Age and uplift rates of Sirius Group sediments in the Dominion Range, Antarctica, from surface exposure dating and geomorphology

Ackert, Robert P.; Kurz, Mark D.

doi:10.1016/j.gloplacha.2004.02.001

Cited by 66 publications

(39 citation statements)

References 51 publications

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“…At issue, however, is the proposed age of the wet-based deposits in the Beardmore region. Interbedded marine microfossils suggest a Pliocene age (Webb et al, 1996), whereas cosmogenic nuclide ages of boulders offset by faults that crosscut cold-based moraines stratigraphically younger than the wet-based Meyer Desert Formation indicate a pre-Pliocene age of older than 5 Ma (Ackert and Kurz, 2004). The similarity in the transition from wet-to cold-based glacial deposits both in the western Olympus Range and in the Beardmore region strongly suggests a shared climatic forcing.…”

Section: Regional Considerationsmentioning

confidence: 97%

Major middle Miocene global climate change: Evidence from East Antarctica and the Transantarctic Mountains

Lewis

Marchant

Ashworth

et al. 2006

Geol Soc America Bull

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We present a glacial record from the western Olympus Range, East Antarctica, that documents a permanent shift in the thermal regime of local glaciers, from wet-to coldbased regimes, more than 13.94 m.y. ago. This glacial record provides the fi rst terrestrial evidence linking middle Miocene global climate cooling to a permanent reorganization of the Antarctic cryosphere and to subsequent growth of the polar East Antarctic Ice Sheet. The composite stratigraphic record constructed from fi eld mapping and analyses of 281 soil excavations shows a classic wetbased till (Circe till, including an extensive melt-out facies), overlain by a weathered colluvial deposit (Electra colluvium), and then a series of stacked tills deposited from cold-based ice (Dido drift). Chronologic control comes from 40 Ar/ 39 Ar analyses of concentrated ash-fall deposits interbedded within glacial deposits. The shift from wetto cold-based glaciation refl ects a drop in mean annual temperature of 25-30 °C and is shown to precede one or more major episodes of ice-sheet expansion across the region, the youngest of which occurred between 13.62 and 12.44 Ma. One implication is that atmospheric cooling, following a relatively warm mid-Miocene climatic optimum ca. 17 to 15 Ma, may have led to, and thus triggered, maximum ice-sheet overriding.

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Section: Regional Considerationsmentioning

confidence: 97%

Major middle Miocene global climate change: Evidence from East Antarctica and the Transantarctic Mountains

Lewis

Marchant

Ashworth

et al. 2006

Geol Soc America Bull

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“…Surface exposure ages of Beardmore moraine boulders overlying the Meyer Desert Formation, and offset by faults, are between 1.9-5.8 Ma (Ackert and Kurz 2004). The estimate assumed no erosion and constant elevation leading the authors of the study to conclude that the Meyer Desert Formation had to be much older than c.3 Ma.…”

Section: Location and Stratigraphy Of The Meyer Desert Formationmentioning

confidence: 99%

Antarctotrechus balli sp. n. (Carabidae, Trechini): the first ground beetle from Antarctica

Ashworth

Erwin

2016

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Fossil elytra of a small trechine carabid are reported from the Oliver Bluffs on the Beardmore Glacier at lat. 85°S. They were compared with counterparts from the extant genera Trechisibus, Tasmanorites, Oxytrechus and Pseudocnides. The fossils share some characters but are sufficiently different to be described as a new genus and species. We named the new species Antarctotrechus balli in honour of George E. Ball who made major contributions to the study of carabids through his own research and the training of students while at the University of Alberta, Edmonton, Alberta, Canada. The closest extant relatives to the extinct Antarctotrechus balli are species of Trechisibus, which inhabit South America, the Falkland Islands and South Georgia, and Tasmanorites, which inhabit Tasmania, Australia. Plant fossils associated with Antarctotrechus balli included Nothofagus (southern beech), Ranunculus (buttercup), moss mats and cushion plants that were part of a tundra biome. Collectively, the stratigraphic relationships and the growth characteristics of the fossil plants indicate that Antarctotrechus balli inhabited the sparsely-vegetated banks of a stream that was part of an outwash plain at the head of a fjord in the Transantarctic Mountains. Other insects represented by fossils in the tundra biome include a listroderine weevil and a cyclorrhaphan fly. The age of the fossils, based on comparison of associated pollen with 40Ar/39Ar dated pollen assemblages from the McMurdo Dry Valleys, is probably Early to Mid-Miocene in the range 14–20 Ma. The tundra biome, including Antarctotrechus balli, became extinct in the interior of Antarctica about 14 Ma and on the margins of the continent by 10–13 Ma. Antarctotrechus balli confirms that trechines were once widely distributed in Gondwana. For Antarctotrechus balli and other elements of the tundra biome it appears they continued to inhabit a warmer Antarctica for many millions of years after rifting of Tasmania (45 Ma) and southern South America (31 Ma).

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“…Some of the major findings are as follows: (1) near-surface deposits in the stable upland zone have not been reworked by wet active-layer cryoturbation for at least the last several million years (Putkonen et al 2008a;Morgan et al 2010a, b; see also Schiller et al 2009); (2) the topographical diffusivity in the stable upland zone is the lowest of any region measured on Earth (Putkonen et al 2012); (3) erosion rates for exposed bedrock (Schaefer et al 1999;Summerfield et al 1999;Ackert & Kurz 2004) and regolith (Morgan et al 2010a) are among the lowest on Earth , reaching approximately 5-20 cm Ma 21 in the stable upland zone (and c. 1-2 m Ma 21 in the coastal thaw zone); and (4) the oldest surfaces at high elevations in the stable upland zone are at least about 12 -14 Ma (Schaefer et al 1999(Schaefer et al , 2000Margerison et al 2005). …”

Section: Cosmogenic Nuclide Analysesmentioning

confidence: 99%

A review of geomorphic processes and landforms in the Dry Valleys of southern Victoria Land: implications for evaluating climate change and ice-sheet stability

Marchant

Mackay

Lamp

et al. 2013

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The Dry Valleys are subdivided into three microclimate zones on the basis of summertime measurements of atmospheric temperature, soil moisture, relative humidity and wind-speed/ direction. Subtle variations in these climate parameters result in considerable differences in process geomorphology and in the development of unique landforms within each zone. The mapped zones include a coastal thaw zone, an inland mixed zone and a stable upland zone. Landforms within each zone are subdivided into macroscale features (e.g. valleys, slopes and gullies), mesoscale features (e.g. polygons and viscous-flow features) and microscale features (e.g. rock and near-surface soil features, including the effects of salt weathering, wind erosion and pitting). We present a review of landscape development in the Dry Valleys with implications for long-term climate change and icesheet stability. Chronological control is afforded by 40 Ar/ 39 Ar dating of volcanic ash-fall deposits and cosmogenic nuclide analyses of surface boulders. Collectively, the data call for persistent cold and dry conditions in the stable upland zone for approximately the last 14 Ma, although some level of climatic amelioration and landform modification may have occurred within low-lying regions and in the inland mixed zone. ) SUZ Beacon Valley* (1176 m a.s.l., 74 km from the coast) 210 (222) 28 (218) 212 (225) 25 (222) 26 (221) 41 (43) Mullins Valley ‡ (1401 m a.s.l, 81 km from the coast) 211 (223) 27 (218) 215 (227) 28 (223) 210 (223) 47 (50) CTZ, coastal thaw zone; IMZ, inland mixed zone; SUZ, stable upland zone; m a.s.l, metres above sea level. Summer defined as December, January and February; annual conditions shown in parenthesis.

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Age and uplift rates of Sirius Group sediments in the Dominion Range, Antarctica, from surface exposure dating and geomorphology

Cited by 66 publications

References 51 publications

Major middle Miocene global climate change: Evidence from East Antarctica and the Transantarctic Mountains

Major middle Miocene global climate change: Evidence from East Antarctica and the Transantarctic Mountains

Antarctotrechus balli sp. n. (Carabidae, Trechini): the first ground beetle from Antarctica

A review of geomorphic processes and landforms in the Dry Valleys of southern Victoria Land: implications for evaluating climate change and ice-sheet stability

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