Parallel Plumbing Systems Feeding a Pair of Coeval Volcanoes in Eastern Australia

Crossingham, Tracey; Ubide, Teresa; Vasconcelos, Paulo; Mallmann, Guilherme

doi:10.1093/petrology/egy054

Cited by 14 publications

(10 citation statements)

References 91 publications

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“…We explored the effect of sector zoning on P-T estimates by solving iteratively the pressure-independent, melt-dependent thermometer T1 (±27°C uncertainty; Putirka et al, 1996) and the temperature-and water-dependent, melt-independent barometer 32b (±200 MPa uncertainty; Putirka, 2008). Clinopyroxene-only barometers have provided reliable results at Etna and other alkaline systems, and are particularly useful when studying recycled parageneses (Ubide et al, 2014;Mollo et al, 2015;Hammer et al, 2016;Miller et al, 2017;Ubide and Kamber, 2018;Crossingham et al, 2018). Barometer 32b requires an esti-mate of the water content of the melt, which was set at 2 wt.% to account for the hydrous nature of Etnean magmas (Armienti et al, 2007(Armienti et al, , 2013Ubide and Kamber, 2018).…”

Section: Clinopyroxene-melt Equilibrium and Thermobarometry On Sectormentioning

confidence: 99%

Sector-zoned clinopyroxene as a recorder of magma history, eruption triggers, and ascent rates

Ubide

Mollo

Zhao

et al. 2019

Geochimica et Cosmochimica Acta

146

129

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Sector-zoned clinopyroxene is common in igneous rocks, but has been overlooked in the study of magmatic processes. Whilst concentric zoning is commonly used as a record of physicochemical changes in the melt feeding crystal growth, clinopyroxene is also highly sensitive to crystallisation kinetics. In sector-zoned crystals, the fidelity of compositional changes as recorders of magma history is dubious and the interplay between thermodynamic and kinetic controls remains poorly understood. Here we combine electron probe and laser ablation micro-chemical maps of titanaugite crystals from Mt. Etna (Sicily, Italy) to explore the origin of sector zoning at the major and trace element levels, and its implications for the interpretation of magmatic histories. Elemental maps afford the possibility to revisit sector zoning from a spatially controlled perspective. The most striking observation is a clear decoupling of elements into sectors vs. concentric zones within single crystals. Most notably, Al-Ti enrichments and Si-Mg depletions in the prism sectors {1 0 0}, {1 1 0} and {0 1 0} relative to the hourglass (or basal) sectors {À1 1 1} correlate with enrichments in rare earth elements and highly charged high field strength elements due to cation exchanges driven by kinetic effects. In contrast, transition metals (Cr, Ni, Sc) show little partitioning into sectors and strong enrichments in concentric zones following resorbed surfaces, interpreted as evidence of mafic recharge and magma mixing. Our results document that kinetic partitioning has minor effects on the compositional variations of cations with low charge relative to the ideal charge/radius of the structural site they occupy in the clinopyroxene lattice. We suggest that this may be due to a lower efficiency in charge balance mechanisms compared to highly charged cations. It follows that compatible metals such as Cr can be considered trustworthy recorders of mafic intrusions and eruption triggers even in sector-zoned crystals. We also observe that in alkaline systems where clinopyroxene crystallisation takes place at nearequilibrium conditions, sector zoning should have little effect on Na-Ca partitioning and in turn, on the application of experimentally calibrated thermobarometers. Our data show that whilst non-sector-zoned crystals form under relatively stagnant conditions, sector zoning develops in response to low degrees of undercooling, such as during slow magma ascent. Thus, we propose that the chemistry of sector-zoned crystals can provide information on magma history, eruption triggers, and possibly ascent rates.

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Section: Clinopyroxene-melt Equilibrium and Thermobarometry On Sectormentioning

confidence: 99%

Sector-zoned clinopyroxene as a recorder of magma history, eruption triggers, and ascent rates

Ubide

Mollo

Zhao

et al. 2019

Geochimica et Cosmochimica Acta

146

129

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“…Consequently the effect of assimilation and crustal contamination do not generally plague the interpretation of chemical signatures in alkaline basalts, particularly those related to small-volume eruptions (McGee and Smith, 2016). Far from being only dominated by nearprimary magmas, however, intraplate alkaline systems have often undergone considerable magmatic evolution to form trachyte/phonolite/rhyolite associations (Ablay et al, 1998;Brenna et al, 2012b;Crossingham et al, 2018;Harangi, 2001;Harangi et al, 1995;Melluso et al, 2018;Moufti et al, 2012). Such magma compositions generally occur in larger volume central volcanoes that are associated with complex, multi-stage plumbing systems and result from magma stalling and evolving through fractional crystallization and assimilation processes.…”

Section: Insights From Whole-rock Chemical Datamentioning

confidence: 99%

“…Plagioclase macrocrysts are prevalently segregated from SiO2 saturated (subalkaline) magmas, such as those erupted in the Kaikohe-Bay of Island Volcanic Field (New Zealand) . They also indicate relatively H2O-poor melts or shallow degassing and crustal processes, with deviation from purely monogenetic basaltic systems (Crossingham et al, 2018;Giacomoni et al, 2014).…”

Section: Insights From Crystal Compositionsmentioning

confidence: 99%

Anatomy of Intraplate Monogenetic Alkaline Basaltic Magmatism

Brenna

Ubide

Nichols

et al. 2021

Geophysical Monograph Series

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Intraplate basaltic systems, often occurring as fields of small monogenetic volcanoes, are dominated by eruption of alkaline basaltic rocks, ranging from nephelinite/basanite to transitional/subalkaline. Their generally primitive erupted compositions imply limited crustal modification, and hence they provide an important probe into deep, lithospheric mantle and partial melting processes. Partial melting and magmatic ascent processes can be investigated using the composition of crystals, glass and wholerock, although a combination of these is preferable. The whole-rock chemical variability within single eruptions or over the temporal and spatial extent of a volcanic field is controlled by the characteristics of the primary melting source, as well as near source percolative/reaction processes. Coupled crystaland -whole-rock detailed investigations are most promising to constrain the processes that modify primary melts into the primitive magmas that accumulate before ascent. Complex crystal textures and chemistry have so far demonstrated that basaltic magmas are principally processed and modified within the lithospheric mantle with minor modification en-route through the crust. Fractional crystallization and magma mixing modify melts throughout ascent, and can imprint secondary chemical intra-eruptive variability. Quantifiable temperature and pressure parameters based on crystalmelt compositions constrain the depth of formation, and hence provide information about the role of different mineral phases in deep versus shallow chemical evolution. Volatile components in the melt (e.g. H2O and CO2) can be quantified on glass and melt inclusions. These analyses, coupled with solubility models, may help to reconstruct initial dissolved volatile content to further constrain the source characteristics and magmatic ascent dynamics. Integrated studies of crystals and melt paint a picture of extended lithospheric mantle to minor crustal processing resulting from the complex deep plumbing of monogenetic basaltic systems. This highlights the need for improved resolution to characterize true primary signatures and hence elucidate the formation of intraplate alkaline basalts.

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“…2008; Mortimer et al, 2010;Sutherland et al, 2012;Cohen et al, 2013;Crossingham et al, 2017;Mortimer et al, 2018;Crossingham et al, 2018a;Crossingham et al, 2018b). 40 Ar/ 39 Ar results, where available, were preferred, but K-Ar ages for Lord Howe Island (McDougall et al, 1981) were included following Mortimer et al (2018).…”

Section: Paleolatitude Reconstructionmentioning

confidence: 99%

“…Cosgrove and Comboyne hotspots appear most constant, but most hotspot pairs accumulate changes in angular distance over time. The cumulative effect of this is generally small, and within the (Doubrovine et al, 2012), and from hotspot catalogs (Courtillot et al, 2003;Montelli et al, 2006) FIGURE 5 | Spline fits to eastern Australian hotspots based on geochronologic data (squares, Ashley et al, 1995;McDougall et al, 1981;McDougall and Duncan, 1988;Cohen et al, 2007;McQueen et al, 2007;Cohen et al, 2008;Knesel et al, 2008;Mortimer et al, 2010;Cohen et al, 2013;Crossingham et al, 2017;Mortimer et al, 2018;Crossingham et al, 2018a;Crossingham et al, 2018b;Sutherland et al, 2012). Present day positions are shown in red, based upon motion paths (in gray) derived from Doubrovine et al (2012) ( Table 1).…”

Section: Geometric Analysismentioning

confidence: 99%

Southward Drift of Eastern Australian Hotspots in the Paleomagnetic Reference Frame Is Consistent With Global True Polar Wander Estimates

Hansma

Tohver

2020

Front. Earth Sci.

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Eastern Australian hotspots produce the longest continental tracks on Earth (> 2, 000 km). These hotspots are generally assumed to be stationary with respect to one another, an observation reinforced by our analysis. If any motion between them occurred, it is within our 95% uncertainties of 370 km of accumulated motion between hotspots. In contrast, motion between eastern Australian hotspots and the spin axis is indicated by changing paleolatitudes of hotspots through time. Reconstructing Australian hotspot paleolatitudes makes use of the global reference frame established by the geocentric axial dipole hypothesis. The classic paleomagnetic approach to establishing paleolatitude typically uses studies of discrete formations of known age, but the nearly continuous record of volcanism over 34 Ma permit using paleomagnetic data from multiple, different studies that overlap in magnetization age in conjunction. This improves the robustness and precision of our paleolatitude estimates for Eastern Australian hotspot volcanoes. A northward shift of hotspot paleolatitudes between 15-24 Ma of ∼300-1,010 km (95% confidence limits) is observed for volcanoes along the Comboyne, Canobolas and Tasmantid tracks, and for interpolated positions along the Cosgrove and Lord Howe tracks but is significantly resolved only for volcanoes along Comboyne and Canobolas tracks, as well as for two ages from the Stradbroke and Britannia seamounts on the Tasmantid track. Before 24 Ma most data plot to the North of a fixed present day hotspot location in the paleomagnetic reference but 95% confidence limits overlap with it. Notable exceptions are an age from Hillsborough Volcano (Cosgrove Hotspot), and an age from Horse Head (Lord Howe Hotspot) that lie a small distance to the North km, and kmNorth, respectively. Importantly, paleolatitude changes observed along eastern Australian tracks are all explainable by the net rotation of the solid Earth, or true polar wander, with hotspots embedded in the global moving hotspot reference frame.

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Parallel Plumbing Systems Feeding a Pair of Coeval Volcanoes in Eastern Australia

Cited by 14 publications

References 91 publications

Sector-zoned clinopyroxene as a recorder of magma history, eruption triggers, and ascent rates

Sector-zoned clinopyroxene as a recorder of magma history, eruption triggers, and ascent rates

Anatomy of Intraplate Monogenetic Alkaline Basaltic Magmatism

Southward Drift of Eastern Australian Hotspots in the Paleomagnetic Reference Frame Is Consistent With Global True Polar Wander Estimates

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