Answers to questions for: Pangea, Gondwanaland
and the supercontinent hypothesis.
will be modification processes that create gaps or overlaps during attmepts to fit the continents back together?
- variable character of continental crustal thinning:
- diachronous rifting along margin.
- different degrees of continental extension before seafloor spreading intiates (rift to drift transition) can produce overlaps, the locked zones of Courtillot and Vink.
- localized significant deposition along the continental margin, the best example of which is the Niger delta.
- internal plate deformation (e.g. Benue trough).
- missing continental slivers rafted out into the ocean basin.
- differing thermal and hotspot histories that cause uplift or subsidence that alters the large scale bathymetry used to piece the margins back together.
described the super continent cycle is far reaching. What does
it not explain, or what might be difficulties?
- Why does the cycle span stay the same when
heat flow rates changed 2 fold over the life time the cycle is
thought to have operated?
- What qualifies as a super continent and what is the rationale behind the criteria of qualification?
- Rifting dispersion in the case of the break-up
of Gondwanaland was over some 200 Ma. This should complicate
the simple cycles they see.
- Why are some supercontinents long lived and some short lived?
- How does the suspect/exotic terrane paradigm
fit into this?
See the Nance et al. (2014) retrospective article for more details.
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.