scholarly journals AMS Dating of a Late Quaternary Tephra at Graham's Terrace, New Zealand

Radiocarbon ◽  
1992 ◽  
Vol 34 (1) ◽  
pp. 21-27 ◽  
Author(s):  
Richard Gillespie ◽  
A. P. Hammond ◽  
K. M. Goh ◽  
P. J. Tonkin ◽  
D. C. Lowe ◽  
...  
Keyword(s):  
New Zealand ◽  
Volcanic Ash ◽  
Reliable Method ◽  
Late Quaternary ◽  
Radiometric Dating ◽  
Low Carbon ◽  
Chemical Pretreatment ◽  
Fine Grained ◽  
Ams Dating ◽  
Charred Wood

The radiocarbon dating of volcanic ash (tephra) deposits in New Zealand has been difficult on sites remote from the eruption, which contain either little carbon or degraded and contaminated charcoal. Although many studies of contamination removal from macroscopic charcoals from tephra sequences have been made, little attention has been paid to those containing no visible charcoal, because of the difficulty of obtaining sufficient carbon for radiometric dating. We report here experiments using accelerator mass spectrometry to establish a reliable method for dating a low-carbon aeolian and peat deposit containing a tephra horizon. Results so far demonstrate that improvements to existing chemical pretreatment methods are possible, and that dates obtained on oxidized fine-grained residues can approach the maximum age determined on good quality charred wood samples.

scholarly journals AMS Dating of Pollen Concentrates—A Methodological Study of Late Quaternary Sediments from South Westland, New Zealand

Radiocarbon ◽  
2003 ◽  
Vol 45 (3) ◽  
pp. 479-491 ◽  
Author(s):  
Marcus J Vandergoes ◽  
Christine A Prior
Keyword(s):  
New Zealand ◽  
Plant Material ◽  
Late Quaternary ◽  
Organic Residue ◽  
Methodological Study ◽  
Quaternary Sediments ◽  
Simple Method ◽  
Younger Age ◽  
Ams Dating ◽  
Age Estimates

A simple method for preparing pollen concentrates for 14C AMS dating is applied to organic and inorganic deposits from a peat bog in south Westland, New Zealand, from which preliminary AMS dating indicated age inversions and severe younger carbon contamination problems. The AMS ages of the pollen concentrates provided consistently older age estimates for each sample than ages derived from their respective organic residue or combined pollen and organic residue fractions. It is likely that the younger age estimates of the organic residue fractions result from the incorporation of younger plant material into the sample and possible contamination from younger humic acids percolating through the site.

scholarly journals AMS Dating of Alluvial Sediments on the Southern Tablelands of New South Wales, Australia

Radiocarbon ◽  
1992 ◽  
Vol 34 (1) ◽  
pp. 29-36 ◽  
Author(s):  
Richard Gillespie ◽  
I. P. Prosser ◽  
Edward Dlugokencky ◽  
R. J. Sparks ◽  
Gavin Wallace ◽  
...  
Keyword(s):  
Radiocarbon Dating ◽  
Late Quaternary ◽  
New South ◽  
Alluvial Deposits ◽  
Fine Grained ◽  
Southeastern Australia ◽  
South Wales ◽  
Humic Materials ◽  
Ams Dating ◽  
Stratigraphic Sequences

The dating of alluvial deposits is frequently hampered by a lack of good-quality charcoal or other material for radiocarbon samples. We have dated two sites in southeastern Australia using traditional radiometric methods with minimal pretreatment. Results yielded an inconsistent chronology, affected by contamination with younger humic materials. A more consistent and older chronology was achieved using AMS dating of rigorously pretreated samples of fine-grained charcoal. The results have important implications for the radiocarbon dating of many Late Quaternary stratigraphic sequences with low charcoal abundance.

Late Quaternary paleolimnology of Onepoto maar, Auckland, New Zealand: Implications for the drivers of regional paleoclimate

2012 ◽  
Vol 253 ◽  
pp. 18-31 ◽  
Author(s):  
Paul Augustinus ◽  
Ursula Cochran ◽  
Giri Kattel ◽  
Donna D’Costa ◽  
Phil Shane
Keyword(s):  
New Zealand ◽  
Late Quaternary

scholarly journals South Pole glacial climate reconstruction from multi-borehole laser particulate stratigraphy

2013 ◽  
Vol 59 (218) ◽  
pp. 1117-1128 ◽  
Author(s):  
Keyword(s):  
Particle Physics ◽  
Volcanic Ash ◽  
Ice Core ◽  
Hot Water ◽  
Radiometric Dating ◽  
South Pole ◽  
Last Glacial Period ◽  
Annual Layer ◽  
Paleoclimate Records ◽  
The Last Glacial

AbstractThe IceCube Neutrino Observatory and its prototype, AMANDA, were built in South Pole ice, using powerful hot-water drills to cleanly bore >100 holes to depths up to 2500 m. The construction of these particle physics detectors provided a unique opportunity to examine the deep ice sheet using a variety of novel techniques. We made high-resolution particulate profiles with a laser dust logger in eight of the boreholes during detector commissioning between 2004 and 2010. The South Pole laser logs are among the most clearly resolved measurements of Antarctic dust strata during the last glacial period and can be used to reconstruct paleoclimate records in exceptional detail. Here we use manual and algorithmic matching to synthesize our South Pole measurements with ice-core and logging data from Dome C, East Antarctica. We derive impurity concentration, precision chronology, annual-layer thickness, local spatial variability, and identify several widespread volcanic ash depositions useful for dating. We also examine the interval around ∼74 ka recently isolated with radiometric dating to bracket the Toba (Sumatra) supereruption.

Evidence for pyroclastic emplacement of the Crowsnest Formation, Alberta

1996 ◽  
Vol 33 (5) ◽  
pp. 715-728 ◽  
Author(s):  
R.N. Adair ◽  
R.A. Burwash
Keyword(s):  
Elevated Temperatures ◽  
Pyroclastic Flows ◽  
Coarse Grained ◽  
Rock Fragment ◽  
Fine Grained ◽  
Rock Fragments ◽  
Explosive Phase ◽  
Graded Structures ◽  
Textural Evidence ◽  
Charred Wood

The middle Cretaceous Crowsnest Formation west of Coleman, Alberta, is composed of bedded alkaline volcanic deposits containing heterolithic volcanic rock fragments and crystal clasts. Comparison with modern examples of subaerial pyroclastic rocks suggests that pyroclastic flows, surges, fallout of material from vertical eruption columns, and minor mud flows emplaced the deposits. Textural evidence in the form of plastically deformed volcanic fragments, chilled deposit margins, baked rock fragment margins, recrystallization, and the presence of charred wood and charred wood molds indicate emplacement at elevated temperature. Massive deposits containing a fine-grained basal zone are interpreted as the product of pyroclastic flows, whereas deposits characterized by a block-rich base overlain by a thin layer of block-depleted stratified material are interpreted as the product of density-stratified surges. Deposits exhibiting pronounced stratification were emplaced by ash-cloud surges. Thickly bedded breccias exhibiting rheomorphic textures were emplaced as vent-proximal pyroclastic flows. Deposits characterized by parallel beds and graded structures are interpreted as fallout tephra deposits, and deposition by lahars is indicated by coarse-grained beds that lack evidence for emplacement at elevated temperatures. The eruptions of the Crowsnest Formation were cyclical. An initial explosive phase generated deposits by pyroclastic flows, surges, fallout, and lahars. As an eruption progressed, it evolved into a poorly gas-charged effusive stage that emplaced coarsely porphyritic domes, plugs, spines, and vent-proximal lava flows. Subsequent eruptions destroyed the effusive vent facies deposits and produced abundant heterolithic clasts typical of the formation.

Occurrence of Imogolite in some Volcanic Ash Soils of New Zealand

Clay Minerals ◽  
1973 ◽  
Vol 10 (2) ◽  
pp. 127-130 ◽  
Author(s):  
N. Yoshinaga ◽  
J. M. Tait ◽  
R. Soong
Keyword(s):  
New Zealand ◽  
Volcanic Ash ◽  
Volcanic Ash Soils
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