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Magma flow within dykes in submarine hyaloclastite environments: an AMS study of the Miocene Cabo de Gata volcanic units

By
M. Porreca
M. Porreca
1
Istituto Nazionale di Geofisica e Vulcanologia (INGV), Via dell’Arcivescovado, 8-67100 L’Aquila, Italy
2
Departamento de Geociências, Centro de Vulcanologia e Avaliação de Riscos Geológicos (CVARG), Universidade dos Açores, 9500-801 Ponta Delgada, Portugal
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F. Cifelli
F. Cifelli
3
Dipartimento di Scienze Geologiche, Università Roma Tre, L.go S. Leonardo Murialdo, 1-00146 Roma, Italy
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C. Soriano
C. Soriano
4
Institut de Ciències de la Terra Jaume Almera (CSIC), Carrer de Lluis Solé Sabaris s/n, 08028 Barcelona, Spain
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G. Giordano
G. Giordano
3
Dipartimento di Scienze Geologiche, Università Roma Tre, L.go S. Leonardo Murialdo, 1-00146 Roma, Italy
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M. Mattei
M. Mattei
3
Dipartimento di Scienze Geologiche, Università Roma Tre, L.go S. Leonardo Murialdo, 1-00146 Roma, Italy
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Published:
January 01, 2015

Abstract

The Miocene Cabo de Gata volcanic arc in SE Spain comprises a wide variety of volcanic facies and eruptive styles in subaqueous to subaerial environments. In the SW sector of the area, 5–100 m-thick, NNW–SSE-orientated dykes feed and intrude submarine hyaloclastite deposits. We analysed the anisotropy of magnetic susceptibility (AMS) of six dykes and five hyaloclastite sites from three volcanic units: the Cerro Cañadillas, Los Frailes, and El Barronal formations. The main magnetic minerals are primary low-Ti titanomagnetite and magnetite. The AMS ellipsoids in the dykes are generally oblate-triaxial in shape, with magnetic foliations subparallel to the dyke walls. Kinematic field evidence supports the inferred flow directions deduced from magnetic lineation and imbrication of magnetic foliation. The geometric relationships between dyke margins and AMS axes indicate that dykes at El Barronal were emplaced via prevalent subvertical upward magma flow. The inferred flow directions are reproduced well by analogue models of AMS simulating magma migration in dykes with a diapiric geometry. The other dykes were emplaced by lateral magma propagation. Conversely, hyaloclastite shows a large scatter of the AMS axes reflecting different degrees of fragmentation. We observe a gradual increase in scatter in the AMS from confined dykes to fragmented hyaloclastite.

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Geological Society, London, Special Publications

The Use of Palaeomagnetism and Rock Magnetism to Understand Volcanic Processes

M. H. Ort
M. H. Ort
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M. Porreca
M. Porreca
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J. W. Geissman
J. W. Geissman
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Geological Society of London
Volume
396
ISBN electronic:
9781862396722
Publication date:
January 01, 2015

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