Detrital zircon resolve longevity and evolution of silicic magmatism in extinct volcanic centers: A case study from the East Fjords of Iceland - CNRS - Centre national de la recherche scientifique Accéder directement au contenu
Article Dans Une Revue Geosphere Année : 2017

Detrital zircon resolve longevity and evolution of silicic magmatism in extinct volcanic centers: A case study from the East Fjords of Iceland

T.L. Carley
  • Fonction : Auteur
C.F. Miller
  • Fonction : Auteur
O. Sigmarsson
M.A. Coble
  • Fonction : Auteur
C.M. Fisher
  • Fonction : Auteur
J.M. Hanchar
  • Fonction : Auteur
A.K. Schmitt
  • Fonction : Auteur
R.C. Economos
  • Fonction : Auteur

Résumé

Breiðuvík and Kækjuskörð are two neighboring extinct eruptive centers in the East Fjords of Iceland. Together, they compose the second-largest volume of silicic rock in the country (after Torfajökull, an active volcanic system in southern Iceland). We use ages and compositions of detrital zircon collected from two riv- ers, the Stóraá and Krossá-Kækjudalsá, to investigate the origins and longevity of silicic magmatism at Breiðuvík-Kækjuskörð. Zircon populations from the two catchments have identical median U-Pb dates (12.9 Ma), O isotopes (d 18 O Vienna standard mean ocean water = 3.1‰ versus 3.3‰), and Hf isotopes ( İ Hf = 14.7). We interpret coherence of zircon elemental and isotopic compositions to indicate that a signifi cant volume of relatively uniform silicic material was produced in close temporal and spatial proximity between 11.2 ± 0.7 Ma and 15.0 ± 0.9 Ma (all errors are 1 ı ), dominated by assimilation–fractional crystallization processes. To test the robustness of this longevity estimate, we applied Monte Carlo modeling to the Breiðuvík-Kækjuskörð detrital zircon results and found the age span to be statistically resolvable at ³2.8 m.y. While this lifespan is comparable to those of large mafi c-silicic volcanic systems that have described in other settings glob- ally, it is the longest reported estimate for any Icelandic volcano, where typical longevity is thought to be ~0.5–1.5 m.y. The ³2.8 m.y. lifespan we present for Breiðuvík-Kækjuskörð is a conservative assessment, because the dates used in this study only represent the zircon-saturated period of magmatic activity. This study demonstrates that detrital zircon analysis of volcanigenic sediment pro- vides an effi cient and powerful tool that can illuminate histories of zircon-satu- rated magmatism at targeted volcanic centers and systems. This approach can be particularly valuable in dominantly mafi c provinces where silicic material is subordinate (e.g., ocean islands, fl ood basalt provinces), where glaciation, ero- sion, or alteration has transformed the landscape, or in areas that are inaccessi- ble (e.g., obscured by glacial ice)

Domaines

Volcanologie

Dates et versions

hal-01713319 , version 1 (20-02-2018)

Identifiants

Citer

T.L. Carley, C.F. Miller, O. Sigmarsson, M.A. Coble, C.M. Fisher, et al.. Detrital zircon resolve longevity and evolution of silicic magmatism in extinct volcanic centers: A case study from the East Fjords of Iceland. Geosphere, 2017, 13 (5), pp.1640 - 1663. ⟨10.1130/GES01467.1⟩. ⟨hal-01713319⟩
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