synclinoria

Synclinoria are large-scale, down-folded geologic structures characterized by multiple anticlines and synclines within a broader, regional synclinal depression. Essentially, they are complex synclines that contain smaller, superimposed folds. The term is typically used in the context of fold-and-thrust belts where compressional forces have led to significant crustal shortening and thickening. The overall shape of a synclinorium is a broad, downward bending of rock layers, and within this large downfold, numerous smaller upward folds (anticlines) and downward folds (synclines) are present. These smaller folds are often concentric or similar in style. The formation of synclinoria is a result of prolonged compressional stress acting over large areas, leading to the buckling and folding of sedimentary or metasedimentary rock sequences. They are important features for understanding the structural evolution of mountain ranges and sedimentary basins. The central axis of a synclinorium usually plunges gently, and the flanking limbs can be quite extensive. Erosion can significantly modify the surface expression of synclinoria, revealing the underlying folded structures.