Global paleo-climate reconstructions are largely based on observations from
the Northern Hemisphere despite increasing recognition of the importance of
the Southern Hemisphere mid-latitudes for understanding the drivers of the
global climate system. Unfortunately, the required complete and
high-resolution terrestrial records from the Southern Hemisphere
mid-latitudes are few. However, the maar lakes in the Auckland Volcanic Field
(AVF), New Zealand, are crucial in this regard as they form outstanding
depositional basins due to their small surface-to-depth ratio, restricted
catchment, and absence of ice cover
since their formation, hence ensuring continuous sedimentation with anoxic
bottom water. Significantly, the estimated age of the AVF of ca. 250 ka may
allow development of a continuous sediment record spanning the last two
glacial cycles. The Orakei maar lake sediment sequence examined in this study
spans the Last Glacial Cycle (ca. 126 to ca. 9.5 ka cal BP) from the
phreatomagmatic eruption to the crater rim breach due to post-glacial
sea-level rise. Two overlapping cores of >100 m sediment were retrieved
and combined to develop a complete composite stratigraphy that is presently
undergoing a wide range of multi-proxy analyses.
Introduction
Lake sediments are important archives for Quaternary paleo-environmental and
paleo-climatic reconstruction, particularly when sedimentation has been
continuous and sedimentation rates high, as they offer a variety of
high-resolution proxy records of environmental change. In the context of the
location of New Zealand in the Southern Hemisphere mid-latitudes, lakes act
as important recorders of past climate in the south-western Pacific (Alloway
et al., 2007). Furthermore, Auckland is situated at an ecological and
climatic boundary between the subtropical north and the south of New Zealand
influenced by subpolar climatic and oceanographic systems (Augustinus, 2007).
Consequently, the up to 250 ka duration and high-resolution laminated
sediment cores retrieved from maar lakes in the Auckland Volcanic Field (AVF)
constitute ideal recorders of past regional climatic variability over the
last two glacial cycles.
Due to their low diameter-to-depth ratio and limited catchment area
(dominated by the lake itself), allochthonous sedimentation is a minor
component of the infill, so that maar lake sediment is largely a direct
archive of regional climatic signals (e.g. Augustinus et al., 2011; Brauer et
al., 1999; Horrocks et al., 2005; Sandiford et al., 2003; Zolitschka et al.,
2013). AVF maar lakes also preserve complete archives of eruptions of the
local basaltic volcanoes as well as rhyolitic and andesitic volcanic systems
situated in the Taupo Volcanic Zone (TVZ) and Egmont Volcano (Fig. 1) to the
south of Auckland (Hopkins et al., 2015; Molloy et al., 2009; Shane, 2005;
Shane and Hoverd, 2002). This is of importance as the City of Auckland, with
>1.5 million inhabitants, is situated on a potentially active volcanic
field for which eruption frequencies cannot be derived from the historical
record (Edbrooke et al., 2003; Molloy et al., 2009; Newnham et al., 1999).
Many basaltic tephra layers have been recorded in the AVF maar sediment
cores, but age estimates rely on sedimentation rate extrapolation to and
correlation with the source volcanoes, which mostly have not been dated
unambiguously (Hopkins et al., 2015, 2017; Leonard et al., 2017; Lindsay et
al., 2011; Molloy et al., 2009). Here, we focus on the Orakei maar
paleo-lake, which contains a finely laminated sediment sequence with high
sedimentation rates (average ∼0.7 mm yr-1) possibly spanning the
Eemian (MIS 5e) to the earliest Holocene. After an initial coring campaign in
2007, which established the potential of the Orakei maar record (Hopkins et
al., 2015; Molloy et al., 2009), two overlapping cores were recovered in 2016
that reached the primary volcanic ejecta at the base of the crater at ca.
105 m depth below the sediment–water interface. Emphasis in the present
study lies in establishing a detailed composite stratigraphy by aligning the
overlapping sediment cores collected.
Map of the Orakei maar study area. (a) New Zealand with
insets (b) and (c) marked. (b) New Zealand's North
Island with Auckland (inset c) and the major volcanic source centres
marked. (c) Auckland area showing the position of Orakei Basin. Red
shading in populated areas; dark shading shows increased elevation.
(d) Satellite image (ESRI world imagery) show the coring locations
with red dots and other important features of the surroundings of the maar.
Many sediment records rely on one master record stitched together from two or
more cores from a sedimentary sequence, although it is often not explained
how these master records are derived. Nakagawa et al. (2012) summarised an
incomplete early sediment sequence retrieved from Lake Suigetsu (Japan)
resulting in potentially erroneous interpretations. Furthermore, they
reported details of aligned sediment core sections from the Lake Suigetsu
(Japan) sequence drilled in 2006, which largely relied on visual
identification of marker layers (i.e. tephra and flood layers), as well as
intervals of lower confidence in the alignment of the sediment cores without
abundant visual markers. A recent approach using core-scanning X-ray
fluorescence (XRF) by Mischke et al. (2017) aligned two cores using visually
distinct features in the down-core elemental variation, but also noted the
need to delete a number of “second order markers” to avoid conflicting and
likely incorrect stratigraphic ordering.
Here we (1) provide details of the approach used for robust construction of a
composite stratigraphy from two (or more) overlapping cores based on visual
markers, and, if the latter are absent, guided by μ-XRF-based
geochemical variability; and (2) introduce and describe the Orakei maar
paleo-lake in a lithostratigraphic framework. In so doing we highlight the
outstanding potential of the sequence for paleo-climatic reconstructions from
an under-studied region of crucial importance to understanding the behaviour
of the global climate system over the Last Glacial Cycle.
Regional setting
Auckland is located in the northern part of the North Island of New Zealand
(Fig. 1a). The coring site, Orakei Basin, is a tidal lagoon with artificially
controlled inflow and outflow to maintain water levels for water sports and
allow regular flushing of pollutants. Subsequent to the highly explosive
maar-forming phreatomagmatic eruption, a lake filled the crater until ca.
9.5 ka cal BP, when post-glacial sea-level rise breached the crater rim and
connected the lake to the sea, allowing mass influx of tidal mud (Hayward et
al., 2008). The modern surroundings of Orakei Basin are characterised by
residential buildings to its south and the crater rim collapse identifiable
from active landslides (Fig. 1d). Erosion and collapse of the steep crater
walls and successive crater widening have led to repeated pulses of recycled
eruptive material (juvenile clast and accidental ejecta/country rock) into
the basin (Németh et al., 2012). Figure 1d shows the location of the two
cores retrieved in 2016. No GPS position was recorded for the core retrieved
in 2007, but the position was noted as near the centre of the basin. No
shallow seismic survey of the sediment strata below the sediment–water
interface has been undertaken. Hence, lateral extent and distribution of
strata remain speculative.
MethodsCoring
Initial coring of Orakei Basin was undertaken from a floating barge in 2007
using a rotating barrel system, with a single core that penetrated to 81 m
depth below the water–sediment interface. A further set of two overlapping
cores with 50 cm vertical offset between them was collected in 2016 from a
barge using wireline drilling and core collection in 1 m long sections. The
lateral offset between the OB16A and OB16B core was 8 m.
Core description and visual facies identification
Split-core surfaces were described in detail for visually distinct changes in
composition, qualitative grain size (clay, silt, very fine to coarse sand),
colour (Munsell Color, 1975), thickness and shape of laminations, signs of
bioturbation (burrows), (coring-induced and natural) disturbance of
laminations and sedimentary features, presence of macrofossils (pieces of
wood/bark and small twigs), and tephra layers. Each facies unit contains
sediment of similar colour, composition, and laminae structure (or absence of
laminations). Subunits differentiate between intervals of smaller
differences, i.e. a change in lamination thickness or a slight colour change
with overall similar sediment type and appearance. Most facies units have
sharp contacts and are hence easily identified.
μ-XRF core scanning and magnetic susceptibility
The Orakei sediment cores were scanned using an Itrax μ-XRF core scanner
(Cox Analytical Systems (Gothenburg, Sweden) at the School of Environment,
University of Auckland, New Zealand. μ-XRF core scanning records
down-core elemental variation in the range Al to U (on the Mo X-ray tube)
rapidly, non-destructively, and with very little sample preparation (Croudace
et al., 2006; Croudace and Rothwell, 2015). Here, μ-XRF data were
acquired for all cores with the Mo X-ray tube (at 30 kv, 55 mA) at 1 mm
spatial resolution and 10 s/step exposure time. High-resolution optical
images (at 47 µm) and radiographic images (at 60 kV, 50 mA and
1 mm resolution) were recorded during the same scanning process. Magnetic
susceptibility was acquired automatically by the same Itrax core scanner at
5 mm resolution for all cores with a Bartington Magnetic Susceptibility MS2e
surface scanning sensor.
Establishing the composite stratigraphy
The two cores retrieved in 2016 were drilled with at least 50 cm vertical
offset to allow for overlaps between both cores around core breaks. The
alignment of these overlapping sections is straightforward by visual means in
the finely laminated sediment sections of the core. However, it is more
difficult to establish a composite stratigraphy in the coarser sediment where
clear marker layers are often absent. Consequently, magnetic susceptibility
and μ-XRF data were used to aid the correlation of the overlapping cores
as described below.
Examples of core photos from the Orakei maar paleo-lake record and
their correlation. (a) Laminated facies easily correlated using
visual marker layers. Down-core μ-XRF
variation can be used for correlation, but does not offer additional markers.
Green bands along the depth axis indicate the record of higher quality, which
is adopted for the composite μ-XRF and MS record. (b) Facies
comprised of silt, sand, and large subfossil wood fragments which are very
difficult to correlate unambiguously. Visual correlation may be incorrect in
large sections, but cannot be improved easily with μ-XRF variation
either. Hence, yellow bands alongside the depth axis indicate unsure
correlation, which is carried forward in the master record.
Visually prominent marker layers allowed most of the correlation using tephra
layers (Table S2 in the Supplement), thick mass movement deposits, and major
sharp facies contacts (i.e. onset of laminations, strong changes in grain
size or colour) as outlined in Figs. 2 and 3. Finely laminated sediment was
aligned on a sub-centimetre scale visually as highlighted by the
high-resolution images in Fig. 2 (left). Coarse sediment showing no clear
features along which to align the cores is shown in Fig. 2 (right). To obtain
a complete composite stratigraphy, these intervals are correlated with
reduced certainty (marked yellow in Fig. 3). These intervals constitute ca.
15 % of the entire sediment sequence and are confined by sharp upper and
lower contacts. K and Fe (normalised to incoherent scatter (inc)) have been
identified as showing the highest potential for cross-core correlation and
have been used to identify chemical changes where visual markers are absent.
The feasibility of this approach is underlined by the alignment of the finely
laminated sediment where XRF-based correlation is in agreement with visual
correlation as shown in Fig. 2 (left). Prominent minima or maxima in the
geochemical XRF curve (i.e. K/inc) occur at sediment horizons different from
sediment below and/or above, such as event layers or facies changes. It is
reasonable to assume that these horizons are recorded in all sediment cores
of the same depositional basin, which underlines their potential as marker
layers. In this way, the down-core elemental variability has been used as an
additional aid to establishing an overlapping composite stratigraphy. Where
no other constraint on correlation could be established, it was guided by the
common offset of the A-core usually showing distinct features ∼1 m
higher than the B-core (note the offset depth scales in Fig. 2 for
visualisation purposes). Horizons of instantaneous deposition such as tephra
layers and mass movement deposits were removed on the event-corrected depth
scale (ECD).
Results and discussionLithostratigraphic units
Figure 3 summarises the 16 major lithostratigraphic units (numbers) with 31
subunits (letters). Their differentiation is driven by visual changes in
colour, grain size, dominant structure, and lamination thickness. Facies
descriptions of the units are provided in Table S1 in the Supplement and are
shown in Fig. 3, with example core photos in Fig. 4.
Orakei maar paleo-lake composite stratigraphy, lithological
description, and rhyolitic marker
tephra layers with ages (tephra layers from Peti et al., 2019).
Example core photographs of the 16 facies units and subunits. Each
core photo graphed is ∼1 m long.
Preliminary age model established from rhyolitic tephra marker
layers (Table S2) and extrapolation of an assumed continuous sedimentation
rate to the core base compared with inferred ages in Hopkins et al. (2017).
Preliminary age model
The dated rhyolitic tephra marker layers and one radiocarbon date near the
top of the sequence from the 2007 core published in Hayward et al. (2008)
(NZA28865: 9512±19 cal ka BP, calibrated with SHCal13; Hogg et al.,
2013) allow for the construction of a preliminary, simplified age model
(Fig. 5). The finely laminated sediment between the Tahuna and Rotoehu tephra
is largely representative for most of the Orakei sediment sequence below
40 m (ECD). The thick sand bands of facies units 9 and 11 have been removed
on the ECD, explaining the difference of 4.83 m between Figs. 3 and 5. The
sediment between those bands is mostly laminated silt, and we assume a
similar sedimentation rate both above and below for this preliminary age
estimate for the core base (Fig. 5). Extrapolation of the sedimentation rate
between the Tahuna and Rotoehu tephras (2300 yr m-1) to the base of
the sequence (hence, eruption age of Orakei crater) produces an age of ca.
123.6 ka BP (Fig. 5, age c). Using the same approach, the age for basaltic
tephra layer AVF1 is estimated to be ca. 80.4 ka BP, only slightly younger
than the 83.1 ka BP estimated by Molloy et al. (2009) and well within
typical errors of tephra ages pre-21 ka BP of ±1–2 ka (Molloy et
al., 2009). Hopkins et al. (2017; Fig. 5) inferred an older age for AVF1 of
106.17±4.3 ka BP together with a basal age of 126.15±3.32 ka BP. Although the age estimate of the base of the sequence
(i.e. the Orakei eruption, correlated with the AVFa horizon in Hopkins
et al., 2017) agrees very well with our estimates, the AVF1 age appears >20 kyr older compared to the estimate from the Orakei sediment accumulation
rates (Fig. 5). This age–depth relationship would result in a low
sedimentation rate between Rotoehu and AVF1 and a marked increase between
AVF1 and the sequence base. Although it is possible that very thin mass
movement deposits have not been recognised which could cause this higher
sedimentation rate, the same would be true for facies units 8 and 10 above
the AVF1 layer (Fig. 3). More rapid infilling of the crater could be
associated with facies units 9 and 11 despite removal of the event layers. On
the other hand, a slower observed sedimentation rate could also be caused by
periods of non-deposition during significantly lower lake levels. Sharp
facies contacts may indicate erosion and non-deposition. However, we consider
this to represent only short time durations since the clay and silt intervals
between the sand bands in facies units 9 and 11 show laminations indicating
continuous sedimentation under deep-lake conditions (Fig. 3). Consequently,
the inferred near-constant sedimentation rate model is preferred here. This
model suggests that the Orakei eruption occurred just after Termination II
(ca. 130 ka BP; Lisiecki and Raymo, 2005) early in the onset of the Last
Interglacial (MIS 5e). Therefore, we infer that the Orakei sediment sequence
spans most of the Last Glacial Cycle. However, these are necessarily crude
estimates based on linear interpolation and extrapolation, and they are being
refined (see Sect. 5).
Possible outcomes of the Orakei maar sediment sequence
A high-resolution multi-method chronology is currently being established
for the
Orakei sediment sequence based on radiocarbon dating, tephrochronology,
post-IR IRSL (luminescence) dating, relative paleo-intensity variation of the
Earth's magnetic field, and 10Be cosmogenic nuclide flux into the
lake. Coeval with this work, pollen and chironomid analyses are underway to
enable detailed reconstruction of changes in the paleo-vegetation and
climatic conditions. Itrax
μ-XRF core scanning data alongside traditional measurements of
loss-on-ignition, carbon and nitrogen content, as well as stable oxygen and
carbon isotopes, will be combined to reconstruct the climatic development of
the area over the Last Glacial Cycle. Micro-facies studies on
resin-impregnated sediment slabs and large-scale thin sections will allow
identification of abrupt climate shifts and events as well as identification
of changes in seasonality recorded in the Orakei composite sediment sequence.
The Orakei maar paleo-lake sequence is expected to do the following.
Constrain the frequency and magnitude of eruptions of the Auckland
Volcanic Field through provision of better age estimates for past basaltic
eruptions.
Constrain the nature, drivers, magnitude, and timing of climatic changes in
this part of the south-western Pacific. In addition, accurate and precise
dating of the age markers and correlation with cosmogenic nuclide production
variation (10Be) may enable identification of climate leads and
lags between the Northern and Southern Hemisphere mid-latitudes, including
European maar lake and polar ice core records.
Understand the role of the westerly winds in climate change on a millennial to
sub-decadal timescale in the south-western Pacific over the Last Glacial
Cycle, with thick laminae likely reflecting a response to strong
south-westerly winds with increased precipitation over the region depositing
wind-blown dust and, hence, controlling biological productivity in the lake.
Conclusions
Even the most detailed observations and most sophisticated coring techniques
cannot produce a perfect sediment core composite stratigraphy. In the case of
finely laminated sediment and no to little coring disturbance, it is
relatively straightforward to align overlapping cores along prominent
sedimentary features, such as mass movement deposits, unique alternations of
laminations, sharp facies contacts, or tephra layers. In the case of coarse
sand and macroscopic organic detritus (e.g. facies units 9 and 11), core
alignments prove to be more challenging. Despite the close proximity of the
two coring positions in Orakei maar (Fig. 1, 10 m distance), the uneven
distribution of mass movement deposits/slumps at the lake bottom results in
small differences of the sediment stratigraphy that reduce confidence in the
development of the composite stratigraphy over these intervals. While it is
important to be aware of this source of uncertainty, the affected interval
will reduce in relative thickness when the record is viewed against a
timescale as opposed to a depth scale (metres below the marine
water–freshwater transition).
Overall, the Orakei maar paleo-lake record constitutes an exceptional,
continuous, long, high-resolution sedimentary record that captures
environmental and climatic changes in the northern North Island of New
Zealand over the Last Glacial Cycle. The history of the lake commenced with
the maar-forming phreatomagmatic eruption, through various stages of changing
deep lacustrine conditions, minor mass movement events associated with
erosion/collapse of the crater rim, and deposition of distal rhyolitic and
locally derived basaltic tephra layers. The deep lake phase was terminated by
fluvial sediment influx at ca. 20.3 cal ka BP (onset of facies unit 3) and
peat accumulation to infill the basin before an episodic breach of the crater
rim associated with rising post-glacial sea level in the early Holocene drove
rapid marine sediment influx to create the modern tidal basin. Correlation of
the Orakei maar lake sediment sequence with those developed from Pupuke and
Onepoto maars (Fig. 1) will enable development of an AVF master stratigraphy
and robust reconstruction of environmental and climatic conditions spanning
the last two glacial cycles for the first time from subtropical northern New
Zealand.
Data availability
Preliminary data presented in this progress report are not
publicly available as they are still being evaluated and expanded. Upon
completion, all data will be made available when scientific papers and
reports are published.
The supplement related to this article is available online at: https://doi.org/10.5194/sd-25-47-2019-supplement.
Author contributions
PCA leads the AVF maar project, secured funding, and is involved in all
aspects of the work. LP conducted the core descriptions, Itrax μ-XRF core
scans, and development of the composite stratigraphy. LP wrote the original
version of this report with refinements from PCA.
Competing interests
The authors declare that they have no conflict of
interest.
Acknowledgements
The drilling investigation team included Paul Augustinus, Jan Lindsay,
Phil Shane, Elaine Smid (University of Auckland), Jenni Hopkins and
Graham Leonard (GNS Science), Valerie van den Bos (Victoria University of
Wellington), Tim Shanahan and Natalia Piatrunia (University of Texas at
Austin), and Frank Sirocko (University of Mainz). The project was funded by
DeVORA (funded by New Zealand's Earthquake Commission and the Auckland
Council), and a grant from the Royal Society of New Zealand Marsden Fund
(UOA1415 to Paul C. Augustinus). Leonie Peti thanks Patricia Gadd (ANSTO,
Australia) and Per Engström (Cox Analytical, Sweden) for outstanding help
with Itrax data. We thank Bernd Zolitschka and David Lowe for thoughtful
comments and improvements on the manuscript and Ulrich Harms for efficient
editorial handling.
Review statement
This paper was edited by Ulrich Harms and reviewed by David
Lowe and Bernd Zolitschka.
ReferencesAlloway, B. V., Lowe, D. J., Barrell, D. J. A., Newnham, R. M., Almond, P.
C., Augustinus, P. C., Bertler, N. A. N., Carter, L., Litchfield, N. J.,
McGlone, M. S., Shulmeister, J., Vandergoes, M. J., Williams, P. W., and
NZ-INTIMATE members: Towards a Climate Event Stratigraphy for New Zealand
over the past 30 000 years (NZ-INTIMATE project), J. Quaternary Sci., 22,
9–35, 10.1002/Jqs.1079, 2007.
Augustinus, P.: NZ-Maars: Extracting high resolution paleoclimate records
from maar crater lakes, Auckland, New Zealand, PAGES News, 15, 18–20, 2007.Augustinus, P., D'Costa, D., Deng, Y., Hagg, J., and Shane, P.: A multi-proxy
record of changing environments from ca. 30 000 to 9000 cal. a BP:
Onepoto maar palaeolake, Auckland, New Zealand, J. Quaternary Sci., 26,
389–401, 10.1002/jqs.1463, 2011.Brauer, A., Endres, C., and Negendank, J. F. W.: Lateglacial calendar year
chronology based on annually laminated sediments from Lake Meerfelder Maar,
Germany, Quaternary Int., 61, 17–25, 10.1016/S1040-6182(99)00014-2,
1999.
Croudace, I. W. and Rothwell, R. G. (Eds.): Micro-XRF Studies of Sediment
Cores: Applications of a non-destructive tool for the environmental sciences,
Springer, DPER Series 17, Dordrecht, 656 pp., 2015.Croudace, I. W., Rindby, A., and Rothwell, R. G.: ITRAX: description and
evaluation of a new multi-function X-ray core scanner, Geol. Soc. Lond. Spec.
Publ., 267, 51–63, 10.1144/GSL.SP.2006.267.01.04, 2006.Edbrooke, S. W., Mazengarb, C., and Stephenson, W.: Geology and geological
hazards of the Auckland urban area, New Zealand, Quaternary Int., 103, 3–21,
10.1016/S1040-6182(02)00129-5, 2003.
Hayward, B. W., Morley, M. S., Sabaa, A. T., Grenfell, H. R., Daymond-King,
R., Molloy, C., Shane, P. A., and Augustinus, P. A.: Fossil Record of the
Post-Glacial Marine Breaching of Auckland's Volcanic Maar Craters, Rec.
Auckl. Museum, 45, 79–99, 2008.Hogg, A., Hua, Q., Blackwell, P. G., Niu, M., Buck, C. E., Guilderson, T. P.,
Heaton, T. J., Palmer, J. G., Reimer, P. J., Reimer, R. W., Turney, C. S. M.,
and Zimmerman, S. R. H.: SHCal13 Southern Hemisphere Calibration, 0–50,000
Years cal BP, Radiocarbon, 55, 1889–1903, 10.2458/azu_js_rc.55.16783,
2013.Hopkins, J. L., Millet, M. A., Timm, C., Wilson, C. J. N., Leonard, G. S.,
Palin, J. M., and Neil, H.: Tools and techniques for developing tephra
stratigraphies in lake cores: A case study from the basaltic Auckland
Volcanic Field, New Zealand, Quaternary Sci. Rev., 123, 58–75,
10.1016/j.quascirev.2015.06.014, 2015.Hopkins, J. L., Wilson, C. J. N., Millet, M. A., Leonard, G. S., Timm, C.,
McGee, L. E., Smith, I. E. M., and Smith, E. G. C.: Multi-criteria
correlation of tephra deposits to source centres applied in the Auckland
Volcanic Field, New Zealand, B. Volcanol., 79, 55,
10.1007/s00445-017-1131-y, 2017.Horrocks, M., Augustinus, P., Deng, Y., Shane, P., and Andersson, S.:
Holocene vegetation, environment, and tephra recorded from Lake Pupuke,
Auckland, New Zealand, New Zeal. J. Geol. Geop., 48, 85–94,
10.1080/00288306.2005.9515100, 2005.Leonard, G. S., Calvert, A. T., Hopkins, J. L., Wilson, C. J. N., Smid, E.
R., Lindsay, J. M., and Champion, D. E.: High-precision
40Ar/39Ar dating of Quaternary basalts from Auckland Volcanic
Field, New Zealand, with implications for eruption rates and paleomagnetic
correlations, J. Volcanol. Geoth. Res., 343, 60–74,
10.1016/j.jvolgeores.2017.05.033, 2017.Lindsay, J., Leonard, G., Smid, E., and Hayward, B.: Age of the Auckland
Volcanic Field: a review of existing data, New Zeal. J. Geol. Geop., 54,
379–401, 10.1080/00288306.2011.595805, 2011.Lisiecki, L. E. and Raymo, M. E.: A Pliocene-Pleistocene stack of 57 globally
distributed benthic δ18O records, Paleoceanography, 20, 1–17,
10.1029/2004PA001071, 2005.Mischke, S., Lai, Z., Aichner, B., Heinecke, L., Mahmoudov, Z., Kuessner, M.,
and Herzschuh, U.: Quaternary Geochronology Radiocarbon and optically
stimulated luminescence dating of sediments from Lake Karakul, Tajikistan,
Quat. Geochronol., 41, 51–61, 10.1016/j.quageo.2017.05.008, 2017.Molloy, C., Shane, P., and Augustinus, P.: Eruption recurrence rates in a
basaltic volcanic field based on tephralayers in maar sediments: Implications
for hazards in the Auckland volcanic field, Bull. Geol. Soc. Am., 121,
1666–1677, 10.1130/B26447.1, 2009.
Munsell Color: Munsell soil color charts, Munsell Color, Baltimore, Md.,
1975.Nakagawa, T., Gotanda, K., Haraguchi, T., Danhara, T., Yonenobu, H., Brauer,
A., Yokoyama, Y., Tada, R., Takemura, K., Staff, R. A., Payne, R., Bronk
Ramsey, C., Bryant, C., Brock, F., Schlolaut, G., Marshall, M., Tarasov, P.,
and Lamb, H.: SG06, a fully continuous and varved sediment core from Lake
Suigetsu, Japan: Stratigraphy and potential for improving the radiocarbon
calibration model and understanding of late Quaternary climate changes,
Quaternary Sci. Rev., 36, 164–176, 10.1016/j.quascirev.2010.12.013,
2012.Németh, K., Cronin, S. J., Smith, I. E. M., and Agustin Flores, J.:
Amplified hazard of small-volume monogenetic eruptions due to environmental
controls, Orakei Basin, Auckland Volcanic Field, New Zealand, B. Volcanol.,
74, 2121–2137, 10.1007/s00445-012-0653-6, 2012.Newnham, R. M., Lowe, D. J., and Alloway, B. V.: Volcanic hazards in
Auckland, New Zealand: a preliminary assessment of the threat posed by
central North Island silicic volcanism based on the Quaternary
tephrostratigraphical record, Volcanoes Quat., 161, 27–45,
10.1144/GSL.SP.1999.161.01.04, 1999.Peti, L., et al.: Reliability and repeatability of bulk μ-XRF
measurements of rhyolitic tephra for their rapid and non-destructive
identification, J. Quaternary Sci., in review, 2019.Sandiford, A., Newnham, R., Alloway, B., and Ogden, J.: A
28 000–7600 cal yr BP pollen record of vegetation and climate change
from Pukaki Crater, northern New Zealand, Palaeogeogr. Palaeocl., 201,
235–247, 10.1016/S0031-0182(03)00611-4, 2003.
Shane, P.: Towards a comprehensive distal andesitic tephrostratigraphic
framework for New Zealand based on eruptions from Egmont volcano, J.
Quaternary Sci., 20, 45–57, 10.1002/jqs.897, 2005.Shane, P. and Hoverd, J.: Distal record of multi-sourced tephra in Onepoto
Basin, Auckland, New Zealand: Implications for volcanic chronology, frequency
and hazards, B. Volcanol., 64, 441–454, 10.1007/s00445-002-0217-2, 2002.Zolitschka, B., Anselmetti, F., Ariztegui, D., Corbella, H., Francus, P.,
Lücke, A., Maidana, N. I., Ohlendorf, C., Schäbitz, F., and
Wastegård, S.: Environment and climate of the last 51,000 years – new
insights from the Potrok Aike maar lake Sediment Archive Drilling prOject
(PASADO), Quaternary Sci. Rev., 71, 1–12,
10.1016/j.quascirev.2012.11.024, 2013.