Microstructural evolution within a partitioned midcrustal transpression zone, northeast Greenland Caledonides

摘要: [1] The thrust-related Imbricate Zone and the sinistral strike-slip Storstrommen Shear (SSZ) are two major orogen-parallel ductile shear zones that mark western limit of intense Caledonian deformation in northeast Greenland transect orogenic hinterland, respectively. Detailed microstructural analysis associated mylonitic fault rocks from Dronning Louise Land Hertugen af Orleans has been carried out to provide insights into evolution these structures constrain relative timing movement. Amphibolite-facies mylonites were developed across entire ca. 8-km-wide SSZ currently exposed an area 3–4 km wide within center zone. In contrast, retrograde greenschist-facies concentrated a 2- 4-km-wide belt along margin This metamorphic pattern is interpreted reflect progressive localization strain with exhumation syntectonic cooling. The 15-km-wide consists numerous east-dipping thrust sheets. At low structural levels, fabrics indicate occurred at middle-greenschist facies. Toward higher however, microstructures suggest grade progressively increases. We propose thrusting was synchronous uplift hinterland SSZ, accounting for observed variations. implies both active broadly contemporaneously during regional partitioned transpression, inference supported by scattered 40Ar/39Ar recent U-Pb zircon ages. observations therefore support models involve sinistrally oblique Silurian-Devonian collision between Laurentia Baltica.