Petrographic effects

Alexandersson, E.T., 1976. Actual and anticipated petrographic effects of carbonate undersaturation in shallow sea water. Nature, 262 653—657. 

Seam correlations, measurements of rank and geologic history, interpretation of petroleum (qv) formation with coal deposits, prediction of coke properties, and detection of coal oxidation can be deterrnined from petrographic analysis. Constituents of seams can be observed over considerable distances, permitting the correlation of seam profiles in coal basins. Measurements of vitrinite reflectance within a seam permit mapping of variations in thermal and tectonic histories. Figure 2 indicates the relationship of vitrinite reflectance to maximum temperatures and effective heating time in the seam (11,15). 

The chemical and petrographic properties of the twenty coals used in the hydrogenation experiments are shown in Tables II and III. Mineral matter was determined directly using a radio frequency low temperature plasma asher at medium power rating for approximately 48 h per coal. The volatile matter was corrected for the effects of the mineral matter by applying the equation used by Given et al (5). 

Clarke, L. Storch, H.H., "Hydrogenation and Liquefaction of Coal, Part 2 - Effect of Petrographic Composition and Rank of Coal", Technical Paper 642, US Bureau of Mines, 1942. 

The effectiveness of these parameters is considered to depend heavily on the liquefaction conditions and the characteristics of the coal which is used. The better parameters can possibly be derived from both the amounts of the petrographic components %9 such as inerts ingredients %9 or reactive macerals % and their quality, such as H/C atomic ratio and so on. Consequently, it must be said that much further study is necessary to finally clarify the more comprehensive parameter. 

When unit B-3b is missing, beds 3 and 4 cannot be recognized solely by quantitative petrography. Here, supplementary geological information is required to effect sensible correlations. Although total bed data yield results which indicate petrographic continuity, layer-by-layer studies indicate that... 

L. L. Newman Dr. Mackowsky has already asked you if you related your studies on the kinetics of volatile matter release from Pennsylvania anthracites to the petrographic constituents of the coal. Can you not say in effect that the coals from the various collieries differ from each other quite significantly with respect to their petrographic composition and that identification of a coal by source may identify it petrographically to some extent How do the results of these studies relate decrepitation actually experienced in industrial operations ... 

The advantage of the method is its speed, both in the measurement itself and also conveision and documentation of results. Another favourable aspect is the possibility of keeping samples with the effects of measurement preserved for future reference. The great variety of parameters that can be estimated indirectly via dynamic abrasion resistance measurement validates this method for wide use in various industries and in petrographic laboratories. 

Rollins, M. S., Cohen, A. D., and Durig, J. R. (1993). Effects of fires on the chemical and petrographic composition of peat in the Snuggedy Swamp, South Carolina. Int. J. Coal Geol. 22,101-117. 

Quantitative FTIR data were combined with chemical and petrographic data for the 24 vitrinite concentrates and subjected to bivariate and multivariate statistical analyses in order to identify the effects of coal ification on the aliphatic and aromatic functional groups. 

This paper reports an investigation of the effects of porous solid structures on their electrical behaviour at different frequencies (from 100 Hz to 100 kHz). For that, we study different parameters such as formation resistivity factor, cementation factor, chargeability, resistivity index and saturation exponent. Different porous solid structures are quantified from the petrographic image analysis and Hg-injection technique. Then, by using different models we obtain the permeability prediction from the electrical behaviour and structure parameters. 

Application of this approach to a Precambrian (1,000 Ma) paleosol from Scotland (Figure 3) showed the expected decrease of hydrolytic weathering down from the surface, and an overall degree of hydrolytic alteration that is modest compared with deeply weathered modern soils (Figure 4). Effects of hydrolysis of this Precambrian paleosol can also be seen in petrographic thin sections and electron microprobe analyses, which document conversion of feldspar into clay (Retallack and Mindszenty, 1994). 

Annual variations in trace elements are now known to be a normal feature of caves in shallow karst environments (Roberts et al., 1998 Fairchild et al., 2001 Finch et al., 2001 Huang et al., 2001 Fairchild, 2002) and subannual variations can also be observed where speleothems grow sufficiently quickly. These variations can be related mainly either to changes in the ion ratios in solution in relation to hydrological effects, or to seasonal changes in supersaturation of karst waters, that is the same two controls that are responsible for petrographic laminae. In section 7.6.2, such variations are related to potential controlling factors. 

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