Interpolated surface of the Mai’iu fault plane that bounds the Dayman Dome metamorphic core complex, based on observations of preserved fault plane remnants in present day topography (gray dots). This interpolation illustrates the tilting of the fault surface with progressive exhumation (distance from the Mai’iu fault trace, shown as a solid red line), until the fault surface is tilted in the opposite direction to its initial dip at the crest of Dayman Dome. The orange and yellow region to the east, enclosed by a red and white dashed line, is a remnant of the Mai’iu fault hanging wall block that has been stranded on the footwall. Credit: Mizera et al. [2019], Figure 5a
Source: Tectonics

Low-angle normal faults are recognized in both oceanic and continental extensional regimes and are commonly associated with metamorphic core complexes. These core complexes are comprised of suites of crustal rocks that have been exhumed to the surface from significant depths, and that record deformation associated with crystal-plastic as well as brittle (seismogenic) processes. The mechanisms by which low-angle normal faults exhume rocks from such deep crustal levels, however, are unclear.

Through a combination of detailed geologic and structural observations and geomorphic mapping, Mizera et al. [2019] present a detailed analysis of the geometry and kinematic evolution of the Mai’iu fault, an active low-angle normal fault that bounds the Dayman Dome metamorphic core complex in Paupa New Guinea. Progressive tilting of the fault surface accompanying exhumation supports a “rolling-hinge” model of extensional tectonism, in which deep crustal plastic flow isostatically uplift and domes the tectonically denuded metamorphic core complex in the foot wall of the fault.  This study should be of wide interest due to the ubiquity of low-angle normal faults in both extensional and contractional orogenic belts globally.

Citation: Mizera, M., Little, T. A., Biemiller, J., Ellis, S., Webber, S., & Norton, K. P. [2019]. Structural and geomorphic evidence for rolling‐hinge style deformation of an active continental low‐angle normal fault, SE Papua New Guinea. Tectonics, 38.

—Nathan Niemi, Editor, Tectonics

Text © 2019. The authors. CC BY-NC-ND 3.0
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