The Tekapo Glacier, New Zealand, during the Last Glacial Maximum: An active temperate glacier influenced by intermittent surge activity

Sutherland, Jenna L.; Carrivick, Jonathan L.; Evans, David J. A.; Shulmeister, James; Quincey, Duncan J.

doi:10.1016/j.geomorph.2019.07.008

Cited by 22 publications

(18 citation statements)

References 272 publications

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“…Once the Pukaki Glacier became lake terminating, its terminus recession was likely partially decoupled from climate. Such hypotheses have been previously proposed in New Zealand for other glaciers (e.g., Shulmeister et al, 2019; Sutherland, Carrivick, Evans, et al, 2019; Sutherland, Carrivick, Shulmeister, et al, 2019) and have been confirmed for glaciers elsewhere by empirical data, for example, from Patagonia (Bendle et al, 2019). This partial decoupling of glacier behavior from climate is potentially important for interpreting the evolution of New Zealand mountain glaciers, particularly over decadal timescales.…”

Section: Discussionsupporting

confidence: 56%

Proglacial Lakes Control Glacier Geometry and Behavior During Recession

Sutherland

Carrivick

Gandy

et al. 2020

Geophysical Research Letters

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Ice-contact proglacial lakes are generally absent from numerical model simulations of glacier evolution, and their effects on ice dynamics and on rates of deglaciation remain poorly quantified. Using the BISICLES ice flow model, we analyzed the effects of an ice-contact lake on the Pukaki Glacier, New Zealand, during recession from the Last Glacial Maximum. The ice-contact lake produced a maximum effect on grounding line recession >4 times further and on ice velocities up to 8 times faster, compared to simulations of a land-terminating glacier forced by the same climate. The lake contributed up to 82% of cumulative grounding line recession and 87% of ice velocity during the first 300 years of the simulations, but those values decreased to just 6% and 37%, respectively, after 5,000 years. Numerical models that ignore lake interactions will, therefore, misrepresent the rate of recession especially during the transition of a land-terminating to a lake-terminating environment. Plain Language Summary Lakes form at the margins of glaciers as meltwater accumulates against hillsides and behind ridges of glacier debris. Lakes at a glacier terminus are known to affect its behavior. However, glaciers terminating into such lakes are usually absent from computer simulations, and the effects of these lakes on the rates of deglaciation and on glacier behavior are poorly quantified. In this study, we tested the effect of a lake on glacier recession under two different scenarios; a land-terminating versus a lake-terminating glacier. We used an ice flow model called BISICLES and applied it to what was once the Pukaki Glacier in New Zealand during the end of the last ice age. We found that the presence of a lake caused the glacier to recede more than 4 times further and it accelerated ice flow by up to 8 times when compared to the same glacier that terminated on land under the same climate. Our simulated lake processes predominantly influenced the glacier over decades to centuries rather than over millennia. We suggest, therefore, that simulations of glacier evolution ignoring glacial lakes will likely misrepresent the timing and rate of recession, especially during the transition from a land-terminating to a lake-terminating environment. Recent observations, both field-based (e.g., Watson et al., 2020) and via satellite imagery (e.g., King et al., 2019), have highlighted the spatiotemporal frequency and magnitude of changes in glacial lakes and the associated glaciers that feed meltwater to them. However, field-based measurements are limited to

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Section: Discussionsupporting

confidence: 56%

Proglacial Lakes Control Glacier Geometry and Behavior During Recession

Sutherland

Carrivick

Gandy

et al. 2020

Geophysical Research Letters

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“…Based on our investigation it is reasonable to assume that glaciation in the Ahuriri River valley was smaller in scale than those in other river valleys in the Waitaki River basin (e.g. Putnam et al, 2013;Strand et al, 2019;Sutherland et al, 2019a), which is broadly consistent with the lower-elevation headwaters of the Ahuriri River valley. Additionally, the distribution and number of post-glacial landforms such as multiple terminal-lateral moraines in the Ahuriri River valley is relatively smaller than in other well-mapped valleys in the central Southern Alps.…”

Section: Discussionsupporting

confidence: 78%

“…They identified six different moraine landforms dating to the Last Glacial Maximum. Sutherland et al (2019a) generated a 1 m digital elevation model (DEM) based on airborne LiDAR data along with high-resolution aerial imagery and field observations to analyse well-preserved glacial geomorphology surrounding Lake Tekapo. They distinguished a group of Last Glacial Maximum moraines and described in detail landform assemblages such as the glacio-lacustrine, glaciofluvial, supra-glacial, sub-glacial, and recessional icemarginal features.…”

Section: Previous Workmentioning

confidence: 99%

Glacial geomorphology of the Ahuriri River valley, central Southern Alps, New Zealand

et al. 2021

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Detailed geomorphological mapping of ice-related and post-glacial landforms is widely used to explain past glacial fluctuations and dynamics. Here we present the first detailed glacial geomorphological description of the landform assemblages produced by the former Ahuriri Glacier, Southern Alps, New Zealand (44°15 ′ S, 169°36 ′ E). The Southern Alps of New Zealand experienced multiple episodes of glaciation during the Late Quaternary with large mountain glaciers in many valleys, but very little is known about the Ahuriri River valley, one of the main tributaries of the Waitaki River. We selected a region extending approximately 45 km downstream from the headwaters of the Ahuriri River covering an area of about 532 km 2 . Our goal was to create a detailed 1:38,000 scale glacial geomorphological map of this area and provide a geomorphological context to support future geochronological work. Glacial geomorphological mapping was performed by combining several field investigations and remote sensing surveys. We provided high-resolution spatial information for all the glacial-related landforms shown on the map (see main Map). The distribution of post-glacial landforms in the middle and lower section of the main valley outline at least three advances or stillstand phases of past glaciers and suggesting the maximum length (∼41 km) of the former glacier during the Last Glacial Maximum. Most of the tributary valleys were also probably covered by ice at this time. Other prominent but smaller size moraine landforms, mostly in the tributary river valleys, also suggest relatively small, post-glacial advance phases of former glaciers.

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“…The sedimentological end products (ice-marginal moraines) in ancient glacial environments can thus be used to reconstruct past glacier dynamics (e.g. Ham and Attig, 2001;Sutherland et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Sub‐annual moraine formation at an active temperate Icelandic glacier

Chandler

Evans

et al. 2020

Earth Surf Processes Landf

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This paper presents detailed geomorphological and sedimentological investigations of small recessional moraines at Fjallsjökull, an active temperate outlet of Öræfajökull, southeast Iceland. The moraines are characterized by striking sawtooth or hairpin planforms, which are locally superimposed, giving rise to a complex spatial pattern. We recognize two distinct populations of moraines, namely a group of relatively prominent moraine ridges (mean height ~1.2 m) and a group of comparatively low‐relief moraines (mean height ~0.4 m). These two groups often occur in sets/systems, comprising one pronounced outer ridge and several inset smaller moraines. Using a representative subsample of the moraines, we establish that they form by either (i) submarginal deformation and squeezing of subglacial till or (ii) pushing of extruded tills. Locally, proglacial (glaciofluvial) sediments are also incorporated within the moraines during pushing. For the first time, to our knowledge, we demonstrate categorically that these moraines formed sub‐annually using repeat uncrewed aerial vehicle (UAV) imagery. We present a conceptual model for sub‐annual moraine formation at Fjallsjökull that proposes the sawtooth moraine sequence comprises (i) sets of small squeeze moraines formed during melt‐driven squeeze events and (ii) larger push moraines formed during winter re‐advances. We suggest the development of this process‐form regime is linked to a combination of elevated temperatures, high surface meltwater fluxes to the bed and emerging basal topography (a depositional overdeepening). These factors result in highly saturated subglacial sediments and high porewater pressures, which induces submarginal deformation and ice‐marginal squeezing during the melt season. Strong glacier recession during the summer, driven by elevated temperatures, allows several squeeze moraines to be emplaced. This process‐form regime may be characteristic of active temperate glaciers receding into overdeepenings during phases of elevated temperatures, especially where their englacial drainage systems allow efficient transfer of surface meltwater to the glacier bed near the snout margin. © 2020 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd

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The Tekapo Glacier, New Zealand, during the Last Glacial Maximum: An active temperate glacier influenced by intermittent surge activity

Cited by 22 publications

References 272 publications

Proglacial Lakes Control Glacier Geometry and Behavior During Recession

Proglacial Lakes Control Glacier Geometry and Behavior During Recession

Glacial geomorphology of the Ahuriri River valley, central Southern Alps, New Zealand

Sub‐annual moraine formation at an active temperate Icelandic glacier

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