A REVIEW OF SULPHUR IN COAL: WITH SPECIFIC REFERENCE TO THE TELKWA DEPOSIT, NORTH-WESTERN BRITISH COLUMBIA
The Jura-Cretaceous coal seams of the Currier, Mist Mountain, &thing and Gates formations generally formed in delta or strand plain environments with little marine influence. The sulphur contents of coal from these formations is therefore generally low, nearly always less than I % and often less than 0.5 %. Coalbearing formations of the Cretaceous Nanaimo and Skeena groups were deposited in coastal areas with more marine influence. Consequently sulphur contents are more variable and tend to be higher. It is therefore important to study aspects of sulphur in Cretaceous coal seams such as the seams in the Skeena Group at Telkwa (Figure I).
Changes in bulk properties and molecular compositions within New Zealand Coal Band solvent extracts from early diagenetic to catagenetic maturity levels
Abstract The bulk properties and bitumen molecular compositions of a rank-series of 38 humic coals from the New Zealand Coal Band (Cretaceous–Cenozoic) have been analysed to investigate early maturation processes affecting coaly organic matter through diagenesis to moderate catagenesis (Rank(S r ) 0.0–11.8, R o 0.23–0.81%). The samples comprise a relatively restricted range of vitrinite rich coal types formed largely from higher land plant material under relatively oxic conditions, but with a significant contribution from microbial biomass. With increasing rank, total organic carbon contents show a general increase, whereas moisture and asphaltene contents decrease. Bitumen yields also decrease through the stages of diagenesis and early catagenesis (Rank(S r )  R o r ) ∼ 5–6 ( R o  ∼ 0.40%) as indicated by the constant occurrence and gradual increase of isoprenoids (e.g., pristane and phytane) and hopanoids in their more mature αβ configuration. This early phase of catagenesis, not previously recognised in New Zealand coals, is followed at Rank(S r ) ∼ 9 ( R o  ∼ 0.55%) by the main catagenesis phase characterised by a more rapid increase in the generation of hydrocarbons, including total n -alkanes, isoprenoids and αβ-hopanes. Changes in the maturity of New Zealand coals can be traced by the Carbon Preference Index and several hopane maturity parameters, including 22 S /(22 S  + 22 R ), αβ/(αβ + βα) and ββ/(αβ + βα + ββ).
The analysis of group contingency data.
The data analyses utilized in group contingency projects are reviewed. Previous studies are cited to emphasize advantages of nonconsolidated ("individual") over consolidated analyses. Several procedures are described that enable applied researchers to incorporate nonconsolidated data analyses in group contingency studies.