Impact of Spreading Rate and Age-Offset on Oceanic Transform Fault Morphology

Oceanic transform faults (OTFs) are an inherent part of seafloor spreading and plate tectonics, whereas the process controlling their morphology remains enigmatic. Here, we systematically quantify variations in transform morphology and their dependence on spreading rate and age-offset, based on a compilation of shipborne bathymetric data from 94 OTFs at ultraslow- to intermediate-spreading ridges. In general, the length, width and depth of OTFs scale systematically better with age-offset rather than spreading rate. This observation supports recent geodynamic models proposing that cross-transform extension scaling with age-offset, is a key process of transform dynamics. On the global scale, OTFs with larger age-offsets tend to have longer, wider, and deeper valleys. However, at small age-offsets (<5 Myr), scatters in the depth and width of OTFs increase, indicating that small age-offset OTFs with weak lithospheric strength are easily affected by secondary tectonic processes.

Automated summary

Oceanic transform faults (OTFs) are an integral part of seafloor spreading and plate tectonics. A new study has systematically quantified the variations in transform morphology and their dependence on spreading rate and age-offset. The research found that the length, width, and depth of OTFs are more systematically correlated with age-offset than spreading rate. This supports recent geodynamic models that propose cross-transform extension scaling with age-offset as a key process in transform dynamics. Furthermore, OTFs with larger age-offsets tend to have longer, wider, and deeper valleys on a global scale.