Additional grid and trackline data have been included, both over land and the oceans. As reflected in the name the resolution has been improved from 3 arc minute to 2 arc minute and the altitude has been reduced from 5 km to 4 km above geoid.
#Anomaly 2 resolution update
Distinct patterns and magnetic signatures can be attributed to the formation (seafloor spreading) and destruction (subduction zones) of oceanic crust, the formation of continental crust by accretion of various terranes to cratonic areas and large scale volcanism (both on continents and oceans).ĮMAG2 is a significant update over our first global magnetic anomaly grid, EMAG3, which provided the base grid for the World Digital Magnetic Anomaly Map of the Commission of the World Geological Map. Furthermore, the global magnetic map is useful in science education to illustrate various aspects of Earth evolution such as plate tectonics and crustal interaction with the deep mantle. Magnetic maps are widely used in the geological sciences and in resource exploration. Anomalies trending parallel to the isochrons (lines of equal age) in the oceans reveal the temporal evolution of oceanic crust. Magnetic anomaly maps provide insight into the subsurface structure and composition of the Earth's crust. GIS GeoTIFF versions of EMAG2 included in the product table at the bottom of this page A second profile, running E‐W between two OCCs, shows high magnetization coinciding with a large seamount, reflecting recent off‐axis volcanism.Print map (paper and digital download) of EMAG2 available at BGR Geoshop A modeled near‐seafloor profile through OCC1320 shows low positive magnetization below the smooth dome. This suggests that a strongly three‐dimensional structure exists, more compatible with a geodynamic model where neighboring OCCs are not connected but evolve independently. We interpret this mismatch as reflecting the differing sensitivities of the two observing geometries and the existence of a highly heterogeneous topography and magnetization. Higher spatial resolution magnetic anomalies near the seafloor, measured by autonomous underwater vehicle, are qualitatively similar to earlier deep‐towed data but differ somewhat from the sea surface magnetics.
The inferred position of the magmatic axis implies ~30% asymmetry of crustal accretion post‐anomaly‐2. A strong negative magnetization is associated with the oceanic core complex (OCC) at 13☂0′N (OCC1320) and is inferred to arise from exhumed old, reversely magnetized lithosphere.
Gaps in the Brunhes anomaly match gaps in the neovolcanic zone inferred from acoustic backscatter. It is often split, both along and across axis, by apparently reversely magnetized crust. The Brunhes anomaly width is highly variable but averages ~60% of that predicted for the regional spreading rate. Inversion of closely spaced sea surface magnetic anomalies reveals a disorganized pattern of magnetization, with anomalies younger than anomaly 2 being poorly delineated. Abstract We describe detailed magnetic and bathymetric studies around 13°N on the Mid‐Atlantic Ridge, a site of extensive detachment faulting.