Changes

Folk (1974) is one of scientists that explains about the importance of Magnesium (Mg), water salinity, and diagenetic environment (vadose, phreatic, or subsurface) as mineralogical control and crystal that form cement. The chronology and micro stratigraphy of cement can be known from the morphology of thin layers of cement. “Cement stratigraphy” shows what happens during burial diagenesis ([[:File:UGM_Subsurface_Fig_1.png|Figure 1]]).

Folk (1974) is one of scientists that explains about the importance of Magnesium (Mg), water salinity, and diagenetic environment (vadose, phreatic, or subsurface) as mineralogical control and crystal that form cement. The chronology and micro stratigraphy of cement can be known from the morphology of thin layers of cement. “Cement stratigraphy” shows what happens during burial diagenesis ([[:File:UGM_Subsurface_Fig_1.png|Figure 1]]).

Because the result of burial and changed composition of water, mineralogy of cement and crystal are also changed. Changed composition of water during burial because of the migration to the mixture of water with in situ interstitial water which will go through various rocks-water reaction. Calcite, dolomite, and other minerals that form cement may be formed, depend on the composition of water and the equilibrium of every minerals. If calcite is formed, usually the shape is big.

Because the result of burial and changed composition of water, mineralogy of cement and crystal are also changed. Changed composition of water during burial because of the migration to the mixture of water with in situ interstitial water which will go through various rocks-water reaction. Calcite, [[dolomite]], and other minerals that form cement may be formed, depend on the composition of water and the equilibrium of every minerals. If calcite is formed, usually the shape is big.

Decreasing porosity from sementation can be identified by the cross-cutting relationship in “cement stratigraphy”. Isopachous cement with rim may be formed on early sementation in marine phreatic zone. Rougher cement may decrease more porosity. Residual effective porosity may be connected to poikilotopic cement that’s formed in deep burial environment. All cements may be crossed by joint that’s filled with mineral or burial-exotic deep cement. Exotic mineral cement and mineralized joints become the indicator of new permeability, followed by migration of mineralization fluid. Exotic fluid is generally associated with hydrocarbon migration and chances of forming new permeability is always as joint that’s formed after diagenesis process.

Decreasing porosity from sementation can be identified by the cross-cutting relationship in “cement stratigraphy”. Isopachous cement with rim may be formed on early sementation in marine phreatic zone. Rougher cement may decrease more porosity. Residual effective porosity may be connected to poikilotopic cement that’s formed in deep burial environment. All cements may be crossed by joint that’s filled with mineral or burial-exotic deep cement. Exotic mineral cement and mineralized joints become the indicator of new permeability, followed by migration of mineralization fluid. Exotic fluid is generally associated with hydrocarbon migration and chances of forming new permeability is always as joint that’s formed after diagenesis process.