Variable crustal structure along the Juan de Fuca Ridge: Influence of on-axis hot spots and absolute plate motions

Publication Type  Journal Article
Year of Publication  2008
Authors  Carbotte, S. M.; Nedimovic, M. R.; Canales, J. P.; Kent, G. M.; Harding, A. J.; Marjanovic, M.
Journal Title  Geochemistry Geophysics Geosystems
Volume  9
Pages  -
Journal Date  Aug 2
ISBN Number  1525-2027
Accession Number  ISI:000258148700001
Key Words  mid-ocean ridges; juan de fuca ridge; hot spot; multichannel seismic; east pacific rise; mid-atlantic ridge; midocean ridge; oceanic-crust; northeast pacific; seismic-reflection; rift propagation; magma chamber; layer 2a; seamount
Abstract  

Multichannel seismic and bathymetric data from the Juan de Fuca Ridge (JDFR) provide constraints on axial and ridge flank structure for the past 4-8 Ma within three spreading corridors crossing Cleft, Northern Symmetric, and Endeavour segments. Along-axis data reveal south-to-north gradients in seafloor relief and presence and depth of the crustal magma lens, which indicate a warmer axial regime to the south, both on a regional scale and within individual segments. For young crust, cross-axis lines reveal differences between segments in Moho two-way traveltimes of 200-300 ms which indicate 0.5-1 km thicker crust at Endeavour and Cleft compared to Northern Symmetric. Moho traveltime anomalies extend beyond the 5-15 km wide axial high and coincide with distinct plateaus, 32 and 40 km wide and 200-400 m high, found at both segments. On older crust, Moho traveltimes are similar for all three segments (similar to 2100 +/- 100 ms), indicating little difference in average crustal production prior to similar to 0.6 and 0.7 Ma. The presence of broad axis-centered bathymetric plateau with thickened crust at Cleft and Endeavour segments is attributed to recent initiation of ridge axis-centered melt anomalies associated with the Cobb hot spot and the Heckle melt anomaly. Increased melt supply at Cleft segment upon initiation of Axial Volcano and southward propagation of Endeavour segment during the Brunhes point to rapid southward directed along-axis channeling of melt anomalies linked to these hot spots. Preferential southward flow of the Cobb and Heckle melt anomalies and the regional-scale south-to-north gradients in ridge structure along the JDFR may reflect influence of the northwesterly absolute motion of the ridge axis on subaxial melt distribution.

Notes  

333JLTimes Cited:2Cited References Count:77

URL  <Go to ISI>://000258148700001
DOI  Doi 10.1029/2007gc001922