Geology+of+Panama

=Post your questions here =

Alex: ** Re: Kirby and MacFadden, 2005: **

1. Kirby and MacFadden (2005) mention “Evidence from marine rocks and volcanic terranes suggest that the volcanic arc during the Miocene consisted of an archipelago separated by shallow straits”. What exactly is this geologic evidence and how strong is it as compared to the tooth size data?

2. Also in Kirby and MacFadden (2005) the earlier Culebra strait was mentioned to have been “a maximum width of 60 km”. How was this value determined using the pre-Miocene volcanic terranes?

** Re: Molnar, 2008: **

1. Molnar (2008) presented a lot of isotopic data which provided inconclusive and even conflicting evidence. It appeared that the most solid temporal evidence remains that of the vertebrate fauna. Given Molnar’s closing statement, what can we take away as useful regarding any association between the closing of the isthmus and northern hemisphere glaciations?

2. The timing of both “major events in the development of Central America” seem to not coincide with the Great American Exchange. What would be some possible reasons for the temporal offset?

Molnar suggests a shift in the depths occupied by NADP and Southern Ocean Water masses, with a weak thermohaline circulation pattern associated to a narrowly open seaway during + /- 3.5 Ma. Could this process be represented by Chagres Formation lithology? Aldo

Kirby and MacFadden suggested that insular insolation might be responsible of interspecific body size change (island rule). By comparing body size of Las Cascadas Fauna with its northamerican counterparts, there are remarkable body size differences (smaller camels, smaller horses, bigger hippo-like mammals, etc; Can that rule coupled with the pre-Cascadas lithologies support a late oligocene island arc older than the miocene peninsula? Aldo

.Were these papers sent to everyone? I didn't get them... (Andy K.)