OASIS Cruise

Excerpt from the CruiseReport of Cruise AT37-05 filed 7 December 2016 

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 and how elements and heat are exchanged between the interior to the surface of our planet. Significant advancements have been made in the use of geodynamic models to investigate mantle melting and melt transport in 3D. 

Our collaborative project proposed 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 is an ideal location for a systematic, spatial analysis of off-axis melting. 

Major products from the seagoing investigation include: 

• (1) a comprehensive, spatially dense geochemical and geophysical dataset from the EPR / Siqueiros RTI out to 200 km (~3.6 My lithosphere), the first data set of this kind; 

• (2) data-validation of geodynamic models of three-dimensional melt migration, and lithospheric evolution, including a statistical parameter estimation and sensitivity study; 

• (3) training of students in integrated marine science research; 

• (4) a new Marine Geology curricular unit targeted at 6th, 7th, and 8th graders; (5) 25+ Educational Videos published on YouTube and advertised on Facebook and Twitter