Erratum to: Bull Volcanol Volume 73 (2) Special Issue: Failed eruptions: Late-stage cessation of magma ascent

AbstractThe Li and B isotopic compositions of gem-quality Cu-bearing tourmalines were used (1) to distinguish among Paraiba tourmalines from Brazil and Cu-bearing tourmalines from Nigeria and Mozambique; and (2) to identify the likely source of Li and B for these gem-quality tourmalines. The δ11B values of tourmaline from Paraiba, Brazil, range from –42.4‰ to –32.9‰, whereas the δ11B values of Cu-bearing tourmaline from Nigeria and Mozambique range from –30.5‰ to –22.7‰ and –20.8‰ to –19.1‰ respectively. Tourmalines from each locality have relatively homogeneous δ11B values and display no overlap. There is slight overlap between δ7Li values of Paraiba tourmaline (+24.5‰ to +32.9‰) and Cu-bearing tourmaline from Nigeria (+32.4‰ to +35.4‰), and δ7Li values of Cu-bearing tourmaline from Nigeria and Mozambique (+31.5‰ to +46.8‰). Nevertheless, Cu-bearing tourmalines from each locality can be fingerprinted using a combination of their δ11B and δ7Li values. The very small δ11B values are consistent with a non-marine evaporite source, and are among the smallest reported for magmatic systems, expanding the global range of B isotopicc omposition for tourmaline by 12‰. The corresponding large δ7Li values are among the largest reported, although they are less diagnostic of the source of the Li. The large δ7Li values in conjunction with the small δ11B values suggest a non-marine evaporite or brine as a source for Li and B, either as constituent(s) of the magma source region or, by assimilation during magma ascent. The large range in δ11B and δ7Li values suggests that B and Li isotope fractionation occurred during magmatic degassing and late-stage magmatic-hydrothermal evolution of the granite-pegmatite system.

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Paleozoic Magmatism and Mineralization Potential of the Sanchakou Copper Deposit, Eastern Tianshan, Northwest China: Insights from Geochronology, Mineral Chemistry, and Isotopes

Economic Geology ◽

10.5382/econgeo.4859 ◽

2021 ◽

Author(s):

Fang-Fang Zhang ◽

Yin-Hong Wang ◽

Jia-Jun Liu ◽

Chun-Ji Xue ◽

Jian-Ping Wang ◽

...

Keyword(s):

Late Stage ◽

Secondary Ion Mass Spectrometry ◽

Copper Deposit ◽

High Water ◽

Mineral Chemistry ◽

Northwest China ◽

Magma Ascent ◽

Eastern Tianshan ◽

Magmatic Arc ◽

Mineralization Potential

Abstract The Sanchakou Cu deposit is located in the eastern section of the Dananhu magmatic arc in the Eastern Tianshan orogenic belt, northwest China. Sanchakou is hosted by quartz diorite and granodiorite intrusions. Chalcopyrite and bornite are the dominant ore minerals and occur as disseminations, patches, veins, and veinlets. Secondary ion mass spectrometry (SIMS) U-Pb dating of zircons shows that the ore-bearing intrusions were emplaced at ca. 435–432 Ma, recording the early subduction of the Paleo-Tianshan oceanic plate. The enrichment in large ion lithophile elements (LILEs), depletion in high field strength elements (HFSEs), and moderate Mg# values, together with mantle-like bulk Sr-Nd and zircon Hf-O isotope signatures (δ18O = 4.0–5.3‰), suggest that they were generated from partial melting of metasomatized mantle materials by subducted slab fluids. In situ S and whole-rock Pb isotope results imply that the Sanchakou diorite magmas provided ore-forming components (S and metals), with additional minor metals (e.g., Cu and Pb) sourced from crustal components beneath the Dananhu arc. The redox state of diorite magmas ranges from initial high fO2 (>FMQ + 2, where FMQ is the fayalite-magnetite-quartz buffer) to relatively low fO2 (<FMQ + 2) upon magma ascent and cooling. The late-stage less oxidized magma compositions are consistent with the presence of magmatic sulfides in primary plagioclase and magnetite. Estimates of water-sulfur-chlorine contents in magma using plagioclase, amphibole, and apatite compositions reveal that the diorite magmas had high water (>7 wt %), normal S (8–393 ppm), and systematically low Cl (38–1,100 ppm) contents. A constant and favorable elevated magma oxidation state appears critical for generating an economic porphyry Cu deposit. Additionally, Cl melt concentrations may be a key factor that controlled metal fertility of the deposits in the Eastern Tianshan, although the mineralization potential may also relate to depth of emplacement of the hydrothermal system. The anomalous presence of stellerite with chalcopyrite in late-stage veins indicates that original porphyry-style mineralization at Sanchakou underwent deformation-related modification after its formation.

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Failed magmatic eruptions: late-stage cessation of magma ascent

Bulletin of Volcanology ◽

10.1007/s00445-010-0444-x ◽

2011 ◽

Vol 73 (2) ◽

pp. 115-122 ◽

Cited By ~ 86

Author(s):

Seth C. Moran ◽

Chris Newhall ◽

Diana C. Roman

Keyword(s):

Late Stage ◽

Magma Ascent

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Shallow magmatic processes revealed by cryptic microantecrysts: a case study from the Taupo Volcanic Zone

Contributions to Mineralogy and Petrology ◽

10.1007/s00410-021-01857-7 ◽

2021 ◽

Vol 176 (11) ◽

Author(s):

Charline Lormand ◽

Georg Florian Zellmer ◽

Naoya Sakamoto ◽

Teresa Ubide ◽

Geoff Kilgour ◽

...

Keyword(s):

Late Stage ◽

Water Saturation ◽

Significant Proportion ◽

Volcanic Eruptions ◽

Oscillatory Zoning ◽

Magma Ascent ◽

Taupo Volcanic Zone ◽

Volcanic Zone ◽

Wide Range ◽

Normal Zoning

AbstractArc 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 microlite-bearing tephras. Major oxide analyses and textural information reveal that microlite rims are commonly out of equilibrium with the surrounding glass. We mapped microlites and microcrysts at submicron resolution for major and trace element distributions and observed three plagioclase textural patterns: (1) resorption and overgrowth, (2) oscillatory zoning, and (3) normal (sharp) zoning. Pyroxene textures are diverse: (1) resorption and overgrowth, (2) calcium-rich bands, (3) hollow textures, (4) oscillatory zoning, (5) sector zoning, (6) normal zoning and (7) reverse zoning. Microlite chemistry and textures inform processes operating during pre-eruptive magma ascent. They indicate a plumbing system periodically intruded by short-lived sub-aphyric dykes that entrain microantecrysts grown under diverse physico-chemical conditions and stored in rapidly cooled, previously intruded dykes. Changes in temperature gradients between the intrusion and the host rock throughout ascent and repeated magma injections lead to fluctuations in cooling rates and generate local heterogeneities illustrated by the microlite textures and rim compositions. Late-stage degassing occurs at water saturation, forming thin calcic microcryst rims through local partitioning effects. This detailed investigation of textures cryptic to conventional imaging shows that a significant proportion of the micrometre-sized crystal cargo of the TVZ is of antecrystic origin and may not be attributed to late-stage nucleation and growth at the onset of volcanic eruptions, as typically presumed.

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Insights from geodynamical modeling on possible fates of continental mantle lithosphere: collision, removal, and overturnThis article is one of a series of papers published in this Special Issue on the theme Lithoprobe — parameters, processes, and the evolution of a continent.

Canadian Journal of Earth Sciences ◽

10.1139/e09-043 ◽

2010 ◽

Vol 47 (4) ◽

pp. 541-563 ◽

Cited By ~ 23

Author(s):

Russell N. Pysklywec ◽

Oguz Gogus ◽

J. Percival ◽

A. R. Cruden ◽

C. Beaumont

Keyword(s):

Late Stage ◽

Continental Collision ◽

Density Stratification ◽

Mantle Lithosphere ◽

Special Issue ◽

Tectonically Active ◽

Tectonic Environments

Geodynamic modeling demonstrates various modes of behaviour of the tectonically active continental mantle lithosphere. At continental collision, mantle lithosphere below thickening crust can be accommodated by mixed subduction-like consumption and viscous drip-like instability, depending on the material rheology, temperature, and convergence velocity. Late-stage slab steepening, dual-sided and ablative consumption, and breakoff can occur as the buoyant crust resists subduction. Removal of accreted crust by erosion can modify how even the deepest portions of the mantle lithosphere evolves during contraction. When gravitational forcing rather than plate shortening dominates, mantle lithosphere may be removed through viscous dripping-like instability or delamination. The removal induces crustal heating, modified topography, and deformation, but distinctive styles of these develop depending on whether mantle lithosphere delaminates or drips. With a modified density stratification postulated for the Archean, relatively buoyant mantle lithosphere may undergo an in-situ overturn when triggered by unstable dense eclogite and basal traction. This causes a pulse of rapid crustal heating as hot lowermost lithosphere is brought into contact with the base of the crust. As an interpretive tool, the geodynamic experiments illustrate some of the dynamically feasible modes of behaviour and controlling parameters for the continental mantle lithosphere in ancient to modern tectonic environments.

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Introduction

South Atlantic Quarterly ◽

10.1215/00382876-8915937 ◽

2021 ◽

Vol 120 (2) ◽

pp. 245-254

Author(s):

Ellen Samuels ◽

Elizabeth Freeman

Keyword(s):

Late Stage ◽

Special Issue ◽

Disabled People ◽

Full Swing

This introduction connects the temporal regimes that disabled people and communities negotiate with the universalization of “crip time” during the COVID-19 pandemic, in full swing at the time of this writing. It discusses the articles and artwork in this special issue in terms of how they express the temporalities lived by disabled subjects both as confining and, potentially, as means of critiquing and transforming the time discipline of late-stage capitalism.

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