See more from this Division: General Discipline Sessions
See more from this Session: Structural Geology / Tectonics / Neotectonics/Paleoseismology II
Abstract:
Mantle peridotites sampled from Arctic Ridges show an unexpected variety of geochemical signatures. The thick conductive lithospheric lid on these ultraslow spreading ridges results in crustal thicknesses that are less than half those seen at slow, intermediate and fast spreading ridges (Jokat, et al., 2003). Yet mantle peridotites sampled from arctic ridges show a range of compositions from relatively fertile (but not approaching pyrolite or similar compositions) to quite depleted. This variability may represent the remnants of primary mineralogical variability in the upwelling mantle, and not be due to melting beneath the Arctic ridges, being instead far more ancient (Liu, et al., 2008).
Pyroxenitic lithologies supportive of the “veined mantle” hypothesis are not seen directly along the Arctic Ridges. However, basalts erupted along the Arctic Ridges, particularly Gakkel Ridge, show a systematic pattern of increased incompatible trace element compositions that is similar to the southern hemisphere “DUPAL” anomaly (Muehe, et al., 1997; Goldstein et al, 2008). This suggests that the DUPAL anomaly may reflect the lower degree of partial melting along ultraslow spreading ridges.
See more from this Division: General Discipline Sessions
See more from this Session: Structural Geology / Tectonics / Neotectonics/Paleoseismology II