Development of Migmatite Structure: Overprinting

Abstract

Regardless of the mechanism involved in the deformation, the basic principle regarding refold relationships stated earlier always applies, namely that where overprinting (Sander’s ‘Uberpragung’, 1911) has taken place, the structural features that are overprinted are earlier than those that overprint them. This rule, fundamental in geology, has as its counterpart in stratigraphy, the ‘Law’, or ‘Principle of Superposition’ enunciated by William Smith (1789-1839) and based on observations by other geologists (Wyatt, 1986, in Challinor’s Dictionary of Geology, 6th Edition, p. 179, and especially p. 309). See also the reference to Hutton (1795) in Chapter 1. The rule is the basis of the approach described here for resolving the structural complexity caused by repeated deformation, in particular multiple folding, an approach that depends on the direct observation of overprinted relationships on the outcrop. Two basic principles can be stated.