Abstract

Detailed petrographic, geochemical and strontium isotope studies, combined with
field observation and rnicrofacies investigations indicate that syngenetic celestite at
the base of Asmari Formation at the Bangestan anticline, Behbahan region, was
deposited directly from Tertiary seawater in an intrasupratidal to supratidal
environment. During diagenesis, the precipitated celestite underwent several textural
and mineralogical modifications, the most important of which was the formation of
diagenetic crystallization rhythmites. Fluid inclusion geotherrnometry and rmR
analyses suggest that the fluid medium, in which recrystallization of the celestite took
place, was among other constituents rich in immature hydrocarbons. It is demonstrated that the celestite concretions were subjected to several low temperature thermal events, the maximum of which did not exceed 255?C