Sedimentary Innllings and Development of Major Tertiary Palaeodrainage Systems of South-Central Australia
- Médard Thiry and
- Régine Simon-Coinçon
Published Online: 14 APR 2009
Copyright © 1999 The International Association of Sedimentologists
Palaeoweathering, Palaeosurfaces and Related Continental Deposits
How to Cite
Alley, N. F., Clarke, J. D. A., Macphail, M. and Truswell, E. M. (1995) Sedimentary Innllings and Development of Major Tertiary Palaeodrainage Systems of South-Central Australia, in Palaeoweathering, Palaeosurfaces and Related Continental Deposits (eds M. Thiry and R. Simon-Coinçon), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444304190.ch14
- Published Online: 14 APR 2009
- Published Print: 26 MAY 1995
Print ISBN: 9780632053117
Online ISBN: 9781444304190
- Temperate rainforest, existing along southern continental margin;
- middle Eocene times, monsoonal-like conditions prevailing in central Australia;
- playas, marking courses of ancient rivers;
- Eucla Basin palaeochannel infillings, extending from eastern basin to western basin margin;
- Biogenic sediments, accumulating in palaeodrainage systems;
- fluvio-lacustrine sedimentation, occurring along palaeochannels in Lake Eyre
Tertiary palaeochannels are widespread on the Australian continent. Their best preserved sedimentary infillings are found in the Eucla Basin and central Australian area. Palaeochannel development had its origins during earliest Cretaceous times in the south-western Eucla Basin and at least in possibly Late Cretaceous times in the central continent. Major phases of sedimentary infilling occurred in Palaeocene–Eocene, late Oligocene–Miocene and Pliocene–Pleistocene times. Marine influence extended several hundred kilometres up the Eucla palaeochannels during at least three major transgressions in the middle Eocene–late Eocene interval. Reduced marine influence occurred in some eastern Eucla channels during the Early Miocene Epoch. The sedimentary and geomorphological evidence indicates that no connection existed between the Eucla and inland channels.
Deep weathering was prevalent prior to deposition in the channels, and may be as old as early Mesozoic times. Later weathering was related to duricrust development. Ferricrete probably formed in early Mesozoic, late Oligocene–Middle Miocene and Late Miocene–Pleistocene times. Major phases of silicification occurred in late Eocene–Middle Miocene and Late Miocene–Pleistocene times, when significant groundwater silcrete formed.
Temperate rainforest existed along the southern continental margin during earliest Palaeocene times. By the late Palaeocene to early Eocene interval, rainforest of megathermal aspect existed in central Australia, indicating that conditions there were warmer than along the southern continental margin. In middle Eocene times, monsoonal-like conditions prevailed in central Australia and moister conditions in the south, where rainforest of meso- to megathermal aspect grew, here extending late into the Eocene Epoch. The ?late Oligocene–Miocene interval was a time of development of extensive shallow, alkaline lakes in parts of the palaeochannels and in two major depocentres in central Australia. Lakes in the inland area supported a diverse fauna, including crocodiles. Vegetation had changed to dry, open woodland throughout the palaeochannel areas, with rainforest-like vegetation confined to wetter valley bottoms. By the Pliocene Epoch further drying had produced a chenopod shrub to open woodland environment, containing isolated pockets of forest in edaphically suitable sites.