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Origin of the sheeted dike complex at superfast spread East Pacific Rise revealed by deep ocean crust drilling at Ocean Drilling Program Hole 1256D

Origin of the sheeted dike complex at superfast spread East Pacific Rise revealed by deep ocean crust drilling at Ocean Drilling Program Hole 1256D
Origin of the sheeted dike complex at superfast spread East Pacific Rise revealed by deep ocean crust drilling at Ocean Drilling Program Hole 1256D
Superfast spread (22 cm/a) upper oceanic crust drilled at Ocean Drilling Program site 1256 comprises a thick sequence of extrusive lavas underlain by a thin region of sheeted dikes. The sheeted dikes at this site are characterized by the intimate association of in situ hyaloclastic fragmentation and hydrothermal alteration. Lithostatic and magmastatic pressure estimates reveal that there is no effective level of neutral buoyancy within the extrusive layer to trap dikes in the crust. This results in a situation that favors the extrusion rather than intrusion of magma. Fractures created by magmas rising in dikes were the loci of intense hydrothermal circulation and provided the pathways for subsequent dike intrusions. Magma-rich conditions expected for fast spreading ridge segments give rise to a rapid increase in magmatic pressure, which can result in dike intrusion even under only small deviatoric stress. This allows for the emplacement of narrow dikes in the upper crust, with magmas more likely to extrude, and hence the high extrusive/intrusive ratio for Site 1256.

1525-2027
Q06O08
Umino, Susumu
77a13980-3cc3-4f28-8136-93ab60abe2fc
Crispini, Laura
8ca02e47-290b-4991-88bf-7a4517f93e13
Tartarotti, Paola
7b14ab6a-465b-4572-9990-23edacb4e308
Teagle, Damon A. H.
396539c5-acbe-4dfa-bb9b-94af878fe286
Alt, Jeffery C.
1c917280-3d47-48f8-8eb6-9e5512402776
Miyashita, Sumio
f8db6bbd-225f-4c30-bb48-33399504664b
Banerjee, Neil R.
5d39afaa-a973-40f5-9aa1-91d68e50745a
Umino, Susumu
77a13980-3cc3-4f28-8136-93ab60abe2fc
Crispini, Laura
8ca02e47-290b-4991-88bf-7a4517f93e13
Tartarotti, Paola
7b14ab6a-465b-4572-9990-23edacb4e308
Teagle, Damon A. H.
396539c5-acbe-4dfa-bb9b-94af878fe286
Alt, Jeffery C.
1c917280-3d47-48f8-8eb6-9e5512402776
Miyashita, Sumio
f8db6bbd-225f-4c30-bb48-33399504664b
Banerjee, Neil R.
5d39afaa-a973-40f5-9aa1-91d68e50745a

Umino, Susumu, Crispini, Laura, Tartarotti, Paola, Teagle, Damon A. H., Alt, Jeffery C., Miyashita, Sumio and Banerjee, Neil R. (2008) Origin of the sheeted dike complex at superfast spread East Pacific Rise revealed by deep ocean crust drilling at Ocean Drilling Program Hole 1256D. Geochemistry, Geophysics, Geosystems, 9, Q06O08. (doi:10.1029/2007GC001760).

Record type: Article

Abstract

Superfast spread (22 cm/a) upper oceanic crust drilled at Ocean Drilling Program site 1256 comprises a thick sequence of extrusive lavas underlain by a thin region of sheeted dikes. The sheeted dikes at this site are characterized by the intimate association of in situ hyaloclastic fragmentation and hydrothermal alteration. Lithostatic and magmastatic pressure estimates reveal that there is no effective level of neutral buoyancy within the extrusive layer to trap dikes in the crust. This results in a situation that favors the extrusion rather than intrusion of magma. Fractures created by magmas rising in dikes were the loci of intense hydrothermal circulation and provided the pathways for subsequent dike intrusions. Magma-rich conditions expected for fast spreading ridge segments give rise to a rapid increase in magmatic pressure, which can result in dike intrusion even under only small deviatoric stress. This allows for the emplacement of narrow dikes in the upper crust, with magmas more likely to extrude, and hence the high extrusive/intrusive ratio for Site 1256.

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Published date: 14 June 2008

Identifiers

Local EPrints ID: 63995
URI: http://eprints.soton.ac.uk/id/eprint/63995
ISSN: 1525-2027
PURE UUID: e31d7966-0e67-4a79-bce3-89cb4f7a30ff
ORCID for Damon A. H. Teagle: ORCID iD orcid.org/0000-0002-4416-8409

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Date deposited: 21 Nov 2008
Last modified: 16 Mar 2024 03:14

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Contributors

Author: Susumu Umino
Author: Laura Crispini
Author: Paola Tartarotti
Author: Jeffery C. Alt
Author: Sumio Miyashita
Author: Neil R. Banerjee

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