Journal article
Forearc ages reveal extensive short-lived and rapid seafloor spreading following subduction initiation
Earth and Planetary Science Letters, Vol.506, pp.520-529
01/15/2019
DOI: 10.1016/j.epsl.2018.11.020
Abstract
The Izu–Bonin–Mariana (IBM) forearc contains a record of a widespread and short-lived subduction initiation event in the early Eocene. We present new high-precision ages to determine the rates and length scales of ocean crust production following subduction initiation along the IBM convergent margin. We also explore the implications of these ages for potential causes of subduction initiation and its far-field effects. Zircons extracted from gabbros collected by Shinkai 6500 diving within the ophiolitic sequence exposed in the outer Bonin and Mariana forearcs give crystallization ages (±2σ) of 51.94 ± 0.13 Ma and 51.81 ± 0.03 Ma, respectively, consistent with a near-synchronous seafloor spreading after initiation of subduction along the entire length of the IBM system. 40Ar/39Ar ages of forearc basalts (51.34 ± 0.78 Ma) and boninites (51.27 ± 0.09 Ma to 50.33 ± 0.55 Ma) cored upslope of the Bonin sample gabbro during IODP Expedition 352 further reveal that the outer forearc comprises oceanic lithosphere with MORB to boninite compositions created by seafloor spreading during a remarkably short time period of 0.6–2 Myr at a full-rate of c. 70 mm/yr. This time period is consistent with those of some well-dated ophiolites. Thus, near-trench seafloor spreading to form basalt then boninite lithosphere is an extensive, rapid, but short-lived process after subduction initiation. •Subduction initiation was nearly simultaneous at 51.8–51.9 Ma in the Bonin and Mariana arcs.•Subduction initiation in the western Pacific was part of a regional reconfiguration of plate motions.•The change from decompression melting to flux melting after subduction began took <1.2 Myr.•Near trench sea-floor spreading ceased within ∼2 Myr of subduction initiation.
Details
- Title: Subtitle
- Forearc ages reveal extensive short-lived and rapid seafloor spreading following subduction initiation
- Creators
- Mark K Reagan - Department of Earth and Environmental Science, University of Iowa, Iowa City, IA, USADaniel E Heaton - CEOAS, Oregon State University, Corvallis, OR, USAMark D Schmitz - Department of Geosciences, Boise State University, Boise, ID, USAJulian A Pearce - School of Earth and Ocean Sciences, Cardiff University, Cardiff, United KingdomJohn W Shervais - Department of Geology, Utah State University, Logan, UT, USAAnthony A.P Koppers - CEOAS, Oregon State University, Corvallis, OR, USA
- Resource Type
- Journal article
- Publication Details
- Earth and Planetary Science Letters, Vol.506, pp.520-529
- Publisher
- Elsevier B.V
- DOI
- 10.1016/j.epsl.2018.11.020
- ISSN
- 0012-821X
- eISSN
- 1385-013X
- Grant note
- DOI: 10.13039/100000001, name: National Science Foundation, award: EAR-0521221, EAR-0824974, EAR-1337887; DOI: 10.13039/501100000270, name: Natural Environment Research Council, award: NE/M012034/1; DOI: 10.13039/100012018, name: US Science Support Program; DOI: 10.13039/100000001, name: National Science Foundation, award: OCE1558647, OCE1558689
- Language
- English
- Date published
- 01/15/2019
- Academic Unit
- Earth and Environmental Sciences
- Record Identifier
- 9983983664302771
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