A new technique for identifying rock avalanche–sourced sediment in moraines and some paleoclimatic implications

Reznichenko, Natalya; Davies, Timothy R. H.; Shulmeister, James; Larsen, Stuart

doi:10.1130/g32684.1

Cited by 51 publications

(48 citation statements)

References 22 publications

(18 reference statements)

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“…, as well as sedimentological evidence, can be used to distinguish between landslide deposits and moraine. Reznichenko et al (2012) have shown that traces of rock avalanche debris in moraines can be identified by the presence of agglomerations of extremely fine particles produced during rock avalanche motion. Their technique has increased our ability to identify rock avalanches that have been emplaced onto glaciers in the past and would otherwise be indistinguishable from other debris types within the moraine.…”

Section: Rock Slope Stability In a Changing Climatementioning

confidence: 99%

Paraglacial rock-slope stability

2012

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Section: Rock Slope Stability In a Changing Climatementioning

confidence: 99%

Paraglacial rock-slope stability

2012

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“…Careful examination of these materials can, however, reveal sedimentary properties diagnostic of a rock avalanche origin, despite considerable alteration (Fauqué et al, 2009;Reznichenko et al, 2012). Careful examination of these materials can, however, reveal sedimentary properties diagnostic of a rock avalanche origin, despite considerable alteration (Fauqué et al, 2009;Reznichenko et al, 2012).…”

Section: Rock Avalanche Deposits and Sedimentary Propertiesmentioning

confidence: 99%

“…However, though infrequent, large volume and long-runout events can have powerful influences on glacier dispersed by glacier transport; (2) widespread misclassifying of rock avalanche deposits as moraines (Heim, 1932;Porter and Orombelli, 1980;Hewitt, 1999;Prager et al, 2009;McColl and Davies, 2011); and (3) recognition that some moraines result from supraglacial rock avalanche deposits rather than from climatic variation (Reznichenko et al, 2012). The more frequent, smaller events may have a significant role as they affect virtually all mountain glaciers seasonally every year.…”

Section: Introductionmentioning

confidence: 99%

Rock Avalanches onto Glaciers

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Hewitt

Reznichenko

et al. 2015

Landslide Hazards, Risks, and Disasters

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“…This accumulating debris serves as a source of material for moraine construction (Reznichenko et al, 2011(Reznichenko et al, , 2012 but can also insulate a glacier and dampen its response to climate (Kirkbride and Warren, 1999;Anderson, 2000;Scherler et al, 2011) and can even trigger phases of glacier advance (see Tovar et al, 2008;Hewitt, 2009). Where steep slopes overlook a glacier's surface, debris accumulation can be considerable, and glaciers can persist far below the regional climatic ELA (Scherler et al, 2011) -with a direct impact on where moraines are deposited.…”

Section: Accumulation Area Topography and Controls On Debris Supplymentioning

confidence: 99%

A review of topographic controls on moraine distribution

2014

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Ice-marginal moraines are often used to reconstruct the dimensions of former ice masses, which are then used as proxies for palaeoclimate. This approach relies on the assumption that the distribution of moraines in the modern landscape is an accurate reflection of former ice margin positions during climatically controlled periods of ice margin stability. However, the validity of this assumption is open to question, as a number of additional, nonclimatic factors are known to influence moraine distribution. This review considers the role played by topography in this process, with specific focus on moraine formation, preservation, and ease of identification (topoclimatic controls are not considered). Published literature indicates that the importance of topography in regulating moraine distribution varies spatially, temporally, and as a function of the ice mass type responsible for moraine deposition. In particular, in the case of ice sheets and ice caps ( > 1000 km 2 ), one potentially important topographic control on where in a landscape moraines are deposited is erosional feedback, whereby subglacial erosion causes ice masses to become less extensive over successive glacial cycles. For the marine-terminating outlets of such ice masses, fjord geometry also exerts a strong control on where moraines are deposited, promoting their deposition in proximity to valley narrowings, bends, bifurcations, where basins are shallow, and/or in the vicinity of topographic bumps. Moraines formed at the margins of ice sheets and ice caps are likely to be large and readily identifiable in the modern landscape. In the case of icefields and valley glaciers (10-1000 km 2 ), erosional feedback may well play some role in regulating where moraines are deposited, but other factors, including variations in accumulation area topography and the propensity for moraines to form at topographic pinning points, are also likely to be important. This is particularly relevant where land-terminating glaciers extend into piedmont zones (unconfined plains, adjacent to mountain ranges) where large and readily identifiable moraines can be deposited. In the case of cirque glaciers (< 10 km 2 ), erosional feedback is less important, but factors such as topographic controls on the accumulation of redistributed snow and ice and the availability of surface debris, regulate glacier dimensions and thereby determine where moraines are deposited. In such cases, moraines are likely to be small and particularly susceptible to post-depositional modification, sometimes making them difficult to identify in the modern landscape. Based on this review, we suggest that, despite often being difficult to identify, quantify, and mitigate, topographic controls on moraine distribution should be explicitly considered when reconstructing the dimensions of palaeoglaciers and that moraines should be judiciously chosen before being used as indirect proxies for palaeoclimate (i.e., palaeoclimatic inferences should only be drawn from moraines when topographic controls on mora...

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A new technique for identifying rock avalanche–sourced sediment in moraines and some paleoclimatic implications

Cited by 51 publications

References 22 publications

Paraglacial rock-slope stability

Paraglacial rock-slope stability

Rock Avalanches onto Glaciers

A review of topographic controls on moraine distribution

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