193 results for Lowe, David J.

  • Detection of thin tephra deposits in peat and organic lake sediments by rapid X-radiography and X-ray fluorescence techniques

    Lowe, David J.; Hogg, Alan G.; Hendy, C.H. (1981)

    Conference item
    University of Waikato

    This paper reports the application of the X-ray image process of X-radiography to unopened, small diameter organic sediment cores containing thin tephra deposits. Second, a rapid technique for detecting tephra layers in peat samples by X-ray fluorescence (XRF) analysis is described.

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  • Late Quaternary tephras in the Hamilton Basin, North Island, New Zealand

    Lowe, David J. (1981)

    Conference item
    University of Waikato

    This paper summarises the occurrence and distribution of late Quaternary tephras in the Hamilton (Middle Waikato) Basin and outlines a model to explain the pattern of soils formed from them. The collaborative work currently in progress on paleoecological aspects of the late Otiran - Aranuian history of the area is also reported.

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  • Tales of the unexpected: halloysite delivers surprises and a paradox

    Lowe, David J.; Churchman, G. Jock (2016)

    Unclassified
    University of Waikato

    Despite being first described nearly 200 years ago, halloysite still has the capacity to surprise. We report here the remarkable discovery in New Zealand of two new morphologies for this 1:1 Si:Al layered aluminosilicate member of the kaolin subgroup. One discovery was entirely serendipitous, thus lending validity to the famous phrase attributed to scientist Isaac Asimov: The most exciting phrase to hear in science, the one that heralds new discoveries, is not “Eureka” but “That’s funny...”. Moreover, the recognition of one of the new morphologies of halloysite helped enable a long-standing problem regarding the geotechnical property of sensitivity and its impact on landsliding in the Tauranga region, eastern North Island, to be solved. Such landsliding has commonly been attributed (possibly erroneously) to the dominance of nanocrystalline allophane, the clay commonly associated with halloysite in many weathered pyroclastic sequences and volcanogenic soils in North Island. In this article, we briefly summarise the circumstances and implications of the two discoveries relating to halloysite morphology, one published in Clay Minerals and the other in Geology, and a third study (also in Clay Minerals) relating in part to the formation of halloysite.

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  • A new attraction-detachment model for explaining flow sliding in clay-rich tephras

    Kluger, Max O.; Moon, Vicki G.; Kreiter, Stefan; Lowe, David J.; Churchman, G.Jock; Hepp, Daniel A.; Seibel, David; Jorat, M. Ehsan; Mörz, Tobias (2017-02-01)

    Journal article
    University of Waikato

    Altered pyroclastic (tephra) deposits are highly susceptible to landsliding, leading to fatali-ties and property damage every year. Halloysite, a low-activity clay mineral, is commonly associated with landslide-prone layers within altered tephra successions, especially in depos-its with high sensitivity, which describes the post-failure strength loss. However, the precise role of halloysite in the development of sensitivity, and thus in sudden and unpredictable landsliding, is unknown. Here we show that an abundance of mushroom cap–shaped (MCS) spheroidal halloysite governs the development of sensitivity, and hence proneness to landslid-ing, in altered rhyolitic tephras, North Island, New Zealand. We found that a highly sensitive layer, which was involved in a flow slide, has a remarkably high content of aggregated MCS spheroids with substantial openings on one side. We suggest that short-range electrostatic and van der Waals interactions enabled the MCS spheroids to form interconnected aggre-gates by attraction between the edges of numerous paired silanol and aluminol sheets that are exposed in the openings and the convex silanol faces on the exterior surfaces of adjacent MCS spheroids. If these weak attractions are overcome during slope failure, multiple, weakly attracted MCS spheroids can be separated from one another, and the prevailing repulsion between exterior MCS surfaces results in a low remolded shear strength, a high sensitivity, and a high propensity for flow sliding. The evidence indicates that the attraction-detachment model explains the high sensitivity and contributes to an improved understanding of the mechanisms of flow sliding in sensitive, altered tephras rich in spheroidal halloysite.

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  • The lore of lakes

    Green, John D.; Lowe, David J. (1992)

    Journal article
    University of Waikato

    Studies of lakes and their many layers of silt and sediment can tell us a great deal, from centuries-old deforestation practices to the climate changes over thousands of years. The study of the history of lake ecosystems is a fast developing field known as palaeolimnology.

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  • Introduction to tephra-derived soils, North Island, New Zealand: University of Waikato and University of Wisconsin-Platteville post-conference Andisol excursion, 21-23 December, 2016

    Lowe, David J. (2016-12-21)

    Report
    University of Waikato

    Provisional itinerary DAY 1 Wednesday 21 December: Mamaku Plateau-Rerewhakaaitu-Lake Tarawera: 1 Goodwin Farm, Tapapa Rd, Tapapa: welded ignimbrite, tephras, loess, buried soils (Tirau soil) - stratigraphy of sequence (230 ka and younger) and upbuilding pedogenesis - Tirau silt loam 2 Brett Rd, Rerewhakaaitu: Holocene tephras and buried soil (Rotomahana soil) - Volcanic landscape, historical importance of area for NZ soil survey - Stratigraphy of sequence (~9.5 cal ka to 10 June 1886 Tarawera eruption) and upbuilding pedogenesis - Rotomahana sandy loam, 3 Ash Pit Rd, Rerewhakaaitu: tephras and buried soils (Matahina soil) - Matahina gravel - buried spodic/podzol soil features, 4 Okareka Loop Rd tephra section with proximal Rotorua Tephra and buried soils, loess, Buried Village Museum, Te Wairoa, Lake Tarawera (Stoney Point). DAY 2 Thursday 22 December: Otorohanga-Waitomo Caves -Pirongia Mountain: 1 Raynes Road section: Ultisol in composite tephra sequence (Kainui soil), 2 Otorohanga Kiwi House, 3 Waitomo Caves,, 4 Pirongia Mountain: Mangakara forest walk, 5 Evening meal on an Andisol. DAY 3 Friday 23 December: Hobbiton, Hamilton gardens including Te Parapara (ancient Maori garden): 1. Hobbiton tour 10.15 am (2 hrs), 2. Hamilton Gardens incl. Te Parapara Garden and human-modified soils (Tamahere soil).

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  • Guidebook for Rangitoto Island AQUA field trip, Auckland, 2016

    Lowe, David J.; Shane, Phil A.R.; de Lange, Peter J.; Clarkson, Bruce D. (2016)

    Conference item
    University of Waikato

    Rangitoto is arguably Auckland’s most beautiful and omnipresent landscape feature. It is a symmetrical, ~6-km wide, basaltic shield volcano that last erupted ~550‒500 cal. yr BP (c. 1400‒1450 AD), not long after the arrival and settlement of Polynesians in the Auckland region (c. 1280 AD). It is by far the largest, and the youngest, volcano in the Auckland Volcanic Field (AVF). The AVF consists of approximately 53 individual eruptive centres, all of which are within the boundaries of the Auckland urban area. Recent research on cryptotephras (defined below) in sediments from Lake Pupuke on North Shore and in wetlands on Motutapu Island, and on a 150-m-long drill core obtained in February, 2014, has revealed that Rangitoto has a much more complex history that previously thought, and may be better viewed as a ‘volcanic complex with multiple episodes of eruptions’ (Linnell et al. 2016). In summary, (1) activity commenced c. 6000 cal. yr BP involving minor effusive and pyroclastic volcanism; (2) a voluminous shield-building phase took place from c. 650550 cal. yr BP (c. 13001400 AD), forming the main island ediface; and (3) the final phase of activity, from c. 550500 cal. yr BP (c. 14001450 AD), was explosive and less voluminous, producing scoria cones at the summit. The flora on Rangitoto is unique among the islands situated in the Hauraki Gulf because of the island’s young age, and the fact that technically Rangitoto is an ‘oceanic’ island. Its flora and fauna are derived entirely from long distance dispersal. The island contains some 582 vascular plant taxa of which 228 (39%) are indigenous. Various other special ecological features, and studies on plant succession and their drivers, make the island a truly fascinating place to visit. At this time of year, we should see many pohutukawa (Metrosideros excelsa) trees in flower.

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  • The time machine. Norman Taylor Memorial Lecture 2002

    Lowe, David J. (2002)

    Conference item
    University of Waikato

    I've chosen to talk about five topics dealing with longstanding pedological or paleoenvironmental problems involving tephrostratigraphy. I'll begin with the oldest tephras and work 'stratigraphically upwards' to the youngest. Along the way I'll mention or show a few of the people I've worked with, or who were involved historically in the research areas. I've allowed around five or six minutes for each topic (but I'd be grateful if you didn't set your stopwatches!). As promised, the second part of the talk will begin when we reach the year 1952. Among a range of personal observations relating to the birth of the society and to Norman Taylor, I will attempt to explain how I came to be giving this lecture today.

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  • Rangitoto volcano excursion, Auckland. Pre-conference field trip

    Lowe, David J.; Kenedi, Kate Lewis; de Lange, Peter J. (2014-08-30)

    Conference item
    University of Waikato

    Rangitoto is one of Auckland City’s more iconic landscape features. Guarding the entrance to the Waitemata Harbour, Rangitoto is a symmetrical, ~6-km wide, basaltic shield volcano that last erupted ~550 years ago shortly after the arrival and settlement of Polynesians in the Auckland region (c. 1280 AD). Rangitoto is by far the largest, and also the youngest, volcano in the Auckland Volcanic Field (AVF). The AVF is a monogenetic volcanic field consisting of approximately 53 individual eruptive centres, all of which are within the boundaries of the Auckland urban area. Recent research has revealed more about Rangitoto’s eruptive history, which may date back to c. 1500 years ago (Shane et al. 2013). Some of these findings have been noted below and will be discussed further while we ascend its summit and explore its various landscape and vegetational features.

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  • Discovery of halloysite books in altered silicic Quaternary tephras, northern New Zealand

    Cunningham, Michael J.; Lowe, David J.; Wyatt, Justin Burns; Moon, Vicki G.; Churchman, G. Jock (2016-10-11)

    Journal article
    University of Waikato

    Hydrated halloysite was discovered in books, a morphology previously associated exclusively with kaolinite. From ~1.5 μm to ~1500 μm in length, the books showed significantly greater mean Fe contents (Fe2O3 = 5.2 wt%) than tubes (Fe2O3 = 3.2 wt%), and expanded rapidly with formamide. They occurred, along with halloysite tubes, spheroids, and plates, in highly porous yet poorly-permeable, silt-dominated, Si-rich, pumiceous rhyolitic tephra deposits aged ~0.93 Ma (Te Puna tephra) and ~0.27 Ma (Te Ranga tephra) at three sites ~10-20 m stratigraphically below the modern land-surface in the Tauranga area, eastern North Island, New Zealand. The book-bearing tephras were at or near saturation, but have experienced intermittent partial drying, favouring the proposed changes: solubilized volcanic glass + plagioclase -> halloysite spheroids -> halloysite tubes -> halloysite plates -> halloysite books. Unlike parallel studies elsewhere involving both halloysite and kaolinite, kaolinite has not formed in Tauranga presumably because the low permeability ensures the sites largely remain locally wet so that the halloysite books are metastable. An implication of the discovery is that some halloysite books in similar settings may have been misidentified previously as kaolinite.

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  • Unique but diverse: some observations on the formation, structure, and morphology of halloysite

    Churchman, G. Jock; Pasbakhsh, Pooria; Lowe, David J.; Theng, B.K.G. (2016-10-11)

    Journal article
    University of Waikato

    New insights from the recent literature are summarised and new data presented concerning the formation, structure and morphology of halloysite. Halloysite formation by weathering always requires the presence of water. Where substantial drying occurs, kaolinite is formed instead. Halloysite formation is favoured by a low pH. The octahedral sheet is positively charged at pH < ~8, whereas the tetrahedral sheet is negatively charged at pH > ~2. The opposing sheet charge would facilitate interlayer uptake of H₂O molecules. When halloysite intercalates certain polar organic molecules, additional (hkl) reflections appear in the X-ray diffractogram, suggesting layer re-arrangement which, however, is dissimilar to that in kaolinite. Associated oxides and oxyhydroxides of Fe and Mn may limit the growth of halloysite particles as does incorporation of Fe into the structure. Particles of different shape and iron content may occur within a given sample of halloysite.

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  • The working life of John McCraw (1925-2014): a remarkable New Zealand pedologist and Earth scientist

    Nelson, Campbell S.; Lowe, David J.; Tonkin, Philip J. (2015)

    Journal article
    University of Waikato

    John McCraw was an Earth scientist who began working as a pedologist with Soil Bureau, DSIR, then became the Foundation Professor of Earth Sciences at the University of Waikato in Hamilton, inspiring a new generation to study and work in Earth sciences, a discipline he introduced into the tertiary education system in New Zealand. In retirement, he was an author and historian with a special emphasis on Central Otago as well as the Waikato region. Throughout his career, marked especially by meritorious leadership, accomplished administration, and commitment to his staff and students at the University of Waikato, John McCraw also contributed widely to the communities in which he lived through public service organizations and as a public speaker. He received a number of awards including an MBE, fellowship, and companionship, and, uniquely, is commemorated also with a glacier, a fossil, and a museum-based research room named for him. The Earth sciences programme today as an integral part of the School of Science at the University of Waikato is stronger than ever. In the past few years several new staff have been appointed, both academic and technical, giving the largest-ever Earth sciences team of about 30 staff. As well as research-led teaching, Earth sciences has strong research groups, at the cores of which are doctoral and masterate students, and postdoctoral fellows, to carry on the work envisaged by John McCraw all those years ago. This thriving continuation of our discipline, which has always had strong multidisciplinary linkages with other sciences, is − alongside the countless students he has taught and inspired − surely his greatest legacy.

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  • The effect of climate on lake mixing patterns and temperatures

    Green, John D.; Viner, A.B.; Lowe, David J. (1987)

    Book item
    University of Waikato

    The maritime geographical location has been said to give distinctive characteristics of water mixing to lakes (Hutchinson 1957, pp. 443-444), but such effects have never been described in detail. New Zealand's lakes should exemplify well these maritime distinctions, and in this chapter features of water column mixing and temperature changes are identified which can distinguish New Zealand lakes from those elsewhere.

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  • Origins and development of the lakes

    Lowe, David J.; Green, John D. (1987)

    Book item
    University of Waikato

    Because of a turbulent and complex recent geological history, New Zealand has an impressively diverse and dynamic landscape, and a correspondingly wide array of lake types, within a small land area (Irwin 1975a; Soons & Selby 1982;). The development of such an active geological environment in New Zealand has been governed largely by its location athwart the Australian and Pacific plate boundary, and its maritime mid-latitude position has made it particularly sensitive to the climatic fluctations and associated glaciations and sea level changes of the Quaternary Period (Suggate et al. 1978). At present, the rates of uplift and erosion of mountainous areas are among the fastest in the world. Earthquakes are common, and volcanism has characterised much of the North Island during the Quaternary with numerous volcanoes active in the last few thousand years. Large, explosive caldera volcanoes in central North Island have erupted repeatedly over the last million years, producing voluminous amounts of lava and widespread pyroclastic deposits. The landforms, soils and lakes are thus typically youthful, almost all being younger than two million years; indeed, much of the landscape is of late Pleistocene and Holocene age, and is still actively developing (Pillans et al. 1982). Our purpose in this chapter is to outline the relationship between these often violent and spectacular geological processes which have led to the formation and development of the various lake types in New Zealand. Against this background we describe the classification and distribution of the main lake types, their ages and mechanisms of formation. We also comment on lake sedimentation patterns, palaeolimnological studies, and on features of lake bathymetry and morphology.

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  • Soil classification in Australia – an outsider’s view

    Lowe, David J. (1992)

    Journal article
    University of Waikato

    Soil classification has many purposes, the main ones being to organize knowledge, to bring out relationships among the objects classified, to facilitate communication, and to provide a framework for soil management practices and soil research. In Australia, there are currently two 'local' classification systems in use, the so-called Great Soil Group system (Stace et al. 1968) and Northcote's Factual Key (Northcote 1979). Recently, however, the spectre of change has arisen. Firstly, Ray Isbell has been developing a new 'National Australian Soil Classification', currently of 'Second Approximation' status (Isbell 1992a). Secondly, there has been renewed interest in the application of Soil Taxonomy to Australian soils, particularly in South Australia. Such interest was clearly shown at the 4th National Soils Conference, held in Adelaide in April this year, where four papers suggesting changes to Soil Taxonomy were presented. These developments appear to have polarised opinion as to whether changes are necessary, which classification system, or systems, are 'best', and the optimum way of introducing such changes.

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  • High-resolution radiocarbon chronologies and synchronization of records

    Hajdas, Irka; Lowe, David J.; Newnham, Rewi M. (2006)

    Journal article
    University of Waikato

    It is now accepted that the precise dating of certain periods is complicated by extreme variability of atmospheric ¹⁴C content shown at times in the ¹⁴C calibration curve. This complication arises from variations in atmospheric ¹⁴C content and is known as wiggles in the calibration curve. Radiocarbon age ‘plateaus’, are caused by a decrease in the atmospheric ¹⁴C concentration and appear as a slowing down of the ¹⁴C clock such as occurred during the Younger Dryas (YD) chronozone. In effect, similar ¹⁴C ages apply across a range of up to 500 calendar years. The opposite is observed when atmospheric ¹⁴C levels increase so that the ¹⁴C clock appears to speed up. In such cases, which include the beginning of the YD and Pre-Boreal intervals, the true age of a sample, taking dating errors into account, may spread across a comparatively wide ¹⁴C age range

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  • Provisional chronology of a late Quaternary core from Lake Waikare, North Island, New Zealand

    Lowe, David J.; Hogg, Alan G. (1992)

    Journal article
    University of Waikato

    Lake Waikare is a shallow ( < 2 m), 34. 4 km² riverine lake near Hamilton, North Island, New Zealand (175° 12' S, 37° 24'E). Ac. 12.5 m long (corrected depth) sediment core taken from the lake in 1990 comprises mainly green-grey lacustrine clays with interbedded layers of peat, brownish clays, occasional fluvial sandy layers, and several thin tephra deposits. Lake sediment at the base of the core has been dated at 26 000 ± 1600 years BP (old half life basis) using the C-14 method; charcoal fragments at c. 11.7 m depth were dated at 17 300 ± 400 years BP; and a tephra layer at c. 8.5 m depth has been provisionally identified, using major element composition of glass, as the Rerewhakaaitu Tephra with an age of 14 700 ± 110 years BP. These ages accord with previous work in the area.

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  • Japan Society for the Promotion of Science – Fellowship for Research in Japan (7-22 May, 2010)

    Lowe, David J. (2010)

    Report
    University of Waikato

    The academic activities involved a wide range of work including: (1) presenting 4 seminars at four different universities: - Kagoshima University, Kagoshima - Kyoto Prefectural University, Kyoto - Tokyo Metropolitan University, Hachioji, Tokyo - Meiji University (Ikuta campus), Kawasaki, Tokyo - the seminar presentations were ~50 minutes in duration with questions and discussion for up to ~30-40 minutes following the presentations (2) presenting a ~40-minute public lecture in Kirishima City (attracted audience >250) (3) presenting/co-presenting two oral papers and two poster papers at the international INTAV-J tephra conference “Active tephra in Kyushu” in Kirishima City (4) co-organising and chairing a special session (at the INTAV-J conference) on the Eyjafjöll eruption of Iceland eruption - session attracted southern Kyushu TV and newspaper coverage (5) leading and taking part in discussions (throughout the INTAV-J conference) on tephrochronology and its application to the study of environmental change and archaeology including commenting on papers by Japanese students and many other participants (6) taking part in field work and associated discussions with academics, geoscientists (including volcanologists), archaeologists, and students in Kyushu over 5 days during field excursions associated with the INTAV-J conference (7) undertaking discussions with academics and graduate and undergraduate students, and others, at four different universities listed in (1) above (8) co-editing a tour guide and writing/co-writing 5 abstracts before the trip, and editing several abstracts by Japanese participants; assisting organising committee in planning and preparing for the INTAV-J conference; co-writing 2 newsletter reports after the trip

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  • Profile descriptions of Quaternary basaltic volcanogenic soils of the Mount Gambier area, southeast South Australia

    Lowe, David J. (1992)

    Report
    University of Waikato

    The volcanoes of southeast South Australia form the western extension of the Newer Volcanics province of Victoria, and comprise two distinct groups: a northern Pleistocene group of 15 eruption centres in the Mount Burr range, and a southern Holocene group of two isolated eruption centres at Mounts Gambier and Schank (Fig. 1). All the volcanoes are basaltic and are formed predominantly of explosively-erupted fragmental (pyroclastic) products including ash, lapilli, and scoria; lava is less common and is rarely soil-forming (Irving & Green, 1976; Sheard, 1978; 1983a, b; 1986; 1990). Mounts Gambier and Schank are aged about 4000-5000 years old and are the youngest volcanoes on the Australian mainland (Fig. 2) (Barton & McElhinny, 1980; Barbetti & Sheard, 1981; Blackburn et al., 1982; Sheard, 1990). They were erupted through consolidated calcareous sands of the Bridgewater Formation, and the resultant pyroclastic deposits may contain up to 25% of non-volcanic material, chiefly limestone fragments (Sheard, 1990).

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  • Palaeolimnology in New Zealand

    Green, John D.; Lowe, David J. (1992)

    Journal article
    University of Waikato

    The study of lakes has attracted many scientists over the years and those who specialise in attempting to understand the complex workings of the entire lake ecosystem are now known as limnologists (Wetzel 1983). Most of them deal specifically with what is happening in lakes today, but in recent years some have begun to appreciate that the present character of the lakes they study is the result of a Jong history. It is now realised that to fully understand the functioning of lakes and how to manage them for the future we have to understand their past.

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