Spatial distribution of micrometre‐scale porosity and permeability across the damage zone of a reverse‐reactivated normal fault in a tight sandstone : Insights from the Otway Basin, SE Australia

This research forms part of a PhD project supported by the Australian Research Council [Discovery Project DP160101158] and through an Australian Government Research Training Program Scholarship. Dave Healy acknowledges the support of the Natural Environment Research Council (NERC, UK) through the award NE/N003063/1 ‘Quantifying the Anisotropy of Permeability in Stressed Rock’. This study was also funded by scholarships from the Petroleum Exploration Society of Australia and the Australian Petroleum Production and Exploration Association. We thank Gordon Holm for preparing thin sections and Colin Taylor for carrying out particle size measurements and mercury injection capillary pressure analyses. Aoife McFadden and David Kelsey from Adelaide Microscopy, Braden Morgan, and Sophie Harland are acknowledged for their assistance with laboratory work. Field assistants James Hall, Rowan Hansberry, and Lachlan Furness are also gratefully acknowledged for their assistance with sample collection. Discussions with Ian Duddy on the mineralogy of the Eumeralla Formation are also greatly appreciated. This forms TRaX record 416.Peer reviewedPublisher PD

An analysis of the microfauna and microflora of the upper eocene of the Hampshire basin

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Geological evolution of the Holocene Yarra Delta and its relationship with Port Phillip Bay

<p>The Holocene and pre-Holocene sediments and stratigraphy of the Yarra Delta have been examined using nearly 600 geotechnical bores. The oldest Holocene unit is the Coode Island Silt that has two depocentres, each up to 20.0–25.0 m thick, separated by a NW–SE belt of older pre-Holocene units. The northern depocentre represents estuarine infill to the Yarra and Maribyrnong, a river system, whereas the southern depocentre appears to be an offshore bay facies. The youngest unit is the Port Melbourne Sand, which is largely restricted to the area south of the present Yarra River. It is between 5.0 and 28.0 m thick, and is diachronous with the underlying Coode Island Silt. New ¹⁴C shell dates from the Coode Island Silt and Port Melbourne Sand have shown an age range between 8341 and 2760 yrs BP. These sediments infill former swamplands covering low-stand river valleys of the Yarra and Maribyrnong rivers across West Melbourne, Fishermans Bend and South Melbourne. After <i>ca</i> 2760 yrs BP active sedimentation in the delta ceased as base-levels fell, and Yarra and Maribyrnong river sediments bypassed the delta because of falling bay levels. The Yarra and Maribyrnong river courses also shifted progressively westwards behind growing beach barriers of the Port Melbourne Sand. A comparable stratigraphy exists between the Yarra Delta and the adjacent Port Phillip Bay, i.e. marine and lagoonal shelly sediments of the Coode Island Silt and barrier sands of the Port Melbourne Sand infill last-glacial channels cut into the middle Pleistocene Fishermans Bend Silt.</p

Late Cretaceous to Oligocene burial and collision in western Papua New Guinea: Indications from low-temperature thermochronology and thermal modelling

International audienceRecent field and analytical work have considerably improved our understanding of the structure of the MullerRange along the frontal trend of the Papuan Fold and Thrust Belt (PFTB) in western Papua New Guinea (PNG).However numerous questions remain unresolved concerning the geological evolution of the region. In particular,the Late Cretaceous to Oligocene history of the region is largely unknown due to the absence of a continuousstratigraphic record. Here, we use both new and existing low-temperature thermochronology data to investigatethe geological history of the Muller Range. Thermal history models based on these data suggest two majorCenozoic cooling episodes. The youngest, and best constrained, is clearly recorded in the stratigraphic recordand relates to Neogene collision at the northern margin of the Australian continent. An older episode of comparableor greater magnitude occurred in the Eocene to Oligocene and may relate to the removal of1500–3000m of Late Cretaceous to Eocene section across the Muller Range prior to the widespread deposition ofthe shelfal Darai Limestone. We suggest that extension along major faults beneath the Muller Range accommodatedsedimentation from the Late Cretaceous to the Eocene, consistent with long-lived extensional structuresobserved in neighbouring regions. In contrast to the Muller Range area, an almost continuous Late Cretaceous toEocene stratigraphic sequence is preserved in the hinterland<50 km to the northeast. The selective removal ofthis sequence across the Muller Range suggests it was uplifted in the Eocene to Oligocene, possibly in partfacilitated by the inversion of extensional faults in the Muller Range area. We suggest that this inversion wasrelated to the Eocene to Oligocene collision of the expansive Sepik Terrane to the northwest of the PNG margin.The new data and interpretations presented here have significant implications for the evolution of the PFTB andfor tectonic reconstructions of PNG