One of the largest batholiths in the world is the Coast Range Plutonic Complex, which extends all the way from the Vancouver region to southeastern Alaska (Figure 4.23). It might be classified as a stock initially, until someone is able to map out its true extent.īatholiths are typically formed when a number of stocks coalesce beneath the surface to create one large body. A body with an area of less than 100 km 2 exposed at the surface might in fact be much larger at depth. Note that our knowledge of the size of a body can be limited to what we see at the surface. If an irregularly shaped body has an area greater than 100 km 2, then it’s a batholith, otherwise it’s a stock. Large irregular-shaped plutons are called either stocks or batholiths, depending on their area. Source: Karla Panchuk (2018) CC BY 4.0 Types of Plutons Stocks and Batholiths They are named according to these characteristics. Figure 4.22 Plutons can have a variety of shapes, and be positioned in a variety of ways relative to the surrounding rocks.

Laccoliths are like sills, except they have caused the overlying rocks to bulge upward. Tabular plutons are called dikes if they cut across existing structures, and sills if they are parallel to existing structures. Large, irregularly shaped plutons are called stocks or batholiths, depending upon their size. These characteristics determine what name the pluton is given. Plutons can have different shapes and different relationships with the surrounding country rock (Figure 4.22). The resulting body of rock is called a pluton. Some of the magma may reach the surface, resulting in volcanic eruptions, but most cools within the crust. Source: Steven Earle (2015) CC BY 4.0 view source The fragments of dark rock have been broken off and incorporated into the light-colored granite. Figure 4.21 Xenoliths of mafic rock in granite, Victoria, B.C.

Xenoliths may appear as dark patches within a rock (Figure 4.21).

When magma forces itself into cracks, breaks off pieces of rock, and then envelops them, this is called stoping. Pushing the rock aside (where the rock is hot enough and under enough pressure to deform without breaking).In most cases, a body of hot magma is less dense than the rock surrounding it, so it has a tendency to creep upward toward the surface.

Gsp5 chapter 9 answers