ORCID Profile
0000-0002-5068-7117
Current Organisation
Monash University
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Publisher: Geological Society of London
Date: 13-03-2023
Abstract: Continental arcs are key sites of granitic magmatism, yet details of the origins of these magmas, including the role and contribution of mafic magma, the timing and location of initial zircon formation and how zircon isotopic signatures relate to granite formation, remain as challenges. Here we use U–Pb dating, trace elements and Hf isotopic systematics of zircon in mafic microgranular enclaves (MMEs), from the convergent plate margin Satkatbong diorite (SKD) in Korea to understand lower arc magmatism and zircon production. The host granitic body and MMEs display similar major element evolutionary trends and similar ranges of Sr, Nd and Hf isotopes, implying a cognatic relationship. Zircons show a large variability in ε Hf ( t ) ( c. 6 units) and age ( Ma). We propose that the SKD and MMEs originated from the same, long-lasting, lower crustal mush reservoir, enabling long and variable residence times for zircons. Prolonged zircon ages, combined with the Hf isotope variability within a single pluton (SKD and its MME), indicate that not all zircons were instantaneously crystallized in a rapidly cooling shallow magma chamber but were continuously formed in a long-lasting hot source. A low-melt-fraction mush type reservoir in a deep crustal hot zone provides a viable model for the source setting. Continuous replenishment of mafic magmas acts as the main re-activator of the reservoir, and provide a critical role in spawning zircons that record a long age span, because (1) the magma adds Zr into the reservoir, enabling it to reach zircon saturation and (2) the generated zircon grains are transported upward as antecrysts by flow inside of the reservoir. This means that antecrysts with different ages may mix with each other in the ascending magma body. The significance of this model is that a conclusive time of intrusion cannot be constrained by such zircon ages, as these antecrysts constitute inherited grains.
Publisher: University of Chicago Press
Date: 09-2014
DOI: 10.1086/677045
Publisher: Elsevier BV
Date: 05-2018
Publisher: Springer Science and Business Media LLC
Date: 06-11-2018
DOI: 10.1038/S41598-018-34669-0
Abstract: Changes in the oxygen fugacity ( f O 2 ) of the Earth’s mantle have been proposed to control the spatial and temporal distribution of arc-related ore deposits, and possibly reflect the evolution of the atmosphere over billions of years. Thermodynamic calculations and natural evidence indicate that fluids released from subducting slabs can oxidise the mantle, but whether their oxidation potential varied in space and time remains controversial. Here, we use garnet peridotites from western Norway to show that there is a linear decrease in maximum f O 2 with increasing depth in the mantle wedge. We ascribe this relation to changes in the speciation of sulfur released in slab fluids, with sulfate, controlling maximum oxidation, preferentially released at shallow depths. Even though the amount of sulfate in the Precambrian oceans, and thus in subducted lithologies, is thought to have been dramatically lower than during the Phanerozoic, garnet peridotites metasomatised during these two periods have a comparable f O 2 range. This opens to the possibility that an oxidised mantle with f O 2 similar to modern-day values has existed since the Proterozoic and possibly earlier. Consequently, early magmas derived from partial melting of metasomatised mantle may have had suitable f O 2 to generate porphyry Cu-Au and iron-oxide Cu-Au deposits.
Publisher: Elsevier BV
Date: 03-2014
Publisher: Elsevier
Date: 2011
Publisher: Elsevier BV
Date: 09-2018
Publisher: Springer Science and Business Media LLC
Date: 12-03-2015
DOI: 10.1038/NCOMMS7554
Abstract: Intra-plate basalt isotopic trends require mixing between enriched mantle components (EM1, EM2, HIMU) and a primordial component with high (3)He/(4)He termed FOZO. However, proportions of components, geometric distributions within in idual plumes, relative proportions of melting components and loci of mixing of melts and residues remain poorly understood. Here we present new Hf-Nd isotopic data of dredged sea floor basalts from the northern Lau backarc basin, ~250 km south of the subaerial and submerged Samoan chain, with high (3)He/(4)He, (20)Ne/(22)Ne and primordial (129)Xe/(130)Xe, characteristic of the FOZO component. Combined Hf-Nd-noble gas isotope systematics require mixing of refractory, sub-northwestern Lau backarc mantle only with a spatially restricted FOZO component, most plausibly sourced from part of the Samoan plume. Other geographically restricted and possibly volumetrically minor enriched Samoan plume components are not detectable in northern Lau backarc s les, consistent with selective plume ingress of the FOZO component beneath the basin.
Publisher: Elsevier BV
Date: 06-2018
Publisher: Elsevier BV
Date: 30-07-2008
Publisher: Elsevier BV
Date: 08-2011
Publisher: Elsevier BV
Date: 03-2021
Publisher: American Association for the Advancement of Science (AAAS)
Date: 30-10-2020
Abstract: Ocean floor lavas from an active spreading ridge keep a geochemical memory of an Early Cretaceous subduction zone.
Publisher: Elsevier BV
Date: 02-2017
Publisher: Wiley
Date: 08-2015
Publisher: American Association for the Advancement of Science (AAAS)
Date: 18-12-2020
Abstract: Slab flux drives the frequency of volcanic eruptions by stimulating an enriched reservoir in the mantle transition zone.
Publisher: Elsevier BV
Date: 2018
Publisher: Springer Science and Business Media LLC
Date: 29-08-2018
DOI: 10.1038/S41467-018-05804-2
Abstract: Subduction zone magmas are more oxidised on eruption than those at mid-ocean ridges. This is attributed either to oxidising components, derived from subducted lithosphere (slab) and added to the mantle wedge, or to oxidation processes occurring during magma ascent via differentiation. Here we provide direct evidence for contributions of oxidising slab agents to melts trapped in the sub-arc mantle. Measurements of sulfur (S) valence state in sub-arc mantle peridotites identify sulfate, both as crystalline anhydrite (CaSO 4 ) and dissolved SO 4 2− in spinel-hosted glass (formerly melt) inclusions. Copper-rich sulfide precipitates in the inclusions and increased Fe 3+ /∑Fe in spinel record a S 6+ –Fe 2+ redox coupling during melt percolation through the sub-arc mantle. Sulfate-rich glass inclusions exhibit high U/Th, Pb/Ce, Sr/Nd and δ 34 S (+ 7 to + 11‰), indicating the involvement of dehydration products of serpentinised slab rocks in their parental melt sources. These observations provide a link between liberated slab components and oxidised arc magmas.
Publisher: Oxford University Press (OUP)
Date: 2016
Publisher: Elsevier BV
Date: 05-2018
Publisher: Elsevier BV
Date: 08-2010
Publisher: Springer Science and Business Media LLC
Date: 04-02-2019
Publisher: Elsevier BV
Date: 2011
Publisher: Geological Society of America
Date: 03-2013
DOI: 10.1130/G33787.1
Publisher: American Geophysical Union (AGU)
Date: 26-11-2013
DOI: 10.1002/2013GL057976
Publisher: Elsevier BV
Date: 03-2014
Publisher: Frontiers Media SA
Date: 10-03-2020
Publisher: Geological Society of America
Date: 20-08-2019
DOI: 10.1130/G46239.1
Abstract: Thermomechanical models of mantle convection and melting in an inferred hotter Archean Earth show the emergence of pressure-temperature (P-T) regimes that resemble present-day plate tectonic environments yet developed within a non–plate tectonics regime. The models’ P-T gradients are compatible with those inferred from evolving tonalite-trondhjemite-granodiorite series rocks and the paired metamorphic belt record, supporting the feasibility of ergent and convergent tectonics within a mobilized, yet laterally continuous, lithospheric lid. “Hot” P-T gradients of 10–20 °C km–1 form along asymmetric lithospheric drips, then migrate to areas of deep lithospheric downwelling within ∼300–500 m.y., where they are overprinted by high-pressure warm and, later, cold geothermal signatures, up to ∼8 °C km–1. Comparisons with the crustal production and reworking record suggest that this regime emerged in the Hadean.
Publisher: Geological Society of London
Date: 29-09-2023
Abstract: Different mineral clocks in granite can provide age information reflecting various aspects of rock formation, including cooling or post-emplacement fluid-rock interaction. However, the dating tool chosen can yield inconclusive age information due to differences in closure temperatures and susceptibility to fluid alteration among chronometers. This has led to an inferred superiority of U-Pb in zircon over U-Pb in monazites or Rb-Sr in micas. Here, we investigate age systematics using Rb-Sr biotite grains, U-Pb in monazite and zircons in a Devonian granite from Australia. Single-grain laser ablation ICP-MS/MS biotite analyses are combined with zircon-monazite U-Pb ages and trace element systematics. Textural and trace element evidence combined with age systematics reveals a Rb-Sr closure age of ∼360-330 Ma relative to a putative 364 Ma emplacement age, suggesting hydrothermal alteration of the granite. Trace element systematics and magnetic susceptibility in biotites reflect their partial chemical reset and fluid overprint in the granite. Similar systematics are, however, also observed for zircon and monazite. Our multiple chronometer dating approach, studied with modern laser-ablation methods, highlights the need for detailed investigation of isotope and trace element systematics in single grains and that in idual ages should be used cautiously when dating altered granitoids. Supplementary material at 0.6084/m9.figshare.c.6758747
Publisher: Elsevier BV
Date: 07-2014
Publisher: The Royal Society
Date: 10-2018
Abstract: The secular evolution of the Earth's crust is marked by a profound change in average crustal chemistry between 3.2 and 2.5 Ga. A key marker for this change is the transition from Archaean sodic granitoid intrusions of the tonalite–trondhjemite–granodiorite (TTG) series to potassic (K) granitic suites, akin (but not identical) to I-type granites that today are associated with subduction zones. It remains poorly constrained as to how and why this change was initiated and if it holds clues about the geodynamic transition from a pre-plate tectonic mode, often referred to as stagnant lid, to mobile plate tectonics. Here, we combine a series of proposed mechanisms for Archaean crustal geodynamics in a single model to explain the observed change in granitoid chemistry. Numeric modelling indicates that upper mantle convection drives crustal flow and subsidence, leading to profound ersity in lithospheric thickness with thin versus thick proto-plates. When convecting asthenospheric mantle interacts with lower lithosphere, scattered crustal drips are created. Under increasing P-T conditions, partial melting of hydrated meta-basalt within these drips produces felsic melts that intrude the overlying crust to form TTG. Dome structures, in which these melts can be preserved, are a positive diapiric expression of these negative drips. Transitional TTG with elevated K mark a second evolutionary stage, and are blends of subsided and remelted older TTG forming K-rich melts and new TTG melts. Ascending TTG-derived melts from asymmetric drips interact with the asthenospheric mantle to form hot, high-Mg sanukitoid. These melts are small in volume, predominantly underplated, and their heat triggered melting of lower crustal successions to form higher-K granites. Importantly, this evolution operates as a disseminated process in space and time over hundreds of millions of years (greater than 200 Ma) in all cratons. This focused ageing of the crust implies that compiled geochemical data can only broadly reflect geodynamic changes on a global or even craton-wide scale. The observed change in crustal chemistry does mark the lead up to but not the initiation of modern-style subduction. This article is part of a discussion meeting issue ‘Earth dynamics and the development of plate tectonics’.
Publisher: Proceedings of the National Academy of Sciences
Date: 08-11-2021
Abstract: Understanding when and how subaerial continental crust first formed is crucial, as it likely played a critical role in establishing Earth’s habitability. Although debated, the broad consensus is that the subaerial rise of continents began ∼2.5 billion years ago and was driven by plate tectonics. Here, we integrate the igneous and sedimentary history of Archean cratons to demonstrate that stable continental landmasses started to emerge above sea level 3.3 to 3.2 billion years ago (i.e., over 700 million years earlier than most models predict). We also demonstrate that these initial episodes of continental emersion were driven by voluminous granitoid magmatism in non–plate tectonic settings that formed ∼50-km-thick, silica-rich crust, which rose above the oceans due to isostasy.
Publisher: Elsevier BV
Date: 2010
Publisher: Elsevier BV
Date: 04-2019
Publisher: Elsevier BV
Date: 09-2019
Publisher: Elsevier BV
Date: 05-2011
Publisher: Elsevier BV
Date: 11-2018
Publisher: Springer Science and Business Media LLC
Date: 16-09-2012
DOI: 10.1038/NGEO1583
Publisher: Elsevier BV
Date: 2014
Publisher: The Royal Society
Date: 10-2018
Abstract: Plate tectonics, involving a globally linked system of lateral motion of rigid surface plates, is a characteristic feature of our planet, but estimates of how long it has been the modus operandi of lithospheric formation and interactions range from the Hadean to the Neoproterozoic. In this paper, we review sedimentary, igneous and metamorphic proxies along with palaeomagnetic data to infer both the development of rigid lithospheric plates and their independent relative motion, and conclude that significant changes in Earth behaviour occurred in the mid- to late Archaean, between 3.2 Ga and 2.5 Ga. These data include: sedimentary rock associations inferred to have accumulated in passive continental margin settings, marking the onset of sea-floor spreading the oldest foreland basin deposits associated with lithospheric convergence a change from thin, new continental crust of mafic composition to thicker crust of intermediate composition, increased crustal reworking and the emplacement of potassic and peraluminous granites, indicating stabilization of the lithosphere replacement of dome and keel structures in granite-greenstone terranes, which relate to vertical tectonics, by linear thrust imbricated belts the commencement of temporally paired systems of intermediate and high dT/dP gradients, with the former interpreted to represent subduction to collisional settings and the latter representing possible hinterland back-arc settings or ocean plateau environments. Palaeomagnetic data from the Kaapvaal and Pilbara cratons for the interval 2780–2710 Ma and from the Superior, Kaapvaal and Kola-Karelia cratons for 2700–2440 Ma suggest significant relative movements. We consider these changes in the behaviour and character of the lithosphere to be consistent with a gestational transition from a non-plate tectonic mode, arguably with localized subduction, to the onset of sustained plate tectonics. This article is part of a discussion meeting issue ‘Earth dynamics and the development of plate tectonics'.
Publisher: Springer Science and Business Media LLC
Date: 02-12-2020
Publisher: Elsevier BV
Date: 10-2016
Publisher: Geological Society of America
Date: 03-2014
DOI: 10.1130/G35373Y.1
Publisher: Elsevier BV
Date: 10-2006
Publisher: Elsevier BV
Date: 2021
Publisher: Elsevier BV
Date: 2016
Publisher: Elsevier BV
Date: 2021
Publisher: Elsevier BV
Date: 07-2015
Publisher: Elsevier BV
Date: 2020
Publisher: American Geophysical Union (AGU)
Date: 06-2012
DOI: 10.1029/2012GC004088
Publisher: Elsevier BV
Date: 08-2009
Publisher: Elsevier BV
Date: 11-2009
Publisher: Elsevier BV
Date: 2020
Publisher: Elsevier BV
Date: 2023
Publisher: Elsevier BV
Date: 05-2010
Publisher: Elsevier BV
Date: 07-2011
Publisher: Elsevier BV
Date: 03-2011
Publisher: American Geophysical Union (AGU)
Date: 2019
DOI: 10.1029/2018GC007767
Publisher: Oxford University Press (OUP)
Date: 10-2016
Publisher: Oxford University Press (OUP)
Date: 2016
Publisher: Elsevier BV
Date: 12-2020
Publisher: Elsevier BV
Date: 02-2013
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/C9JA00308H
Abstract: We present a method for the determination of δ 146 Nd, 143 Nd/ 144 Nd and Sm–Nd ratios from a single spiked aliquot.
Publisher: Elsevier BV
Date: 12-2013
Publisher: Elsevier BV
Date: 11-2005
Publisher: Elsevier BV
Date: 07-2018
Publisher: Elsevier BV
Date: 11-2023
Publisher: Elsevier BV
Date: 10-2023
Publisher: Elsevier BV
Date: 12-2015
Publisher: Elsevier BV
Date: 12-2022
Publisher: Elsevier BV
Date: 11-2009
Publisher: Elsevier BV
Date: 11-2019
Publisher: Schweizerbart
Date: 11-2013
Publisher: Elsevier BV
Date: 2019
Publisher: Elsevier BV
Date: 09-2016
Publisher: Geological Society of London
Date: 03-04-2018
DOI: 10.1144/SP453.1
Publisher: Springer Science and Business Media LLC
Date: 21-06-2011
Publisher: Wiley
Date: 12-2009
Publisher: Elsevier BV
Date: 03-2020
Publisher: Elsevier BV
Date: 02-2017
Publisher: Elsevier BV
Date: 12-2015
Publisher: Springer Science and Business Media LLC
Date: 27-11-2018
Publisher: European Association of Geochemistry
Date: 2017
Publisher: Elsevier BV
Date: 2020
Publisher: Schweizerbart
Date: 31-10-2018
No related grants have been discovered for Oliver Nebel.