Tertiary bituminous coals

Geoffrey H. Taylor. Tertiary bituminous coals examined in C.S.I.R.O. (Sydney) contain fusinite but little micrinite, sometimes virtually none. This would seem to preclude a genetic connection between fusinite and micrinite origin. 

In addition to the Permian coals there are occurrences of Mesozoic and Tertiary coals in Australia. Mesozoic coals occur in small basins in South Australia, Tasmania, New South Wales and Queensland and vary in rank from brown to bituminous. Perhaps the most notable occurrences in the present context are the Walloon coals in the Clarence-Morton basin in Queensland, e.g. Millmerran bituminous coal (78% carbon, vitrinite plus exinite 90%). ... 

Let us take another example. At the U.S. Gulf Coast, the Pleistocene and the Upper Tertiary (Pliocene and Miocene) reach a thickness of more than 6000 meters. Nevertheless, the coaliflcation has only reached the stage of high volatile bituminous at this depth. This observation resulted from our studies of samples from a deep borehole located in Terrebonne Parish, La. By reflectance measurements on humic inclusions in claystones of the uppermost Middle Miocene encountered at a depth of 5440 meters, we obtained a mean value (under oil) of 0.95% reflectance, which is equivalent to the reflectance of vitrinites (out of deep boreholes) with 35-40% volatile matter (daf). On the other hand, we found low volatile bituminous coals (14-16% volatile matter, daf) at a depth of 5100 meters in a borehole in the Lower... 

During the Tertiary period which dates back approximately 65 million years. Deposits include the sub-bituminous coal and lignite beds in the Great Plains Province, which includes northeastern Wyoming, eastern Montana, western North Dakota, and northwestern North Dakota. 

Major coal deposits coincided with periods following regression, which is consistent with the most suitable conditions for deposition—a steady increase in accommodation space—being predominantly found in lowland coastal swamps (Section 3.4.2a). Two main episodes of coal formation can be distinguished the first during the Carboniferous—Permian and a second smaller episode spanning the Jurassic to early Tertiary. The majority of coals formed in the earlier episode are now bituminous coals or anthracites, whereas those from the Tertiary are mainly brown coals. 

Another maceral of the inertinite group is sclerotinite, which is the result of fungal remains. Sclerotinite occurs as ovoid bodies with cell structure, with reflectance covering the entire inertinite range. Sclerotinite is found mainly in coals of the Tertiary Period, particularly in the lignites, and also in bituminous coals of the Paleozoic era. Sclerotinite (Figure 4.3) is opaque, highly reflective, and, in the oval or round form, may vary in size from 20 to 300 pm (30 to 300 x 10 mm). 

Resinite macerals (Anderson et al., 1992) occur widely (often in minor amounts) throughout most American coals below medium-volatile bituminous rank. They are usually absent in coals of higher rank. Although resinite macerals usually make up less than 3% of most US coals, they are particularly abundant in coal of the Wasatch Plateau in Utah where they can account for as much as 15% of the macerals present. In most Appalachian and mid-western US coal seams, resinites occur as primary (present at the time of deposition) ovoid bodies with a long axis ranging from 25 to 200 jm. While primary ovoid bodies of resinite are also found in western US coals of Cretaceous/Tertiary... 

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