Dolomite cement poikilotopic

The poikilotopic dolomite cement occurs in irregular patches (Fig. 10A) and locally completely cements the rock (Fig. lOB). The cement is common... 

Stable isotope analysis of intergranular, vein-fill and poikilotopic dolomite cements produced very similar results (Fig. 12). Overall, dolomite 5 0 values fall between -3.8 and -0.9%o pdb and 5 C values between -4.2 and -9.5%o pdb. The bulk of the data display a crude positive covariance, albeit with several outlying points. However, no consistent trends were detected across individual cemented fractures. Three samples of ferroan dolomite pseudomorphing gastropods in the overlying... 

In addition to dissolution, the destabilization of carbonate cements may result in recrystallization and replacement by other carbonates. Microcrystalline calcite and dolomite are sensitive to recrystallization at various burial depths. The recrystallization of dolomite has been reviewed by Mazzullo (1992). Burial recrystallization of micritic/microsparitic cements in sandstones may result in the formation of poikilotopic calcite (Saigal Bjorlykke, 1987). However, poikilotopic calcite is also a common primary cement in calcretes (e.g. Knox, 1977 Tan-don Narayan, 1981). Recrystallized calcite and dolomite are recognized as patchily distributed, coarsened crystals. In contrast, precipitational vari-... 

Dolomite/ankerite D2 occurs as blocky to poikilotopic, irregularly zoned rhombs (90-200 pm) which marginally replace and cover, and thus postdate, D1 (Fig. 7F). Samples cemented mainly by D2 show moderate packing, indicating a dominantly... 

---