Coal Facies and Depositional Environment
In the preceding chapters coal components have been classified on the basis of physical, chemical and genetic relationships. In the following discussion these will be employed in a filtering process that is designed to detect the signatures left behind by depositional environments in the form of a distinctive coal facies. The concept of depositional environment will be targeted at two levels: one is specific and refers to the type of mire and the conditions of peat accumulation within it, whereas the other takes a broader view and seeks to establish the relationship between coal facies and the sedimentary setting of the mire. The questions to be asked in the first case, which is the main subject of this chapter, will concern the hallmarks of rheotrophy and ombrotrophy, as well as the influence on coal type of the vegetal progenitors after the local variabilities have been filtered out. The aim is akin to what Walker (1980, Fig. 4) calls the “pure essence of environmental summary”, which constitutes a facies model obtained from the common denominator of a variety of local examples. The results of this enquiry are then linked to their sedimentary settings, such as delta plains, alluvial valleys and the like, which will be discussed in detail in Chap. 7.
KeywordsCoal Seam Brown Coal Vitrinite Reflectance Coal Rank Sydney Basin
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