Publication Date:
2021-12-16
Description:
The greater area of the Lau Basin consists of a mosaic of microplates with various spreading centers and arc rifts. Repeated crustal recycling and addition of volatiles and metals in this tectonic setting leads to fertilization of the crust. This assimilation of mineral deposits is associated with building blocks of continental crust, and is thus an important setting to study crustal growth on Earth. During research cruise SO267 in 2018/2019, multi method geophysical and geological data were acquired on the newly formed Niuafo’ou microplate in the Lau Basin to study the links of rifting, magmatism and hydrothermal circulation in the early evolution of back arc spreading. The geophysical data encompass refraction- and reflection seismic, seismological, backscatter, gravity, magnetic and magnetotelluric data. Here we present a first electrical conductivity model derived from 3D inversion of marine magnetotelluric (MT) data. Electrical conductivity is a key proxy for imaging hydrothermal circulation and magmatic processes, since both processes effect the bulk electrical conductivity strongly. Our model exhibits three larger scale crustal conductivity anomalies. Based on the electrical conductivity model alone, we cannot discern whether the anomalies are caused by hydrothermal activity through pathways created by tectonic spreading or by melt accumulation caused by magmatic processes. However, a spatial correlation of our major conductivity anomaly with a seismicity cluster and a comparison with seismic velocity and backscatter data allows us to hypothesizeinfer about the geodynamic processes acting in the region. Our study documents the benefit of integrating different geophysical methods to understand rift arc evolution.
Type:
Conference or Workshop Item
,
NonPeerReviewed
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