Project Leader:
Dr. Spahr Webb
Earth Institute Contact: Dr. Spahr Webb
EI Collaborators:
Steven Goldstein
Charles Langmuir
Additional External Researchers:
Charles Langmuir, langmuir@ldeo.columbia.edu; Don Forsyth, Brown University; Dan Schrierer, USGS
Locations: Pacific Ocean
Description:
There are intraplate, volcanic ridges on the Pacific plate whose origin is not well understood. Their origin seems to be linked to equally enigmatic gravity lineations that are aligned in the direction of absolute plate motion. They are not hotspot traces, they do not form in the nearridge, spreading environment, and they are not volcanic arcs in a subduction setting. Suggestions for their origin include small-scale convective rolls, lithospheric boudinage, and small plumes resembling mini-hotspots that originate in the upper mantle. We propose to investigate their origin by studying two neighboring intraplate ridges: one in the active phase of construction and another that is the largest and most continuous of these intraplate ridges, which may have formed very quickly adjacent to a fracture zone. We will test existing hypotheses of the formation of the gravity lineations and volcanic ridges with new observations not available for any other ridge of this type. Measurements will include oceanbottom seismometer observations of mantle structure, a seismic refraction/reflection profile of crustal structure, microearthquake recordings extensive geochemical probing of the melting conditions and composition of the mantle, radiometric dating of the timing of volcanic activity, and mapping of bathymetry, seafloor sidescan reflectivity, sediment thickness, and gravity and magnetic anomalies.
EI Unit:
Lamont-Doherty Earth Observatory (LDEO)
Core Disciplines:
Earth Sciences
Project Web Site:
National Science Foundation
Collaborating Institutions:
Brown University, USGS
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