Development of dolomite crystals during diagenesis in the lower Jurassic deposits in the AL-Querdaha sheet.

Abstract

This study was carried out in the northern part of the Qardaha area (Shatha village), located in the middle of the coastal chain in northwestern Syria, to determining the diagenetic stages in which the dolomitization occurred, in addition to the depth and temperatures of the diagenetic environments in which dolomite crystals were formed, given the importance of the dolomitization. And its role in understanding Diagenetic history in the area. stratigraphic sections were raised of the Lower Jurassic deposits there, 20 rock samples were collected from these deposits. And prepared to study them under a polarizing microscope, to determine their petrographic composition and morphology of dolomite crystals. The study showed the presence of several types of dolomite crystals formed at different diagenetic depths. The first type (I) is dolomicrite with a planar texture and subhedral crystals. The second type (II) is fine-crystalline dolomite with non-planar texture. The third type (III) is cemente dolomite with non-planar texture, the fourth type (IV) is composed rhombic flats of dolomite crystal, which include the tectonic uplift processes to which the area was exposed. The study also showed the presence of two types of stylolite formed as a result of compression of sediments during diagenesis: the first type is impermeable (closed). It separates dolomicrite from fine-crystalline dolomite. The second type is open and leads to the restriction of diagenetic reactions and the formation of cemented dolomite and micrite clay. It also revealed the presence of microscopic faults that affected the stylolite and led to an increase in the size of the dolomite crystals.