Lateral moraine age in Park Valley, Tararua Range, New Zealand

Brook, Martin

doi:10.1080/03014220909510564

Cited by 12 publications

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“…In New Zealand, large glaciers were hosted along the Southern Alps throughout the Quaternary, although on North Island, apparently, only the Tongariro and Ruapehu composite cones and south-facing basins of the Tararua Ranges were glaciated (Brook 2009). Ruapehu edifice displays diagnostic evidence for past glacial activity, including large U-shaped valleys and glacial deposits (till) that cover large areas on all flanks of the volcano (Fig.…”

Section: Geological Setting and Glacial History Of Ruapehumentioning

confidence: 98%

Lava-ice interaction on a large composite volcano: a case study from Ruapehu, New Zealand

et al. 2015

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Ice exerts a first-order control over the distribution and preservation of eruptive products on glaciated volcanoes. Defining the temporal and spatial distributions of ice-marginal lava flows provides valuable constraints on past glacial extents and is crucial for understanding the eruptive histories of such settings. Ice-marginal lava flows are well displayed on Ruapehu, a glaciated andesite-dacite composite cone in the southern Taupo Volcanic Zone, New Zealand. Flow morphology, fracture characteristics and 40 Ar/ 39 Ar geochronological data indicate that lavas erupted between~51 and 15 ka interacted with large valley glaciers on Ruapehu. Icemarginal lava flows exhibit grossly overthickened margins adjacent to glaciated valleys, are intercalated with glacial deposits, display fine-scale fracture networks indicative of chilling against ice, and are commonly ridge-capping due to their exclusion from valleys by glaciers. New and existing 40 Ar/ 39 Ar eruption ages for ice-marginal lava flows indicate that glaciers descending to 1300 m above sea level were present on Ruapehu between~51-41 and~27-15 ka. Younger lava flows located within valleys are characterised by blocky flow morphologies and fracture networks indicative of only localised and minor interaction with ice and/or snow, mainly in their upper reaches at elevations of~2600-2400 m. An 40 Ar/ 39 Ar eruption age of 9±3 ka (2σ error) determined for a valley-filling flow on the northern flank of Ruapehu indicates that glaciers had retreated to near-historical extents by the time of emplacement for this lava flow. The applicability of 40 Ar/ 39 Ar dating to ice-marginal flows on glaciated andesitedacite composite volcanoes makes this technique an additional proxy for paleoclimate reconstructions.

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Section: Geological Setting and Glacial History Of Ruapehumentioning

confidence: 98%

Lava-ice interaction on a large composite volcano: a case study from Ruapehu, New Zealand

et al. 2015

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“…Much of this work is limited to the South Island, where large valley glaciers extended out from a small ice sheet formed along the axis of the Southern Alps (Porter, 1975;Doughty et al, 2013;Putnam et al, 2013). In contrast, on the North Island, terrestrial evidence for former glaciation is much less obvious, and appears to have been limited to volcanoes (Mathews, 1967;McArthur and Shepherd, 1990;Eaves et al, 2016b) and the Tararua Range on the southern North Island (Brook and Brock, 2005;Brook, 2009). Indeed, while quantitative reconstructions of paleoclimate (namely temperature and precipitation) during the LGM based on glacier fluctuations have shown some consistency across the South Island, independent estimates of paleoclimatic variables based on evidence from North Island glaciers are extremely rare Eaves et al, 2016a,b).…”

Section: Introductionmentioning

confidence: 99%

“…Below the summit of Aston (1376 m a.s.l.) a shallow cirque basin lies ~25 km south of established former glacial sites further north in the Tararua Range (Brook and Brock, 2005;Brook, 2009). Among the latter, the well-documented Park Valley moraine forms the basis for a second glacier-climate reconstruction.…”

Section: Introductionmentioning

confidence: 99%

“…The two cirque basins at the head of Park Valley are grade 1 'classic' cirques according to theEvans and Cox (1995) classification scheme, and are perched above the valley floor, with their thresholds incised by postglacial fluvial incision. report cosmogenic 10 Be moraine and bedrock exposure ages of c. 18 ka in Park Valley Brook (2009). later identified the Kawakawa Tephra within the Park Valley moraine, which suggests the valley represents a composite glacial landsystem, first occupied prior to 25.4 ka.4.2 Glacier reconstruction and paleoclimatic implicationsReconstruction of the former equilibrium line altitude (ELA) of a small glacier such as the Aston cirque glacier is problematic, as lateral moraines are absent.…”

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confidence: 99%

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Reconstruction and paleoclimatic significance of late Quaternary glaciers in the Tararua Range, North Island, New Zealand

Brook

Kirkbride

2018

Quaternary International

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Reconstructed mountain glaciers are routinely used as a proxy for climate in the search for evidence of interhemispheric climate fluctuations during the Quaternary. In New Zealand, valley glaciers at the Last Glacial Maximum (LGM) extended from an ice sheet centred on New Zealand's Southern Alps to below present-day sea level. In contrast, evidence of LGM glacial activity on the North Island is rare. Here, a glacioclimatic reconstruction is presented of two former glaciers in the Tararua Range (41°S) in the southern North Island. At Mt. Aston, an isolated cirque basin contains landform evidence of a marginal niche glacier. At Park Valley, the lateral moraine of a larger cirque glacier has yielded published cosmogenic isotope ages. The paleoglacier reconstruction shows that paleoequilibrium line altitudes increased northwards across New Zealand during the local LGM. Hence, at this latitude only topography >1200 m above present day sea-level was of sufficient elevation to allow small glaciers to form. The Mt Aston glacier covered only 0.18 km 2 with an equilibrium line altitude (ELA) of c. 1287 m above present sea level. A mean ELA glacier thickness of c. 25 m gives a basal shear stress at the ELA of c. 100 kPa-1 , with a mean summer (December, January, February, DJF) temperature at the ELA of no lower than 5.5°C below present, below which precipitation would have been insufficient to support the reconstructed glacier. Implied LGM paleo-temperatures from both the ELA reconstruction and the glaciological reconstruction broadly accord with other paleo-temperature proxies from the North Island. Park Valley glacier covered c. 0.45 km 2 with an ELA of c. 1270 m and a mean ELA basal shear stress of 65 kPa. Its balance discharge was 9× greater than at Mt Aston. It appears to have been glaciologically viable across a wide range of paleotemperatures: thus, the more marginal glacier is a more useful paleoclimatic indicator because it places a maximum limit on LGM temperature depression, which the larger glacier does not. ELAs of both glaciers closely approximate the regional LGM ELA trend surface. The paleo-glacier reconstructions imply that together with temperature driving LGM paleo-ELA depression, changes in south-westerly airflow over New Zealand, bringing moisture-laden but cool air, maximized snowfall and minimised winter melt. The corollary is that patterns of Quaternary glacier fluctuations may be interpreted as responses, at least in-part, to precipitation-driven changes, and secondly, North Island glaciation was probably more extensive than previously assumed.

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“…Porter, 1975;McCarthy et al, 2008), although some reconstructions from small cirque glaciers indicate much greater lowering (e.g. Brook, 2009). Golledge et al (2012) found a best fit to identified LGM limits when modern climate was 6-6.5 • C cooler and c. 25 % drier than present.…”

Section: Last Glacial Maximum (C 35 -18ka)mentioning

confidence: 99%

The glacial history of Tongariro and Ruapehu volcanoes, New Zealand

Eaves¹

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<p>Understanding the drivers and mechanisms of past, natural changes in Earth’s climate is a fundamental goal of palaeoclimate science. Recent advances in cosmogenic surface exposure dating and numerical glacier modelling have greatly improved the utility of geological glacial records for palaeoclimatic reconstruction. Here, I apply these techniques to investigate the timing and magnitude of late Quaternary mountain glacier fluctuations on Tongariro massif and Mt. Ruapehu volcanoes in central North Island, New Zealand (39°S). First, I constrain the local cosmogenic ³He production rate, in order to compare my subsequent ³He moraine chronologies with other well-dated palaeoclimate records. I present a new radiocarbon age for a large debris avalanche event on the northwest slopes of Mt. Ruapehu that occurred at 10.4-10.6 cal. ka BP. Cosmogenic ³He concentrations in surficial boulders deposited during this event are consistent with that predicted by a global compilation of similar production rate calibrations. Thus, I conclude that this globally compiled production rate is suitable for cosmogenic ³He exposure age calculations in New Zealand. Exposure ages from moraine boulders on both volcanoes constrain the timing of two periods of glaciation during the last glacial cycle, when the termini of valley glaciers reached c. 1200 m asl. The most recent of these events occurred between c. 31-17 ka, which corresponds with the global Last Glacial Maximum. During this period, the local equilibrium line altitude was depressed by c. 800-1100 m. Numerical model simulations of the glaciers, using a coupled energy balance/ice flow model, suggest that local atmospheric temperature was 4-7 °C colder than present. This palaeotemperature estimate is not greatly impacted by post-glacial topographic change on these active volcanoes. Surface exposure ages from a degraded lateral moraine on Tongariro massif indicate that an earlier period of glaciation, of similar extent to that at the LGM, culminated during Marine Isotope Stage 4. During the last glacial-interglacial transition (c. 18-11 ka), glacial retreat on Mt. Ruapehu was interrupted by a re-advance during the late-glacial (c. 15-11 ka). Exposure ages for this event exhibit some scatter, likely due to surface processes. Accounting for these processes with a topographic diffusion model yields a best-estimate age of 14-13 ka, corresponding to the Lateglacial reversal in New Zealand. Glacier model experiments indicate this re-advance resulted from a temperature lowering of 2.5-3.4 °C relative to present. Comparison with other proxy records suggests that this cooling was most pronounced during summer. Due to its lower elevation, it is unlikely that glaciers were present on Tongariro massif at this time. The results of this research provide the first direct age constraint and quantitative palaeoclimate reconstructions for late Quaternary glacier fluctuations in central North Island, New Zealand. The timing and magnitude of these changes are in good agreement with glacial records from the Southern Alps and South America. This suggests that glaciers in the southern mid-latitudes were responding to common climatic forcings at orbital- and millennial-timescales, during the last glacial cycle.</p>

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Lateral moraine age in Park Valley, Tararua Range, New Zealand

Cited by 12 publications

References 11 publications

Lava-ice interaction on a large composite volcano: a case study from Ruapehu, New Zealand

Lava-ice interaction on a large composite volcano: a case study from Ruapehu, New Zealand

Reconstruction and paleoclimatic significance of late Quaternary glaciers in the Tararua Range, North Island, New Zealand

The glacial history of Tongariro and Ruapehu volcanoes, New Zealand

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