Abstract
The up to 1000 km-long Magallanes Fault System (MFS) is the southernmost onshore strike-slip plate boundary and located between the South American and Scotia Plates. Slip-rates, a key factor for understanding neotectonics and seismic hazard are only available there from geodetic models. In this study, we present the first direct geologic evidence of MFS slip rates. Late-Cenozoic slip rates along the main MF is 5.4 ± 3.3 mm/yr based on lithologic geological separations found in regional mapping. Late-Quaternary deformation from offset geomorphologic markers was documented along the MFS in Chile and Argentina based on a combination of satellite mapping, fieldwork, and Structure from Motion (SfM) models developed from drone photography. By combining displacements observed in SfM models with regional Late-Quaternary dating, sinistral slip rates are 10.5 ± 1.5 mm/yr (Chile) and 7.8 ± 1.3 mm/yr (Argentina). By comparing our results with regional models, contemporary plate boundary deformation is narrow, approximately ~20–50 km wide from Tierra Del Fuego (TdF) and east (one of the narrowest on Earth), which widens and becoming more diffuse from Cabo Froward north and west (>100 km wide). In addition to the tectonic implications, these faults should be considered important sources of fault rupture and seismic hazard.
Highlights
Plate boundary faults are first-order neotectonic structures which accommodate large proportions of crustal scale deformation along narrow zones and are important sources of seismic hazard
Magallanes Fault System (MFS)-Northern Scotia Ridge (NSR) transform system development may have initiated at ~6 Ma19, coeval with cessation of western Scotia seafloor spreading and a significant increase in the Eastern Scotia ridge activity[17,18] (Fig. 1), which led to the current plate geometry with the inactive West Scotia Ridge and ongoing sinistral motion
Geological horizontal separations between lithologic units we identified along the MFS main trace (Fig. 1) suggest that total left-lateral Magallanes fault (MF) slip ranges from 40 ± 5 km to 60 ± 5 km
Summary
Plate boundary faults are first-order neotectonic structures which accommodate large proportions of crustal scale deformation along narrow zones and are important sources of seismic hazard. Onshore it is ~11 km long but likely continues offshore within the Almirantazgo Fiord according to seismic reflection data from the Strait of Magellan[4], and to the east www.nature.com/scientificreports trending parallel or merging with the MF in Lake Fagnano.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
