Crustal evolution from the Costa Rica Rift to borehole 504B

Oceanic crust undergoes rapid transformation in both its thermal and physical structure within the first 10 Ma from the ridge axis. Large departures in observed heat flow measurements from global depth and heat flow models reveal the importance of hydrothermal systems in heat dissipation and crustal alteration. Hydrothermal systems have the greatest influence on young oceanic crust due to its high porosity and permeability and low sediment cover. Much is still unknown about the scale and processes involved, especially the interaction between the solid Earth and the oceans.

We will examine crustal evolution from 0 at the Costa Rica Rift to ~6 Ma at borehole 504B in the Panama Basin. Analysis of our primary dataset, from an active-source seismic refraction and reflection experiment, will produce a 330 km long P-wave velocity model of the oceanic crust that can be related to bulk density and, hence, broad-scale structure. Here we present the preliminary results of this modelling, which we hope to provide initial answers to the following questions:

How does crustal structure change from the ridge axis to 6 Ma?

At what rate do changes in crustal structure occur?

This research is part of a major, interdisciplinary NERC-funded research collaboration entitled: Oceanographic and Seismic Characterisation of heat dissipation and alteration by hydrothermal fluids at an Axial Ridge (OSCAR).