Open-system magmatic behaviour beneath monogenetic volcanoes revealed by the geochemistry, texture and thermobarometry of clinopyroxene, Kaikohe-Bay of Islands volcanic field (New Zealand)

Coote, Alisha; Shane, Philip

doi:10.1016/j.jvolgeores.2018.11.006

Cited by 25 publications

(11 citation statements)

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“…The study of volcanic rocks could help us investigate deep magma chamber processes and their evolutionary history. Magma chamber processes such as magma mixing, recharge, crystal mush remobilization, fractional crystallization, and assimilation are all part of the magma evolution process and can trigger volcanic eruptions [1][2][3]. However, these processes may not always be documented in the whole-rock composition of volcanic rocks if the mixing process is efficient [2,[4][5][6].…”

Section: Introductionmentioning

confidence: 99%

“…Magma chamber processes such as magma mixing, recharge, crystal mush remobilization, fractional crystallization, and assimilation are all part of the magma evolution process and can trigger volcanic eruptions [1][2][3]. However, these processes may not always be documented in the whole-rock composition of volcanic rocks if the mixing process is efficient [2,[4][5][6]. When magma ascends from deep to shallow, changes in physical and chemical conditions affect the texture and composition of minerals; these changes may be recorded and preserved in the affected minerals [7,8].…”

Section: Introductionmentioning

confidence: 99%

“…Clinopyroxene is an important rock-forming mineral in volcanic rocks due to its wide crystallization range. The textural characteristics and compositional zoning of clinopyroxene record magmatic crystallization history and constrain magma storage conditions, which provides an opportunity to investigate the processes during magma ascent [2,9,10]. Clinopyroxene has been studied worldwide for a long period of time [2,7,[11][12][13][14][15][16][17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

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Geochemical Insights from Clinopyroxene Phenocrysts into the Magma Evolution of an Alkaline Magmatic System from the Sanshui Basin, South China

2021

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The Sanshui Basin is located at the northern continental margin of the South China Sea and characterized by a continental rift basin. The bimodal volcanic rocks in Sanshui Basin record the early Cenozoic magmatic activity in the South China Block, but the magmatic evolution that produced the bimodal volcanic rocks is poorly understood. Clinopyroxenes in bimodal volcanic rocks in the Sanshui Basin provide an opportunity to investigate magma during magma ascent. In this work, we classified nine types of clinopyroxene phenocrysts according to composition and texture in cogenetic basalt-trachyandesite-comenditic trachyte, while the composition of unzoned clinopyroxene have an evolution sequence of diopside-hedenbergite-aegirine along with an increase in trace element contents with a decrease of Mg#, indicating that the genesis of clinopyroxene was dominated by fractional crystallization in a closed magma system. However, the clinopyroxenes with reversed zoning and multiple zoning record the process of magma mixing and recharge indicating an open magma system. While fractional crystallization is the dominant process, magma mixing, recharge, and crystal settling were also found to influence magma evolution. Thermobarometric calculations showed that clinopyroxene crystallized a several structural levels in the crust during magma ascent. In this study, we established a magma plumbing system that provides new constraints for the magma evolution in the Sanshui Basin.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Geochemical Insights from Clinopyroxene Phenocrysts into the Magma Evolution of an Alkaline Magmatic System from the Sanshui Basin, South China

2021

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“…The study of volcanic rocks can help us investigate the deep magma process and its evolutionary history. However, the magma chamber process such as magma mixing, recharge, crystal mush remobilization, fractional crystallization, and assimilation complicates the magma evolution process and may trigger volcanic eruption [1][2][3], these characteristics are not obvious only taking the whole volcanic rock analysis if the mixing process is efficient [2,[4][5][6]. When magma ascends from deep magma depths to shallow reservoir, the changes of physical and chemical conditions affect the texture and composition of minerals and are recorded and preserved in minerals [7,8].…”

Section: Introductionmentioning

confidence: 99%

“…Clinopyroxene is an important rock-forming mineral in volcanic rocks, due to its wide crystallization range. The textural characteristics and composition zoning of clinopyroxene record the magmatic crystallization history and constrain the magma storage conditions, which provides an opportunity to investigate the magma process during magma ascent [2,9,10]. Clinopyroxene has been studied worldwide for a long time [2,7,[11][12][13][14][15][16][17][18][19][20], The mineral scales study of clinopyroxene with different textures and compositions can be used to distinguish open-and closed-magma systems and provide a good indicator to unravel the evolution of magma system and establish magma plumbing system [1,2,11].…”

Section: Introductionmentioning

confidence: 99%

Geochemical Insights From Clinopyroxene Phenocrysts Into the Magma Evolution of an Alkaline Magmatic System From the Sanshui Basin, South China

Chen¹,

Fang²,

Yuan³

2021

Preprint

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The Sanshui Basin (SSB) is located at the northern continental margin of the South China Sea and characterized by a continental rift basin. The bimodal volcanic rocks in SSB record the early Cenozoic magmatic activity in the South China Block, on the magmatic evolution process of bimodal volcanic rocks are poorly understood. Clinopyroxenes in bimodal volcanic rocks in the SSB provide an opportunity to investigate the magma process during magma ascent. We classified nine types of clinopyroxene phenocrysts according to the different compositions and textures types in cogenetic basalt-trachyandesite-comenditic trachyte, the composition of unzoned clinopyroxene have an evolution sequence of diopside- hedenbergite- aegirine with the decrease of Mg#, and the trace element contents of unzoned clinopyroxenes also increase systematically during magma evolution, indicating that the genesis of clinopyroxene dominated by fractional crystallization in a closed magma system; however, the clinopyroxenes with reverse zoning and multiple zoning record the process of magma mixing and recharge indicating an open magma system. Whilst fractional crystallization is the dominated process, magma mixing, recharge, and crystal settling complicate magma evolution. Thermobarometric calculations show that clinopyroxene phenocrysts in bimodal volcanic rocks of SSB are distributed in the whole crust during magma ascent. We have established a magma plumbing system, which provides a new constrain for the complex magmatic evolution history in the SSB by detailed mineral-scale analysis.

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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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Open-system magmatic behaviour beneath monogenetic volcanoes revealed by the geochemistry, texture and thermobarometry of clinopyroxene, Kaikohe-Bay of Islands volcanic field (New Zealand)

Cited by 25 publications

References 40 publications

Geochemical Insights from Clinopyroxene Phenocrysts into the Magma Evolution of an Alkaline Magmatic System from the Sanshui Basin, South China

Geochemical Insights from Clinopyroxene Phenocrysts into the Magma Evolution of an Alkaline Magmatic System from the Sanshui Basin, South China

Geochemical Insights From Clinopyroxene Phenocrysts Into the Magma Evolution of an Alkaline Magmatic System From the Sanshui Basin, South China

Anatomy of Intraplate Monogenetic Alkaline Basaltic Magmatism

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