Multibeam bathymetry data of the western part of the Romanche Trench (Equatorial Atlantic)

We present the multibeam bathymetry data of the western part of the Romanche Trench (Equatorial Atlantic) which is the main natural corridor that regulates inflow of Antarctic Bottom Water into the eastern basin of the Atlantic Ocean. Multibeam bathymetry survey was carried out during the 33^th cruise of the research vessel Akademik Nikolaj Strakhov in November 2016. The data were collected using the multibeam echosounder RESON SeaBat 7150 and processed using PDS2000 software. The multibeam bathymetry data are presented as digital elevation models in XYZ tabular format ASCII (*.txt), ESRI ASCII grid (*.asc) and GeoTIFF raster (*.tif) formats with a resolution of 100 m. The dataset is available with the article.

Mapping of surface radiogenic heat production from in situ gamma spectrometry and chemical data of exhumed mantle peridotites at the St. Peter and St. Paul archipelago (equatorial Atlantic)

This work presents the first mapping of the radiogenic heat production (RHP) and the respective radiogenic heat flow (RHF) of the Saint Peter and Saint Paul Archipelago (SPSPA) located at 1°N in the Equatorial Atlantic Ocean. Using radiogenic heat producing elements (RPE) we inferred a radiogenic heat production ranging 0.08-0.68 μW/m³ (Median: 0.21 μW/m³ and Geometric mean: 0.25 μW/m³) by whole-rock chemical analysis and between 0.08 and 0.48 μW/m³ (Median: 0.19 μW/m³; Geometric mean: 0.19 μW/m³) by in situ Gamma radiation spectrometry. The mean of radiogenic heat production of mylonite rocks from SPSPA (0.22 μW/m³) is significantly higher than predicted values for ultramafic rocks as those largely outcropping in the SPSPA. This is probably due to the pervasive alteration of these rocks and the incorporation of little magma fractions during mylonitization. By converse, the average surface radiogenic heat flow (49.7 μW/m²) is lower than that predicted for the oceanic lithosphere, suggesting that the upper mantle contribution to the heat flow is also low in the SPSPA region. Based on the acquired data and the peculiar tectonics of the SPSPA we propose that the lithospheric mantle around the SPSPA area is colder than that surrounding the Equatorial Atlantic region.