Georg Florian Zellmer

Georg Florian Zellmer
Massey University · Earth Sciences

PhD

About

115
Publications
31,094
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
3,214
Citations
Additional affiliations
January 2018 - present
Massey University
Position
  • Professor
Description
  • Georg F. Zellmer received his PhD from the Open University (UK) in 1999, and subsequently worked as research fellow at the University of Bristol (UK), the Lamont-Doherty Earth Observatory (USA), the University of Hawaii (USA), and Academia Sinica (ROC). At Massey University since 2013, Professor Zellmer investigates the timescales of magmatic processes, volatiles in subduction zones, and other fundamental aspects of magmatic systems on Earth and beyond.
January 2016 - December 2017
Massey University
Position
  • Professor (Associate)
September 2013 - December 2015
Massey University
Position
  • Professor (Associate)
Education
October 1995 - March 1999
The Open University (UK)
Field of study
  • Igneous Geochemistry
October 1992 - June 1995
University of Cambridge
Field of study
  • Earth Science

Publications

Publications (115)
Article
Magma differentiation in arc settings has usually been attributed to an interplay of processes (fractional crystallization, assimilation, and magma mixing). Homogeneous fractional crystallization has been widely used to model the magmatic evolution of volcanic systems in arc settings due to its simplicity, even though boundary layer fractionation (...
Article
Given the prolific work on the petrography and mineral chemistry of volcanic rocks to understand magmatic processes for well over a century, it is surprising that there are no quantitatively rigorous size classifications or commonly accepted terminologies regarding the origin of such crystals. This causes some confusion when attempting to make mean...
Article
Full-text available
Arc magmas typically contain phenocrysts with complex zoning and diverse growth histories. Microlites highlight the same level of intracrystalline variations but require nanoscale resolution which is globally less available. The southern Taupo Volcanic Zone (TVZ), New Zealand, has produced a wide range of explosive eruptions yielding glassy microli...
Article
The sources and processes involved in the genesis of the voluminous rhyolitic magmas of cataclysmic caldera-forming eruptions, and the intervening lower-volume intra-caldera extrusions, have been subject to much debate. To better understand generation of high-volume and low-volume silicic eruptions within a single volcanic centre, and how they may...
Article
The Okataina Volcanic Centre (OVC), located in the Taupo Volcanic Zone, New Zealand, is a dominantly rhyolitic magmatic system in an arc setting, where eruptions are thought to be driven by mafic recharge. Here, Sr-Pb isotopes, and compositional and textural variations in plagioclase phenocrysts from ten rhyolitic deposits (two caldera, one immedia...
Article
Lava flows that constitute the current edifice of Taranaki volcano, New Zealand, contain a complex crystal cargo including plagioclase, pyroxene, amphibole, oxides, and rarely olivine. Amphibole textures and mineral chemistry indicate that crystals are pargasitic antecrysts entrained at various depths by ascending magmas. The crystals record a comp...
Article
Long‐lived stratovolcanoes display a thick volcanic apron surrounding the edifice. This sedimentary succession incorporates the majority of the deposits from both growth and destruction phases of a volcanic massif. The ring plain of Taranaki Volcano (>200 ka) is composed of volcaniclastic mass‐flow deposits that are exceptionally well‐exposed along...
Article
Full-text available
Olivine-hosted melt inclusions (MIs) are widely used as a tool to study the early stages of magmatic evolution. There are a series of processes that affect MI compositions after trapping, including post-entrapment crystallization (PEC) of the host mineral at the MI boundaries, exsolution of volatile phases into a “shrinkage bubble” and diffusive ex...
Article
Boninites are rare high magnesium andesites that often contain trace chromites. These chromites precipitate from primitive boninitic melts and are thought to be carried to the surface in melts that continue to crystallize a significant volume of silicate minerals. Such magmatic differentiation drives primitive chromite out of equilibrium with the r...
Article
Pyroxene crystals from recent Central Plateau tephras are used to deduce their formation conditions through two-pyroxene thermobarometry. Crystals return pseudo-pressures and pseudo-temperatures that are artefacts of uptake of antecrysts formed at a range of crustal levels by isobaric cooling of previously intruded magmas. MELTS modelling of tephra...
Article
Full-text available
Mafic magmatism of the rifting Taupo Volcanic Zone (TVZ) of the North Island, New Zealand, is volumetrically minor, but is thought to tap the material that provides the heat source for voluminous rhyolite production through partial melting of the crust, which ultimately results in very large volume explosive eruptions. We have studied the major and...
Chapter
The rates and timescales of crustal magma transfer, storage, emplacement, and eruption are a key to understanding subvolcanic processes, characterizing volcanic hazards, and developing mitigation strategies. In this chapter, we review the most pertinent open questions in this field, as well as the many geochemical and geophysical methods that are a...
Article
Full-text available
Near-source measurements of smoke emissions from household stove combustion in a rural area of South China were conducted with 7 typical biomass fuels. Particulate matter samples (both PM10 and PM2.5) were analyzed for their carbonaceous components, including organic and elemental carbon (OC, EC) as well as levoglucosan (molecular tracer of biomass...
Conference Paper
The Tongariro Volcanic Centre (TgVC), located at the southern end of the Taupo Volcanic Zone in New Zealand, has produced historical explosive eruptions of different eruptive styles. To understand magma ascent processes and their associated timescales, the textures and compositions of microlites and micro-phenocrysts from glass shards (c. 12 ka BP...
Conference Paper
Full-text available
Volcanic ring-plain deposits record sedimentary successions of long-lived stratovolcanoes. The ring-plain of the >130 ka Mt. Taranaki is composed of volcaniclastic (mass flow) deposits that are well-exposed along its coastal-cliff shoreline. The volcanic successions contained within the ring-plain record a cyclic behaviour of growth and destruction...
Conference Paper
Full-text available
Andesitic stratovolcanoes are characterized by cycles of cone growth interspersed by periods of cone collapse. The long-term record of the evolution of their magmatic system is mainly preserved in the deposits of the ring-plain surrounding an active cone. Taranaki volcano in northern New Zealand provides an unusually detailed example of these proce...
Article
Full-text available
Subduction zone magmatic budgets and crustal growth processes depend on poorly constrained intrusive:extrusive ratios of arc magmas. Published ambient noise tomography data from northeast Japan reveal upper crustal low-VS bodies, indicating elevated temperatures of plutonic rocks beneath most sites of active arc-front volcanoes, with the exception...
Article
Sr isotope analysis of plutonic rocks is an important method for deriving the provenance and age of ancient magmatic episodes, and the petrogenetic processes operating during intrusive activity. We determined the ⁸⁷Sr/⁸⁶Sr isotopic compositions of fresh and variably altered feldspars from the 1.14 Ga gabbroic Great Abitibi Dyke, Ontario, Canada, th...
Conference Paper
Full-text available
Submission 612 Pre-and syn-eruptive processes visualized through semi-automatic Crystal Size Distribution analysis of microlites from Tongariro Volcanic Centre tephras, New Zealand Microlite Crystal Size Distributions (CSDs) in volcanic rocks have become a useful tool to assess pre-and syn-eruptive processes such as nucleation and growth at the ons...
Article
Mineral, groundmass and bulk rock chemical analyses of samples from the Tongariro Volcanic Complex were made to estimate depths of magma reservoirs for selected eruptive deposits. The sample set consists of two units from the 11,000 cal. yrs. B.P. Mangamate Formation (Te Rato and Wharepu) and more recent deposits from near 1717 cal. yrs. B.P. (Ngau...
Article
Full-text available
Crystal nucleation and growth are first order processes captured in volcanic rocks and record important information about the rates of magmatic processes and chemical evolution of magmas during their ascent and eruption. We have studied glass-rich andesitic tephras from the Central Plateau of the Southern Taupo Volcanic Zone by electron- and ion-mi...
Article
Full-text available
The Ohakune Volcanic Complex is a late Pleistocene tuff ring - scoria/spatter cone complex located south of Ruapehu volcano. This small-volume volcano consists of an outer E-W elongated compound tuff ring edifice, three inner scoria-spatter cones and further volcanic depressions, located on the Ohakune Fault. We quantified accurately the variations...
Conference Paper
The Trans-Mexican Volcanic Belt (TMVB) is known for the chemical diversity in its erupted products. We have analyzed the olivine, pyroxene and plagioclase mineral chemistry of 30 geochemically well-characterized mafic eruptives from Isla Maria at the western end of the arc to Palma Sola in the East. The mineral major oxide data indicate the dominan...
Article
The Trans-Mexican Volcanic Belt (TMVB) is known for the chemical diversity in its erupted products. We have analyzed the olivine, pyroxene, and plagioclase mineral chemistry of 30 geochemically well-characterized mafic eruptives from Isla Maria at the western end of the arc to Palma Sola in the east. The mineral major oxide data indicate the domina...
Article
Magmas play a key role in the genesis of epithermal and porphyry ore deposits, notably by providing the bulk of ore metals to the hydrothermal fluid phase. It has been long shown that the formation of major deposits requires a multi-stage process, including the concentration of metals in silicate melts at depth and their transfer into the exsolved...
Article
Using a high resolution ion microprobe with SCAPS imaging, the peritectic reaction of forsterite + silica to enstatite was studied down to submicron level in natural andesitic tephras from the Central Plateau of North Island, New Zealand. The fayalitic component of natural olivines is stable in high-silica melts, and therefore the reaction is in fa...
Article
U–Th–Ra isotope analyses of whole rocks and mineral separates were conducted in order to perform isochron dating of three morphologically young lavas from Tatun volcano, northern Taiwan (from Mt Cising, the Shamao dome and the Huangzuei volcano). The data do not yield tight U–Th isochrons, indicating open-system magmatic processes. However, crystal...
Article
Full-text available
Recycling of upper plate crust in subduction zones, or ‘subduction erosion’, is a major mechanism of crustal destruction at convergent margins. However, assessing the impact of eroded crust on arc magmas is difficult owing to the compositional similarity between the eroded crust, trench sediment and arc crustal basement that may all contribute to a...
Article
U–Th–Ra isotope analyses of whole rocks and mineral separates were conducted in order to perform isochron dating of three morphologically young lavas from Tatun volcano, northern Taiwan (from Mt Cising, the Shamao dome and the Huangzuei volcano). The data do not yield tight U–Th isochrons, indicating open-system magmatic processes. However, crystal...
Article
Full-text available
In this volume, the authors have compiled an impressive record of ground deformation and seismicity to quantify Kilauea’s eruptive and intrusive history over the last 200+ years. The book presents these data and their interpretation chronologically in six chapters (1790-1924, 1925-1953, 1953-1967, 1967-1975, 1975-1983, and 1983-2008), preceded by a...
Chapter
Full-text available
Pleistocene basalts from Daisen and Mengameyama in the SW Japan volcanic arc of western Honshu are characterized by an abundance of olivine crystals with Fe-rich rims. At Daisen, these have previously been interpreted to have formed from their host melt by equilibrium crystal fractionation and by disequilibrium fractionation during supercooling. He...
Article
The Pliocene–Pleistocene northern Taiwan volcanic zone (NTVZ) is located within a trench-arc–back-arc basin and oblique arc–continent collision zone. Consequently the origin and tectonic setting of the andesitic rocks within the NTVZ and their relation to other circum-Pacific volcanic island-arc systems is uncertain. Rocks collected from the Tatun...
Article
Full-text available
The volatile cycle at subduction zones is key to the petrogenesis, transport, storage and eruption of arc magmas. Volatiles control the flux of slab components into the mantle wedge, are responsible for melt generation through lowering the solidi of mantle materials, and influence the crystallizing phase assemblages in the overriding crust. Globall...
Chapter
Full-text available
Minerals of mafic rocks from theSWJapan arc have been studied to deduce P–T–XH2O conditions and their variations in mafic arc magmas. Two-pyroxene thermobarometry of magmas from several volcanoes yields constant temperatures and variable pressures. MELTS fractional crystallization modelling is employed to show that such ‘pseudo-decompression paths’...
Article
Full-text available
Andesite petrogenesis is inextricably linked to plate processing at convergent margins. The details of andesite formation, however, remain poorly understood because the signatures of the initial arc mantle melts are often modified in the overlying crust. To distinguish initial mantle from crustal signatures in arc magmas, we studied two composition...
Article
Full-text available
Recent studies of large mafic dyke swarms in the Deccan Traps flood basalt province, India, indicate that some of the correlative lava flows reached several hundred kilometers in length. Here we present field, petrographic, mineral chemical, and whole-rock geochemical (including Sr-Nd isotopic) data on the Palitana lava sequence and nearby dykes in...
Article
Full-text available
Uranium-thorium (U-Th) isotope compositions of whole rocks, groundmasses and minerals from mafic to intermediate Andean arc magmas were determined to assess the influence of crustal stress on rates of pre-eruptive crystallization and the significance of crystal uptake. Volcanoes investigated include Lascar in the central Andes, situated in a compre...
Article
This chapter provides an overview of the current state of research on orogenic andesites. While their importance as proxies to the evolution of the continental crust has long been recognized, andesite genesis has remained highly controversial with a broader consensus yet to be reached. The controversy is fuelled by the question of whether orogenic...
Article
Full-text available
A fundamental question in the formation of orogenic andesites is whether their high melt SiO 2 reflects the recycling of silicic melts from the subducted slab or the processing of basaltic mantle melts in the overlying crust. The latter model is widely favoured, because most arc magmas lack the ‘garnet’ signature of partial slab melts. Here we pres...
Article
Full-text available
Residence times of olivine and plagioclase phenocrysts and xenocrysts in mid-ocean ridge (MOR) basaltic melts have been studied since the mid 1980s using geospeedometric techniques (i.e. using diffusion of major and trace elements) in order to constrain the processes of melt ascent and differentiation in this important magmatic setting. Residence t...
Article
Full-text available
Determining correlated major and trace element zoning profiles is an important goal in modern microanalysis and is critical to some geospeedometric applications. We show that a precise determination of relative variations in major element compositions of simple solid solutions is possible by LA-ICPMS, and that low accuracy (analytical bias) can be...
Article
Full-text available
At volcanic arcs, water released from the subducting slab lowers the mantle solidus and causes melting. Further, slab melts may infiltrate the mantle wedge, and have been suggested to generate "adakitic" (residual garnet) signatures at some arc volcanoes. However, experimental work indicates that garnet will replace amphibole in the lower overridin...
Article
Full-text available
Processing of the oceanic lithosphere in subduction zones gives rise to arc magmatism, and strong compositional links exist between trench input and arc output. Here we address the question whether these compositional links are sufficiently strong to allow for ‘tracing’ the composition of the sedimentary and igneous oceanic crust through the chemis...
Article
Full-text available
Products of contrasting mingled magmas are widespread in volcanoes and intrusions. Subvolcanic trachyte intrusions hosting mafic enclaves crop out in the Manori–Gorai area of Mumbai in the Deccan Traps. The petrogenetic processes that produced these rocks are investigated here with field data, petrography, mineral chemistry, and whole rock major, t...
Article
The Quaternary central Mexican Volcanic Belt, constructed on ~50 km thick continental crust, erupts a broad spectrum of basaltic to dacitic calc-alkaline magmas with the arc-typical high ratios of large-ion lithophile to high-field strength elements. In order to understand their genesis, we investigated high-Mg# olivine-phyric calc-alkaline basalts...
Article
Full-text available
The Permian (260 Ma) Emeishan large igneous province of SW China contains three nearly identical gabbro-granitoid complexes that host giant Fe-Ti oxide deposits. The Fe-Ti oxide deposits are within the lower portions of evolved layered gabbroic intrusions and are spatially and temporally associated with A-type granitic plutons. The 264 3 Ma Taihe l...
Article
Full-text available
Brothers volcano is one of several hydrothermally active volcanoes that occur along the Kermadec active arc front, NE of New Zealand. It forms an elongate edifice 13 km long by 8 km across that strikes NW-SE. The volcano has a caldera with a basal diameter of ~3 km and a floor at 1,850 m below sea level, surrounded by 290 to 530 m high walls. A vol...
Article
Full-text available
Profiles of a total of 23 plagioclase crystals erupted within the 1982–1991 and 1993 flows of the Coaxial segment of the Juan de Fuca ridge, the 1996 flow of the North Gorda ridge, and from the Western Volcanic Zone of the ultra-slow spreading Gakkel Ridge, have been studied for variations in major and trace element concentrations. We derive equili...
Article
Full-text available
Andesite magmatism at convergent margins is essential for the differentiation of silicate Earth, but no consensus exists as to andesite petrogenesis. Models proposing origin of primary andesite melts from mantle and/or slab materials remain in deadlock with the seemingly irrefutable petrographic and chemical evidence for andesite formation through...