I am sure some of us have heard of geological “hotspots.” But I bet that most of us didn’t realize that a hotspot occurred right underneath us in the Keweenaw Peninsula. There is no need to worry, however, because that was about 1.2 to 1.0 billion years ago. What is a hotspot? They are areas of volcanic activity that are believed to be caused by an anomalously hot underlying mantle or an unusually thin lithosphere (crust and uppermost mantle). Some very well-known current examples are the Hawaiian Islands and underneath our fellow national park, Yellowstone. The hotspot in the Keweenaw was a big one with its focus somewhere underneath the Lake Superior area. Its effects are found starting around where Kansas is now and extended up through eastern Nebraska, Iowa, Minnesota, Wisconsin, and then it curled around through the middle of Lake Superior and back down through the eastern U.P. and finally ended around the Detroit area. This hotspot is responsible for the super eruption that laid down our thick series of basalts that later were mineralized with copper and other minerals. Some of these layers became hosts to the world’s largest known deposits of native metallic copper. #ThrowbackThursday If you are interested in learning more about the hotspot in the Keweenaw Peninsula visit: geo.mtu.edu/~raman/SilverI/KeweenawGeoheritage/Hot_Spot.html
Posted on: Thu, 23 Oct 2014 13:00:01 +0000
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