scholarly journals Post-Oruanui supereruption recovery, reconstruction and evolution of Taupo volcano, New Zealand

2021 ◽  
Author(s):  
◽  
Simon James Barker
Keyword(s):  
New Zealand ◽  
Trace Element ◽  
Melt Inclusion ◽  
Silicic Magma ◽  
Magma Source ◽  
Caldera Collapse ◽  
Fine Scale ◽  
Magma Body ◽  
Magma System ◽  
Taupo Volcano

<p>This thesis research presents geochemical perspectives on the magmatic recovery of Taupo volcano (New Zealand) in the aftermath of the 25.4 ka Oruanui supereruption. Following the Oruanui, and after only ~5 kyr of quiescence, Taupo erupted three small volume (~0.1 km3) dacitic units, followed by another ~5 kyr break, and then the modern sequence from ~12 ka onwards of 25 rhyolitic units organised into 3 geochemically distinct subgroups (SG1-SG3). The eruptive units are stratigraphically constrained over exceptionally short time intervals, providing fine-scale temporal snapshots of the magma system. In this thesis I compare and contrast whole-rock, mineral and glass compositions of Oruanui and post-Oruanui magmas through time to investigate the post-supereruption reconstruction and evolution of Taupo through to the latest eruption.  Despite overlapping vent sites and crustal source domains between the Oruanui and post-Oruanui eruptions, U/Th disequilibrium model-ages in zircons from Taupo SG1 rhyolites (erupted 12 ka-10 ka) and SG2 rhyolites (erupted 7 ka-2.6 ka) imply the presence of only minor inheritance of crystals from the Oruanui magma source. Post-Oruanui model-age spectra are instead typically centred close to eruption ages with subordinate older pre-300 ka equiline grains. U-Pb dating of these equiline grains shows that both 300-450 ka plutonic-derived and pre-100 Ma greywacke basement-derived zircons are present. The former largely coincide in age with zircons from the 350 ka Whakamaru eruption products, and are dominant over greywacke in young units which were vented within the published Whakamaru caldera outline. Despite multiple ages and vent sites, trace element compositions are broadly similar in zircons, regardless of their ages. However, a small subset of zircons analysed from SG1 rhyolites have notably high concentrations of U, Th, P, Y+ (REE)3+ and Nb but with only minor changes in Hf and Ti. SG2 zircons typically have higher Sc, reflecting large-scale changes in melt chemistry and crystallising mineral phases with time. The age spectra indicate that most Oruanui zircons were removed by thermally induced dissolution immediately following the supereruption. U-Th ages from individual post-Oruanui eruptions show consistent inheritance of post-Oruanui grains with model ages that centre between the temporally separated but geographically overlapping eruption groups, generating model-age modes. Within the statistical limitations of the isotopic measurements, we interpret these repeated modes to be significant, resulting from incorporation of crystal populations from cyclic post-Oruanui periods of magmatic cooling and crystallisation, acting within a crustal protolith chemically independent of that which built the Oruanui. Cooling periods alternate with times of rejuvenation and eruption, in some cases demonstrably accompanying syn-eruptive regional rifting and mafic injection. Not only were the processes that developed the supersized Oruanui magma body unusually rapid, but this huge magma system was effectively reset and rebuilt on a comparably short timescale.  Major and trace element whole rock, glass and mineral chemistry of post-Oruanui eruptive products indicate how the host magma system re-established and evolved. The dacite units show wide variations in melt inclusion compositions and strongly zoned minerals consistent with interaction of less-evolved mafic magmas at a depths of >8 km, overlapping with the inferred base of the old Oruanui mush system. The dacites reflect the first products of the rebuilding silicic magma system, as most of the Oruanui mush was reconfigured or significantly modified in composition following thermal fluxing accompanying post-caldera collapse readjustment. The first (SG1) rhyolites erupted from 12 ka formed through shallow fractionation (4-5 km depth) and cooling of a parental melt similar in composition to the earlier dacite melts, with overlapping melt inclusion and crystal core compositions between the two magma types. For the younger rhyolite units, fine-scale temporal changes in melt chemistry and mineral phase stability occur over time, which are closely linked to the development, stabilisation and maturation of a new and likely unitary rhyolite mush system at Taupo. The new mush system is closely linked to and sometimes physically interacts with the underlying mafic melts, which are similar in composition to those involved in the Oruanui eruption and provide the long-term thermal and chemical driving force for magmatism. We consider that the new mush body has expanded to >250 km3 (and possibly up to 1000 km3) but has not yet been located by geophysical investigations.  For the most recent SG3 eruptions, the system once again underwent widespread destabilisation, resulting in increased levels of melt extraction from the silicic mush. Trends in whole-rock chemistry and close links between melt inclusions and mineral zoning with earlier units indicates that the 35 km3 Unit Y (Taupo eruption) melt dominant body formed in response to mafic disruption of the silicic mush pile. Associated Fe-Mg diffusion timescales in orthopyroxene suggest that Taupo is capable of changing behaviour and generating large eruptible melt bodies on timescales as short as decades to centuries. The 232 AD Unit Y eruption culminated from a critical combination of high differential tectonic stress build up, and increased potency in the silicic magma system resulting from elevated levels of mafic magma input, resulting in one of the largest and most violent worldwide Holocene eruptions. The post-Y magma system then responded to further disruption with the eruption of sub-lacustrine dome(s). Taupo is considered to be capable of rapidly recovering in its modern form to continue its hyperactive eruptive behaviour on timescales that are of human interest and concern.</p>

scholarly journals Post-Oruanui supereruption recovery, reconstruction and evolution of Taupo volcano, New Zealand

2021 ◽  
Author(s):  
◽  
Simon James Barker
Keyword(s):  
New Zealand ◽  
Trace Element ◽  
Melt Inclusion ◽  
Silicic Magma ◽  
Magma Source ◽  
Caldera Collapse ◽  
Fine Scale ◽  
Magma Body ◽  
Magma System ◽  
Taupo Volcano

<p>This thesis research presents geochemical perspectives on the magmatic recovery of Taupo volcano (New Zealand) in the aftermath of the 25.4 ka Oruanui supereruption. Following the Oruanui, and after only ~5 kyr of quiescence, Taupo erupted three small volume (~0.1 km3) dacitic units, followed by another ~5 kyr break, and then the modern sequence from ~12 ka onwards of 25 rhyolitic units organised into 3 geochemically distinct subgroups (SG1-SG3). The eruptive units are stratigraphically constrained over exceptionally short time intervals, providing fine-scale temporal snapshots of the magma system. In this thesis I compare and contrast whole-rock, mineral and glass compositions of Oruanui and post-Oruanui magmas through time to investigate the post-supereruption reconstruction and evolution of Taupo through to the latest eruption.  Despite overlapping vent sites and crustal source domains between the Oruanui and post-Oruanui eruptions, U/Th disequilibrium model-ages in zircons from Taupo SG1 rhyolites (erupted 12 ka-10 ka) and SG2 rhyolites (erupted 7 ka-2.6 ka) imply the presence of only minor inheritance of crystals from the Oruanui magma source. Post-Oruanui model-age spectra are instead typically centred close to eruption ages with subordinate older pre-300 ka equiline grains. U-Pb dating of these equiline grains shows that both 300-450 ka plutonic-derived and pre-100 Ma greywacke basement-derived zircons are present. The former largely coincide in age with zircons from the 350 ka Whakamaru eruption products, and are dominant over greywacke in young units which were vented within the published Whakamaru caldera outline. Despite multiple ages and vent sites, trace element compositions are broadly similar in zircons, regardless of their ages. However, a small subset of zircons analysed from SG1 rhyolites have notably high concentrations of U, Th, P, Y+ (REE)3+ and Nb but with only minor changes in Hf and Ti. SG2 zircons typically have higher Sc, reflecting large-scale changes in melt chemistry and crystallising mineral phases with time. The age spectra indicate that most Oruanui zircons were removed by thermally induced dissolution immediately following the supereruption. U-Th ages from individual post-Oruanui eruptions show consistent inheritance of post-Oruanui grains with model ages that centre between the temporally separated but geographically overlapping eruption groups, generating model-age modes. Within the statistical limitations of the isotopic measurements, we interpret these repeated modes to be significant, resulting from incorporation of crystal populations from cyclic post-Oruanui periods of magmatic cooling and crystallisation, acting within a crustal protolith chemically independent of that which built the Oruanui. Cooling periods alternate with times of rejuvenation and eruption, in some cases demonstrably accompanying syn-eruptive regional rifting and mafic injection. Not only were the processes that developed the supersized Oruanui magma body unusually rapid, but this huge magma system was effectively reset and rebuilt on a comparably short timescale.  Major and trace element whole rock, glass and mineral chemistry of post-Oruanui eruptive products indicate how the host magma system re-established and evolved. The dacite units show wide variations in melt inclusion compositions and strongly zoned minerals consistent with interaction of less-evolved mafic magmas at a depths of >8 km, overlapping with the inferred base of the old Oruanui mush system. The dacites reflect the first products of the rebuilding silicic magma system, as most of the Oruanui mush was reconfigured or significantly modified in composition following thermal fluxing accompanying post-caldera collapse readjustment. The first (SG1) rhyolites erupted from 12 ka formed through shallow fractionation (4-5 km depth) and cooling of a parental melt similar in composition to the earlier dacite melts, with overlapping melt inclusion and crystal core compositions between the two magma types. For the younger rhyolite units, fine-scale temporal changes in melt chemistry and mineral phase stability occur over time, which are closely linked to the development, stabilisation and maturation of a new and likely unitary rhyolite mush system at Taupo. The new mush system is closely linked to and sometimes physically interacts with the underlying mafic melts, which are similar in composition to those involved in the Oruanui eruption and provide the long-term thermal and chemical driving force for magmatism. We consider that the new mush body has expanded to >250 km3 (and possibly up to 1000 km3) but has not yet been located by geophysical investigations.  For the most recent SG3 eruptions, the system once again underwent widespread destabilisation, resulting in increased levels of melt extraction from the silicic mush. Trends in whole-rock chemistry and close links between melt inclusions and mineral zoning with earlier units indicates that the 35 km3 Unit Y (Taupo eruption) melt dominant body formed in response to mafic disruption of the silicic mush pile. Associated Fe-Mg diffusion timescales in orthopyroxene suggest that Taupo is capable of changing behaviour and generating large eruptible melt bodies on timescales as short as decades to centuries. The 232 AD Unit Y eruption culminated from a critical combination of high differential tectonic stress build up, and increased potency in the silicic magma system resulting from elevated levels of mafic magma input, resulting in one of the largest and most violent worldwide Holocene eruptions. The post-Y magma system then responded to further disruption with the eruption of sub-lacustrine dome(s). Taupo is considered to be capable of rapidly recovering in its modern form to continue its hyperactive eruptive behaviour on timescales that are of human interest and concern.</p>

Stratigraphy, chronology, styles and dynamics of late Quaternary eruptions from Taupo volcano, New Zealand

1993 ◽  
Vol 343 (1668) ◽  
pp. 205-306 ◽  
Keyword(s):  
New Zealand ◽  
Fractal Dimensionality ◽  
Pyroclastic Flows ◽  
Taupo Volcanic Zone ◽  
Caldera Collapse ◽  
Volcanic Zone ◽  
Oruanui Eruption ◽  
Self Similar ◽  
Taupo Volcano ◽  
Fall Deposits

Taupo volcano is the southerly of two dormant caldera volcanoes in the rhyolite-dominated central portion of the Taupo Volcanic Zone in the North Island of New Zealand. Taupo has an average magma output rate of 0.2 m 3 s -1 over the past 65 000 years, and is one of the most frequently active and productive rhyolite volcanoes known. The structure of the modern ‘inverse’ volcano was formed largely by caldera collapse associated with the voluminous 22 600 14 C years BP Oruanui eruption, and has been little modified since except for collapse following the 1850 14 C years BP eruption. The products of 28 eruptions (labelled T, f2, A, ..., Z), all of which post-date the Oruanui eruption, are defined and described here. Twenty-seven of these eruptions are represented by pyroclastic deposits (of which three were accompanied by a mappable lava extrusion), and one eruption (Z) solely by evidence for a lava extrusion. The deposits of seven eruptions (B, C, E, S, V, X and Y) largely correspond to previously defined tephra formations (Karapiti, Poronui, Opepe, Waimihia, Whakaipo, Mapara and Taupo, respectively). The previously defined Motutere and Hinemaiaia Tephras are reinterpreted to represent the products of 12 eruptions (G to R), while the remaining eight deposits and one eruption are newly recognized. Eruption T occurred at ca . 17200 14 C or 20500 calibrated years BP and eruption Z about 1740 calibrated years BP. Eruption volumes vary by more than three orders of magnitude between 0.01 and more than 44 km 3 , and repose periods by more than two orders of magnitude from ca . 20 to 6000 years. The eruption deposits reflect great variations in parameters such as volume, the dispersal characteristics of the fall deposits, the presence or absence of intraeruptive time breaks, the formation of pyroclastic flows, the degree of magmawater interaction, the vesiculation state of the magma on fragmentation and the relative proportions of juvenile obsidian versus foreign lithologies in the lithic fractions. All but seven fall deposits are plinian in dispersal; two (Y1 and probably W) are sub-plinian, one (Y5) has been termed ‘ultraplinian’, while 4/ and A are too poorly preserved for their dispersal to be assessed. The lengths of repose periods in the post-Oruanui sequence range are not randomly distributed but show self-similar properties (fractal dimensionality); repose intervals ( r , in years) of not more than 350 years follow n = 53.5r-0'21, and those of not less than 350 years follow n = 2096 r -0-83 , where n is the number of eruptions. The shorter repose periods may reflect triggering processes, such as regional extension, affecting magma bodies during their viable lifetimes, while longer repose intervals (i.e. not less than 350 years) may reflect an episodicity of major rifting events or the production of magma bodies below the volcano. Bulk volumes ( v , in km 3 ) of the eruption products also show self-similar properties (fractal dimensionality), with n = 6.17 v -0.46 . However, there are then apparently random relationships between eruption volumes and the preceding or succeeding repose period such that prediction of the time and size of the next eruption is impossible. The post-Oruanui activity at Taupo represents ‘noise’ superimposed on the more uniform, longer term activity in the central Taupo Volcanic Zone, where large (greater than 100 km 3 ) eruptions, such as the Oruanui, occur at more evenly spaced intervals of one per 40-60000 years.

scholarly journals Crustal deformation using GPS and InSAR analysis at Taupo volcano, New Zealand

2021 ◽  
Author(s):  
Cyril Journeau ◽  
Sigrun Hreinsdottir ◽  
Ian Hamling
Keyword(s):  
New Zealand ◽  
Crustal Deformation ◽  
Taupo Volcano

scholarly journals TephraNZ: a major and trace element reference dataset for prominent Quaternary rhyolitic tephras in New Zealand and implications for correlation

2020 ◽  
Author(s):  
Jenni L. Hopkins ◽  
Janine E. Bidmead ◽  
David J. Lowe ◽  
Richard J. Wysoczanski ◽  
Bradley J. Pillans ◽  
...  
Keyword(s):  
New Zealand ◽  
Trace Element ◽  
Major Element ◽  
Chemical Compositions ◽  
Volcanic Centre ◽  
Reference Dataset ◽  
Future Studies ◽  
Glass Shard ◽  
Tephra Deposits ◽  
Glass Shards

Abstract. Although analyses of tephra-derived glass shards have been undertaken in New Zealand for nearly four decades (pioneered by Paul Froggatt), our study is the first to systematically develop a formal, comprehensive, open access, reference dataset of glass-shard compositions for New Zealand tephras. These data will provide an important reference tool for future studies to identify and correlate tephra deposits and for associated petrological and magma-related studies within New Zealand and beyond. Here we present the foundation dataset for TephraNZ, an open access reference dataset for selected tephra deposits in New Zealand. Prominent, rhyolitic, tephra deposits from the Quaternary were identified, with sample collection targeting original type sites or reference locations where the tephra's identification is unequivocally known based on independent dating or mineralogical techniques. Glass shards were extracted from the tephra deposits and major and trace element geochemical compositions were determined. We discuss in detail the data reduction process used to obtain the results and propose that future studies follow a similar protocol in order to gain comparable data. The dataset contains analyses of twenty-three proximal and twenty-seven distal tephra samples characterising 45 eruptive episodes ranging from Kaharoa (636 &amp;pm; 12 cal. yrs BP) to the Hikuroa Pumice member (2.0 &amp;pm; 0.6 Ma) from six or more caldera sources, most from the central Taupō Volcanic Zone. We report 1385 major element analyses obtained by electron microprobe (EMPA), and 590 trace element analyses obtained by laser ablation (LA)-ICP-MS, on individual glass shards. Using PCA, Euclidean similarity coefficients, and geochemical investigation, we show that chemical compositions of glass shards from individual eruptions are commonly distinguished by major elements, especially CaO, TiO2, K2O, FeOt (Na2O+ K2O and SiO2/K2O), but not always. For those tephras with similar glass major-element signatures, some can be distinguished using trace elements (e.g. HFSEs: Zr, Hf, Nb; LILE: Ba, Rb; REE: Eu, Tm, Dy, Y, Tb, Gd, Er, Ho, Yb, Sm), and trace element ratios (e.g. LILE / HFSE: Ba / Th, Ba / Zr, Rb / Zr; HFSE / HREE: Zr / Y, Zr / Yb, Hf / Y; LREE / HREE: La / Yb, Ce / Yb). Geochemistry alone cannot be used to distinguish between glass shards from the following tephra groups: Taupō (Unit Y in the post-Ōruanui eruption sequence of Taupō volcano) and Waimihia (Unit S); Poronui (Unit C) and Karapiti (Unit B); Rotorua and Rerewhakaaitu; and Kawakawa/Ōruanui, Okaia, and Unit L (of the Mangaone subgroup eruption sequence). Other characteristics can be used to separate and distinguish all of these otherwise-similar eruptives except Poronui and Karapiti. Bimodality caused by K2O variability is newly identified in Poihipi and Tahuna tephras. Using glass shard compositions, tephra sourced from Taupō Volcanic Centre (TVC) and Mangakino Volcanic Centre (MgVC) can be separated using bivariate plots of SiO2/K2O vs. Na2O+K2O. Glass shards from tephras derived from Kapenga Volcanic Centre, Rotorua Volcanic Centre, and Whakamaru Volcanic Centre have similar major- and trace-element chemical compositions to those from the MgVC, but can overlap with glass analyses from tephras from Taupō and Okataina volcanic centres. Specific trace elements and trace element ratios have lower variability than the heterogeneous major element and bimodal signatures, making them easier to geochemically fingerprint.

Current issues in trace element nutrition of grazing livestock in Australia and New Zealand

1999 ◽  
Vol 50 (8) ◽  
pp. 1341 ◽  
Author(s):  
D. G. Masters ◽  
G. J. Judson ◽  
C. L. White ◽  
J. Lee ◽  
N. D. Grace
Keyword(s):  
Trace Elements ◽  
New Zealand ◽  
Trace Element ◽  
Recent Work ◽  
Cost Effective ◽  
Trace Element Composition ◽  
Scientific Data ◽  
Pastoral System ◽  
Trace Element Nutrition ◽  
Grazing Livestock

Improving trace element nutrition of grazing animals, in a way that is cost effective and that meets consumer perceptions and preferences, is a continuing challenge. This review focuses on research over the past 10 years, addressing issues and perspectives on the roles, risks of inadequacy, and supplementary remedies of key trace elements, both essential and deleterious, which have an impact on the productivity and product quality of grazing livestock throughout Australia and New Zealand. The emphasis is on copper (Cu), cobalt (Co), iodine (I), selenium (Se), and, to a lesser extent, zinc (Zn) — the trace elements most frequently found to be deficient in parts of Australia and New Zealand. Research continues to elucidate new roles for trace elements in the animal, and as this leads to a better understanding of requirements, diagnostic criteria and supplementation strategies need re-evaluation. Newer perspectives on marginal deficiency for Cu, I, Se, and Zn are given and issues for risk management discussed. Advances in sustained delivery of trace elements such as Co (as vitamin B12), I, and Se are reported. The diagnosis and management of marginal Cu deficiency continue to be difficult, especially in New Zealand where recent work has shown that dietary antagonists [iron (Fe), molybdenum (Mo), and sulfur (S)] may impair Cu absorption at lower intakes than previously thought. There is still a dearth of scientific data on the advantages of using so-called organic trace element supplements (metals complexed or chelated with amino acids or peptides). Nevertheless their usage continues to increase. There is increasing evidence that trace elements influence the pathophysiology arising from the ingestion of toxins. This review summarises recent work on the role of Co in annual ryegrass toxicity; Cu, Se, and Zn in lupinosis; Cu and alkaloid toxicity; Zn and facial eczema; and Co and white liver disease. Trace elements are required to support immune function (e.g. as imposed parasite infection) and marginal deficiencies may be exacerbated by an immunological challenge. The roles of Cu, Co, Mo, Se, and, to a lesser extent, chromium and Zn have attracted attention and under conditions of stress there may be an additional need for these elements. Diversification in farming has led to the introduction of species such as deer (Cervus), alpacas (Camilids), emus, and ostriches (Ratites) and the paucity of information on trace element requirements for these species, and also for horses, indicates the need for further work. The effect of supplementation on trace element composition of meat, milk, and wool is also reviewed, both in terms of product characteristics and human health. Of the deleterious elements, cadmium has attracted the most interest and concern because of its introduction into the pastoral system from phosphate-based fertilisers.

Trace element partitioning during high-P partial melting and melt-rock interaction; an example from northern Fiordland, New Zealand

2004 ◽  
Vol 22 (5) ◽  
pp. 443-457 ◽  
Author(s):  
F. C. Schröter ◽  
J. A. Stevenson ◽  
N. R. Daczko ◽  
G. L. Clarke ◽  
N. J. Pearson ◽  
...  
Keyword(s):  
New Zealand ◽  
Trace Element ◽  
Partial Melting ◽  
Rock Interaction ◽  
Trace Element Partitioning ◽  
Element Partitioning

The 2018 rift eruption and summit collapse of Kīlauea Volcano

Science ◽  
2018 ◽  
Vol 363 (6425) ◽  
pp. 367-374 ◽  
Author(s):  
C. A. Neal ◽  
S. R. Brantley ◽  
L. Antolik ◽  
J. L. Babb ◽  
M. Burgess ◽  
...  
Keyword(s):  
Rift Zone ◽  
Kilauea Volcano ◽  
Caldera Collapse ◽  
Flow Volume ◽  
Kīlauea Volcano ◽  
Historical Observation ◽  
Magma System ◽  
Volume Estimates ◽  
Earthquake Moment ◽  
Eruptive Fissures

In 2018, Kīlauea Volcano experienced its largest lower East Rift Zone (LERZ) eruption and caldera collapse in at least 200 years. After collapse of the Pu‘u ‘Ō‘ō vent on 30 April, magma propagated downrift. Eruptive fissures opened in the LERZ on 3 May, eventually extending ~6.8 kilometers. A 4 May earthquake [moment magnitude (Mw) 6.9] produced ~5 meters of fault slip. Lava erupted at rates exceeding 100 cubic meters per second, eventually covering 35.5 square kilometers. The summit magma system partially drained, producing minor explosions and near-daily collapses releasing energy equivalent toMw4.7 to 5.4 earthquakes. Activity declined rapidly on 4 August. Summit collapse and lava flow volume estimates are roughly equivalent—about 0.8 cubic kilometers. Careful historical observation and monitoring of Kīlauea enabled successful forecasting of hazardous events.

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