Quantifying passive margin denudation and landscape development using a combined fission-track thermochronology and cosmogenic isotope analysis approach

Cockburn, H. A. P.; Brown, R. W.; Summerfield, Michael A.; Seidl, Michele A.

doi:10.1016/s0012-821x(00)00144-8

Cited by 172 publications

(151 citation statements)

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“…Some authors propose, therefore, that similar climatic conditions have persisted across southern Africa throughout much of the Cenozoic, and that the denudation rates estimated from cosmogenic nuclide analyses might be extrapolated over the whole of the Cenozoic (e.g. Cockburn et al, 2000). This hypothesis is now questioned by the recent recognition of at least two periods of enhanced rainfall and drainage reactivation in the past 20 Ma (Bamford, 2000;Tyson and Partridge, 2000;Brandt et al, 2005).…”

Section: Discussionmentioning

confidence: 99%

“…Fleming et al, 1999;Cockburn et al, 2000;Brown et al, 2000;Bierman and Caffee, 2001; Van der Wateren and Dunai, 2001;Brown et al, 2002;Raab et al, 2002;Bierman and Nichols, 2004;Tinker, 2005; Tinker et al, in review; Kounov et al, in review). These studies suggest that since the onset of the rifting phase, significant changes in denudation rates have occurred, in particular a substantial decrease when Cenozoic rates are compared to those for the Cretaceous.…”

Section: Introductionmentioning

confidence: 99%

“…These studies suggest that since the onset of the rifting phase, significant changes in denudation rates have occurred, in particular a substantial decrease when Cenozoic rates are compared to those for the Cretaceous. The high denudation rates during the Cretaceous are likely related to intense tectonic activity coupled with warm and humid climatic conditions, whereas the more arid climate that prevailed during the Quaternary and possibly throughout much of the Tertiary, and an apparent lack of significant uplift, were responsible for a remarkable subsequent decrease in the denudation rates 2002;Cockburn et al, 2000;Tinker, 2005;Kounov et al, in review).…”

Section: Introductionmentioning

confidence: 99%

“…Along the relatively dry west coast (Atlantic Ocean), Cockburn et al (2000) reported cosmogenic 10 Be and 26 Al concentrations for siliciclastic rocks from the Gamsberg escarpment area in Namibia. Their results suggest a mean rate of horizontal escarpment retreat of ~ 10 m/Ma and vertical downwearing at its summit of 0.4 m/Ma, and a mean denudation rate of coastal inselbergs of ~5 m/Ma (Figure 1).…”

Section: Introductionmentioning

confidence: 99%

“…In contrast to the relatively short-lived radionuclide 36 Cl (T1 / 2 = 0.3 Ma), the stable noble gas isotopes are ideally suited to study relatively long exposure histories (low denudation rates) in lithologies such as the Karoo dolerites, from which pyroxene phenocrysts can be Cockburn et al, 2000) and Drakensberg (Fleming et al, 1999) separated. Reliable measurements of the radionuclides 10 Be and 26 Al (T1 / 2 = 1.5 and 0.7 Ma, respectively), on the other hand, are at present only possible in quartz, where 21 Ne analyses have also been successfully applied (e.g.…”

Section: Introductionmentioning

confidence: 99%

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Present denudation rates at selected sections of the South African escarpment and the elevated continental interior based on cosmogenic 3He and 21Ne

Kounov

Niedermann

Wit

et al. 2007

South African Journal of Geology

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Originally published as:Kounov, A., Niedermann, S., Viola, G., Andreoli, M., Erzinger, J. (2007) IntroductionSince the break-up of Gondwana, Southern Africa has been surrounded by elevated passive margins flanked by a classic escarpment (King, 1951;1967). The evolution of passive continental margins and their adjacent escarpments reflects the long-term interaction of tectonic and surface processes. It is now known that passive margin morphology is the result of positive and negative feedback between tectonic uplift and subsidence on the one hand and sedimentation and denudation on the other hand (Beaumont et al., 2000).Apatite fission track and cosmogenic nuclide studies along the escarpment-flanked continental margin of Southern Africa have recently revealed variable denudation rates for various morphological features of the passive margin, including its coastal plain, the seaward-facing escarpment and the elevated inland plateau (e.g. Fleming et al., 1999;Cockburn et al., 2000;Brown et al., 2000;Bierman and Caffee, 2001; Van der Wateren and Dunai, 2001;Brown et al., 2002;Raab et al., 2002;Bierman and Nichols, 2004;Tinker, 2005; Tinker et al., in review; Kounov et al., in review). These studies suggest that since the onset of the rifting phase, significant changes in denudation rates have occurred, in particular a substantial decrease when Cenozoic rates are compared to those for the Cretaceous. The high denudation rates during the Cretaceous are likely related to intense tectonic activity coupled with warm and humid climatic conditions, whereas the more arid climate that prevailed during the Quaternary and possibly throughout much of the Tertiary, and an apparent lack of significant uplift, were responsible for a remarkable subsequent decrease in the denudation African coastal escarpment and the interior plateau provide valuable estimates of the short-term (i.e., a few hundred thousand years) denudation rates. Present-day denudation rates at the summit of the escarpment and on the inland plateau are more than an order of magnitude lower than those in the Cretaceous. Values between 1.0 and 2.1 m/Ma obtained from resistant quartzite samples and between 1.5 and 3 m/Ma from dolerite sills suggest a strong lithology control on the erosion. The observed patterns of denudation across different landform sites on the high plateau and along its flanking escarpment suggest that the morphology of the sampling sites together with the local climate conditions have controlled the denudation processes.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Present denudation rates at selected sections of the South African escarpment and the elevated continental interior based on cosmogenic 3He and 21Ne

Kounov

Niedermann

Wit

et al. 2007

South African Journal of Geology

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The chronology and tectonic style of landscape evolution along the elevated Atlantic continental margin of South Africa resolved by joint apatite fission track and (U‐Th‐Sm)/He thermochronology

et al. 2016

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Atlantic-type continental margins have long been considered "passive" tectonic settings throughout the entire postrift phase. Recent studies question the long-term stability of these margins and have shown that postrift uplift and reactivation of preexisting structures may be a common feature of a continental margin's evolution. The Namaqualand sector of the western continental margin of South Africa is characterized by a ubiquitously faulted basement but lacks preservation of younger geological strata to constrain postrift tectonic fault activity. Here we present the first systematic study using joint apatite fission track and apatite (U-Th-Sm)/He thermochronology to achieve a better understanding on the chronology and tectonic style of landscape evolution across this region. Apatite fission track ages range from 58.3 ± 2.6 to 132.2 ± 3.6 Ma, with mean track lengths between 10.9 ± 0.19 and 14.35 ± 0.22 μm, and mean (U-Th-Sm)/He sample ages range from 55.8 ± 31.3 to 120.6 ± 31.4 Ma. Joint inverse modeling of these data reveals two distinct episodes of cooling at approximately 150-130 Ma and 110-90 Ma with limited cooling during the Cenozoic. Estimates of denudation based on these thermal histories predict approximately 1-3 km of denudation coinciding with two major tectonic events. The first event, during the Early Cretaceous, was driven by continental rifting and the development and removal of synrift topography. The second event, during the Late Cretaceous, includes localized reactivation of basement structures as well as regional mantle-driven uplift. Relative tectonic stability prevailed during the Cenozoic, and regional denudation over this time is constrained to be less than 1 km.

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Contrasting Mesozoic evolution across the boundary between on and off craton regions of the South African plateau inferred from apatite fission track and (U‐Th‐Sm)/He thermochronology

et al. 2017

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The timing and mechanisms involved in creating the elevated, low‐relief topography of the South African plateau remain unresolved. Here we constrain the thermal history of the Southwest African plateau since 300 Ma by using apatite fission track (AFT) and (U‐Th‐Sm)/He (AHe) thermochronology. Archean rocks from the center of the Kaapvaal Craton yield AFT ages of 331.0 ± 11.0 and 379.0 ± 23.0 Ma and mean track lengths (MTLs) of 11.9 ± 0.2 and 12.5 ± 0.3 µm. Toward the southwest margin of the craton and in the adjacent Paleozoic mobile belt, AFT ages are significantly younger and range from 58.9 ± 5.9 to 128.7 ± 6.3 Ma and have longer MTLs (>13 µm). The range of sample AHe ages complements the AFT ages, and single‐grain AHe ages for most samples are highly dispersed. Results from joint inverse modeling of these data reveal that the center of the craton has resided at near‐surface temperatures (<60°C) since 300 Ma, whereas the margins of the craton and the off‐craton mobile belt experienced two discrete episodes of cooling during the Cretaceous. An Early Cretaceous cooling episode is ascribed to regional denudation following continental breakup. Late Cretaceous cooling occurs regionally but is locally variable and may be a result of a complex interaction between mantle‐driven uplift and the tectonic setting of the craton margin. Across the entire plateau, samples are predicted to have remained at near‐surface temperatures throughout the Cenozoic, suggesting minimal denudation (<1 km) and relative tectonic stability of the plateau.

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Quantifying passive margin denudation and landscape development using a combined fission-track thermochronology and cosmogenic isotope analysis approach

Cited by 172 publications

References 12 publications

Present denudation rates at selected sections of the South African escarpment and the elevated continental interior based on cosmogenic 3He and 21Ne

Present denudation rates at selected sections of the South African escarpment and the elevated continental interior based on cosmogenic 3He and 21Ne

The chronology and tectonic style of landscape evolution along the elevated Atlantic continental margin of South Africa resolved by joint apatite fission track and (U‐Th‐Sm)/He thermochronology

Contrasting Mesozoic evolution across the boundary between on and off craton regions of the South African plateau inferred from apatite fission track and (U‐Th‐Sm)/He thermochronology

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