A discordant pluton is a type of igneous intrusion that cuts across the existing rock layers (strata) it intrudes. This means it forms at an angle to the bedding planes of the surrounding rock.

Here's why this is important:

* Discordant intrusion: The pluton "disagrees" with the existing layering, creating a clear boundary between the intruded rock and the surrounding rock.

* Formation: Discordant plutons are typically formed by magma rising through the Earth's crust, often along fractures or zones of weakness.

* Examples: Examples of discordant plutons include:

* Dikes: Tabular, relatively narrow intrusions that cut across the strata.

* Sills: Tabular intrusions that are parallel to the bedding planes but can sometimes have discordant portions.

* Stocks and Batholiths: Large, irregularly shaped intrusions that may have both discordant and concordant portions.

Contrast with concordant plutons: Concordant plutons, in contrast, are parallel to the existing layering, following the bedding planes. They are often called concordant intrusions.

Let me know if you'd like more information about specific types of plutons or how they form!