Message #258120

[Lisa Wolfe]

Keith's Hypothetical Model of Proposed Mid-Ocean Ridge Dynamics and Structure. Keith proposes a structure for a mid-ocean ridge tosatisfy geophysical observations and his intuition about how, dynamically, the ocean-floor crust and underlying mantle behave. He calls this structure a “flexload syncline.” A syncline is simply a fold in Earth's rocks, the core of which contains younger material and which is generally concave upward. The adjective flexload is used to emphasize the effects of gravity-produced flexure on the crustal stress regime. In his proposed ocean-ridge model, the structure of the crestal zone is attributed mainly to gravitational deformation that results from two types of loading: crestward-increasing volcanic loading and downward increasing densification. Keith cites evidence that major flexload sinking “is not restricted to the near-axial zone but is broadly effective beneath the ridge flanks and formerly extended over the full width of Mesozoic to Early Tertiary ocean ridges.”

What will a cross-section diagram of a mid-ocean ridge structure look like for Keith's crustal-collapse-under-cooling model? Figure 5 gives us the picture.