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Emplacement of the Cabezo Maria lamproite volcano (Miocene, SE Spain)

Emplacement of the Cabezo Maria lamproite volcano (Miocene, SE Spain)
Emplacement of the Cabezo Maria lamproite volcano (Miocene, SE Spain)
Lamproite volcanoes are uncommon in the geological record but are exceptionally well preserved in the Betic Cordilleras of SE Spain, where they erupted during the Late Miocene (Tortonian to Messinian stages). The parent melts are thought to have been channelled through major lithospheric faults to erupt at or near the faulted margins of Neogene sedimentary basins. Lamproite magmas are thought to be relatively CO2-poor (<1 wt %) and are typically characterised by an effusive eruption style and the development of lava lakes and scoria cones. Cabezo María is a relatively small (∼550 m diameter) lamproite volcano that was emplaced within the shallow-water marine-influenced Vera Basin. The lamproites are compositionally similar to those of the Roman Province and generally less potassic (K2O<5 wt%) than other (ultra-) potassic rocks in SE Spain (e.g. Cancarix, Fortuna). The initial eruption stages were dominated by explosive magma-water interactions and the formation of peperites. These are characterised by angular fragments of glassy lamproite lavas (and isolated lobes) incorporated in sediments, locally showing the effects of thermal metamorphism. Further, elutriation pipes and ‘jigsaw-fit’ textures are observed in the peperites. The lavas and peperites are overlain by outward-dipping well-stratified scoria deposits defining part of a cinder cone, which is inferred to have emerged above sea level. Steep internal contacts with inward-dipping, structureless breccias likely represent the inner wall deposits of a central conduit. The deposits are cross-cut by late-stage dykes, which supplied fissure eruptions of geochemically similar lavas capping the scoria cone. The transition from explosive to effusive behaviour may reflect the decreased availability of water, possibly due to downward migration of the feeder conduit below the level of water-saturated sediments.
0258-8900
Gernon, Thomas
658041a0-fdd1-4516-85f4-98895a39235e
Sam, Spence
e68aff7c-801c-4118-859b-4601623b48b8
Trueman, Clive
d00d3bd6-a47b-4d47-89ae-841c3d506205
Taylor, Rex
094be7fd-ef61-4acd-a795-7daba2bc6183
Rohling, Eelco
a2a27ef2-fcce-4c71-907b-e692b5ecc685
Hatter, Stuart, James
b43a8c1b-8ae3-4764-8238-3dc597aa0d71
Harding, Ian
5d63b829-a9a7-447f-aa3f-62e8d0e715cb
Gernon, Thomas
658041a0-fdd1-4516-85f4-98895a39235e
Sam, Spence
e68aff7c-801c-4118-859b-4601623b48b8
Trueman, Clive
d00d3bd6-a47b-4d47-89ae-841c3d506205
Taylor, Rex
094be7fd-ef61-4acd-a795-7daba2bc6183
Rohling, Eelco
a2a27ef2-fcce-4c71-907b-e692b5ecc685
Hatter, Stuart, James
b43a8c1b-8ae3-4764-8238-3dc597aa0d71
Harding, Ian
5d63b829-a9a7-447f-aa3f-62e8d0e715cb

Gernon, Thomas, Sam, Spence, Trueman, Clive, Taylor, Rex, Rohling, Eelco, Hatter, Stuart, James and Harding, Ian (2015) Emplacement of the Cabezo Maria lamproite volcano (Miocene, SE Spain). Bulletin of Volcanology, 77 (6), [52]. (doi:10.1007/s00445-015-0934-y).

Record type: Article

Abstract

Lamproite volcanoes are uncommon in the geological record but are exceptionally well preserved in the Betic Cordilleras of SE Spain, where they erupted during the Late Miocene (Tortonian to Messinian stages). The parent melts are thought to have been channelled through major lithospheric faults to erupt at or near the faulted margins of Neogene sedimentary basins. Lamproite magmas are thought to be relatively CO2-poor (<1 wt %) and are typically characterised by an effusive eruption style and the development of lava lakes and scoria cones. Cabezo María is a relatively small (∼550 m diameter) lamproite volcano that was emplaced within the shallow-water marine-influenced Vera Basin. The lamproites are compositionally similar to those of the Roman Province and generally less potassic (K2O<5 wt%) than other (ultra-) potassic rocks in SE Spain (e.g. Cancarix, Fortuna). The initial eruption stages were dominated by explosive magma-water interactions and the formation of peperites. These are characterised by angular fragments of glassy lamproite lavas (and isolated lobes) incorporated in sediments, locally showing the effects of thermal metamorphism. Further, elutriation pipes and ‘jigsaw-fit’ textures are observed in the peperites. The lavas and peperites are overlain by outward-dipping well-stratified scoria deposits defining part of a cinder cone, which is inferred to have emerged above sea level. Steep internal contacts with inward-dipping, structureless breccias likely represent the inner wall deposits of a central conduit. The deposits are cross-cut by late-stage dykes, which supplied fissure eruptions of geochemically similar lavas capping the scoria cone. The transition from explosive to effusive behaviour may reflect the decreased availability of water, possibly due to downward migration of the feeder conduit below the level of water-saturated sediments.

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More information

Published date: June 2015
Organisations: Ocean and Earth Science, Geochemistry, Geology & Geophysics, Paleooceanography & Palaeoclimate

Identifiers

Local EPrints ID: 406252
URI: http://eprints.soton.ac.uk/id/eprint/406252
ISSN: 0258-8900
PURE UUID: 97ffc556-ff9c-43d2-bc04-c20f7127d252
ORCID for Eelco Rohling: ORCID iD orcid.org/0000-0001-5349-2158
ORCID for Stuart, James Hatter: ORCID iD orcid.org/0000-0003-0760-5275
ORCID for Ian Harding: ORCID iD orcid.org/0000-0003-4281-0581

Catalogue record

Date deposited: 10 Mar 2017 10:43
Last modified: 20 Jul 2019 01:25

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