Dr. Johan Lissenberg, Prof. Chris MacLeod and colleagues uncover unique evidence of crustal generation
16 May 2012
In the first ever study of the timescales of crystallisation in the magma chamber beneath a fast-spreading mid-ocean ridge, Dr Johan Lissenberg, Prof Chris MacLeod and colleagues have demonstrated that crustal accretion is far more protracted than previously supposed.
In a paper published in the April 2012 issue of Nature Geoscience they present high-precision U-Pb dates from zircon crystals in gabbro samples collected by remotely-operated vehicle from the Hess Deep rift valley. Because rates of crustal generation are higher at fast spreading rates than at slow, it has previously been supposed that melts in fast-spreading magma chambers should crystallise correspondingly more quickly. However, the group found that the timescales of crystallisation are instead similar to those at slow-spreading ridges, an unexpected finding that necessitates a profound re-evaluation of rates and mechanisms of generation of the lower ocean crust at fast-spreading ridges.