Ultra-fast early Miocene exhumation of Cavalli Seamount, Northland Plateau, Southwest Pacific Ocean.

Mortimer, N., Dunlap, W. J., Palin, J. M., Herzer, R. H., Hauff, Folkmar and Clark, M. (2008) Ultra-fast early Miocene exhumation of Cavalli Seamount, Northland Plateau, Southwest Pacific Ocean. New Zealand Journal of Geology and Geophysics, 51 (1). pp. 29-42. DOI 10.1080/00288300809509848.

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We present new photographic, petrological, geochronological, and isotopic data for gneissic and granitic rocks obtained from six sample stations on Cavalli Seamount during two cruises in 2002. These data lead to revision of earlier conclusions based on two dredges of schist in 1999. Based on c. 100 Ma ages of zircon cores, and whole rock petrochemistry and tracer isotopes, we interpret the protoliths of paragneisses and orthogneisses to probably have been sedimentary and plutonic correlatives of the Late Cretaceous Houhora Complex. U‐Pb dating of low Th/U zircon rims confirms an earliest Miocene high‐grade metamorphic episode. A cooling history based on Ar‐Ar K‐feldspar dating indicates ultra‐rapid cooling (c. 2000°C/m.y.) and vertical exhumation (c. 100 mm/yr) of the rocks at 19.9 Ma. Our preferred tectonic model relates the amphibolite facies metamorphism to Northland Allochthon emplacement and the rapid exhumation to dextral transtension along the Vening Meinesz Fracture Zone system and/or a rapidly retreating Pacific trench.

Document Type: Article
Keywords: New Zealand, Southwest Pacific Ocean, Northland Plateau, Vening Meinesz Fracture Zone, Northland Allochthon, tectonics, exhumation, strike‐slip faulting, geo‐chronology, Miocene
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS Magmatic and Hydrothermal Systems
OceanRep > The Future Ocean - Cluster of Excellence
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1080/00288300809509848
ISSN: 0028-8306
Projects: Future Ocean
Date Deposited: 15 Dec 2008 10:01
Last Modified: 05 Dec 2016 11:17
URI: http://oceanrep.geomar.de/id/eprint/1966

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