Zircon Dates Long-Lived Plume Dynamics in Oceanic Islands
Metadatos
Mostrar el registro completo del ítemEditorial
American Geophysical Union
Fecha
2022-10-10Referencia bibliográfica
Rojas-Agramonte, Y... [et al.] (2022). Zircon dates long-lived plume dynamics in oceanic islands. Geochemistry, Geophysics, Geosystems, 23, e2022GC010485. [https://doi.org/10.1029/2022GC010485]
Patrocinador
German Research Foundation (DFG) RO4174/3-1 RO4174/3-3; Ministry of Science and Innovation, Spain (MICINN); Spanish Government; European Commission PID2019-105625RB-C21 PY20_00550; European Research Council (ERC) European Commission MAGMA 771143Resumen
In this contribution we report the first systematic study of zircon U-Pb geochronology and
δ 18O-εHf(t) isotope geochemistry from 10 islands of the hot-spot related Galapagos Archipelago. The data
extracted from the zircons allow them to be grouped into three types: (a) young zircons (0–∼4 Ma) with εHf(t)
(∼5–13) and δ 18O (∼4–7) isotopic mantle signature with crystallization ages dating the islands, (b) zircons
with εHf(t) (∼5–13) and δ 18O (∼5–7) isotopic mantle signature (∼4–164 Ma) which are interpreted to date
the time of plume activity below the islands (∼164 Ma is the minimum time of impingement of the plume
below the lithosphere), and (c) very old zircons (∼213–3,000 Ma) with mostly continental (but also juvenile)
εHf(t) (∼−28–8) and δ 18O (∼5–11) isotopic values documenting potential contamination from a number of
sources. The first two types with similar isotopic mantle signature define what we call the Galápagos Plume
Array (GPA). Given lithospheric plate motion, this result implies that GPA zircon predating the Galápagos
lithosphere (i.e., >14–164 Ma) formed and were stored at sublithospheric depths for extended periods of time.
In order to explain these observations, we performed 2D and 3D thermo-mechanical numerical experiments of
plume-lithosphere interaction which show that dynamic plume activity gives rise to complex asthenospheric
flow patterns and results in distinct long-lasting mantle domains beneath a moving lithosphere. This
demonstrates that it is physically plausible that old plume-derived zircons survive at asthenospheric depths
below ocean islands.