กก
|
กก |
|
COMPARATIVE
SEDIMENTOLOGICAL ANALYSIS OF LATEGLACIAL TO EARLY POSTGLACIAL PERMIAN SEQUENCES
OF S. AFRICA AND QUATERNARY DEPOSITS OF CANADA I.P. MARTINI1 AND B. CAIRNCROSS2 1Department
of Land Resource Science, University of Guelph, Guelph, Ontario, Canada. กก
The
objective of this work is to analyze the early post-glacial development of
Permian coal on a cratonic setting, and compare and contrast it with
Pleistocene-Holocene settings of the northern Hemisphere. Most commonly
preserved pre-Pleistocene glacial and early-post glacial rock record consists of
basinal deposits, generally marine. In S. Africa the whole range of basinal,
shelf and continental glacial deposits are preserved sufficiently well to
warrant a comparative analysis with Pleistocene sediments and morphologies.
Major emphasis is on coal and peat bearing sequences. A brief critical review of
what is known and published about the cold-climate Permian coal measures of
southern Africa will be made. Much original basic information derives from
cores, and from occasional outcrop. The cores are available from drilling for
coal exploitation and can provide local detailed architecture of the subsurface,
in places cores are available on a 50 to 150m spacing. The disadvantages of
working with cores are, however, that large scale features are difficult to
recognize, that regionally, information is available in selected areas only, and
stratigraphically the majority of the cores are terminated just below the coals
extracted and seldom penetrate deep into the sub-coal material, glacial or
marine it might be.
The interpreted Permian setting will be compared and contrasted with
Quaternary analogs. Rather than to seek a perennially
elusive perfect overall analogous settings, matching tectonic realm,
structure, climate, morphology, types of sediments sources and deposits, good
specific analogs for each feature will be considered. |
|
กก
|