Fichas
Proterozoic cont. (18)
Fichas del conjunto (8)
- 1What is the timing of the Paleoproterozoic glaciation?~2.3 Ga
- 2☼What specific rock evidence (for example, in the Gowganda Formation?) tells geologists that there was an Ice Age at this time?☼Finely-laminated shales (varves), dropstones, interbedded tillites, glacially scratched clasts
- 3☼Neoproterozoic glaciations: When did they occur? Where did they occur?☼~850-600 Ma
-All of Earth, even at the paleo-equator (evidence says so) - 4☼ How did Earth escape from being ~completely frozen in Neoproterozoic glaciation?☼-Plate tectonics & volcanism continued, so volcanic gas emissions increased CO2 in the air.
-The ice melted when high CO2 levels caused greenhouse effect warming - 5☼What happened just after each Snowball Earth glaciation?☼-Earth got severe climate heating (Earth fried)
-odd carbonate rocks formed on seafloors called cap carbonates (light colored) - 6Did lots of intrusive igneous rocks (magmatic rocks) form during the Mesoproterozoic & Neoproterozoic?Lots of intrusive igneous rocks formed because of extensive magmatism
- 7What are the two largests preserved impact structures on Earth? When were they?-Vredefort Impact (#1 biggest) - 2.023 Ga PP
-Sudbury Impact (squished) - 1.85 Ga PP - 8Where are they the two impacts? What is their significance (if any)?Vredefort - South Africa
Sudbury - Ontario Canada
-the Sudbury impact may have disrupted the oceans
-possible made BIFs stop forming