Apatite (U–Th)/He age constraints on the development of the Great Escarpment on the southeastern Australian passive margin

Persano, Cristina; Stuart, Finlay M.; Bishop, Paul; Barfod, Dan N.

doi:10.1016/s0012-821x(02)00614-3

Cited by 114 publications

(152 citation statements)

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“…Standard 4 He abundance measurements have within-run precision of better than 0.1% (1σ) and between-run precision of 0.2% (1σ) [Persano et al, 2002].…”

Section: Apatite (U-th-sm)/he Analysismentioning

confidence: 99%

Cenozoic extension in the Kenya Rift from low‐temperature thermochronology: Links to diachronous spatiotemporal evolution of rifting in East Africa

et al. 2015

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Key points: Data and modeling show Paleogene and middle Miocene cooling episodes  Cooling episodes separated by stable conditions, slow exhumation or subsidence  Extension pattern is compatible with random rift initiation above a plume This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1002/2015TC003949 ©2015 American Geophysical Union. All rights reserved. AbstractThe cooling history of rift shoulders and the subsidence history of rift basins are cornerstones for reconstructing the morphotectonic evolution of extensional geodynamic provinces, assessing their role in paleoenvironmental changes, and evaluating the resource potential of their basin fills. Our apatite fission-track and zircon (U-Th)/He data from the Samburu Hills and the Elgeyo Escarpment in the northern and central sectors of the Kenya Rift indicate a broadly consistent thermal evolution of both regions. Results of thermal modeling support a three-phased thermal history since the early Paleocene. The first phase (~65-50 Ma) was characterized by rapid cooling of the rift shoulders and may be coeval with faulting and sedimentation in the Anza Rift basin, now located in the subsurface of the Turkana depression and areas to the east in northern Kenya. In the second phase, very slow cooling or slight reheating occurred between ~45 and 15 Ma as a result of either stable surface conditions, very slow exhumation, or subsidence. The third phase comprised renewed rapid cooling starting at ~15 Ma. This final cooling represents the most recent stage of rifting, which followed widespread flood-phonolite emplacement and has shaped the present-day landscape through rift shoulder uplift, faulting, basin filling, protracted volcanism, and erosion. When compared with thermochronologic and geologic data from other sectors of the East African Rift System, extension appears to be diachronous, spatially disparate, and partly overlapping, likely driven by interactions between mantle-driven processes and crustal heterogeneities, rather than the previously suggested north-south migrating influence of a mantle plume.

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“…Standard 4 He abundance measurements have within-run precision of better than 0.1% (1σ) and between-run precision of 0.2% (1σ) [Persano et al, 2002].…”

Section: Apatite (U-th-sm)/he Analysismentioning

confidence: 99%

Cenozoic extension in the Kenya Rift from low‐temperature thermochronology: Links to diachronous spatiotemporal evolution of rifting in East Africa

et al. 2015

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“…Observations on other Gondwanan margins suggest that most erosion occurs within 10-20 million years of the rift opening up (Persano et al, 2002). Subsequently, cooling and crustal flexure may cause subsidence and the seaward ends of the valleys are flooded by the sea.…”

Section: Hypothesismentioning

confidence: 99%

Landscape evolution of Antarctica

Jamieson¹,

Sugden²

2007

Open-File Report

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The relative roles of fluvial versus glacial processes in shaping the landscape of Antarctica have been debated since the expeditions of Robert Scott and Ernest Shackleton in the early years of the 20th century. Here we build a synthesis of Antarctic landscape evolution based on the geomorphology of passive continental margins and former northern mid-latitude Pleistocene ice sheets. What makes Antarctica so interesting is that the terrestrial landscape retains elements of a record of change that extends back to the Oligocene. Thus there is the potential to link conditions on land with those in the oceans and atmosphere as the world switched from a greenhouse to a glacial world and the Antarctic ice sheet evolved to its present state. In common with other continental fragments of Gondwana there is a fluvial signature to the landscape in the form of the coastal erosion surfaces and escarpments, incised river valleys, and a continent-wide network of river basins. A selective superimposed glacial signature reflects the presence or absence of ice at the pressure melting point. Earliest continental-scale ice sheets formed around 34 Ma, growing from local ice caps centered on mountain massifs, and featured phases of ice-sheet expansion and contraction. These ice masses were most likely cold-based over uplands and warm-based across lowlands and near their margins. For 20 million years ice sheets fluctuated on Croll-Milankovitch frequencies. At ~14 Ma the ice sheet expanded to its maximum and deepened a preexisting radial array of troughs selectively through the coastal mountains and eroded the continental shelf before retreating to its present dimensions at ~13.5 Ma. Subsequent changes in ice extent have been forced mainly by sea-level change. Weathering rates of exposed bedrock have been remarkably slow at high elevations around the margin of East Antarctica under the hyperarid polar climate of the last ~13.5 Ma, offering potential for a long quantitative record of ice-sheet evolution with techniques such as cosmogenic isotope analysis.

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“…The most recent thermal modelling of AFTT and apatite-He data from several high-elevation PCMs convincingly points to either very rapid erosion of at least the bulk of -and in some cases virtually all of -the full width of the coastal plain with its backing escarpment within 10 Myr or so of rifting and breakup, and an essentially stable escarpment thereafter (e.g., Brown et al, 2000b;Cockburn et al, 2000;Persano et al, 2002Persano et al, , 2005. These low rates of escarpment retreat after the escarpment was formed are confirmed by Late Cenozoic denudation rates of the escarpment and the coastal plain based on terrestrial cosmogenic nuclide (TCN) analysis (southern Africa, Fleming et al, 1999;Brown et al, 2000b;Bierman and Caffee, 2001;Cockburn et al, 2000;Van der Wateren and Dunai, 2001; southeastern Australia, Heimsath et al, 2000).…”

Section: Evolution Of Passive Continental Marginsmentioning

confidence: 96%

“…the Drakensberg escarpment in southeastern Africa - Brown et al, 2002) or a secondary, but still major, drainage divide between coastal rivers and rivers that initially flow inland before turning back out to the sea (e.g. the escarpment in far southeastern Australia - Persano et al, 2002Persano et al, , 2005. On type-3 escarpments, various data, including TCN measurements, point to high rates of gorge extension where the coastal rivers cross the escarpment (Nott et al, 1996;Weissel and Seidl, 1998).…”

Section: Evolution Of Passive Continental Marginsmentioning

confidence: 99%

Long‐term landscape evolution: linking tectonics and surface processes

Bishop

2007

Earth Surf Processes Landf

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Research in landscape evolution over millions to tens of millions of years slowed considerably in the mid-20th century, when Davisian and other approaches to geomorphology were replaced by functional, morphometric and ultimately process-based approaches. Hack's scheme of dynamic equilibrium in landscape evolution was perhaps the major theoretical contribution to long-term landscape evolution between the 1950s and about 1990, but it essentially 'looked back' to Davis for its springboard to a viewpoint contrary to that of Davis, as did less widely known schemes, such as Crickmay's hypothesis of unequal activity. Since about 1990, the field of long-term landscape evolution has blossomed again, stimulated by the plate tectonics revolution and its re-forging of the link between tectonics and topography, and by the development of numerical models that explore the links between tectonic processes and surface processes. This numerical modelling of landscape evolution has been built around formulation of bedrock river processes and slope processes, and has mostly focused on high-elevation passive continental margins and convergent zones; these models now routinely include flexural and denudational isostasy.Major breakthroughs in analytical and geochronological techniques have been of profound relevance to all of the above. Low-temperature thermochronology, and in particular apatite fission track analysis and (U-Th)/He analysis in apatite, have enabled rates of rock uplift and denudational exhumation from relatively shallow crustal depths (up to about 4 km) to be determined directly from, in effect, rock hand specimens. In a few situations, (U-Th)/He analysis has been used to determine the antiquity of major, long-wavelength topography. Cosmogenic isotope analysis has enabled the determination of the 'ages' of bedrock and sedimentary surfaces, and/or the rates of denudation of these surfaces. These latter advances represent in some ways a 'holy grail' in geomorphology in that they enable determination of 'dates and rates' of geomorphological processes directly from rock surfaces. The increasing availability of analytical techniques such as cosmogenic isotope analysis should mean that much larger data sets become possible and lead to more sophisticated analyses, such as probability density functions (PDFs) of cosmogenic ages and even of cosmogenic isotope concentrations (CICs). PDFs of isotope concentrations must be a function of catchment area geomorphology (including tectonics) and it is at least theoretically possible to infer aspects of source area geomorphology and geomorphological processes from PDFs of CICs in sediments ('detrital CICs'). Thus it may be possible to use PDFs of detrital CICs in basin sediments as a tool to infer aspects of the sediments' source area geomorphology and tectonics, complementing the standard sedimentological textural and compositional approaches to such issues.One of the most stimulating of recent conceptual advances has followed the considerations of the relationships between te...

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Apatite (U–Th)/He age constraints on the development of the Great Escarpment on the southeastern Australian passive margin

Cited by 114 publications

References 37 publications

Cenozoic extension in the Kenya Rift from low‐temperature thermochronology: Links to diachronous spatiotemporal evolution of rifting in East Africa

Cenozoic extension in the Kenya Rift from low‐temperature thermochronology: Links to diachronous spatiotemporal evolution of rifting in East Africa

Landscape evolution of Antarctica

Long‐term landscape evolution: linking tectonics and surface processes

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