Cite this

Petrogenesis of the alkaline basalts, west Shalatein, Egypt : Evidence from clinopyroxene chemistry. / Abdel-Karim, Abdel; Dobosi, G.

In: Arab Gulf Journal of Scientific Research, Vol. 20, No. 1, 03.2002, p. 33-43.

Research output: Contribution to journalArticle

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