Coals Antarctic

Jhis paper is a progress report on the analytic qualities of Antarctic coal. 

The Antarctic coal beds are apparently less persistent, and locally may be thicker, than many of the beds in Paleozoic coal fields of North America. It is hazardous to generalize about petrographic composition from hand specimens that are available from many of the coal beds, but one obtains the impression that dull, moderately dull, and midlustrous attrital layers are more prevalent than in Paleozoic coal of the Northern Hemisphere. Vitrain bands tend to be relatively sparse and thin fusain chips and partings generally are present and may be abundant. Many coal specimens are relatively impure, apparently owing to well-dispersed detrital mineral matter. 

Problems of access affect any effort to obtain information about Antarctic coal. Coal commonly crops out in inaccessible steep slopes swept clean by the wind and, even where accessible, the climate and the occurrence of permafrost are not favorable for sampling coal beds according to accepted standards. Coal samples obtained in the Antarctic generally are not standard. Even though modem standards of analysis have been used in treating the samples (14), no amount of laboratory technique can compensate for inadequacy in sampling. Nearly all of the available analytic data are based on analyses of the available coal specimens which were exposed on surfaces of outcrops. This is the type of sample that can be obtained practically under commonly existing conditions of climate and transport. 

Nearly all the Antarctic coal analyses are based upon determinations of the U.S. Bureau of Mines Coal Analysis Section under the supervision of Forrest E. Walker. Sources of other analytic data and sources of collections upon which they are based are cited in the locality listing of respective analyses tabulated. Ultimate values as well as results of proximate determination are given whenever available. 

Schapiro and Gray (36) have shown that microscopic voids commonly occur in Antarctic coals altered by igneous heating. These voids occur without necessarily affecting the megascopic appearance of the coal. Possibly coked coals such as this, which may be called cryptovesicular, include moisture in excess of that which is driven off by standard drying procedure. It is conceivable that unusual moisture relations would be reflected by the unusual samples. 

Most of the analyses of Antarctic coal were based on blocks of transportable size taken from surface outcrops. In earlier work, sections of purer coal were cut from the blocks and submitted for analysis. In later work, selected blocks were crushed, and a float fraction of purer coal was submitted to provide analytic data from each deposit. These samples, while not useful for determining coal grade, may be adequate for indicating rank. Practically all of the Antarctic coal, with the exception of that at Amery (which may represent high volatile bituminous coal), corresponds to medium volatile bituminous or higher rank. The high apparent rank Antarctic coal may be classified according to conventional ASTM standards of rank based on proximate analysis, but it seems clear that these results serve only as a first approximation. 

Figure 1. Relation of fixed carbon and heating value (dry, mineral-free basis) for Antarctic coal samples with less than 20% as-received ash...

All analyses of Antarctic coal samples submitted from the U.S. Geological Survey have been analyzed at the U.S. Bureau of Mines, Coal Analysis Section under supervision of Forrest E. Walker. Preparation of samples for analyses as well as field sampling and shipment was supported, in part, by NSF grant G-17216 administered by the Institute of Polar Studies through the Research Foundation, The Ohio State University. 

Table III. Antarctic Coal Analytes Central Victoria Land Allan Nunatak Proximate Analysis, % Ultimate Analysis, % ...

Physical Variations in Highly Metamorphosed Antarctic Coals... 

The Antarctic coal samples are reportedly of Permian age and were collected in 1957 as part of the Antarctic exploration program of the Ohio State University Institute of Polar Studies. The bulk of the samples are from two localities shown in Figure 1 (1) the Terrace Ridge in the Ohio Range of the Horlick Mountains, and (2) Mount Gran in the Granite Harbour area of South Victoria Land. In each instance the coals were sampled from each of the accessible coal seams in the stratigraphic sequence exposed. Thus, these sam-... 

The 36 Antarctic coal samples were analyzed chemically (proximate and ultimate analyses) at the U. S. Bureau of Mines in Pittsburgh. The results of these analyses accompanied the samples when received from J. M. Schopf. The samples were collected by W. E. Long in the Ohio Range on NSF grant... 

G-17216, and in Victoria Land by John Mulligan, also on an NSF grant to the Bureau of Mines. Each sample was crushed by hand with a mortar and pestle to approximately 0.625 by 0.25 inch. A split of each crushed sample was embeaaed in epoxy resin, polished, examined microscopically, photographed, and then its reflectance was determined. Knoop indention hardnesses were also determined by using a 20-gram load on the diamond indenter. The indenter was kept in contact with the sample for 15 seconds. Additional splits of each sample were crushed to minus 60 mesh, dried at 100°C. for 24 horns, and their electrical resistivity was determined at 20,000 p.s.i. The sample locations, chemistry, petrography, reflectance, electrical resistivity, and hardness of the 36 Antarctic coal samples studied are included in Table I. 

Figure 2. Photomicrographs showing some of the common entities found in Antarctic coals reflected light, X 150 A—Vitrinoia with cracks. B—Bright inerts in a mixture of vitrinoids (gray) and clays (black), C—Semifusinoids preserving cellular structure. D—Clay minerals (black) containing thin vitrinoid bands (gray)...

Figure 4. The appearance of natural coke that occurs in the Antarctic coal measures reflected light X 150...

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