Mid-Ocean Ridges and the formation of Oceanic CrustOne of the last frontiers for Plate Tectonics
August 21 (Tuesday), Presbyterian Church of Jackson Hole 6 p.m., “Mid-Ocean Ridges & the formation of Oceanic Crust- One of the last frontiers for Plate Tectonics”.Presented by Mike Cheadle & Barbara John, University of Wyoming.
The 80,000 km long mid-ocean ridge system is the longest mountain range on Earth and is the location where new oceanic crust is created to form 60% of our planet’s surface. However, because of its relative inaccessibility, lying at depths of ~3km below the sea surface, we are still exploring and learning about the processes that operate to form ocean crust and consequently, mid-ocean ridges are one of the last frontiers for understanding plate tectonics. Broadly there are two mid ocean ridge end members, which exhibit very different topography, and a very different balance of magmatic and tectonic processes. Fast (>8cm/yr) spreading ridges such as the East Pacific Rise are relatively smooth, and wide, have small offset (~ 100m) faults and are magmatically robust. Slow (<5cm/yr) spreading ridges such as the Mid Atlantic Ridge show extreme (up to 5-6 km) relief and complicated topography, possess the largest (>100km of slip) normal faults in the world, and are magmatically much less robust. Video
In this talk, we’ll report on our work studying the formation of oceanic crust at slow spreading ridges in the Atlantic and Indian Oceans using drillships and both manned and remotely operated submersibles and from our recent (Jan 2016) exploration of Pito Deep, located on the fast spreading East Pacific Rise. During this last cruise, we mapped and sampled a cliff section exposing a 2-3km section through the ocean crust, for the first time at a resolution of sampling and mapping one might carry out on the continents. The first and foremost result of this work is the recognition of lateral petrological and structural variation, which challenges the longstanding simple layered Penrose model for fast spread crust. https://www.youtube.com/watch?v=zZLnISohShg&t