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| Titel |
Magmatism and crustal deformation during subduction and tearing of a ridge-transform system |
| VerfasserIn |
Ryo Anma, Yuji Orihashi, Eugenio Veloso, Kicheol Shin |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250038443
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| Zusammenfassung |
| Chile ridge subducts underneath South American plate at latitude 46S, forming a ridge-trench-trench type triple junction that migrated to the north along the Pacific coast. At ~6 Ma, a short segment of the Chile ridge system collided and subducted in the south of the present triple junction. This ridge subduction event resulted in emplacement of the Taitao ophiolite (5. 7 to 5. 2 Ma) and contemporaneous granite intrusions (5.7 to 4.9 Ma) and rapid crustal uplift (partly emerged after 4.9 Ma) in the trench-side, and adakitic volcanisms (dating in progress), subsidence and > 1 km thick basin-fill sedimentation behind the ophiolite. Recent acoustic survey by JAMSTEC R/V Mirai revealed that a graben is still developing in this area. Gabbro and ultramafic sections were folded due to high-T deformation. Gabbro structures restored using paleomagnetic data indicate that it was eastern part of the ridge center that was obducted. Presence of ~ 5 Ma mafic and dacitic volcanism along the eastern margin of the ophiolite (Chile Margin Unit) with higher Sr isotopic ratios suggests perhaps that a transform fault subducted prior to the ridge segments started opening as the subducted ridge torn away by slab-pull. |
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