Melt Generation at Very Slow-Spreading Oceanic Ridges: Constraints from Geochemical and Geophysical Data

We show that there is a strong and consistent correlation between mantle plume brings hotter than normal mantle beneath the spreading centre at the time of crustal formation geochemical and geophysical estimates of the amount of melt generated in the mantle beneath oceanic ridges. This correlation holds across (White, 1997), causing enhanced melting and the production of thicker crust. Elsewhere, the consistency of all spreading rates and on scales down to the size of individual ridge segments. There is an abrupt decrease in the amount of oceanic crustal thickness over nearly an order of magnitude range of spreading rates (from 20 mm/a in the melt generated at full spreading rates below >20 mm/a. Our observations are consistent with the conclusion that <10% of the North Atlantic to 150 mm/a on the East Pacific Rise) points to a uniform normal mantle potential temperature melt is frozen in the mantle before it reaches the crust and that serpentine probably represents only a small percentage of the material of about 1300 20C using batch melt parameterizations for an entropy of melting of 400 J/kg per above the Moho. The melt is well mixed on a ridge segment scale, C if the seismic crustal thickness is taken as representative probably in high-level magma chambers, but the melts remain of the melt thickness distinct between segments. The rare earth element concentrations of As no melting occurs on an oceanic ridge where the basalts from very slow-spreading ridges are higher than those from spreading rate is zero, whereas the percentage of mantle normal oceanic ridges, which is directly indicative of reduced mantle melting is constant at rates of 20 mm/a and above, it is melting, and they show characteristic light rare earth element instructive to examine the variation of melt generation enrichment, interpreted as caused by a deep tail of small percentage with spreading rate over the interval between 0 and wet melting. The decrease in melt production at rates below 20 mm/a; this may help constrain the controls on melting >20 mm/a points to the importance of conductive cooling inhibiting at mid-ocean ridges. In particular, it may discriminate melting of the upwelling mantle at very slow-spreading centres.