Difference between Tectonic plates and Shields?

Question

What is really the difference beween the Tectonic Plates and Shields. As there are 19 plates all over the world, there is also a mention of Shields. Plates are decribed as Eurasian, Indian etc and Shields are often described as Laurentian , Gondawana etc . What is the difference between the two?

Answer 1

Shields are the very old cores of continents. For example, the Canadian (also called Laurentian or Precambrian) Shield is the region in North America underlain by Precambrian rocks.
The rocks are mostly igneous, including lots of granitic rocks, and metamorphic. The geographic extent of the shields is smaller than the size of a whole continent or a whole tectonic plate. Because they are very old, the worn-down surfaces are not very mountainous.
"Shield" is not a descriptor of any part of the modern ocean floor. So, the Pacific and Nazca plates, for instance, don't have shields. Neither does the Atlantic ocean floor.

Answer 2

Shield volcanoes have low viscosity and cover a very large area with a gradual slope unlike their more viscous counterparts. In addition, they form as a result of deep "hotspots" that exist far below any tectonic plate above. The best example of this are the Hawaiian Islands, which were formed over the course of millions of years as the Pacific Ocean Plate moved but the hotspot ejecting very liquid basalt lava to form the islands stayed where it was. The reason for this low viscosity has to do with the content of the magma that comes from hotspots as opposed to rifting or subduction zones, which see much more violent, viscous eruptions.

Answer 3

I could be very wrong on this, but Gondawana was a super continent many millenia ago. So, that would be the difference, but I could easily be very wrong.

Answer 4

tricky subject. do a search with the search engines. just that can assist!