Reconnaissance Survey of the Petrology of New Zealand Coals with Recommendations as to Their Utilisation

摘要

New Zealand coals have the petrographic properties typical of many young coals: i.e., strongly detrital nature, high vitrinite (huminite) and very low inertinite contents in comparison with the older Carboniferous and Gondwana (Permian-Mesozoic) coals which have high inertinite content including an abundance of fusinite. It is the high vitrinite content of the New Zealand coals which gives them their very high reactivity and swelling capacity in comparison with Carboniferous (North American and European) and Gondwana (Australian, Indian, and South African) coals. New Zealand lignites can be compared with lignites and brown coals from elsewhere in the world since most of these coal types are Tertiary in age. Higher rank New Zealand coals have, under the microscope, the morphological appearance and contain some of the macerals characteristic of brown coals, but the rank (reflectance) of hard coals. Tertiary coals of bituminous rank are not common. Elsewhere they occur in active geological environments similar to that of New Zealand (e.g., Japan, Columbia). High rank Tertiary coals do not occur in stable continental environments (unless the high rank is a result of igneous intrusion) and these coals should not be compared to the Carboniferous and Gondwana coals of similar rank. (ERA citation 05:028343)