Answers to -> Week 3: Parting the continents - continental rifting.

What are the responsible mechanisms for lithospheric attenuation?

• by ductile flowage (yet lithosphere strong, component 5).
• by lithospheric detachments (how to detect or image? component 6).
• by lithospheric delamination.
• by elevation of geotherm and transfer of material from lithosphere to asthenosphere (component 7).

What are all factors that determine the chemical composition of a melt?

• mantle source composition:
  • mantle heterogeneity vs. convective stirring.
  • depleted vs. undepleted mantle material.
  • stratified vs. whole mantle convection.
• degree of partial melting.
• pressure and tempature of partial melting.
• volatile activity (effects unexplored).
• fractionation on way up.
• contamination on way up.

What might be factors that determine the pattern of faulting during continental rifting?

• previous structural weaknesses.
• curvature of crust (will produce arcuate patterns).
• position of underlying plumes.
• evolving/changing stress fields.
• along srike propagation history of growing faults.
• rate of extension.
• interpretative style.

Course materials for Plate Tectonics, GEOL 3700, University of Nebraska at Omaha. Instructor: H. D. Maher Jr., copyright. This material may be used for non-profit educational purposes with appropriate attribution of authorship. Otherwise please contact author.