New age and geochemical data from the Walvis Ridge: The temporal and spatial diversity of South Atlantic intraplate volcanism and its possible origin.

Homrighausen, Stephan, Hoernle, Kaj , Hauff, Folkmar , Wartho, Jo-Anne , van den Bogaard, Paul and Garbe-Schönberg, Dieter (2019) New age and geochemical data from the Walvis Ridge: The temporal and spatial diversity of South Atlantic intraplate volcanism and its possible origin. Open Access Geochimica et Cosmochimica Acta, 245 . pp. 16-34. DOI 10.1016/j.gca.2018.09.002.

[thumbnail of Accepted manuscript]
Preview
Text (Accepted manuscript)
10.1016_j.gca.2018.09.002.pdf - Accepted Version

Download (12MB) | Preview
[thumbnail of Homrighausen et al GCA_2019_Print.pdf] Text
Homrighausen et al GCA_2019_Print.pdf - Published Version
Restricted to Registered users only

Download (2MB) | Contact
[thumbnail of AppendixA_Homrighausen et al GCA_2019.docx] Text
AppendixA_Homrighausen et al GCA_2019.docx - Supplemental Material
Restricted to Registered users only

Download (718kB) | Contact
[thumbnail of Excel File] Other (Excel File)
AppendixB_Homrighausen et al GCA_2019.xlsx - Supplemental Material
Restricted to Registered users only

Download (82kB) | Contact
[thumbnail of Excel File] Other (Excel File)
AppendixC_Homrighausen et al GCA_2019.xlsx - Supplemental Material
Restricted to Registered users only

Download (1MB) | Contact
[thumbnail of Excel File] Other (Excel File)
AppendixD_Homrighausen et al GCA_2019.xlsx - Supplemental Material
Restricted to Registered users only

Download (27kB) | Contact
[thumbnail of Excel File] Other (Excel File)
AppendixE_Homrighausen et al GCA_2019.xlsx - Supplemental Material
Restricted to Registered users only

Download (30kB) | Contact
[thumbnail of Excel File] Other (Excel File)
AppendixF_Homrighausen et al GCA_2019.xlsx - Supplemental Material
Restricted to Registered users only

Download (12kB) | Contact

Supplementary data:

Abstract

Highlights

• New 40Ar/39Ar age and geochemical (major, trace element, Sr-Nd-Pb-Hf isotope) data are presented from the Walvis Ridge, belonging to the Tristan-Gough hotspot track in the South Atlantic.
• The entire Tristan-Gough hotspot system, including Walvis Ridge, display a spatially continuous age progression.
• The Gough-type component is the dominant geochemical flavor of the Tristan-Gough plume and has also been identified in the Discovery and Shona hotspot systems.
• The geochemical heterogeneity in the South Atlantic DUPAL region can be reproduced by mixing of Gough-type enriched mantle with continental crust and a FOZO/PREMA-like component.
• The HIMU-type alkalic lavas on the Walvis Ridge and older part of Shona hotspot track are ∼30 Ma younger in age than the EMI-type primarily tholeiitic basement lavas at a given locality.

Abstract

Long-lived spatial geochemical zonation of the Tristan-Gough and Discovery hotspot tracks and temporal variations from EMI-type basement to HIMU-type late-stage volcanism at the Walvis Ridge and Shona hotspot tracks point to a complex evolution and multiple source areas for the South Atlantic hotspots. Here we report 40Ar/39Ar age and geochemical (major and trace element, Sr-Nd-Pb-Hf isotope) data for samples from 16 new sites on the Walvis Ridge. This aseismic ridge is the oldest submarine expression of the Tristan-Gough mantle plume and represents the initial reference locality of the EMI end member in the South Atlantic Ocean. The EMI-type lavas display an excellent age progressive trend of ∼31 mm/a along the entire Tristan-Gough hotspot track, indicating constant plate motion over a relatively stationary melt anomaly over the last ∼115 Ma. The Gough-type EMI composition of the Tristan-Gough hotspot track is the dominant composition on the >70 Ma part of the Walvis Ridge, the Etendeka and Parana flood basalts, and along the Gough sub-track, extending from DSDP Site 525A on the SW Walvis Ridge to Gough Island, whereas Tristan-type EMI dominates on the Tristan Track, extending from DSDP Sites 527 and 528 to Tristan da Cunha Island. Gough-type EMI is also the dominant composition of the northern Discovery and Shona hotspot tracks, suggesting that these hotspots tap a common source reservoir. The continuous EMI-type supply over ≥132 Ma, coupled with high 3He/4He (>10 RA), points to a deep-seated reservoir for this mantle material. The Tristan and Southern Discovery EMI-type flavors can be reproduced by mixing of the Gough-type component with (1) FOZO/PREMA to produce Tristan-type lavas, and (2) marine sediments or upper continental crust to generate the Southern Discovery-type composition. South Atlantic hotspots with EMI-type compositions overlie the margin (1 % ∂Vs velocity contour) of the African Large Low Shear Velocity Province (LLSVP), which may promote the emergence of geochemical “zonation”. The St. Helena HIMU-type volcanism, however, is located above internal portions of the LLSVP, possibly reflecting a layered LLSVP.

Document Type: Article
Keywords: Walvis Ridge, Isotope geochemistry, 40Ar/39Ar dating, DUPAL-anomaly, EMI mantle end member, HIMU, SO233, SO234/1
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS
Kiel University
Refereed: Yes
Open Access Journal?: No
Publisher: Elsevier
Expeditions/Models/Experiments:
Date Deposited: 24 Sep 2018 10:19
Last Modified: 31 Jan 2022 09:20
URI: https://oceanrep.geomar.de/id/eprint/44375

Actions (login required)

View Item View Item