The Holocene Glacial History of Dart Glacier, Southern Alps, New Zealand

10.26686/wgtn.17136842 ◽

2021 ◽

Author(s):

◽

Lisa Dowling

Keyword(s):

New Zealand ◽

Southern Alps ◽

Rare Isotope ◽

Geological Record ◽

The Holocene ◽

Surface Exposure Dating ◽

Exposure Dating ◽

History Of ◽

Glacier Length ◽

Length Changes

Mountain glaciers are sensitive climate indicators, as climate variability drives mass changes that are expressed in glacier length fluctuations. These length changes are preserved in the geological record, thus offering the potential to generate new palaeoclimate proxy data that can be used to extend instrumental climate records. This study presents geomorphological mapping and cosmogenic ¹⁰Be surface exposure dating of the Holocene moraines at Dart Glacier, New Zealand. These findings show that an early Holocene advance (~6 km longer than present-day) took place ~7817 ± 336 years ago. Moraine ages also show that a more restricted glacier readvance (~4 km longer than present-day) occurred ~321 ± 44 years ago. Through better constraining the timing and magnitude of Holocene glacier length changes, we extend the ~100-year history of observational records in the upper Dart valley. Net retreat of Dart Glacier during the Holocene is consistent with other moraine chronologies from New Zealand, which supports existing hypotheses that suggest summer insolation was the dominant driver of multi-millennial climate change at southern mid-latitudes during the current interglacial. Individual moraine forming events at Dart Glacier also coincide with moraine ages from several other catchments in the Southern Alps and likely reflect shorter-term (decadal-centennial-scale) climatic changes. The new geological record constraints of length changes at Dart Glacier offer the opportunity to test such hypotheses more formally using physics-based modelling. Connecting Holocene moraine records to historical glacier observations using ¹⁰Be surface exposure dating requires consistently low background levels of this rare isotope. Systematic blank experiments show that concentrated analytical grade hydrofluoric acid and reused beakers are likely the largest contributors of ¹⁰Be to the average process blank in the VUW Cosmogenic Laboratory. Based on these findings I recommend small methodological improvements that could be implemented to lower process blank ratios for routine application of ¹⁰Be surface exposure dating to near-historic glacial landforms.

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The movements of Alpine glaciers throughout the last 10,000 years as sensitive proxies of temperature and climate changes

EPJ Web of Conferences ◽

10.1051/epjconf/202023202002 ◽

2020 ◽

Vol 232 ◽

pp. 02002

Author(s):

Walter Kutschera ◽

Gernot Patzelt ◽

Joerg M. Schaefer ◽

Christian Schlüchter ◽

Peter Steier ◽

...

Keyword(s):

New Zealand ◽

Southern Hemisphere ◽

Northern Hemisphere ◽

Climate Changes ◽

European Alps ◽

Cosmogenic Isotopes ◽

The Holocene ◽

Surface Exposure Dating ◽

Exposure Dating ◽

Alpine Glaciers

A brief review of the movements of Alpine glaciers throughout the Holocene in the Northern Hemisphere (European Alps) and in the Southern Hemisphere (New Zealand Southern Alps) is presented. It is mainly based on glacier studies where 14C dating, dendrochronology and surface exposure dating with cosmogenic isotopes is used to establish the chronology of advances and retreats of glaciers. An attempt is made to draw some general conclusions on the temperature and climate differences between the Northern and Southern Hemisphere.

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Slip history of the Magnola fault (Apennines, Central Italy) from 36Cl surface exposure dating: evidence for strong earthquakes over the Holocene

Earth and Planetary Science Letters ◽

10.1016/j.epsl.2004.06.012 ◽

2004 ◽

Vol 225 (1-2) ◽

pp. 163-176 ◽

Cited By ~ 85

Author(s):

Luigi Palumbo ◽

Lucilla Benedetti ◽

Didier Bourlès ◽

Aldo Cinque ◽

Robert Finkel

Keyword(s):

Central Italy ◽

Strong Earthquakes ◽

The Holocene ◽

Surface Exposure Dating ◽

Exposure Dating ◽

Slip History ◽

History Of

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First attempt to combine terrestrial cosmogenic nuclide (10Be) and Schmidt hammer relative-age dating: Strauchon Glacier, Southern Alps, New Zealand

Open Geosciences ◽

10.2478/v10085-009-0026-3 ◽

2009 ◽

Vol 1 (3) ◽

Cited By ~ 10

Author(s):

Stefan Winkler

Keyword(s):

New Zealand ◽

Southern Alps ◽

Age Dating ◽

Schmidt Hammer ◽

Relative Age ◽

Surface Exposure Dating ◽

Exposure Dating ◽

Cosmogenic Nuclide ◽

Calibration Curves ◽

Cosmogenic 10Be

AbstractThis study provides the first attempt to combine terrestrial (in situ) cosmogenic nuclide (10Be) surface exposure dating with Schmidt hammer relative-age dating for the age estimation of Holocene moraines at Strauchon Glacier, Southern Alps, New Zealand. Numerous Schmidt hammer tests enable a multi-ridged lateral moraine system to be related to three late-Holocene ‘Little Ice Age’-type events. On the basis of cosmogenic 10Be ages, those events are dated to c. 2400, 1700, and 1100 years ago. Linear age-calibration curves are constructed in order to relate Schmidt hammer R-values to cosmogenic 10Be ages. The high explanation yielded reveals the causal link between both data sets. The potential of combining both methods in a ‘’multiproxy approach’ is discussed alongside possible future improvements. Terrestrial cosmogenic nuclide dating delivers absolute ages needed as fixed points for Schmidt hammer age-calibration curves. The Schmidt hammer technique can be used to crosscheck the boulder surfaces chosen for surface exposure dating by terrestrial cosmogenic nuclides. It should, therefore, reduce the number of samples necessary and costs.

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Reconstructing the Timing of Flash Floods Using 10Be Surface Exposure Dating at Leidy Creek Alluvial Fan and Valley, White Mountains, California–Nevada, USA

Quaternary Research ◽

10.1016/j.yqres.2014.08.006 ◽

2015 ◽

Vol 83 (1) ◽

pp. 178-186 ◽

Cited By ~ 4

Author(s):

Markus Fuchs ◽

Rebecca Reverman ◽

Lewis A. Owen ◽

Kurt L. Frankel

Keyword(s):

Flash Floods ◽

Alluvial Fan ◽

Optically Stimulated Luminescence ◽

Alluvial Fans ◽

White Mountains ◽

The Holocene ◽

Surface Exposure Dating ◽

Exposure Dating ◽

Outburst Floods ◽

Glacial Lake Outburst Floods

AbstractLarge alluvial fans characterize the piedmonts of the White Mountains, California–Nevada, USA, with large boulders strewn across their surfaces. The boulders are interpreted as flash floods deposits with an unclear trigger for the transport process. Several triggers are possible, including glacial lake outburst floods (GLOFs), thunderstorms or rainfall on snow cover. From a paleoenvironmental perspective, the origin of the flash floods is of fundamental importance. The alluvial fans that flank the White Mountains at Leidy Creek display particularly impressive examples of these deposits. The boulder deposits and the source catchment at Leidy Creek were examined using 10Be terrestrial cosmogenic nuclide (TCN) surface exposure dating to help elucidate their age and origin. All boulders dated on the alluvial fans date to the Holocene. This is in accordance with the geomorphic analyses of the Leidy Creek catchment and its terraces and sediment ridges, which were also dated to the Holocene using optically stimulated luminescence (OSL) and 10Be surface exposure. The results suggest that the boulders on the alluvial fan were deposited by flash floods during thunderstorm events affecting the catchment of the Leidy Creek valley. Paleomonsoonal-induced mid-Holocene flash floods are the most plausible explanation for the discharges needed for these boulder aggradations, but a regional dataset is needed to confirm this explanation.

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Late Quaternary glacial history of the Nalati Range, central Tian Shan, China, investigated using10Be surface exposure dating

Journal of Quaternary Science ◽

10.1002/jqs.2891 ◽

2016 ◽

Vol 31 (7) ◽

pp. 659-670 ◽

Cited By ~ 11

Author(s):

Mei Zhang ◽

Yixin Chen ◽

Yingkui Li ◽

Gengnian Liu

Keyword(s):

Late Quaternary ◽

Glacial History ◽

Surface Exposure Dating ◽

Exposure Dating ◽

History Of ◽

Tian Shan

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A Study of Some Aspects of the Volcanic History of the Lake Taupo Area, North Island, New Zealand

10.26686/wgtn.16949329 ◽

2021 ◽

Author(s):

◽

Paul C Froggatt

Keyword(s):

New Zealand ◽

Late Pleistocene ◽

Pyroclastic Flow ◽

Microprobe Analysis ◽

Pyroclastic Flow Deposit ◽

The Holocene ◽

Volcanic History ◽

Flow Deposit ◽

History Of ◽

Glass Shards

Rhyolitic pyroclastic eruptives from the Taupo area, New Zealand have been mapped as nine tephra formations of Holocene (0-10 kyr B.P.), and six of late Pleistocene age (20-c.50 kyr B.P.). Only the 10 younger tephras are dated by radiocarbon. All formations contain PLINIAN type airfall units but three, KAWAKAWA, WAIMIHIA and TAUPO also contain a major pyroclastic flow deposit (IGNIMBRIIE) unit. Dome extrusion can only be demonstrated for KARAPITI eruptive episode, but is inferred for the other Holocene episodes. TAUPO IGNIMBRITE is the product of the most recent eruption and is a particularly well preserved and extensive, unwelded pyroclastic flow deposit, up to 50m thick. Its variety of appearance is described in terms of three lithofacies; valley facies, fines depleted facies and veneer facies, each being formed by particular mechanisms within a pyroclastic flow. Abundant charred logs, lying prone within Taupo Ignimbrite, are radial about the source and attest to a radially outward moving mass dominated by laminar flow. Lake Taupo today covers most of the volcanic source area, preventing close examination and the identification of individual source vents. A vent for each Holocene tephra is inferred from isopachs, grainsize and lake bathymetry, but the vents so inferred show no spatial distribution with time. Nevertheless they are evenly spaced along a northeast trending line and lie on intersections with a northwest trending set of lineations, indicating deep, crustal, structural control on volcanism. Cumulative volume of airfall and ignimbrite material erupted in the Taupo area in the last 50 kyr has amounted to about 175 km3 of magma. Eruptions have proceeded in a step-wise manner, indicating the period to the next eruption is about 8 kyr. By the same approach, the next eruption from the Okataina area, 50 km to the north of Taupo is expected in less than 400 years. Whole rock and mineral chemistry clearly distinguishes between the Holocene and the late Pleistocene tephras, but within each group variations are subtle and no trends with time are apparent. None of the formations exhibit evidence for a chemically zoned magma body, but some data, especially pyroxene phenocryst chemistry, suggests magma inhomogeneities of mafic elements. The Holocene tephra were probably all erupted from the same magma chamber in which crystallisation was the dominant process but convection, crystal element diffusion and chamber replenishment were all probably operative. Results obtained by electron microprobe analysis of glass shards are critically dependent on the beam diameter and current used. By standardising these at 10 microns and 8 nanoamps respectively, comparable major element analyses on glass shards from numerous tephras ranging in age from 20 kyr to 600 kyr were obtained. The stratigraphic relationships between sets of samples (located mainly distal from source) and the close chemical similarity of some samples enabled a comprehensive tephrostratigraphy to be established. In particular, MT. CURL TEPHRA has a glass chemistry quite different from other stratigraphically separate tephras, establishing correlation of Mt. Curl Tephra to Whakamaru Ignimbrite. Likewise, other ignimbrite formations can be correlated to widespread airfall tephras, so establishing an absolute ignimbrite stratigraphy. Microprobe analysis of glass shards provides a method for indirectly determining the amount of hydration. For dated samples from a known weathering environment, the parameters controlling hydration can be quantified. For glass of uniform chemistry, shard size and porosity, ground temperature and groundwater movements are the most important parameters. No shards in the 63-250 micron size range have been found with more than 9% water, suggesting once this maximum is reached, glass rapidly alters to secondary products. Detailed knowledge of the volcanic history of the Taupo area, particularly since 50 kyrs B.P. allows the volcanic hazards of the region to be assessed. Fifteen major eruptions in 50 kyr gives a frequency of 1 in 3300 years, but the timing of individual events is not evenly spread throughout that time. Monitoring for volcanic Precursory events (not being undertaken at present) is essential to gauge the present and short-term future volcanic activity of the Taupo Volcanic Zone.

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A Study of Some Aspects of the Volcanic History of the Lake Taupo Area, North Island, New Zealand

10.26686/wgtn.16949329.v1 ◽

2021 ◽

Author(s):

◽

Paul C Froggatt

Keyword(s):

New Zealand ◽

Late Pleistocene ◽

Pyroclastic Flow ◽

Microprobe Analysis ◽

Pyroclastic Flow Deposit ◽

The Holocene ◽

Volcanic History ◽

Flow Deposit ◽

History Of ◽

Glass Shards

Rhyolitic pyroclastic eruptives from the Taupo area, New Zealand have been mapped as nine tephra formations of Holocene (0-10 kyr B.P.), and six of late Pleistocene age (20-c.50 kyr B.P.). Only the 10 younger tephras are dated by radiocarbon. All formations contain PLINIAN type airfall units but three, KAWAKAWA, WAIMIHIA and TAUPO also contain a major pyroclastic flow deposit (IGNIMBRIIE) unit. Dome extrusion can only be demonstrated for KARAPITI eruptive episode, but is inferred for the other Holocene episodes. TAUPO IGNIMBRITE is the product of the most recent eruption and is a particularly well preserved and extensive, unwelded pyroclastic flow deposit, up to 50m thick. Its variety of appearance is described in terms of three lithofacies; valley facies, fines depleted facies and veneer facies, each being formed by particular mechanisms within a pyroclastic flow. Abundant charred logs, lying prone within Taupo Ignimbrite, are radial about the source and attest to a radially outward moving mass dominated by laminar flow. Lake Taupo today covers most of the volcanic source area, preventing close examination and the identification of individual source vents. A vent for each Holocene tephra is inferred from isopachs, grainsize and lake bathymetry, but the vents so inferred show no spatial distribution with time. Nevertheless they are evenly spaced along a northeast trending line and lie on intersections with a northwest trending set of lineations, indicating deep, crustal, structural control on volcanism. Cumulative volume of airfall and ignimbrite material erupted in the Taupo area in the last 50 kyr has amounted to about 175 km3 of magma. Eruptions have proceeded in a step-wise manner, indicating the period to the next eruption is about 8 kyr. By the same approach, the next eruption from the Okataina area, 50 km to the north of Taupo is expected in less than 400 years. Whole rock and mineral chemistry clearly distinguishes between the Holocene and the late Pleistocene tephras, but within each group variations are subtle and no trends with time are apparent. None of the formations exhibit evidence for a chemically zoned magma body, but some data, especially pyroxene phenocryst chemistry, suggests magma inhomogeneities of mafic elements. The Holocene tephra were probably all erupted from the same magma chamber in which crystallisation was the dominant process but convection, crystal element diffusion and chamber replenishment were all probably operative. Results obtained by electron microprobe analysis of glass shards are critically dependent on the beam diameter and current used. By standardising these at 10 microns and 8 nanoamps respectively, comparable major element analyses on glass shards from numerous tephras ranging in age from 20 kyr to 600 kyr were obtained. The stratigraphic relationships between sets of samples (located mainly distal from source) and the close chemical similarity of some samples enabled a comprehensive tephrostratigraphy to be established. In particular, MT. CURL TEPHRA has a glass chemistry quite different from other stratigraphically separate tephras, establishing correlation of Mt. Curl Tephra to Whakamaru Ignimbrite. Likewise, other ignimbrite formations can be correlated to widespread airfall tephras, so establishing an absolute ignimbrite stratigraphy. Microprobe analysis of glass shards provides a method for indirectly determining the amount of hydration. For dated samples from a known weathering environment, the parameters controlling hydration can be quantified. For glass of uniform chemistry, shard size and porosity, ground temperature and groundwater movements are the most important parameters. No shards in the 63-250 micron size range have been found with more than 9% water, suggesting once this maximum is reached, glass rapidly alters to secondary products. Detailed knowledge of the volcanic history of the Taupo area, particularly since 50 kyrs B.P. allows the volcanic hazards of the region to be assessed. Fifteen major eruptions in 50 kyr gives a frequency of 1 in 3300 years, but the timing of individual events is not evenly spread throughout that time. Monitoring for volcanic Precursory events (not being undertaken at present) is essential to gauge the present and short-term future volcanic activity of the Taupo Volcanic Zone.

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