EXPLAINING ANOMALOUSLY HIGH MAGMA FLUX AT VOLCANIC CENTERS ON THE NORTHERN KOLBEINSEY AND SOUTHERN MOHNS RIDGES USING BATHYMETRY AND BASALT GEOCHEMISTRY

The slow-spreading Northern Kolbeinsey Ridge (NKR) and Southern Mohns Ridge (SMR) segments immediately adjacent to the Jan Mayen Fracture Zone exhibit similar types of volcanism along their spreading axes. Each segment hosts small, flat-topped cones and hummocky pillow basalt flows typical of slow-spreading ridges as well as an unusually large volcanic edifice, indicating a focused zone of high magma flux to the ridge. We compare the bathymetry and geochemistry of these two ridge segments to better understand oceanic crust formation at slow-spreading mid-ocean ridges with anomalously high magma supply. We use focused sampling along each ridge in combination with new bathymetric data from RV Poseidon leg 436 (2012) and a recent expedition to the Mohns Ridge by Pedersen et al. (2010). A comparison between the physical morphology (e.g., crustal thickness) and basalt trace element geochemistry of the SMR and NKR helps constrain melting beneath the two segments by fingerprinting the source of the unusually focused magmatism suggested by the large cones and locally thick crust. We expect trace element geochemistry to indicate high degrees of melting and mantle source enrichment similar to that observed for Jan Mayen Island, with the strongest enrichments focused at the large volcanic centers. We further attempt to constrain whether or not the Jan Mayen Fracture Zone disrupts the flow of magma between ridges segments using detailed geochemical analysis.