Flow dynamics in mid-Jurassic dikes and sills of the Ferrar large igneous province and implications for long-distance magma transport

Airoldi, Giulia; Muirhead, James D.; Long, S. M.; Zanella, Elena; White, James D. L.

doi:10.1016/j.tecto.2016.06.029

Cited by 29 publications

(9 citation statements)

References 104 publications

(145 reference statements)

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“…One important aspect of rhyolite volcanism within large flood basalt provinces is that rhyolite centers may provide better information than the basalts about the location of crustal basalt reservoirs that are implicated in the generation of these rhyolite magmas (Hildreth, 1981;Johnson, 1991). It is now recognized that flood basalt magmas can be transported and then erupt at significant distances from where they were stored in the crust or supplied from the mantle (Ernst et al, 1995;Ernst and Buchan, 1997;Hastie et al, 2014;Airoldi et al, 2016). In the case of the CRBG province, there must have been widespread crustal reservoirs during the most voluminous phase, the Grande Ronde Basalt, in which Grande Ronde magmas could have undergone evolution to their evolved basaltic andesitic composition (Wolff et al, 2008).…”

Section: Littlefield Rhyolite In Context Of Other Co-flood Basalt Rhymentioning

confidence: 99%

The Littlefield Rhyolite and associated mafic lavas: Bimodal volcanism of the Columbia River magmatic province, with constraints on age and storage sites of Grande Ronde Basalt magmas

et al. 2018

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We present data that distinguishes the long-known Littlefield Rhyolite of eastern Oregon (northwestern United States) into two distinct, voluminous, Snake River-type, high-temperature rhyolite lava packages that erupted in short sequence over <100 k.y., with minimum volumes of 100 and 150 km 3 respectively, contemporaneous with flood basalt volcanism of the Grande Ronde Basalt phase of the Columbia River Basalt Group. Contemporaneity of rhyolites with flood basalts is exceptionally demonstrated within the Malheur Gorge by intercalated mafic units belonging to the Grande Ronde Basalt that are stratigraphically constrained by underlying and overlying Littlefield Rhyolite flows, and the underlying Dinner Creek Tuff (unit 1). Our new ages of 16.11 Ma and 16.02 Ma for the lower and upper Littlefield Rhyolite, respectively, provide a narrow age constraint on the controversial lower age of Grande Ronde Basalt volcanism. Petrological data on local, intercalated Fe-rich andesitic (icelanditic) lavas provide further evidence for coeval existence of rhyolitic and mafic magmas, and additionally provide location evidence for storage sites of Grande Ronde Basalt magmas. Based on these data in addition to similar data on the nearby Dinner Creek Tuff rhyolite center, as well as the locations of other rhyolite centers that fall within the same period of intense rhyolite volcanism of ca. 16.1 Ma, we infer that Grande Ronde Basalt crustal magma reservoirs were widespread in this area of eastern Oregon. We further infer that the main eruptions of stored flood basalt magmas followed the magmas' lateral transport from these reservoirs to the well-known dike swarms located at the periphery of the rhyolite distribution area where local eruptions of rhyolites are notably absent. Our study highlights the interplay of mafic and crustally derived rhyolite magmas, with implications for other continental flood basalt provinces that are less well preserved than the Columbia River Basalt province.

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Section: Littlefield Rhyolite In Context Of Other Co-flood Basalt Rhymentioning

confidence: 99%

The Littlefield Rhyolite and associated mafic lavas: Bimodal volcanism of the Columbia River magmatic province, with constraints on age and storage sites of Grande Ronde Basalt magmas

et al. 2018

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“…These sheet intrusions are an important structure for the transport and storage of magma in the crust, helping to build large magma reservoirs at depth, and are a key contributor to crustal growth (see review by Putirka, 2017; and references therein). The importance of dykes as feeders of magma to the surface is well known (e.g., Geshi et al, 2010;Gudmundsson et al, 2014), with sills also providing pathways for magma to travel many kilometers from their source regions (e.g., Airoldi et al, 2016). Understanding magma intrusion dynamics that occurred in the past is therefore important for mitigating volcanic hazards in the future through monitoring of active volcanoes (e.g., Sparks and Cashman, 2017).…”

Section: Introductionmentioning

confidence: 99%

The Origin and Evolution of Magnetic Fabrics in Mafic Sills

et al. 2019

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Studying extinct volcanoes where erosion has exposed dykes and sills provides direct access to the fossil remnants of magma movement, however, linking crystallized magma to emplacement dynamics is challenging. This study investigates how magma flow varies across the thickness of a thin (6 m thick) mafic sill. We use a high-resolution sampling regime to measure micro-scale variations in magnetic anisotropy, which is associated with the orientation of the magnetic particles present within the crystalline rock. Fieldwork was conducted on exposed sills of the British and Irish Palaeogene Igneous Province, Isle of Skye, Scotland. Here Jurassic sedimentary rocks have been intruded by a series of sills, of picrite to crinanite composition, from the Little Minch Sill Complex (c.60 Ma). Anisotropy of magnetic susceptibility (AMS) and anisotropy of anhysteretic remanent magnetization (AARM) signals have been used to separate a crinanite sill into distinct magnetic groupings. We identified two AMS groups (the upper and lower sill margins, and the central region) and four AARM groups (the lower margin, the middle region, a region just below the upper margin, and the upper margin). Both AMS and AARM signals originate from titanomagnetite of multi-domain or vortex-state to single-domain sized grains, respectively. The AMS and AARM fabrics are aligned with each other in the margin regions preserving a history of magma flow toward the North during initial emplacement. However, in the sill interior the magnetic fabrics are oblique to each other, thus reflecting multiple origins. We suggest the AMS fabrics have recorded magma flow during sill growth, and AARM fabrics have recorded melt percolation flow as the interstitial melt migrated upward through a solidifying crystal mush. We demonstrate that when AMS and AARM are used in combination they enable a detailed understanding of magma flow and solidification dynamics to be obtained, from initial emplacement to solidification. Overall, our detailed sampling and analysis indicates that magnetic fabrics can be highly variable over small distances, supporting the suggestion of horizontal flow restriction and propagation path migration within growing sills, and that previous reports of magma flow and solidification dynamics based on under-sampled bodies may require reconsideration.

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“…Igneous sill complexes represent a significant volumetric contribution to upper crustal magma systems (e.g., Planke et al, 2005;Muirhead et al, 2011), and they can play an important role in basin development, petroleum system maturation, and greenhouse gas generation (e.g., Svensen et al, 2004). Although vertical igneous dikes are typically assumed as being the dominant subvolcanic supply route for effusive volcanism (e.g., Ebinger et al, 2008), recent studies have shown that sills can also act as an important regional transport network (e.g., Galland et al, 2007;Airoldi et al, 2011;Muirhead et al, 2011;Airoldi et al, 2016;Magee et al, 2016). Dikes are commonly inferred to represent magma--filled extension mode (mode I) cracks that accommodate crustal extension, with the dike plane forming parallel to the plane of minimum normal stress: the plane containing σ 1 --σ 2 (in this paper stresses are reckoned positive when compressive, with σ 1 ≥ σ 2 ≥ σ 3 ).…”

Section: Introductionmentioning

confidence: 99%

Igneous sills as a record of horizontal shortening: The San Rafael subvolcanic field, Utah

Walker

Healy

Kawanzaruwa

et al. 2017

Geological Society of America Bulletin

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Igneous sills can facilitate significant lateral magma transport in the crust, therefore it is important to constrain controls on their formation and propagation. Close spatial association between sills and dikes in layered (sedimentary) host rocks has led to a number of sill emplacement mechanisms that involve stress rotation related to layering; from horizontal extension and dike emplacement, to horizontal compression and sill emplacement. Here we use field observations in the San Rafael subvolcanic field (Utah, USA), on the Colorado Plateau, supported by mechanical modelling, to show that layering is not the dominant control in all cases of sill formation. We found no compelling evidence of large sills fed by dikes; all observed cases show that either dikes cut sills, or vice versa. Local sill contacts activate and follow host layer interfaces, but regionally, sills cut the stratigraphy at a low angle. The sills cut and are cut by reverse faults (1-3 m

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Flow dynamics in mid-Jurassic dikes and sills of the Ferrar large igneous province and implications for long-distance magma transport

Cited by 29 publications

References 104 publications

The Littlefield Rhyolite and associated mafic lavas: Bimodal volcanism of the Columbia River magmatic province, with constraints on age and storage sites of Grande Ronde Basalt magmas

The Littlefield Rhyolite and associated mafic lavas: Bimodal volcanism of the Columbia River magmatic province, with constraints on age and storage sites of Grande Ronde Basalt magmas

The Origin and Evolution of Magnetic Fabrics in Mafic Sills

Igneous sills as a record of horizontal shortening: The San Rafael subvolcanic field, Utah

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