Submarine mass‐wasting deposits as an indicator of the onset of foreland thrust loading—Late Permian Bowen Basin, Queensland, Australia

Abstract

In the eastern part of the Permo-Triassic Bowen Basin of Queensland, Australia, a transition from passive, thermal subsidence to flexural (foreland basin) subsidence is recorded within the Upper Permian stratigraphy. Two coarse-grained intervals containing deposits of mass-wasting processes occur within an otherwise siltstonedominated succession over 1500 m thick (the Moah Creek Beds and equivalents). These intervals can be traced over at least 350 km north±south, along the structural eastern margin of the basin. The lower of the coarse-grained intervals is spectacularly exposed in the banks of the Fitzroy River, west of Rockhampton. Here, interbedded sandstones and siltstones of marine shelf origin are abruptly truncated by a mudrock succession containing evidence of slumping and contemporaneous magmatic activity. This unit passes up-section into packages of mass-flow conglomerates and diamictites, interpreted to have formed on an unstable submarine slope. The character of the mass-flow deposits, their stratigraphic position and lateral extent are interpreted in terms of destabilization of a sloping marine surface by pulsed, subsurface thrust propagation.

Stratigraphic imprint of the Late Palaeozoic Ice Age in eastern Australia: a record of alternating glacial and nonglacial climate regime

“…Care has been taken to separate out stratigraphic signatures of tectonic processes, such as the onset of the Hunter-Bowen Contractional Event in the Late Permian (e.g. Fielding et al 1997Fielding et al , 2001Glen 2005), from those likely to be of glacial origin.…”

“…It is marked in the western Bowen Basin by an abrupt change in sand composition from quartz dominated to first cycle volcanic dominated at the base of the Peawaddy Formation (Baker et al 1993), and in the east by the disruption of the shallow marine depositional setting by submarine debris flows and magmatic activity (Fielding et al 1997). These effects can be separated from facies patterns resulting from ice-rafting and other glacial influences.…”

Sedimentological evidence for rotation of the Early Permian Nambucca block (eastern Australia)

“…Such failures are common on modern submarine slopes, where they may reach considerable size and are termed mass-transport complexes (e.g., Sawyer et al, 2007;Moscardelli and Wood, 2008;Khani and Back, 2012). The facies B5 occurrence at Crescent Head closely resembles a series of Middle Permian submarine debris flow deposits in the Moah Creek Beds of east-central Queensland, which were interpreted (Fielding et al, 1997) to record the onset of Middle Permian to Triassic multiphase contractional deformation. The range of lithologies and the physical and biogenic sedimentary structures in facies association B are entirely consistent with deposition on a submarine slope, below storm wave base.…”

Lithostratigraphy of the late Early Permian (Kungurian) Wandrawandian Siltstone, New South Wales: record of glaciation?

“…The Moah Creek beds, however, record activity on the orogenic margin of the Bowen Basin, whereas the Wandrawandian Siltstone was deposited on the cratonic margin (Tye et al 1996;Fielding et al 1997). Additionally, the ages of the two horizons have not been confidently linked, and the slumps in the Moah Creek beds may have occurred at a time significantly later than those in the Wandrawandian Siltstone.…”