Physical Sciences and Mathematics Commons^™

Strain Accommodation, Metamorphic Evolution, And 3d Kinematics Of Transpressional Flow Within The Lower Crust Of A Cretaceous Magmatic Arc In Fiordland, New Zealand, Griffin Amoss Moyer

Graduate College Dissertations and Theses

The George Sound Shear Zone (GSSZ) exposed in Bligh Sound within Fiordland, New Zealand allowed us to reconstruct the kinematics of transpressive flow in >100 km2 of exhumed Cretaceous lower crust. We compare the three-dimensional characteristics of the deformation to theoretical models of transpression that assume steady-state flow in a homogeneous medium. This assumption is rarely the case for shear zones that experience metamorphism during deformation. We determined the three-dimensional kinematics of the GSSZ and evaluated the effects of metamorphism on strain accommodation and structural fabric evolution in the GSSZ to determine if metamorphism is an important parameter that transpressional …

4d Strain Path Recorded In The Lower Crust During The Transition From Convergence To Continental Rifting, Doubtful Sound, Fiordland, New Zealand, Michael Ingram

Graduate College Dissertations and Theses

ABSTRACT

Doubtful Sound, in SW New Zealand, exposes an exhumed section of lower crust that represents the root of an Early Cretaceous magmatic arc. Here, the lower crust underwent a change from contraction to extension and these tectonic cycles are fundamental to the growth of continental crust. Mafic-intermediate granulite gneisses occur below the extensional Doubtful Sound shear zone (DSSZ) which records the retrogression and transposition of granulite fabrics at the upper amphibolite facies. I compared 3D rock fabrics, microstructures and textures within and below the DSSZ to determine the processes involved in the shift from contraction to extension and to …