GEOL 1020 Lecture Notes - Lecture 21: Forearc, Triple Junction, Iceland Plume
Document Summary
In 1962, hess proposed seafloor spreading as the mechanism for how the. The basis for seafloor spreading is mantle convection. Convection in the mantle can be likened to the circular motion going on in a heating pot of thick soup. The heated soup rises to the surface, spreads out and begins to cool, and then sinks back down to the bottom of the pot where it gets reheated and rises again ( = convection cell). Harry hess hypothesized that mid-ocean ridges (ex: mid atlantic ridge) are zones where oceanic crust forms as mantle material rises to the surface. Oceanic crust cools and flow laterally away from the ridge (ie seafloor spreading), and eventually gets subducted back into the mantle at a deep-sea trench. According to hess" theory of seafloor spreading, the youngest oceanic crust would be at the mid-ocean ridges, and oldest oceanic crust would be at trenches. Paleomagnetism (pmag) - at mid-ocean ridges, new oceanic crust has.