Gas filter-pressing origin for segregation vesicles in dykes

Sanders, I. S.

doi:10.1017/s0016756800026546

Cited by 29 publications

(6 citation statements)

References 12 publications

(25 reference statements)

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“…Plagioclase crystals immediately outside these spheroids lie tangential to them. The spheroids appear to represent segregation vesicles (Sanders 1986).…”

Section: Td Dikesmentioning

confidence: 99%

Carboniferous dikes of West Connacht, Ireland

Mitchell

Mohr

1987

Transactions of the Royal Society of Edinburgh: Earth Sciences

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Vigorous Carboniferous extensional tectonism and associated igneous activity is a feature of Ireland and the neighbouring areas of Newfoundland and Britain. In West Connacht, Ireland, dolerite dikes of late Carboniferous age are newly recognised and distinguished from Tertiary dolerites. In the N, the 320 Ma-old Logmor dike trends N–S across the Ordovician South Mayo Trough, and has an evolved, mildly alkaline basalt geochemistry. In the S, in Connemara, a diffuse and arcuate swarm of ENE–NE trending, 305 Ma-old dolerite dikes, the Teach Doite swarm, cuts the Galway Granite batholith and its envelope of Dalradian gneisses. These more tholeiitic dolerites reveal the mineralogical and geochemical effects of varying degrees of pervasive hydrothermal alteration, imposed on an original magmatic composition similar to that of mid-ocean ridge basalts. Variscan overprinting on k–Ar ages from West Connacht dolerites clusters at 300, 245 and 205 Ma. Overprinting is also a feature of much of the Galway Granite. Carboniferous diking in West Connacht may have responded to nascent opening of the proximate North Atlantic, its pattern related to domal uplift adjacent to the rifted zone.

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“…Plagioclase crystals immediately outside these spheroids lie tangential to them. The spheroids appear to represent segregation vesicles (Sanders 1986).…”

Section: Td Dikesmentioning

confidence: 99%

Carboniferous dikes of West Connacht, Ireland

Mitchell

Mohr

1987

Transactions of the Royal Society of Edinburgh: Earth Sciences

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“…Sim i larly, the for ma tion of seg re ga tion ves i cles (Fig. 4B) has been ex plained as a fea ture of magma en ter ing an en vi ron ment with high ex ter nal pres sure (Smith, 1967;An derson et al, 1984;Sanders, 1986;Caroff et al, 2000;Vernon, 2004) such as great ocean depth (Smith, 1967).…”

Section: Volcano-sedimentary Environmentmentioning

confidence: 99%

“…(3) the seg re ga tion ves i cles (Fig. 4B) in the ba saltic sheet lavas and also the swal low-tail plagioclase crys tals are fea tures that have been pro posed by some re search ers (e.g., Smith, 1967;Lofgren, 1974;Mevel and Velde, 1976;Swanson and Schiffman, 1979;An der son et al, 1984;Sanders, 1986;Caroff et al, 2000;Vernon, 2004) as in dicat ing deep sub ma rine erup tions. Ac cord ing to Lofgren (1974), Mevel and Velde (1976) and Swanson and Schiffman (1979), hyalomicrolithic and swal low-tail plagioclase crys tals may be pro duced by a high rate of undercooling of lava at great depths of wa ter.…”

Section: Volcano-sedimentary Environmentmentioning

confidence: 99%

Cretaceous magmatic evolution in the Deylaman igneous complex, Alborz zone, Iran: change from extensional to compressional regime

Akmali

Asiabanha

Haghnazar

2019

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As so ci ate ed i tor: Tomasz Bajda The Deylaman ig ne ous com plex, as a part of the Late Cre ta ceous rock unit that lies be hind the Paleogene Alborz mag matic arc, in the north ern Alborz zone, is com posed of ba saltic sheet lavas al ter nat ing with the pe lagic cal car e ous sed i ments, basaltic pil low lavas, fel sic lavas and gabbroic-monzodioritic in tru sions. The pe lagic cal car e ous de pos its con tain microfossils rep re sent ing the Santonian-Maastrichtian ages. Fur ther more, petrographic tex tures such as the hyalomicrolitic tex ture and swal low-tail plagioclase crys tals in the pil low lavas, and also seg re ga tion ves i cles in the ba saltic sheet lavas, im ply high exter nal (hy dro static) pres sures as the magma was ex truded in a deep-wa ter en vi ron ment. The rock sam ples show both compositional bimodality and char ac ter is tic trends in the vari a tion di a grams. Also, some geo chem i cal char ac ter is tics im ply that the ba saltic lavas orig i nated from the par tial melt ing of an undepleted deep man tle source con tain ing spinel lherzolite: the en rich ment pat terns of LREE/HREE ra tios of the sam ples [(La/Yb)n = 3.93-4.16 for ba saltic lavas and 10.92 for fel sic lavas] ly ing be tween those char ac ter is tic of OIBs [(La/Yb)n = 12.92] and EMORBs [(La/Yb)n = 1.91]; sim i lar i ties be tween the pat terns of multi-el e ment spi der-di a grams; LILE bulges in the ba saltic sam ples com pared with those of OIBs. More over, the sam ples show in flu ence from two geotectonic en vi ron ments: su pra-subduction zone (SSZ) set tings and plume-type within-plate mag mas. There fore, be cause of the deep sub ma rine en vi ron ment in ferred for the ef fu sive vol ca nic erup tions in Santonian-Maastrichtian time, it seems that the Deylaman ig ne ous com plex evolved through two stages: first, a ten sional re gime in a su pra-subduction zone (far ther from the Me so zoic mag matic arc) and for ma tion of an em bry onic rift-re lated oceanic ba sin in the Late Ju ras sic-Early Cre ta ceous; sec ondly, a com pres sive re gime in the Late Cre ta ceous-Early Paleocene and in land mi gra tion of the mag matic arc. Con se quently, the Cre ta ceous magmatism can be in ter preted as a pre lude to the Eocene mag matic flare-up in the mag matic arcs of Iran.

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“…Although diktytaxitic texture has long been recognized in petrographic literature (e.g., Fuller 1931), its formation conditions and mechanisms remain elusive. Two possible formation mechanisms of diktytaxitic textures accompanied by cristobalite have been proposed: melt segregation by gas-driven filter pressing (Peck 1978;Anderson et al 1984;Bacon 1986;Sanders 1986;Goff 1996;Sisson and Bacon 1999;Pistone et al 2015Pistone et al , 2020 and melt or glass corrosion by halogen-bearing vapor (De Hoog et al 2005;Horwell et al 2013;Schipper et al 2015Schipper et al , 2017Schipper et al , 2019Yoshimura and Nakagawa 2021). Gas filter pressing is generally attributed to secondary boiling associated with rapid crystallization during the intrusion of mafic magma into a felsic host rock or a mash-like magma chamber.…”

Section: Introductionmentioning

confidence: 99%

Vapor-phase crystallization from a hydrous silicate melt: an experimental simulation of diktytaxitic texture

Sakurai,

Nakamura,

Okumura

et al. 2024

Contrib Mineral Petrol

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Groundmass textures of volcanic rocks provide valuable insights into the processes of magma ascent, crystallization, and eruption. The diktytaxitic texture, characterized by a lath-shaped arrangement of feldspar microlites forming glass-free and angular pores, is commonly observed in silicic dome-forming rocks and Vulcanian ashfall deposits. This texture has the potential to control the explosivity of volcanic eruptions because its micropore network allows pervasive degassing during the final stages of magma ascent and eruption. However, the exact conditions and kinetics of the formation of diktytaxitic textures, which are often accompanied by vapor-phase cristobalite, remain largely unknown. Here, we show that the diktytaxitic texture and vapor-phase minerals, cristobalite and alkali feldspar, can be produced from bulk-andesitic magma with rhyolitic glass under water-saturated, near-solidus conditions (± ~10 MPa and ± ~20 °C within the solidus; 10–20 MPa and 850 °C for our starting pumices). Such crystallization proceeds through the partial evaporation of the supercooled melt, followed by the deposition of cristobalite and alkali feldspar as a result of the system selecting the fastest crystallization pathway with the lowest activation energy. The previously proposed mechanisms of halogen-induced corrosion or melt segregation by gas-driven filter pressing are not particularly necessary, although they may occur concurrently. Diktytaxitic groundmass formation is completed within 4–8 days, irrespective of the presence or composition of the halogen. These findings constrain the outgassing of lava domes and shallow magma intrusions and provide new insights into the final stages of hydrous magma crystallization on Earth.

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Gas filter-pressing origin for segregation vesicles in dykes

Cited by 29 publications

References 12 publications

Carboniferous dikes of West Connacht, Ireland

Carboniferous dikes of West Connacht, Ireland

Cretaceous magmatic evolution in the Deylaman igneous complex, Alborz zone, Iran: change from extensional to compressional regime

Vapor-phase crystallization from a hydrous silicate melt: an experimental simulation of diktytaxitic texture

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