ACF ACF DIAGRAME/PLOT IN METAMORPHIC PETROLOGY

5.3 Facies Diagrams: ACF and AKF Diagrams. Chemographics refers to the graphical representation of the chemistry of mineral assemblages. Such chemographic diagrams, when applied to a group of coexisting mineral assemblages under a limited range of P-T conditions, are called compatibility diagrams.. The document discusses the plotting of ACF-AKF-AFM diagrams for metamorphic rocks, emphasizing the reduction of complex oxide compositions to three components for easier visualization. It explains the significance of tie lines in triangular composition diagrams, the phase rule, and how to calculate plotting parameters for ACF diagrams. The document also outlines methods to simplify component.

AKF DIAGRAM Because pelitic sediments are high in Al2O3 and K2O, and low in CaO, Eskola proposed a different diagram that included K2O to depict the mineral assemblages that develop in them. In AKF diagrams we assume that both alkali feldspar and plagioclase feldspar can be present, thus the amount of Al2O3 that we use is the excess Al2O3 left after allotting it to all of the feldspars. The K.. AKF diagram The AKF diagram is intended for rocks containing excess aluminium and silica. Its components are: A = Al2O3 - (CaO + Na2O + K2O) K = K2O F = FeO + MgO + MnO This diagram is less useful, because magnesium does not freely substitute for ferrous iron in many metamorphic minerals important in aluminium-rich rock.