SO267 ARCHIMEDES I

Country / Region: Lau-Basin

Begin of project: September 1, 2018

End of project: January 31, 2021

Status of project: March 1, 2019

Arc Rifting, Metallogeny and Microplate Evolution: An Intergrated Geodynamic, Magmatic and Hydrothermal Study of the Fonualei Rift System, NE Lau Basin

Map of cruise SO267 with seismic lines BGR18-201 to BGR18-206 Source: GEOMAR

Over half of the world’s exploited metal deposits were formed in a submarine environment, the majority by processes related to rifting of arc crust. Such rifting is observed today in the NE Lau Basin, where a complex microplate mosaic offers a unique opportunity to study crustal growth and mineral endowment of emerging continental crust.

During the expedition ARCHIMEDES I (SO267) with RV Sonne the Fonualei Rift at the edge of the Niuafo’ou microplate was investigated in detail. This project was a cooperation between GEOMAR and BGR. The work was focused to the central question: at what stage in the structural and thermal evolution of the crust does arc rifting occur and seafloor spreading initiate?

On 43 working days a multidisciplinary program was conducted: reflection seismic images the upper crust as well as the fault structures. Refraction seismic delivered a deeper look into the lower crust. Magnetotellurics delivers indications for melt accumulations, while magnetic data contain information on the formation of igneous rocks. The geophysical transects where complemented by dredging, and sidescan imaging using AVU ABYSS.

Seismic line BGR18-205 in the southern survey area. It images the transition from the back-arc crust in the east (left) to the volcanic arc in the west (right) Source: BGR

Literature:

• SO267 ARCHIMEDES BLOG

• Short Cruise Report R/V SONNE cruise SO267 Suva (Fiji) - Suva (Fiji) 11.12.2018 - 26.01.2019

Partner:

GEOMAR Helmholtz Centre for Ocean Research

Promotion / document number:

03G267B (BMBF)