I moved this article out of the main Wikipedia because, as I was doing additional research to flesh out the article, I found a second date for it. Most of the references have it in the 2800 million year ago time period, just prior to the Algoman Orogenty (3/20/10 - I'm working on that now at one of my user pages). A few references show the 3800 million year ago date. So, until I have time to resolve the issue, I decided to move it.
The Saganagan Orogeny occurred during the Archaean Eon some 3,500 million years ago.[1] The mountains uplifted by this orogeny are in the area of the international border between Minnesota, U.S., and Ontario, Canada, in the vicinity of the Rove Formation. These mountains have completely eroded and the remnants are buried by sediments from later erosions.
Beginning of Archaean Eon
editDuring the Archaean Eon Earth's interior was probably about three times hotter than it is today; there was a higher concentration of radioactive isotopes, plus the residual heat from Earth's accretion contributed to this heat.[2] The additional heat flow probably caused the mantle to be more fluid than today and the crust much thinner.[2]
Protocontinents
editIt is theorized that there were multiple small continental crustal pieces, called protocontinents, which were probably less than 500 km (310 mi) in diameter.[3] The collision of at least two of these probably created the Saganagan Mountains.
The theorized first supercontinent, Vaalbara, existed during the early Archaean Eon.[4]
End of Archaean Eon
editBy the end of the Archaean Eon heat flows fell to two times current levels.[5]
References
edit- ^ George-Williams, Sylvia (March 22, 2001). "Geologic Time (review)". p. slide 2. Retrieved February 13, 2010.
- ^ a b Benninton, J Bret. "Geol 02 Archean lecture". p. 1. Retrieved February 13, 2010.
{{cite web}}: Cite has empty unknown parameter:|1=(help) - ^ Wright, JD. "Chapter 6 Lecture Notes, The Archean Eon of Precambrian Time" (PDF). p. 5. Retrieved February 13, 2010.
{{cite web}}: Cite has empty unknown parameter:|1=(help) - ^ "Supercontinents". enotes.com Science. pp. 1–2. Retrieved March 14, 2010.
- ^ "Paleogeology: Paleogeology, Paleoclimate, in relation to Evolution of Life on Earth". posted 12/31/2008 at 11:59:00 PM. p. 3. Retrieved March 7, 2010.
{{cite web}}: Check date values in:|date=(help); Cite has empty unknown parameter:|1=(help)
See also
editSaganaga Lake Saganaga Lake, Ontario
Category:Orogeny Category:Geology of Minnesota Category:Geology of Ontario Canada - United State border {{tectonics-stub}}