Radial dikes of Lyttelton Volcano — their structure, form, and petrography

Shelley, David

doi:10.1080/00288306.1988.10417810

Cited by 14 publications

(6 citation statements)

References 12 publications

(13 reference statements)

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“…Circumferential orientations of σ 3 can be caused by a source of pressure at the swarm centre (e.g., a magma chamber) or by a radially decreasing topographic load (as is typically imposed by a volcanic edifice), although topographic stresses tend to dominate at shallow depths 23 . Similar radial dyke swarms have been reported from Mt Somma/Vesuvio (Italy) 24 , Summer Coon (USA) 25 , Oki-Dozen (Japan) 26 and Lyttleton (New Zealand) 27 .…”

Section: Scientific Reportssupporting

confidence: 82%

Dyke apertures record stress accumulation during sustained volcanism

Thiele

Cruden

Micklethwaite

et al. 2020

Sci Rep

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The feedback between dyke and sill intrusions and the evolution of stresses within volcanic systems is poorly understood, despite its importance for magma transport and volcano instability. Long-lived ocean island volcanoes are crosscut by thousands of dykes, which must be accommodated through a combination of flank slip and visco-elastic deformation. Flank slip is dominant in some volcanoes (e.g., Kilauea), but how intrusions are accommodated in other volcanic systems remains unknown. Here we apply digital mapping techniques to collect > 400,000 orientation and aperture measurements from 519 sheet intrusions within Volcán Taburiente (La Palma, Canary Islands, Spain) and investigate their emplacement and accommodation. We show that vertically ascending dykes were deflected to propagate laterally as they approached the surface of the volcano, forming a radial dyke swarm, and propose a visco-elastic model for their accommodation. Our model reproduces the measured dyke-aperture distribution and predicts that stress accumulates within densely intruded regions of the volcano, blocking subsequent dykes and causing eruptive activity to migrate. These results have significant implications for the organisation of magma transport within volcanic edifices, and the evolution and stability of long-lived volcanic systems.

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Section: Scientific Reportssupporting

confidence: 82%

Dyke apertures record stress accumulation during sustained volcanism

Thiele

Cruden

Micklethwaite

et al. 2020

Sci Rep

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“…This concept of two centres being active is supported by the trends of lava flows in these regions, towards an earlier and later eruptive vent. Shelley (1988) noted that the dykes of Lyttelton Volcano have a blade shape form; a similar form has been acknowledged by Rubin and Pollard (1987), Dieterich (1988), Ryan (1988), Parfitt (1991), and Delaney et al (1993). Blade shape dykes are acknowledged as representing upper level (2-4 km) basaltic dykes, laterally injected as blade-like intrusions from shallow magma reservoirs beneath the summit.…”

Section: Intrusionsmentioning

confidence: 86%

“…Dykes of Lyttelton Volcano are predominantly basaltic in composition, 1-2m in width, with a blade-like form (Shelley, 1988). Large dykes (N 5m wide) of trachytic composition are exposed along the erosional crater rim of Lyttelton Volcano and have a close affinity with blocky lava flows.…”

Section: Hypabyssal Volcanic Featuresmentioning

confidence: 99%

Lyttelton Volcano, Banks Peninsula, New Zealand: Primary volcanic landforms and eruptive centre identification

Hampton

Cole

2009

Geomorphology

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“…The geometry of dykes is often treated as part of a regional geological, a structural, or a more petrologically oriented account (e.g. PARK & CRESS-WELL, 1973;ESCHER et al, 1976;HAGESKOV, 1985;WALKER, 1987;ROGERS & BIRD, 1987;SHELLEY, 1988;RYAN, 1988;HUANG, 1988;FOLEY, 1989). Other papers present theoretical mechanical models based upon specific dyke geometries (e.g.…”

Section: Relation To Other Workmentioning

confidence: 97%

A classification of dyke-fracture geometry with examples from Precambrian dyke swarms in the Vestfold Hills, Antarctica

Hoek

1991

Geol Rundsch

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ZusammenfassungEine Klassifizierung der Geometrie von Dilatationsbrtichen wird vorgeschlagen. Sie wird angewendet auf Strukturen die charakterisiert werden k6nnen als die Kombination eines Bruchsystems und eines Dilatationsvektorfeldes. Die Klassifizierung wird illustriert dutch Beispiele von magmatischen Gfingen, Pegmatitien und Pseudotachyliten. Segmentierung in Form yon Vers~itzen, StoBfugen oder Gabelungen sind hfiufig in vielen Bruchsystemen. Vier Grundtypen von Dilatationsbruchsystemen k6nnen an Hand der Segmentierungsgeometile unterschieden werden, diese sind: Unregelm~i-gige -, verzweigte -, kulissenf6rmige -und zickzack Typen. Die Zickzack-Bruchsysteme werden weiter untergliedert. Sie bestehen aus neu gebildeten sich schief ausdehenden Brtichen, oder aber aus bereits bestehenden Flfichen des Muttergesteins, welche yon der schiefen Erweiterung reaktiviert wurden. Dies ist die erste Ver6ffentlichung, die von magmatischen Zickzack-Gfingen berichtet, die neu geformte Brtiche entwickeln.Die AbstractA classification of dilational fracture geometry is proposed. It applies to structures that can be characterized by the combination of a fracture system and a dilation vector field. The classification is illustrated with examples of igneous dykes, pegmatites, and pseudotachylites. Segmentation in the form of offsets, jogs, or bifurcations is common to most fracture systems. Four basic types of dilational fracture systems are distinguished on the basis of the geometry of segmentation. These are: irregular, braided, en-echelon, and zigzag. Zigzag fracture systems are further differentiated. They consist of newly formed, obliquely dilated fractures or, alternatively, of pre-existing planes in the host-rock that are reactivated by oblique dilation. This paper is the first to actually report an igneous zigzag-dyke involving newly formed fractures.Rotation of the regional stress field in the direction of propagation leads to en-echelon segmentation. Braided fracture systems reflect high local stress-intensities, probably related to propagation rate. Two possibilities exist for the formation of zigzag dykes consisting of newly formed fractures that are obliquely dilated. They may form by extreme interaction of tensile fracture segments in a regional stress field with a low differential stress. Alternatively, they may form in a regional stress field with high differential stress through the propagation of shear fractures.Segmentation of dykes, characterized by offsets, is common. Such segmentation can be the result of protrusions of the fracture termination. Offsets also occur where a dyke cuts an older planar structure. Such offsets are the result of the local inhibition of fracture propagation. The resulting apparent offset can lead to a misinterpretation of relative age.Apophyses form as a result of the dilation of a segmented fracture system. R6sum6Cette note propose une classification des fractures de dilatation, basge sur leur g6om6trie. Elle s'applique aux structures que l'on peut caractdriser par la combinaison d'...

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Radial dikes of Lyttelton Volcano — their structure, form, and petrography

Cited by 14 publications

References 12 publications

Dyke apertures record stress accumulation during sustained volcanism

Dyke apertures record stress accumulation during sustained volcanism

Lyttelton Volcano, Banks Peninsula, New Zealand: Primary volcanic landforms and eruptive centre identification

A classification of dyke-fracture geometry with examples from Precambrian dyke swarms in the Vestfold Hills, Antarctica

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