Geology of the Matata Fault Block, Taupo Volcanic Zone

Abstract

This study investigates the past and present geological history of Matata with a particular focus on the extent to which the geomorphology of the Matata Fault Block is influenced by the relationship between active tectonics and the engineering geological properties of the stratigraphy. I describe in detail the geomorphic features observed throughout the Matata Fault block, and compare the geotechnical, structural, and geomorphic aspects for each catchment. Using the structural and stratigraphic data collected throughout Awatarariki and Waitepuru Streams it is possible to produce a timeline of development for the Matata Fault Block. Analysis of the geometry and kinematics of faults within the Whakatane rift system allows a greater understanding of the relationships between the formation and evolution of the Matata Fault Block. The Matata Fault Block is characterised by predominantly SE-dipping normal faults, which appear to be antithetic to large NW-dipping structures on the eastern margin of the Whakatane Graben. Striations and stereonet representations of conjugate faults throughout the MFB indicate that dip slip is the primary method of fault movement, although a small component of strike slip is occurring throughout the Matata Fault Block.