New Age and Geochemical Data from the Southern Colville and Kermadec Ridges,SW Pacific: Insights into the recent geological history and petrogenesis of the Proto-Kermadec (Vitiaz) Arc |
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| Institution: | 1. GNS Science, PO Box 30-368, Lower Hutt, New Zealand;2. GEOMAR, Helmholtz Center for Ocean Research Kiel, Wischhofstrasse 1-3, 24148 Kiel, Germany;3. Institut für Geowissenschaften, Christian-Albrechts-Universität zu Kiel, Ludewig-Meyn-Strasse 10, 24118 Kiel, Germany;4. Department of Earth Sciences, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S5B6, Canada;5. National Institute of Water and Atmospheric Research, PO Box 14-901, Wellington, New Zealand;6. School of Geography, Environment and Earth Sciences, Victoria University of Wellington, PO Box 600, Wellington 6140, New Zealand;1. Urweltmuseum GEOSKOP/Burg Lichtenberg (Pfalz), Burgstrasse 19, 66871 Thallichtenberg, Germany;2. New Mexico Museum of Natural History and Science, 1801 Mountain Road N.W., Albuquerque, NM 87104, USA;1. Geology Department, Faculty of Science, Beni-Suef University, Beni-Suef 62521, Egypt;2. Geology Department, Faculty of Science, Helwan University, 11790 Cairo, Egypt;3. Geology Department, Faculty of Science, Cairo University, Giza 12613, Egypt;4. Economic Geology Research Unit (EGRU), Department of Earth and Oceans, James Cook University, Townsville, 4011, QLD, Australia;5. Department of Economic Geology and Petrology, Institute of Mineralogy, Technische University Bergakademie, Freiberg, Brennhausgasse 14, 09596 Freiberg/Sachsen, Germany;1. Chengdu Centre, China Geological Survey, Chengdu, Sichuan 610081, China;2. Key Laboratory of Tectonic Controls on Mineralisation and Hydrocarbon Accumulation of Ministry of Land and Resources, Chengdu University of Technology, Chengdu, Sichuan 610059, China;3. State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;4. MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, CAGS, Beijing 100037, China;5. Centre of Exploration Targeting, The University of Western Australia, 35 Stirling Highway, CRAWLEY, WA 6009, Australia;1. Departamento de Geología Regional, Instituto de Geología, Universidad Nacional Autónoma de México, 04510 México, DF, Mexico;2. National Taiwan Normal University, Department of Earth Sciences, 88 Tingzhou Road Section 4, Taipei 11677, Taiwan;3. Department of Geology, St. Mary''s University, Halifax, Nova Scotia, Canada B3H 3C3;4. Department of Energy, Halifax, Nova Scotia B3J 3J9, Canada;1. Department of Earth and Environmental Sciences, The Earth and Environmental Science System Research Center, Chonbuk National University, Jeonju 561–756, Republic of Korea;2. Geology Division, Korea Institute of Geoscience and Mineral Resources, Daejeon 34132, South Korea;3. Divisions of Earth and Environmental Sciences, Korea Basic Science Institute, Ochang 363–883, Republic of Korea |
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| Abstract: | The intra-oceanic Kermadec arc system extends ~1300 km between New Zealand and Fiji and comprises at least 30 arc front volcanoes, the Havre Trough back-arc and the remnant Colville and Kermadec Ridges. To date, most research has focussed on the Kermadec arc front volcanoes leaving the Colville and Kermadec Ridges virtually unexplored. Here, we present seven 40Ar/39Ar ages together with a comprehensive major and trace element and Sr-, Nd-, and Pb-isotope dataset from the Colville and Kermadec Ridges to better understand the evolution, petrogenesis and splitting of the former proto-Kermadec (Vitiaz) Arc to form these two remnant arc ridges. Our 40Ar/39Ar ages range from ~7.5–2.6 Ma, which suggests that arc volcanism at the Colville Ridge occurred continuously and longer than previously thought. Recovered Colville and Kermadec Ridge lavas range from mafic picro-basalts (MgO = ~8 wt%) to dacites. The lavas have arc-type normalised incompatible element patterns and Sr and Pb isotopic compositions intermediate between Pacific MORB and subducted lithosphere (including sediments, altered oceanic crust and serpentinised uppermost mantle). Geochemically diverse lavas, including ocean island basalt-like and potassic lavas with high Ce/Yb, Th/Zr, intermediate 206Pb/204Pb and low 143Nd/144Nd ratios were recovered from the Oligocene South Fiji Basin (and Eocene Three Kings Ridge) located west of the Colville Ridge. If largely trench-perpendicular mantle flow was operating during the Miocene, this geochemical heterogeneity was likely preserved in the Colville and Kermadec sub arc mantle. Between 4.41 ± 0.35 and 3.40 ± 0.24 Ma some Kermadec Ridge lavas record a shift from Colville Ridge- to Kermadec arc front-like, suggesting the proto-Kermadec (Vitiaz-) arc split post 4.41 ± 0.35 Ma. The Colville and Kermadec Ridge data therefore place new constraints on the regional tectonic evolution and highlight the complex interplay between pre-existing mantle heterogeneities and material fluxes from the subducting Pacific Plate. The new data allow us to present a holistic (yet simplified) picture of the tectonic evolution of the late Vitiaz Arc and northern Zealandia since the Miocene and how this tectonism influences volcanic activity along the Kermadec arc at the present. |
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