Fission Track Thermochronology: Application to Continental Rifting of South-Eastern Australia

Abstract

Over the last five to ten years, apatite fission track analysis has developed into a sophisticated technique for studying the low-temperature thermal history of rocks. It has particular utility in oil exploration because its temperature range of sensitivity, about 20° to 125°C, overlaps the oil generation window. Whereas older fission track thermal history approaches relied solely on the sample fission track age, the new interpretive approaches use sample age, single grain age and track length data. They also emphasise the analysis of systematic variations in data patterns in sequences of samples, such as samples from various depths in a well. Laboratory study of the thermal annealing of fission tracks and compilation of fission track data from geological case studies has greatly improved our understanding of apatite fission track systematics, allowing considerably more detailed interpretations of thermal histories.Application of apatite fission track analysis to the rifted continental margins of south-eastern Australia shows that rifting and separation of Australia from Antarctica and the Lord Howe Rise were accompanied by at least 1.5-3 km of uplift and erosion along the Tasman Sea and Bass Strait coasts. Uplift and erosion were much less 100 km or so inland. This shows that the uplift of the south-eastern Australian margins was caused by the continental rifting process, the same process that initiated major subsidence in the sedimentary basins in Bass Strait. The consistent fission track data patterns around south-eastern Australia suggest a generally similar tectonic setting for the Tasman Sea and Bass Strait parts of the margin. Lister et al. (in press) propose that the Tasman part of the margin is an upper plate type of margin that formed above a west-dipping detachment zone. The fission track data suggest that the Bass Strait part of the margin may also be of upper plate type.

Thermal history of the early Miocene Waitemata Basin and adjacent Waipapa Group, North Island, New Zealand

“…This cooling event is similar to the cooling phase documented by fission track data further south along the West Coast of South Island (White & Green 1986;Seward 1989;Kamp et al 1989). It is also broadly similar to a major phase of cooling recorded along the east coast of Australia (Moore et al 1986;Dumitru et al 1991;Raza et al 1995Raza et al ,1996. This implies crustal cooling at this time was more widespread than previously thought and affected large regions along the eastern margin of Gondwana.…”

Late Quaternary erosion in southeastern Australia: a field example using cosmogenic nuclides

“…This is separated from the coastal belt by what is commonly referred to as the Great Escarpment (Ollier, 1982(Ollier, , 1985. Fission track ages from the coastal region suggest higher denudation rates, on the order of 20 m Myr À1 (Moore et al, 1986;Dumitru et al, 1991;van der Beek and Braun, 1998).…”

“…Apatite fission track thermochronology from the southeastern highlands suggests rapid uplift and erosion in the Cretaceous Period, associated with Tasman Sea rifting, and that present morphologies were established about 60 Myr ago (e.g. Dumitru et al, 1991;Brown et al, 1994;O'Sullivan et al, 1995O'Sullivan et al, , 1996. On a shorter time scale, Seidl et al (1996) and Seidl (1997, 1998) used a mass balance approach and cosmogenic nuclide measurements to determine denudation rates near the eastern margin of the New England tablelands.…”

Role of pre-rift rheology in kinematics of extensional basin formation: constraints from thermomechanical models of Mediterranean and intracratonic basins

“…(Ebinger et al, 1991;), Baikal rift (D6verch6re et al, 1993, the Barents Sea margin (Reemst et al, (1994; 1995) and van Balen et al (unpublished data), it is important to take onshore rift shoulder erosion into account when explaining the observed topography and basin architecture. Practically the only record of rift margin erosion in these settings is provided by apatite fission track thermo-chronology of the exposed basement rocks (Dumitru et al, 1991;van der Beek et al, 1994;1995). Kinematic modelling, incorporating margin erosion estimates constrained by fission track thermochronology, has been applied to the Transantarctic Mountains and the Saudi Arabian Red Sea margin (van der Beek et al, 1994).…”