Hot Spot

Keweenaw Hot Spot: K Schulz, USGS

Volcanologists agree that super-eruptions lie in the Earth’s future, but the time and place is uncertain.

Heat flow bottom line:

The Keweenaw Rift record shows how Earth has highly irregular deep seated convective events that help shape the planet.  They come and go in time and space.  Once the hot spot of the whole world, now the Keweenaw has heat flow that is far below average.

So in Stenian time, 1.2 to 1.0 billion years ago, a hot spot began underneath us (Rodinia, then).  This led to a supereruption!

Then what?  The heat led to magma which rose in dikes that eventually split the continent and started rifting---great fissures opened from Kansas, through Lake Superior and on to Detroit. And the cracks widened, forming a deep trench in the continent, like many rifts that are active around the world today.

The USGS map above shows the East African rift zone and the Red Sea.  These are areas where rifting is occurring now.  In these places there are many black basaltic lava flows accumulating within rift basins, and there are also broad alluvial fans filling the basins from the steep flanks. The hot spot is the triple junction of rifts near the S end of the Red Sea. Below is a map of some other hot spots.

GeoElements of Michigan’s Keweenaw:

Lavas    Sandstone    Fault    Glaciers    Lake

How LIPS relate to extinctions: