Multiphase Boudinage: a case study of Amphibolites in Marble in the Naxos Migmatite core

Abstract

In multiply deformed terrains, multiphase boudinage should be common, but identification and analysis of these is difficult.Here we present an analysis of multiphase boudinage and fold structures in deformed amphibolite layers in marble from the migmatitic center of the Naxos metamorphic core complex. Reconstruction of multiple boudinage generations is possible due to the exceptional 3D outcrop conditions. We identify five distinct generations of boudinage, reflecting the transition 10 from high-strain -high-temperature ductile deformation to medium to low strain brittle boudins on the retrograde path during cooling and exhumation. All boudin generations indicate E-W horizontal shortening and variable directions of bedding parallel extension, evolving from subvertical extension in the earliest boudins to subhorizontal N-S extension during exhumation. Two phases of E-W shortening can be inferred, indicating E-W shortening in the Aegean before activity of the brittle North Anatolian Fault. This study highlights the wealth of information that can be gained from detailed analysis of 15 multiphase boudinage structures.