Mantle Convection Flashcards
What correlates with plate movements at Earth’s surface?
Corresponding movements of the mantle beneath.
How do rocks behave near the surface versus in the mantle?
Near the surface: Rocks fracture and displace along faults, causing earthquakes.
In the mantle: Solid-state flow occurs in the ductile asthenosphere.
How does postglacial rebound demonstrate mantle flow?
Continents rise after ice melts, indicating slow but measurable mantle flow over thousands of years.
What does Earth’s topography reflect?
The response of the underlying mantle to weight changes (isostasy).
What evidence supports mantle flow?
Gravity measurements, seismic data, and isostasy explaining variations in ocean depth and continental elevation.
What drives mantle convection?
Density variations caused by temperature differences.
What are convection cells in the mantle?
Ascent and descent of material driven by temperature variations, similar to plate tectonics but not definitive.
What factors influence mantle convection?
Density anomalies, material viscosity, distances, and the Rayleigh number.
What does the Rayleigh number indicate about mantle convection?
Despite high mantle viscosity, large distances and temperature differences make convection inevitable.
What complexities exist in understanding mantle convection?
High Rayleigh numbers lead to complex patterns, with Earth’s unique conditions complicating the exact form of convection.
Do plate margins correspond to mantle convection cells?
No, plate boundaries don’t align neatly with convection cells, with inconsistent cell sizes and passive ridge migration.
What drives plate movements?
Changes in mineralogy at subduction zones, ridge push, and slab pull mechanisms.
What evidence supports active mantle upwelling?
Intraplate volcanism, such as Hawaii and Yellowstone, and the formation of island chains and hot spots.
What are the characteristics of hot spots and mantle plumes?
Fixed hot spots beneath moving plates, originating from deep thermal boundary layers, potentially at the core/mantle boundary.
What does the distribution of hot spots suggest?
Concentration in the central Pacific and near Africa, indicating plume-driven mantle upwelling.
