Collaborative Research: Melting in the Off-Axis Environment - Interdisciplinary Field and Modeling Studies of the 8 20'N Seamount Chain, EPR

University Of Illinois At Urbana-Champaign, Urbana IL

Investigators

Abstract

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 Earth's ocean crust is formed and how elements and heat are exchanged between the interior of our planet and its surface. Significant advancements have been made in the use of computer models to investigate mantle melting and melt transport. However, the lack of complementary geophysical and geochemical data from the same area is a critical information gap that needs to be filled before progress can be made in refining present models. This research entails a multidisciplinary geophysical and geochemical program to map, sample, and analyze samples from the 8°20'N Seamount Chain that extends 200 km westward from the East Pacific Rise Siqueiros ridge-transform intersection in the Pacific Ocean. Seamounts provide a unique opportunity to test hypotheses of melt distribution and source variation that occur away from spreading centers. Melts that build these seamounts provide geochemical windows into the upper mantle. The research includes an oceanographic cruise to map and sample the targeted region. This will be followed by geophysical data processing and petrographic, petrologic, and geochemical analyses of samples collected by both using ALVIN, a manned deep submersible, and dredging. Goals of the research are to develop new, integrated models for upper lithosphere structure, deformation, and melt distribution at a fast-spreading center and investigate the dynamics of off-axis melting. The approach is interdisciplinary and includes analysis of geophysical and geochemical data and geodynamic modeling. Rock samples will be analyzed for all major and trace elements and radiogenic isotopes of Nd, Sr, and Pb will also be analyzed. Broader impacts of the project include creation of a marine geology curricular unit targeted at the middle school level and compliant with Next Generation Sciences Standards that have currently been adopted by 45 states. The project involves working closely with teachers and administrators of Pipkin Middle School, a nationally ranked Title I school that serves 580 students in the low-income center-city of Springfield, MO (poverty index of 78%). The teachers will work closely with the reserachers and both parties will jointly create the educational materials. Emphasis will be placed on inquiry learning and connecting fundamental science processes with current research. The pilot implementation will coincide with the proposed field program. The developed unit will be made broadly available via the web on curricular resource sites.