Relict non-glacial surfaces in formerly glaciated landscapes

Goodfellow, Bradley W.

doi:10.1016/j.earscirev.2006.08.002

Cited by 81 publications

(44 citation statements)

References 217 publications

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“…The absence of glacial evidence on a particular unit does not necessarily preclude the possibility of it having been covered for some time after it formed, as long as the snow and ice was relatively stagnant and generated little erosion. Ice toward the stable interior of an ice sheet might have low velocity compared with the more active outer margins, or, if conditions were cold enough, the base of the ice could have been frozen to the underlying bedrock, as occurs in some polar glaciers (e.g., Goodfellow 2007). Thin glaciers are unlikely to flow, and it is therefore possible that some tuyas could have experienced extended periods of ice burial without exhibiting much surface damage.…”

Section: Subaerial Lava Surfacesmentioning

confidence: 95%

Effects of deglaciation on the petrology and eruptive history of the Western Volcanic Zone, Iceland

2015

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New observations and geochemical analyses of volcanic features in the 170-km-long Western Volcanic Zone (WVZ) of Iceland constrain spatial and temporal variations in volcanic production and composition associated with the last major deglaciation. Subglacial eruptions represent a significant portion of the late Quaternary volcanic budget in Iceland. Individual features can have volumes up to ∼48 km 3 and appear to be monogenetic. Subaqueous to subaerial transition zones provide minimum estimates of ice sheet thickness at the time of eruption, although water-magma interactions and fluctuating lake levels during eruption can lead to complex lithological sequences. New major and trace element data for 36 glacial and postglacial eruptive units, combined with observations of lava surface quality, passage zone heights, and 3 He exposure ages of some glacial units, indicate a maximum in volcanic production in the WVZ during the last major ice retreat. Anomalously high volcanic production rates continue into the early postglacial period and coincide with significant incompatible element depletions and slightly higher CaO and SiO 2 and lower FeO content at a given MgO. Subglacial units with strong incompatible element depletions also have lava surfaces that lack evidence of subsequent glaciation. These units likely formed after the onset of deglaciation, when rapidly melting ice sheets increased decompression rates in the underlying mantle, leading to anomalously high melting rates in the depleted upper mantle. This process also can explain the eruption of extremely depleted picritic lavas during the early postglacial period. These new observations indicate that the increased volcanic activity associated with glacial unloading peaked earlier than previously thought, before Iceland was completely ice free.

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Section: Subaerial Lava Surfacesmentioning

confidence: 95%

Effects of deglaciation on the petrology and eruptive history of the Western Volcanic Zone, Iceland

2015

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“…According to Colman (1981), the rate of weathering is constant only when an equilibrium thickness of the residue is reached. Generally, the rate of weathering changes substantially with climate conditions, oscillating between rapid deterioration of the rock surface during the interglacial period and slow modifi cations to the rock surface under cold and dry glacial conditions (Goodfellow, 2007). Thus, the linear weathering rate is not valid, at least for evaluating age in surfaces originating prior to the Holocene.…”

Section: Effective Age Range Of Schmidt Hammer Datingmentioning

confidence: 98%

Surface and sub‐surface Schmidt hammer rebound value variation for a granite outcrop

Černá

Engel

2011

Earth Surf Processes Landf

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This study presents rock strength variations at granite outcrops and in subsurface vertical profi les in the Jizerské hory Mountains, Czech Republic. Schmidt hammer rebound values in subsurface profi les change gradually from the bedrock surface downward. An exponential relation has been observed between the R-values and depth in rock outcrops to a depth of around 4·5 m. The exponential nature of the curve indicates that rock hardness increases more rapidly with depth in the uppermost 1 m section of the rock profi le. A detailed study of rebound values obtained from both intact and polished rock exposures reveal effects of surface grinding on results of the Schmidt hammer method. The range of data collected increases after grinding, allowing more precise discrimination of rock surfaces in respect of age and weathering. The Schmidt hammer method may be used effectively as a relative-age dating tool for rock surfaces that originated during the Late Pleistocene. It is concluded that this time limitation can be signifi cantly mitigated by surface grinding before measurement.

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“…Cold-based ice, frozen to its bed, effectively protects the surface and any erosional effects and associated sediments are uncommon and distinctive (e.g. Gellatly et al 1988;Stroeven and Klemen 1999;Atkins et al 2002;Fabel et al 2002;Goodfellow 2007;Lewis et al 2007). A cold and arid Antarctic climate may also have been responsible for the virtual lack of denudation of the surfaces of the tuff cone and cinder cone landforms interbedded with the lava-fed deltas, and it is a logical explanation for the remarkable absence of outwash sediments, sedimentary lacustrine deposits, ice-marginal channel and kame terrace deposits and/or other glaciofluvial/waterlain sediments.…”

Section: Evidence For Basal Thermal Regimementioning

confidence: 99%

Late Miocene volcanic sequences in northern Victoria Land, Antarctica: products of glaciovolcanic eruptions under different thermal regimes

2010

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Late Miocene (c. 13-5 Ma) volcanic sequences of the Hallett Volcanic Province (HVP) crop out along >250 km of western Ross Sea coast in northern Victoria Land. Eight primary volcanic and six sedimentary lithofacies have been identified, and they are organised into at least five different sequence architectures as a consequence of different combinations of eruptive and/or depositional conditions. The volcanoes were erupted in association with a Miocene glacial cover and the sequences are overwhelmingly glaciovolcanic. The commonest and most representative are products of mafic aa lava-fed deltas, a type of glaciovolcanic sequence that has not been described before. It is distinguished by (1) a subaerially emplaced relatively thin caprock of aa lavas lying on and passing down-dip into (2) a thicker association of chaotic to crudely bedded hyaloclastite breccias, water-chilled lava sheets and irregular lava masses, collectively called lobe-hyaloclastite. A second distinctive sequence type present is characterised by water-cooled lavas and associated sedimentary lithofacies (diamictite (probably glacigenic) and fluvial sands and gravels) similar to some mafic glaciovolcanic sheet-like sequences (see Smellie, Earth-Science Reviews, 74, 241-268, 2008), but including (for the first time) examples of likely sheet-like sequences with felsic compositions. Other sequence types in the HVP are minor and include tuff cones, cinder cones and a single ice-marginal lacustrine sequence. The glacial thermal regime varied from polar, characterised by sequences lacking glacial erosion, glacigenic sediments or evidence for free water, to temperate or sub-polar for sequences in which all of these features are conspicuously developed.

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Relict non-glacial surfaces in formerly glaciated landscapes

Cited by 81 publications

References 217 publications

Effects of deglaciation on the petrology and eruptive history of the Western Volcanic Zone, Iceland

Effects of deglaciation on the petrology and eruptive history of the Western Volcanic Zone, Iceland

Surface and sub‐surface Schmidt hammer rebound value variation for a granite outcrop

Late Miocene volcanic sequences in northern Victoria Land, Antarctica: products of glaciovolcanic eruptions under different thermal regimes

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