Nature of Plutons

-known to occur in a great variety of sizes and shapes
-some structures have a tabular (tabletop) shape, some being massive in size
-classified by their shaps either tabular or massive
-Plutons are discordant or to disagree if they cut across existing structures
-Concordant or to agree if they form parallel features


-are tubular discordant bodies that are produced when magma is injected into fractures
-great enough to seperate the walls of the fracture further
-often found in groups that once served as veritcal oriented pathways followed by molten rock that fed ancient rock flows

Sills and Laccoliths

-Sills are tubular plutons formed when magma is injected along sedimentary bedding surfaces, mostly common when horizontal
-Laccoliths are similar to sills because they form when magma is intruded between sedimentary layers in a near surface environment


-Largest intrusive igneous bodies
-occur as linear structures several hundreds of kilometers long and 100 killometers wide

Stocks- appear to be portions of batholiths that are not yet fully exposed
-consists of rock types having chemical compositions toward the granatic end of the spectrum
-may compose the core of mountain systems