Ice thickness and topographic relief in glaciated landscapes of the western USA

Brocklehurst, Simon H.; Whipple, K. X.; Foster, David A.

doi:10.1016/j.geomorph.2007.02.037

Cited by 22 publications

(19 citation statements)

References 39 publications

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“…However, rapid rock uplift and river incision must have occurred since c. 10 Ma, consistent with previous constraints on the uplift of the Frontal Cordillera. Stream profile analysis shows specific regions of the Frontal Cordillera where headwall relief is very pronounced, which we interpret to reflect a zone of active rock uplift, similar to that observed by Brocklehurst et al (2008). This zone of active uplift also corresponds to where the highest non-volcanic relief occurs in both catchments.…”

Section: Resultssupporting

confidence: 74%

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Near pure surface uplift of the Argentine Frontal Cordillera: insights from (U–Th)/He thermochronometry and geomorphic analysis

Hoke

Graber

Mescua³

et al. 2014

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Apatite (U-Th)/He thermochronology from palaeosurface-bounded vertical transects collected in deeply incised river valleys with .2 km of relief, as well as geomorphic analysis, are used to examine the timing of uplift of the Frontal Cordillera and its relation to the evolution of the proximal portions of the Andean foreland between 328 and 348S latitude. The results of apatite (U-Th)/He (AHe) analyses are complex. However, the data show positive age-elevation trends, with higher elevation samples yielding older AHe ages than samples at lower elevation. Slope breaks occur at c. 25 Ma in both profiles, separating very slow cooling and or residence within a partial retention zone (slope of c. 10 m/Myr) at the highest elevations from a slope of c. 60-100 m/ Myr cooling rate at lower elevations. The older AHe ages suggest either (1) minimal burial of the Frontal Cordillera and/or (2) significant pre -middle Miocene local relief. Geomorphic analysis of the adjacent, east-draining Río Mendoza and Río Tunuyán catchments reveals a glacial imprint to the landscape at elevations above 3000 m, including greater channel steepness and lower profile concavities developed during glacial erosion. Detailed analysis of headwall heights provides evidence of ongoing rock uplift along the entire eastern flank of the Frontal Cordillera and in the eastern flank of the Principal Cordillera south of the slab dip transition.

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Section: Resultssupporting

confidence: 74%

“…4c). Geomorphic analysis (Brocklehurst & Whipple 2007;Brocklehurst et al 2008) of the three arc-second resolution Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM) is employed to identify areas currently undergoing rock uplift.…”

mentioning

confidence: 99%

Near pure surface uplift of the Argentine Frontal Cordillera: insights from (U–Th)/He thermochronometry and geomorphic analysis

Hoke

Graber

Mescua³

et al. 2014

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“…For each valley the LGM trimline was mapped using a combination of slope and hillshade maps processed from 10-m-resolution USGS digital elevation models (DEMs), topographic maps, and high-resolution aerial photos on GoogleEarth™ and NASA WorldWind™. A combination of four key features in the valley wall were used to identify the LGM trimline: (i) the transition from smooth to rough bedrock surfaces that defines those portions of the valley wall that have been glacially eroded versus those that were continuously subaerially exposed; (ii) where the gradient of the valley side changes because of the oversteepening of the lower valley wall by glacial erosion; (iii) where talus and scree deposits mantle the lower valley sides, we mark the trimline as corresponding to the top of talus cones, which tend to mark the top of the steepened valley wall (from our field observations, and those of Gillespie (1982) and Brocklehurst et al (2008)); and (iv) in the ablation zone, the ridgelines of the outermost moraines are taken to represent the position of the LGM glacier terminus (Fig. 3A,B).…”

Section: Ela Estimatesmentioning

confidence: 92%

Small valley glaciers and the effectiveness of the glacial buzzsaw in the northern Basin and Range, USA

2008

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“…To understand the former distribution of glaciers, LGM ice extents are reconstructed following the methods of Brocklehurst et al [2008] and Foster et al [2008]. In each valley, LGM trimlines are mapped using a combination of topographic maps, field observations, and aerial photography draped onto DEMs and viewed in virtual globes (NASA Worldwind™ and GoogleEarth™).…”

Section: Methodsmentioning

confidence: 99%

Glacial‐topographic interactions in the Teton Range, Wyoming

2010

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[1] Understanding interactions among tectonics, topography, climate, and erosion is fundamental to studies of mountainous landscapes. Here, we combine topographic analyses with modeled distributions of precipitation, insolation, and flexural isostasy to present a conceptual model of topographic evolution in the Teton Range, Wyoming, and test whether efficient glacial relief production has contributed to summit elevations. The conceptual model reveals a high degree of complexity inherent in even a relatively small, glaciated, mountain range. Back tilting has caused topographic asymmetry, with the greatest relief characterizing eastern catchments in the center of the range. Two high summits, Grand Teton and Mount Moran, rise hundreds of meters above the surrounding landscape; their elevations set by the threshold hillslope angle and the spacing between valleys hosting large, erosionally efficient glaciers. Only basins >20 km 2 held glaciers capable of eroding sufficiently rapidly to incise deeply and maintain shallow downvalley gradients on the eastern range flank. Glacial erosion here was promoted by (1) prevailing westerly winds transporting snow to high-relief eastern basins, leading to cross-range precipitation asymmetry; (2) the wind-blown redistribution of snow from open western headwaters into sheltered eastern cirques, with the associated erosion-driven migration of the drainage divide increasing eastern accumulation areas; and (3) tall, steep hillslopes providing shading, snow influx from avalanching, and insulating debris cover from rockfalls to valley floor glaciers. In comparison, the topographic enhancement of glacial erosion was less pronounced in western, and smaller eastern, basins. Despite dramatic relief production, insufficient rock mass is removed from the Teton Range to isostatically raise summit elevations.

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Ice thickness and topographic relief in glaciated landscapes of the western USA

Cited by 22 publications

References 39 publications

Near pure surface uplift of the Argentine Frontal Cordillera: insights from (U–Th)/He thermochronometry and geomorphic analysis

Near pure surface uplift of the Argentine Frontal Cordillera: insights from (U–Th)/He thermochronometry and geomorphic analysis

Small valley glaciers and the effectiveness of the glacial buzzsaw in the northern Basin and Range, USA

Glacial‐topographic interactions in the Teton Range, Wyoming

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