BATHYCHEM The Effect of Intraplate Volcanism on the Geochemical Evolution of Oceanic Lithosphere: Detailed Mapping and Sampling of the Bathymetrists Seamounts and Adjacent Fracture Zones, December 26, 2017 – February 01, 2018 Mindelo (Cape Verde) – Las Palmas de Gran Canaria, Canaries (Spain) .

van der Zwan, Froukje M. and Garbe-Schönberg, C.-Dieter and Scientific Shipboard Party of MSM70 (2018) BATHYCHEM The Effect of Intraplate Volcanism on the Geochemical Evolution of Oceanic Lithosphere: Detailed Mapping and Sampling of the Bathymetrists Seamounts and Adjacent Fracture Zones, December 26, 2017 – February 01, 2018 Mindelo (Cape Verde) – Las Palmas de Gran Canaria, Canaries (Spain) . Open Access . MERIAN S. MERIAN-Berichte, MSM70 . Gutachterpanel Forschungsschiffe, Bonn, 133 pp. DOI 10.2312/cr_msm70.

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Abstract

Intraplate volcanism, in contrast to mid-ocean-ridge (MOR) oceanic crustal basalts, is formed by low degrees of deep mantle melting and has a unique and distinct major and trace element and isotopic composition. Intraplate magmatism can therefore significantly alter the composition of the lithosphere, but may also trigger local structural changes and fluid flow causing large-scale hydrothermal activity, which would also modify the original composition of the lithosphere. The BATHYCHEM (MSM70, Dec 2017-Febr 2018) cruise aimed to study the effect of the magmatism of the, so far poorly researched, Bathymetrists and Grimaldi Seamounts intraplate volcanic province on the Atlantic oceanic plate. The Bathymetrists Seamounts were formed on oceanic crust that has a wide range of ages from 30 to >100 Ma and thus has been exposed to variable degrees of seafloor alteration. This project aims at characterizing the structure, age and composition of the Bathymetrists Seamounts and adjacent areas to understand their origin and formation mechanism, which will allow a better assessment of how intraplate volcanism modifies the structure and composition of oceanic lithosphere through time. To achieve these aims the MSM70 expedition undertook high-resolution mapping and dense rock sampling of the intraplate Bathymetrists Seamount Chain and its corresponding N-bounding fracture zones; Cape Verde Ridge and Kane Gap. Hydro-acoustic models could be greatly improved to a resolution of 50 m and the position of 40 named and unnamed seamounts could be refined. The bathymetric maps reveal a complicated pattern of emplacement and indicate that most of the seamounts (62%) resemble guyots capped by carbonated platforms. A total of 65 dredge-tows recovered volcanic samples, carbonates, phosphorites, mudstones and manganese crusts and nodules. Volcanic samples from 27 seamounts revealed dense basaltic samples and vesicular volcanoclastic material of mafic origin containing pyroxenes, amphiboles and biotite.

Document Type: Report (Cruise Report)
Keywords: RV Maria S. Merian, MSM70, Cruise report, BATHYCHEM, bathymetrists seamounts, bathymetric mapping, volcanic samples, intraplate volcanism, bathymetrists seamounts, Atlantic
Research affiliation: Kiel University
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS Magmatic and Hydrothermal Systems
DOI etc.: 10.2312/cr_msm70
ISSN: 2195-8483
Expeditions/Models/Experiments:
Date Deposited: 07 Feb 2019 10:50
Last Modified: 07 Feb 2019 11:31
URI: http://oceanrep.geomar.de/id/eprint/45754

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