What is an ACF diagram?
ACF diagram A three-component, triangular graph used to show how metamorphic mineral assemblages vary as a function of rock composition within one metamorphic facies. Besides SiO 2, the five most abundant oxides found in metamorphic rocks are Al 2O 3, CaO, FeO, MgO, and K 2O.
What is Chemographic diagram?
Minerals and rocks have chemical compositions that comprise some of the most important data for phase equilibria studies. Important relationships among rocks and minerals can be discovered or demonstrated by the construction of composition diagrams (also called chemographic diagrams) to display the data.
What is a pelitic rock in geology?
A pelite (Greek: pelos, “clay”) or metapelite is a metamorphosed fine-grained sedimentary rock, i.e. mudstone or siltstone.
What are barrovian zones?
Barrovian metamorphism takes place during regional metamorphism, caused by crustal thickening in the roots of an orogenic belt (under mountain chains). Barrovian zones are especially easy to recognize in pelitic rocks.
How do you read a ternary diagram?
Reading Ternary Diagrams
- Locate the 1 (or 100%) point on the axis.
- Draw a line parallel to the base that is opposite the 100% point through the point you wish to read.
- Follow the parallel line to the axis.
- Repeat these steps for the remaining axes.
Is shale a pelitic?
Metamorphic rocks Disten or sillimanite, cordierite, and staurolite schists occur in conditions of high-degree metamorphism from pelite sediment, that is, shale, mudstone, and marl.
What is the barrovian sequence?
A sequence of regional metamorphic mineral reactions recorded by the successive mineral assemblages seen in metapelites (metamorphosed or sandy shales) from the Barrovian terrain around Glen Esk in north-eastern Scotland and characteristic of medium regional metamorphic gradients of temperature and pressure.
What is the purpose of ternary diagram?
A ternary diagram is a triangular coordinate system; the edges of the triangle are the axes. Ternary diagrams are used to plot three dependent variables that always add up to a fixed value, for example, to visualize the compositional variations of rocks or minerals.
What is the difference between slate and shale?
Main Differences Between Shale and Slate Slate is soft, whereas Shale is hard as shale undergoes a metamorphosis. Shale is a sedimentary rock, and Slate is a metamorphic rock, but both are fine-grained. Shale looks dull, and Slate looks shiny when observed in daylight.