The Petrological study of Clay deposits belonging to the lower
Cretaceous in the northern part of South Palmyra Folding Zone.
Showed they were formed as a result of weathering processes of
igneous rocks within Sedimentary continental climate is ho
t and wet
conditions, and formed lateritic iron soil, followed by enrich,
erosion and washing caused by watery agitate and re-replaced for
short distances within valleys or grooves or local karst cavities, and
later filled by crust erosion materials through the Cretaceous Sea
transgression.
Shiranish formation in Sazaba Oil fields region had been divided by
Petrology study and well Logs measurements to three major members (lower –
middle – upper). Then these members have been divided to lithostratigraphic
units and subunits. This stu
dy showed that the lower member is formed of
clayey - limestone rocks rich in planktonic foraminifera and glaconitic sand.
The middle member consists of organic limestone facies, dolomitic-limestone,
sometimes clayey - limestone rocks with crystals of pyrite and glaconitic sand.
Organic- limestone rocks and detrital limestone are predominant in the upper
member interbeded by dolomitic-limestone and rare clayey – limestone. This
facies contains pelagic and planktonic foraminifera.
The role of diagenes phenomenon is evident on Shiranish’s facies through:
dolomitization according to burial and miksing processes. It is also clear
through chemical compaction, mechanical compaction, cemenation,
micretisation and silisification.