1.1 Previous Studies of Permian …
3
1.1 Previous Studies of Permian Pollen/Spores in the Collie
and South Perth Basins
While a number of comprehensive studies and biostratigraphic correlations of Permian pollen in Australian Basins were published (Foster 1982; Price 1983; Mory
and Backhouse 1997; Kemp et al. 1977), only a few studies were carried out on
the pollen/spores of the Collie Basin. The earliest were pioneered by Balme (1952,
1959), Balme and Hennelly (1955, 1956a, b). More recent studies by Backhouse
(1991; 1993) were detailed and covered both, the pollen and spore descriptions as
well as stratigraphic correlations within Collie Basin and between Collie and Perth
Basin. The present study focuses on the Collie Basin, including the smaller Wilga
Basin next to it and South Perth Basin.
1.2 The Collie Basin
The Collie Basin in Western Australia (Key map, Fig. 1.1) is situated about 160 km
south of Perth and about 22 km east of the Darling scarp. It is centred on the coordinates 33.5° S latitude, 116.4° E longitude. The basin forms a NW–SE-oriented
depression in the Precambrian basement and is drained by the Collie River. The area
rises from 200 m to about 250 m above the sea level and is about 22.5 km long and
12.8 km wide. The Collie Basin was considered a remnant of “…an erosional plain
sloping gently to the Eucla Basin in the east, truncated by the Darling scarp in the
west” (Hills 1961). This plain was assumed by Hills (1961) to be a low-lying land in
the Permian. The origin of the depression was attributed to erosion by glaciers (Lord
1952). The detailed study of the Collie Basin by LeBlanc Smith (1993) describes
the basin as a “fault bounded, post-depositional pull apart structure”. The detailed
study of LeBlanc Smith supports Lord’s glacially eroded depression, filled with
sediments, subject to later, post-depositional faulting. Similar conclusions of postdepositional faulting of a coal basin have been reached by Ghosh (2002) in his study
of the Raniganj Basin in India, another Gondwana Permian post-glacial depositional
basin.
The Collie Basin is 226 km
2 in area (LeBlanc Smith 1993) and is divided into
two parts by a granitic-gneiss ridge (see map, Fig. 1.2): the eastern part of which is
sub-divided again into a northern depression and a southern depression, termed the
Shotts and the Muja, respectively. LeBlanc Smith (1993) states that a stratigraphic
section of about 1400 m of faulted Permian sediments is preserved in the basin, of
which over 900 m are coal-bearing.
Coal samples were examined from bores in the Collie Basin, sites A and B (text
Fig. 1.2), and from the Muja sub-basin sites C and D and Wilga Basin Bore No. 1. The
Permian sequence in the Collie Basin as well as the Perth Basin starts with tillites nonconformably overlying the glacially striated basement. These tillites are correlated
on lithological and microfloral basis with the Nangetty Formation in the northern
3
1.1 Previous Studies of Permian Pollen/Spores in the Collie
and South Perth Basins
While a number of comprehensive studies and biostratigraphic correlations of Permian pollen in Australian Basins were published (Foster 1982; Price 1983; Mory
and Backhouse 1997; Kemp et al. 1977), only a few studies were carried out on
the pollen/spores of the Collie Basin. The earliest were pioneered by Balme (1952,
1959), Balme and Hennelly (1955, 1956a, b). More recent studies by Backhouse
(1991; 1993) were detailed and covered both, the pollen and spore descriptions as
well as stratigraphic correlations within Collie Basin and between Collie and Perth
Basin. The present study focuses on the Collie Basin, including the smaller Wilga
Basin next to it and South Perth Basin.
1.2 The Collie Basin
The Collie Basin in Western Australia (Key map, Fig. 1.1) is situated about 160 km
south of Perth and about 22 km east of the Darling scarp. It is centred on the coordinates 33.5° S latitude, 116.4° E longitude. The basin forms a NW–SE-oriented
depression in the Precambrian basement and is drained by the Collie River. The area
rises from 200 m to about 250 m above the sea level and is about 22.5 km long and
12.8 km wide. The Collie Basin was considered a remnant of “…an erosional plain
sloping gently to the Eucla Basin in the east, truncated by the Darling scarp in the
west” (Hills 1961). This plain was assumed by Hills (1961) to be a low-lying land in
the Permian. The origin of the depression was attributed to erosion by glaciers (Lord
1952). The detailed study of the Collie Basin by LeBlanc Smith (1993) describes
the basin as a “fault bounded, post-depositional pull apart structure”. The detailed
study of LeBlanc Smith supports Lord’s glacially eroded depression, filled with
sediments, subject to later, post-depositional faulting. Similar conclusions of postdepositional faulting of a coal basin have been reached by Ghosh (2002) in his study
of the Raniganj Basin in India, another Gondwana Permian post-glacial depositional
basin.
The Collie Basin is 226 km
2 in area (LeBlanc Smith 1993) and is divided into
two parts by a granitic-gneiss ridge (see map, Fig. 1.2): the eastern part of which is
sub-divided again into a northern depression and a southern depression, termed the
Shotts and the Muja, respectively. LeBlanc Smith (1993) states that a stratigraphic
section of about 1400 m of faulted Permian sediments is preserved in the basin, of
which over 900 m are coal-bearing.
Coal samples were examined from bores in the Collie Basin, sites A and B (text
Fig. 1.2), and from the Muja sub-basin sites C and D and Wilga Basin Bore No. 1. The
Permian sequence in the Collie Basin as well as the Perth Basin starts with tillites nonconformably overlying the glacially striated basement. These tillites are correlated
on lithological and microfloral basis with the Nangetty Formation in the northern