Poster Abstract Title: 
Changes in the formation of axial volcanic edifices in response to changes in magma supply rate
Authors and their affiliations: 
Howell, J.K. (1), White, Scott M. (1), Bohnenstiehl, DelWayne R. (2), Bizimis, Michael (1); (1) University of South Carolina, (2) North Carolina State University


The spatial and abundance distributions of volcanic edifices along mid-ocean ridges have a well known correlation with spreading rate. Along slow spreading centers, volcanic edifices are normally distributed about the segment center.  Volcanic edifices along fast spreading centers have the opposing trend, i.e. edifices form primarily at the ends of segments. Along ridges affected by plumes and in back arc basins, the spatial and abundance distributions of volcanic edifices differ from that observed at normal ridges of the same spreading rate. This suggests that magma supply rate may control the spatial and abundance distribution of volcanic edifices. Recent geophysical and geochemical studies along the Juan de Fuca Ridge (JdFR), Southeast Indian Ridge (SEIR) and the Valu Fa (VF) and Eastern Lau Spreading Centers (ELSC) put tight constraints on crustal thickness, making it possible investigate the effect of magma budget and axial morphology on the formation of volcanic edifices.  Volcanic edifices are described according to their volume, shape (their height to basal radius ratio) and their location relative to the end or center of a segment (abundance distribution).  Edifices along the SEIR and JdFR show little variation with changes in axial morphology at relatively constant spreading rates. Results for VF and ELSC are what we expect for changes in spreading rate, not axial morphology.  Our study suggests that the formation of volcanic edifices at the SEIR, JdFR, VF and ELSC are not significantly influenced by magma supply rate.  


Contributions to Integration and Synthesis: 
This work utilizes multibeam bathymetry, geochemical analyses and crustal thickness approximations obtained from two of the three study sites (Lau and Juan de Fuca) and compares those results to another intermediate spreading rate ridge (Southeast Indian Ridge). We are also attempting to compare segmentation patterns represented by the location, size and shape of volcanic edifices in the neovolcanic zone to specific mantle attributes, such as abnormal magma supply rates.