PhD 2007
The Depositional Environment of the Newcastle Coal Measures: Insights from Tuffaceous Sedimentation, Tree Preservation and Long Distance Correlations” Newcastle University, 2007.
Abstract
The Late Permian Newcastle Coal Measures of the northern Sydney Basin of Australia consist of non-marine strata with a large proportion of tuffaceous rocks derived from volcanic ash falls. As a result of their rapid deposition thick interseam tuffs have in places entombed trees in their growth positions thereby influencing some researchers to conclude that the ancient peat forming environment was widely forested.
The ubiquitous thin ash layers preserved within coal seams (known as tonsteins), however preserve some archetypal features of the peat forming environment which have to date not been considered collectively, nor incorporated satisfactorily, in models of local peat formation. The two more enigmatic features of these deposits are the lack of any preserved trees and their uniform distribution over large distances.
This study has found no fossil evidence to support the notion of a forest setting. Although this should be recognized as a negative argument (the lack of tree fossils does not directly indicate a lack of trees) various investigative methods are used to support this conclusion. The uniform distribution of tonsteins has also been interpreted to suggest that they were deposited on a subaqueous peat surface that protected them from subsequent redistribution from rainfall and surface runoff.
As a consequence of this research the extents of the various seams and tuffs of the Newcastle Coal Measures have increased almost ten fold. This has resulted in a re-assessment of the size and location of the volcanic sources and also suggests that the seams of the Newcastle Coal Measures formed predominantly by vertical aggradation rather than progradation. The uniform distribution of detrital coal components across the study area also suggest distribution by aerial processes, warning against the assumption that an increase in these components reflects flooding of the peat environment.
This research has been used to successfully support a stratigraphic revision of the Late Permian of the northern Sydney Basin. It has also identified over a billion tonnes of shallow coal resources that were not previously recognized.
One large open cut coal mine was founded on the basis of this research and it now operated by Xstrata as Mangoola Mine.
This research also led to the replacement of the Wollombi Coal Measures with Newcastle Coal Measure nomenclature, ratified by the NSW Coalfield Geological Council in 2004.
