OFR 151.pdf - CRC LEME

7.4 Time Slice T-1. Paleocene [65-54.8 Ma]
Zones: Lower to Upper Lygistepollenites balmei Zone
Trithyrodinium evittii to Lower Apectodinium hyperacanthum Zone
Figure 8: Early Paleocene (64 Ma) palaeogeography (from Veevers et al. 1991)
7.4.1 Palaeogeography
During the Paleocene, Australia was located between palaeolatitudes 45 0 -70 0 S (Figure 8).
The continent remained linked to a largely ice-free Antarctica via the partially submerged
South Tasman Rise (STR). In northern Australia, regression at the Cretaceous-Tertiary
boundary was followed by widespread transgression in the Paleocene, with maximum
flooding of the North West Shelf occurring during the Late Paleocene (Bradshaw et al. 1988).
Carbonates accumulating on the North West Shelf contain less siliciclastic material than those
deposited during the Late Cretaceous, possibly reflecting low relief and increasing aridity
(Apthorpe 1988). During the same period, sea-floor spreading in the Tasman Sea had rotated
the submerged Lord Howe Rise and a partially emergent Campbell Plateau away from
Australia. Ranges on the eastern margin (Eastern Cordillera) had shrunk in width and height
to form the present-day Eastern Highlands, although much of the area now occupied by the
Great Barrier Reef remained dry land. Taylor et al. (1990) estimate regional relief on the
Southeastern Highlands of New South Wales was at least 400 m and possibly greater than 800
m by ca. 58-60 Ma. Subsidence in northern South Australia produced a large, shallow basin
(Lake Eyre Basin) in which fluvio-lacustrine sands, silts and clays (Eyre Formation)
accumulated possibly during latest Paleocene to Middle Eocene time. Paleocene
(Lygistepollenites balmei Zone) facies reach thicknesses of up to 950 m in the offshore
Gippsland Basin (Partridge 1999). Elsewhere, deep weathering or erosion seems to have
continued unabated across much of the continent (Bain and Draper 1997, Alley 1998, Alley et
al. 1999).
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