Geomorphic response of submarine canyons to tectonic activity: Insights from the Cook Strait canyon system, New Zealand

Abstract

Abstract:Active margins host more than half of submarine canyons worldwide. Understanding the coupling between active tectonics and canyon processes is required to improve modeling of canyon evolution and derive tectonic information from canyon morphology. In this paper we analyze high resolution geophysical data and imagery from Cook Strait canyon system (CS), offshore New Zealand, to characterize the influence of active tectonics on the morphology, processes and evolution of submarine canyons, and to deduce tectonic activity from canyon morphology. Canyon location and morphology bear the clearest evidence of tectonic activity, with major faults and structural ridges giving rise to sinuosity, steep and linear longitudinal profiles, crosssectional asymmetry, and breaks in slope gradient, relief and slope-area plots. Faults are also associated with stronger and more frequent sedimentary flows, steep canyon walls that promote gully erosion, and seismicity that is considered the most likely trigger of failure of canyon walls. Tectonic activity gives rise to two types of knickpoints in CS. Gentle, rounded and diffusive knickpoints form due to short wavelength folds or fault break outs. The more widespread steep and angular knickpoints have migrated through canyon floor slope failures and localized quarrying/plucking. Migration is driven by base level lowering due to regional margin uplift and deepening of lower Cook Strait Canyon, and is likely faster in larger canyons because of higher sedimentary flow throughput. The knickpoints, non-adherence to Playfair's Law, linear longitudinal profiles and lack of canyon-wide, inverse power-law slope-area relationships indicate that the CS is in a transient state, adjusting to perturbations associated with tectonic displacements and changes in base level and sediment fluxes. We conclude by inferring unmapped faults and regions of more pronounced uplift, and proposing a generalized model for canyon geomorphic evolution in tectonically-active margins. Powered by Editorial Manager® and ProduXion Manager® from Aries Systems CorporationCover Letter Click here to download Cover Letter: Cover letter.

A 3‐D Model of Gas Generation, Migration, and Gas Hydrate Formation at a Young Convergent Margin (Hikurangi Margin, New Zealand)

“…Trends in hydrate distribution; (a) bathymetric map of the southern Hikurangi Margin showing predicted trends of high gas hydrate concentrations (I: yellow vertical bars, II: white horizontal bars, III: red diagonal bars, IV: black diagonal bars), direct evidence for occurrence of concentrated hydrate from seismic data from Crutchley et al (; blue marks), seep sites at Opouawe Bank (green circles), the principal deformation front at present‐day (black lines, after Barnes et al, and Micallef et al, ) and related to Mesozoic subduction (dotted line). (B) Hydrate saturations predicted in scenario B for the lowermost layer within the HSZ, overlain on the same bathymetric map (grayscale).…”

“…Subduction beneath Gondwana ceased when the young buoyant Hikurangi Plateau entered the subduction system at about 105 Ma (Davy et al, 2008). Late Kroeger et al (2015, red line), plate convergence vectors (yellow arrows) based on Beavan and Haines (2001,), and thrusts of the principal deformation front (black lines, after Barnes et al, 2010 andMicallef et al, 2014). The blue line indicates the transect shown in Figure 2.…”

“…Map of the study area showing the outline of the PetroMod™ 3‐D model (yellow polygon), seismic reflection surveys used in this study (white lines), the location of the 2‐D model of Kroeger et al (, red line), plate convergence vectors (yellow arrows) based on Beavan and Haines (,), and thrusts of the principal deformation front (black lines, after Barnes et al, and Micallef et al, ). The blue line indicates the transect shown in Figure .…”

The Kongsfjorden Channel System offshore NW Svalbard: downslope sedimentary processes in a contour-current-dominated setting

“…Multiple factors contribute to the formation of canyons, in particular mass wasting [63], but also tectonic activity (e.g. [42]). Canyon formation can originate at both the lower and upper slopes (see [59], and references therein).…”

A review of marine geomorphometry, the quantitative study of the seafloor

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