ORCID Profile
0000-0002-3165-3480
Current Organisation
GEOMAR Helmholtz-Zentrum für Ozeanforschung Kiel
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Publisher: Springer Science and Business Media LLC
Date: 09-02-2017
DOI: 10.1038/NCOMMS14322
Abstract: The Ontong Java and Manihiki oceanic plateaus are believed to have formed through high-degree melting of a mantle plume head. Boninite-like, low-Ti basement rocks at Manihiki, however, imply a more complex magma genesis compared with Ontong Java basement lavas that can be generated by ∼30% melting of a primitive mantle source. Here we show that the trace element and isotope compositions of low-Ti Manihiki rocks can best be explained by re-melting of an ultra-depleted source (possibly a common mantle component in the Ontong Java and Manihiki plume sources) re-enriched by ≤1% of an ocean-island-basalt-like melt component. Unlike boninites formed via hydrous flux melting of refractory mantle at subduction zones, these boninite-like intraplate rocks formed through adiabatic decompression melting of refractory plume material that has been metasomatized by ocean-island-basalt-like melts. Our results suggest that caution is required before assuming all Archaean boninites were formed in association with subduction processes.
Publisher: Proceedings of the National Academy of Sciences
Date: 19-11-2021
Abstract: We report the discovery of anomalously high 3 He/ 4 He in “cold” geothermal fluids of central Panama, far from any active volcanoes. Combined with independent constraints from lava geochemistry, mantle source geochemical anomalies in Central America require a Galápagos plume contribution that is not derived from hotspot track recycling. Instead, these signals likely originate from large-scale transport of Galápagos plume material at sublithospheric depths. Mantle flow modeling and geophysical observations further indicate these geochemical anomalies could result from a Galápagos plume-influenced asthenospheric “mantle wind” that is actively “blowing” through a slab window beneath central Panama. The lateral transport of plume material represents a potentially widespread yet underappreciated mechanism that scatters enriched geochemical signatures in mantle domains far from plumes.
Publisher: MDPI AG
Date: 03-03-2022
DOI: 10.3390/GEOSCIENCES12030118
Abstract: Lava s les from the Christmas Island Seamount Province (CHRISP) record an extreme range in enriched mantle (EM) type Sr-Nd-Pb-Hf isotope signatures. Here we report osmium isotope data obtained on four s les from the youngest, Pliocene petit-spot phase (Upper Volcanic Series, UVS ~4.4 Ma), and four s les from the earlier, Eocene (Lower Volcanic Series, LVS ~40 Ma) shield building phase of Christmas Island. Osmium concentrations are low (5–82 ppt) with initial Os isotopic values (187Os/188Osi) ranging from (0.1230–0.1679). Along with additional new geochemical data (major and trace elements, Sr-Nd-Pb isotopes, olivine δ18O values), we demonstrate the following: (1) The UVS is consistent with melting of shallow Indian mid-ocean ridge basalt (MORB) mantle enriched with both lower continental crust (LCC) and subcontinental lithospheric mantle (SCLM) components and (2) The LVS is consistent with recycling of SCLM components related to Gondwana break-up. The SCLM component has FOZO or HIMU like characteristics. One of the LVS s les has less radiogenic Os (γOs –3.4) and provides evidence for the presence of ancient SCLM in the source. The geochemistry of the Christmas Island lava series supports the idea that continental breakup causes shallow recycling of lithospheric and lower crustal components into the ambient MORB mantle.
Location: United States of America
Location: United States of America
Location: No location found
No related grants have been discovered for Kaj Hoernle.