scholarly journals Peak metamorphic temperature and thermal history of the Southern Alps (New Zealand)

2016 ◽  
Vol 676 ◽  
pp. 229-249 ◽  
Author(s):  
O. Beyssac ◽  
S.C. Cox ◽  
J. Vry ◽  
F. Herman
1999 ◽  
Vol 42 (3) ◽  
pp. 469-488 ◽  
Author(s):  
Asaf Raza ◽  
Roderick W. Brown ◽  
Peter F. Ballance ◽  
Kevin C. Hill ◽  
Peter J. J. Kamp

2021 ◽  
Author(s):  
◽  
Lisa Dowling

<p>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.</p>


2010 ◽  
Vol 147 (6) ◽  
pp. 801-813 ◽  
Author(s):  
UWE RING ◽  
MATTHIAS BERNET

AbstractWe apply fission-track thermochronology to shed new light on the tectonic history of Zealandia during Late Cretaceous continental extension and the onset of Late Tertiary mountain building in the Southern Alps of New Zealand. The Southern Alps are one of the fastest erosionally exhuming mountain belts on Earth. Exhumation of the Bonar Range in Westland just to the northwest of the Alpine Fault is orders of magnitude slower. We report apatite and zircon fission-track ages from samples that were collected along an ENE–WSW profile across the central Bonar Range, parallel to the tectonic transport direction of a prominent ductile fabric in the basement gneiss. Zircon fission-track (ZFT) ages show a large spread from 121.9 ± 12.1 Ma to 74.9 ± 7.2 Ma (1σ errors). The youngest ZFT ages of 78 to 75 Ma occur at low elevations on either side of the Bonar Range and become older towards the top of the range, thereby showing a symmetric pattern parallel to the ENE-trending profile across the range. Age–elevation relationships suggest an exhumation rate of 50–100 m Ma−1. We relate the ZFT ages to slow erosion of a tectonically inactive spot in the Late Cretaceous magmatic arc of Zealandia. Therefore, the first main significance of the paper is that it demonstrates that not all of 110–90 Ma Zealandia was necessarily participating in extreme core complex-related extension but that there were enclaves of lithosphere that underwent slow erosion. The apatite fission-track (AFT) ages range from 11.1 ± 1.9 Ma to 5.3 ± 1.0 Ma and age–elevation relationships suggest an exhumation rate of c. 200 m Ma−1. We relate the AFT ages to the inception of transpressive motion across the Alpine Fault and modest exhumation in its footwall in Late Miocene times. If so, the second significant point of this paper is that transpressive motion across the Alpine Fault was already under way by c. 11 Ma.


2021 ◽  
Author(s):  
◽  
Lisa Dowling

<p>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.</p>


2021 ◽  
Author(s):  
◽  
Maree Prebensen

<p>Thelma Kent was a well-known pictorialist photographer of her day, highly regarded for her photographs of the landscape of the South Island. Born in 1899, she was active in the decades of the 1920s and 1930s and throughout the war years before her early death in 1946. Her short life encapsulates a fascinating period in the history of New Zealand photography and focuses this thesis on to a previously little studied window. Kent reflected a lot of the dominant ideals and passions of photographic practice and thus becomes an exemplar of her times. Only a small amount of research has previously been attempted on Kent‘s life and work because fragmentary photographic archives yielded few clues. I solved this by concentrating on her published photographs and writings in the nation‘s newspapers and magazines, which proved to be extensive, and provided new insights in to photographic practices of the era. I also used the tools of the biographer; electoral rolls, directories, and interviews with individuals with links to Kent to enable a broader view of my subject. Chapter one looks at Kent‘s early years and examines the biographical methods involved in researching an individual‘s life. Chapter two explores Kent‘s love of travel to remote corners of the South Island to capture photographs. These images fed the nation‘s craze for travel and recreation in an era where new forms of transport such as cars and rail opened up the countryside to droves of ordinary New Zealanders. Chapter three delves into Kent‘s more adventurous trips, particularly to regions in the Southern Alps, and looks at her written accounts and photographs from these journeys. Chapter four shows Kent‘s involvement with camera clubs, photographic salons and the paths that a pictorialist photographer could take to gain national and international exposure. The final chapter looks at Kent mature career during the war years, a time when photographers faced challenges to their practices in terms of limitations of materials and subject matter.</p>


2021 ◽  
Author(s):  
◽  
Maree Prebensen

<p>Thelma Kent was a well-known pictorialist photographer of her day, highly regarded for her photographs of the landscape of the South Island. Born in 1899, she was active in the decades of the 1920s and 1930s and throughout the war years before her early death in 1946. Her short life encapsulates a fascinating period in the history of New Zealand photography and focuses this thesis on to a previously little studied window. Kent reflected a lot of the dominant ideals and passions of photographic practice and thus becomes an exemplar of her times. Only a small amount of research has previously been attempted on Kent‘s life and work because fragmentary photographic archives yielded few clues. I solved this by concentrating on her published photographs and writings in the nation‘s newspapers and magazines, which proved to be extensive, and provided new insights in to photographic practices of the era. I also used the tools of the biographer; electoral rolls, directories, and interviews with individuals with links to Kent to enable a broader view of my subject. Chapter one looks at Kent‘s early years and examines the biographical methods involved in researching an individual‘s life. Chapter two explores Kent‘s love of travel to remote corners of the South Island to capture photographs. These images fed the nation‘s craze for travel and recreation in an era where new forms of transport such as cars and rail opened up the countryside to droves of ordinary New Zealanders. Chapter three delves into Kent‘s more adventurous trips, particularly to regions in the Southern Alps, and looks at her written accounts and photographs from these journeys. Chapter four shows Kent‘s involvement with camera clubs, photographic salons and the paths that a pictorialist photographer could take to gain national and international exposure. The final chapter looks at Kent mature career during the war years, a time when photographers faced challenges to their practices in terms of limitations of materials and subject matter.</p>


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