Greenstone belt facts for kids
Greenstone belts are huge areas of very old rocks. These rocks were once volcanic rocks, but they have changed a lot over millions of years. They get their name because many of the minerals inside them are green. Common green minerals found in these belts include chlorite and actinolite.
What are Greenstone Belts?
Greenstone belts are made mostly of igneous rocks. These are rocks that formed from melted rock, like lava. The most common type of rock found in them is basalt. Basalt is a dark, fine-grained rock.
These belts first formed in ancient oceans. They appeared at places where new ocean floor was being created. They also formed in areas with chains of volcanoes, like islands. Some greenstone belts can be thousands of kilometers long. Over time, these rocks were deeply buried and heated. This process changed them into the "greenstone" rocks we see today. You can also find smaller amounts of sedimentary rocks mixed in.
Where to Find Greenstone Belts
Today, many greenstone belts are found on land. They are often in very old, stable parts of Earth's crust. These stable areas are called cratons. You can find them between other types of rocks, like granite and gneiss.
Most of the rocks in greenstone belts are "mafic." This means they have a lot of magnesium and iron. They also contain a mineral called silica. These rocks tell us a lot about how Earth's crust formed billions of years ago.
Images for kids
-
Kilimafedha greenstone belt in Tanzania
-
Metamorphosed pillow lava from the Ishpeming Greenstone Belt in Michigan
See also
In Spanish: Cinturón de rocas verdes para niños
