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Early stages in the evolution of Izu–Bonin arc volcanism: new age, chemical, and isotopic constraints

Early stages in the evolution of Izu–Bonin arc volcanism: new age, chemical, and isotopic constraints
Early stages in the evolution of Izu–Bonin arc volcanism: new age, chemical, and isotopic constraints
A remarkable record of early arc volcanism in the Izu–Bonin–Mariana (IBM) arc is exposed in and around the Bonin Islands, an uplifted segment of the IBM forearc. New 40Ar/39Ar dating results imply that the boninitic volcanism on Chichijima Island occurred in a brief period during Eocene time, between 46–48 Ma. A slightly younger volcanic succession is identified along the Bonin Ridge, including 44.74 ± 0.23 Ma high-Mg andesite from the Mikazukiyama Formation, the youngest volcanic sequence on Chichijima, 44.0 ± 0.3 Ma tholeiitic to calcalkaline andesite from Hahajima Island, and 3 samples of andesite collected by the submersible SHINKAI 6500 from the Bonin Ridge Escarpment (BRE) that range in age from 41.84 ± 0.14 to 43.88 ± 0.21 Ma. Four SHINKAI 6500 dives (YK 04–05) on the BRE mapped an elongated constructional volcanic ridge atop the escarpment; we observed steeply west-dipping volcaniclastic debris flows shed from the summit of this ridge into the Ogasawara Trough to the west. These dives recovered fresh andesitic clasts from debris flows along the northern segment of the ridge, and high-Mg andesite lava blocks and Nummulitic limestone of middle Eocene age from the escarpment northwest of Chichijima. Our results also confirm previous inferences that melting of depleted mantle at shallow levels beneath the length of the arc with the aid of hydrous fluids from newly subducted slab to produce boninitic volcanism occurred nearly simultaneously along the entire length of the IBM arc system during the earliest stage of arc evolution. BRE–Mikazukiyama Formation–Hahajima andesites represent a transitional stage from forearc spreading (represented by ODP site 786-Chichijima boninites) and the stable, mature arc that developed in the Oligocene. These OPX-bearing high-Mg or tholeiitic to calcalkaline andesites were erupted along the BRE, as the arc magmatic axis localized and retreated from the trench.
Infant arc, Izu–Bonin–Mariana arc, 40Ar/39Ar dating, boninite, igneous geochemistry
0012-821X
385-401
Ishizuka, O.
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Kimura, J.
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Li, Y.B.
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Stern, R.J.
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Taylor, R.N.
094be7fd-ef61-4acd-a795-7daba2bc6183
Ohara, Y.
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Bloomer, S.H.
62bfb13c-74a8-4cd6-8348-67940c2b1442
Ishii, T.
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Hargrove, U.S.
044329b4-8585-4b51-98b6-506483ec504b
Haraguchi, Y.
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Ishizuka, O.
8fe117e5-b0da-41ef-83ec-9e0bd6658747
Kimura, J.
7a9b5097-2533-48de-8b80-b20452a41aac
Li, Y.B.
1e4406fc-dce0-456b-856b-f304fd895d07
Stern, R.J.
b34668ff-292e-4b31-8603-8cc040204510
Taylor, R.N.
094be7fd-ef61-4acd-a795-7daba2bc6183
Ohara, Y.
65b4e676-282b-4fc8-9cbf-a96620f76848
Bloomer, S.H.
62bfb13c-74a8-4cd6-8348-67940c2b1442
Ishii, T.
60ad9798-3eed-47bf-bb07-8b66ec461de0
Hargrove, U.S.
044329b4-8585-4b51-98b6-506483ec504b
Haraguchi, Y.
bfd2bb68-c345-46f1-a1bb-5c2b8e4b76a4

Ishizuka, O., Kimura, J., Li, Y.B., Stern, R.J., Taylor, R.N., Ohara, Y., Bloomer, S.H., Ishii, T., Hargrove, U.S. and Haraguchi, Y. (2006) Early stages in the evolution of Izu–Bonin arc volcanism: new age, chemical, and isotopic constraints. Earth and Planetary Science Letters, 250 (1-2), 385-401. (doi:10.1016/j.epsl.2006.08.007).

Record type: Article

Abstract

A remarkable record of early arc volcanism in the Izu–Bonin–Mariana (IBM) arc is exposed in and around the Bonin Islands, an uplifted segment of the IBM forearc. New 40Ar/39Ar dating results imply that the boninitic volcanism on Chichijima Island occurred in a brief period during Eocene time, between 46–48 Ma. A slightly younger volcanic succession is identified along the Bonin Ridge, including 44.74 ± 0.23 Ma high-Mg andesite from the Mikazukiyama Formation, the youngest volcanic sequence on Chichijima, 44.0 ± 0.3 Ma tholeiitic to calcalkaline andesite from Hahajima Island, and 3 samples of andesite collected by the submersible SHINKAI 6500 from the Bonin Ridge Escarpment (BRE) that range in age from 41.84 ± 0.14 to 43.88 ± 0.21 Ma. Four SHINKAI 6500 dives (YK 04–05) on the BRE mapped an elongated constructional volcanic ridge atop the escarpment; we observed steeply west-dipping volcaniclastic debris flows shed from the summit of this ridge into the Ogasawara Trough to the west. These dives recovered fresh andesitic clasts from debris flows along the northern segment of the ridge, and high-Mg andesite lava blocks and Nummulitic limestone of middle Eocene age from the escarpment northwest of Chichijima. Our results also confirm previous inferences that melting of depleted mantle at shallow levels beneath the length of the arc with the aid of hydrous fluids from newly subducted slab to produce boninitic volcanism occurred nearly simultaneously along the entire length of the IBM arc system during the earliest stage of arc evolution. BRE–Mikazukiyama Formation–Hahajima andesites represent a transitional stage from forearc spreading (represented by ODP site 786-Chichijima boninites) and the stable, mature arc that developed in the Oligocene. These OPX-bearing high-Mg or tholeiitic to calcalkaline andesites were erupted along the BRE, as the arc magmatic axis localized and retreated from the trench.

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More information

Published date: 2006
Keywords: Infant arc, Izu–Bonin–Mariana arc, 40Ar/39Ar dating, boninite, igneous geochemistry

Identifiers

Local EPrints ID: 42881
URI: http://eprints.soton.ac.uk/id/eprint/42881
ISSN: 0012-821X
PURE UUID: 0f4a541e-2982-46d3-bca3-ed952fbbd84c
ORCID for R.N. Taylor: ORCID iD orcid.org/0000-0002-9367-0294

Catalogue record

Date deposited: 13 Dec 2006
Last modified: 16 Mar 2024 02:51

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Contributors

Author: O. Ishizuka
Author: J. Kimura
Author: Y.B. Li
Author: R.J. Stern
Author: R.N. Taylor ORCID iD
Author: Y. Ohara
Author: S.H. Bloomer
Author: T. Ishii
Author: U.S. Hargrove
Author: Y. Haraguchi

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