Interdisciplinary Studies of the 8° 20'N Seamount Chain, EPR

Posted on 09.12.2018
Map of the East Pacific Rise between the Clipperton and Siqueiros Transform Faults showing the location of the 8 20’ Seamounts. We will be conducting a field experiment here in the winter of 2016 to better understand crustal accretion at mid-ocean ridges.

Understanding how melts are generated and focused across hundreds of kilometers through the upper mantle to the narrow mid-ocean ridge (MOR) axis is fundamental to understanding how most of Earth’s lithosphere is formed. Significant advancements have been made in the use of geodynamic models to investigate mantle melting and melt transport in 3D. However, the lack of comprehensive off-axis geophysical and correlative geochemical data presents a critical information gap that needs to be filled before progress can be made in refining these models. Our collaborative project proposes to fill these data gaps through a multidisciplinary field program to survey and sample the 8 20’N Seamount Chain which extends 200 km westward from the East Pacific Rise (EPR) / Siqueiros ridge-transform intersection (RTI). Seamounts provide a unique opportunity to test hypotheses of off-axis melt distribution and source variation, as melts delivered through the crust to build these seamounts provide geochemical ‘probes’ into the upper mantle. The ~200 km long continuous 8 20’N Seamount Chain will provide an ideal location for a systematic, spatial analysis of off-axis melting.

This project utilizes a comprehensive geophysical and geochemical field and modeling study of off-axis volcanic construction to directly test hypotheses for 3D melt generation and transport. Petrologic and geochemical analyses of dredged samples will be used in conjunction with morphological and geophysical data analyses to develop new, integrated models for upper lithosphere structure, deformation, and melt distribution at a fast-spreading center. The goal of this work is to investigate specific hypotheses for the dynamics of off-axis melting. Our strategy is to utilize an interdisciplinary approach where spatially and temporally related geophysical and geochemical data analyses inform each other and are linked by geodynamic modeling.

This work is funded by NSF OCE and includes 2 field expeditions to the 8 20’N Seamount Chain off of the East Pacific rise. 

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COLLABORATORS: Dan Fornari (WHOI), Mike Perfit (U Florida), Dorsey Wanless (Boise State University), Steve Shirey (Carnegie DTM), W. Ian Ridley (USGS)

FUNDING: This work is funded by the National Science Foundation


LAS News Bureau: 3 kilometers under the sea: Illinois leads expedition to explore underwater volcanoes



§Student, +Postdoc

§E. M. Conrad, M. Perfit, M. Anderson, V. D. Wanless, D. Fornari, P. M. Gregg Geochemical Diversity of Lavas from the 8°20'N Seamount Chain Provides Insights into Seamount Evolution from a Heterogeneous Mantle, AGU Fall Meeting, 2018.

+V. Romano, P. M. Gregg, Three-dimensional mantle melt generation, migration and extraction at the Quebrada-Discovery-Gofar fracture zones on the southern East Pacific Rise, GSA Annual Meeting, 2018.

S. B. Shirey, M. R. Perfitt, V. D. Wanless, P. M. Gregg, D. J. Fornari, W. I. Ridley, Petrogenesis of Siquieros FZ & Off-Axis Seamounts: Os Isotopic and Trace Element Constraints, Goldschmidt 2018.

§E. McCully, D. J. Fornari, P. M. Gregg, M. R. Perfit, V. D. Wanless, M. Anderson, M. Lubetkin, Geophysical and Geochemical Analysis of the 8°20’ N Seamount Chain: Studies of Off-Axis Volcanism, AGU Fall Meeting, 2017.

§M. Anderson, V. D. Wanless, M. R. Perfit, P. M. Gregg, D. J. Fornari, E. McCully, W. I. Ridley, Off-Axis Seamount Lavas at 8°20’ N Span the Entire Range of East Pacific Rise MORB Compositions, AGU Fall Meeting, 2017. 

§V. Romano, P. M. Gregg, D. J. Fornari, M. R. Perfit, M. Battaglia, Formation and evolution of the near axis 8˚20’N seamount chain: Evidences from the geophysical data analysis, AGU Fall Meeting, 2017.


P.M. Gregg, D. J. Fornari, M. R. Perfit, V. Romano, D. Wanless, D. Geist, S. Shirey, W. Ridley, M. Smith, C. Lundstrom, Y. Zhan, E. McCully, C. Trim, H. Cabaniss, J. Albright, B. Boulahanis, Y. Tan, Emplacement of the 8° 20’N Seamount Chain: Preliminary results from the 2016 OASIS Expedition, IAVCEI Scientific Assembly, Portland, OR, 2017.

D. Fornari, P. M. Gregg, M. Perfit, E. McCully, M. Lubetkin, OASIS Science Team, High resolution mapping using the submersible Alvin and Sentry AUV at the 8 20'N Seamounts: Morphostructural analysis and volcanic history, IAVCEI Scientific Assembly, Portland, OR, 2017.

M. Perfit, D. Fornari, P. M. Gregg, D. Wanless, M. Smith, W. I. Ridley, Diversity of Lavas from the 8 20’N Seamount Chain: Windows into Small-scale Geochemical Heterogeneity of the Mantle Proximal to the Northern East Pacific Rise, IAVCEI Scientific Assembly, Portland, OR, 2017.

D. Fornari, M. Perfit, P. M. Gregg, V. D. Wanless, & AT37-05 Science Team, Seamount Calderas and Craters – Keys to Submarine Magmatic and Volcanic Processes, AGU Chapman Conference on Submarine Volcanism: New Approaches and Research Frontiers, 2017.