Urlaub, Morelia, Schmidt-Aursch, Mechita, Jokat, Wilfried and Kaul, Norbert
Gravity crustal models and heat flow measurements for the Eurasian Basin, Arctic Ocean.
Marine Geophysical Researches, 30, (4), . (doi:10.1007/s11001-010-9093-x).
The Gakkel Ridge in the Arctic Ocean with its
adjacent Nansen and Amundsen Basins is a key region for
the study of mantle melting and crustal generation at
ultraslow spreading rates. We use free-air gravity anomalies
in combination with seismic reflection and wide-angle data
to compute 2-D crustal models for the Nansen and
Amundsen Basins in the Arctic Ocean. Despite the permanent
pack-ice cover two geophysical transects cross both
entire basins. This means that the complete basin geometry
of the world’s slowest spreading system can be analysed in
detail for the first time. Applying standard densities for the
sediments and oceanic crystalline crust, the gravity models
reveal an unexpected heterogeneous mantle with densities
of 3.30 9 103, 3.20 9 103 and 3.10 9 103 kg/m3 near the
Gakkel Ridge. We interpret that the upper mantle heterogeneity
mainly results from serpentinisation and thermal
effects. The thickness of the oceanic crust is highly variable
throughout both transects. Crustal thickness of less than
1 km dominates in the oldest parts of both basins, increasing
to a maximum value of 6 km near the Gakkel Ridge.
Along-axis heat flow is highly variable and heat flow
amplitudes resemble those observed at fast or intermediate
spreading ridges. Unexpectedly, high heat flow along the
Amundsen transect exceeds predicted values from global
cooling curves by more than 100%.
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