Tectonic controls on Quaternary landscape evolution in the Ventura basin, southern California, quantified using cosmogenic isotopes and topographic analyses
File(s)
Accepted version
Author(s)
Type
Journal Article
Abstract
The quantification of rates for the competing forces of tectonic uplift and erosion has important implications for understanding topographic evolution. Here, we quantify the complex interplay between tectonic uplift, topographic development, and erosion recorded in the hanging walls of several active reverse faults in the Ventura basin, southern California, USA. We use cosmogenic 26Al/10Be isochron burial dating and 10Be surface exposure dating to construct a basin-wide geochronology, which includes burial dating of the Saugus Formation: an important, but poorly dated, regional Quaternary strain marker. Our ages for the top of the exposed Saugus Formation range from 0.36 +0.18/-0.22 Ma to 1.06 +0.23/-0.26 Ma and our burial ages near the base of shallow marine deposits, which underlie the Saugus Formation, increase eastwards from 0.55 +0.08/-0.07 Ma to 3.30 +0.30/-0.42 Ma. Our geochronology is used the calculate a rapid long-term fault throw rate of 4.7–6.3 mm yr-1 since ~1.5 Ma for the San Cayetano fault and a slip rate of 1.3–3.0 mm yr-1 since ~1.5 Ma for the Oak Ridge fault, both of which agree with contemporary reverse slip rates derived from GPS data. We also calculate total cosmogenic nuclide (TCN)-derived catchment-averaged erosion rates that range from 0.18–2.21mm yr-1 and discuss the applicability of TCN-derived catchment-averaged erosion rates in rapidly-uplifting, landslide-prone landscapes. We compare patterns in erosion rates and tectonic rates to fluvial response times and geomorphic landscape parameters to show that in young, rapidly-uplifting mountain belts, catchments may attain a quasi-steady state on timescales <105 years, even if catchment-averaged erosion rates are still 34 adjusting to tectonic forcing.
Date Issued
2022-09-01
Date Acceptance
2021-08-16
Citation
Geological Society of America Bulletin, 2022, 134 (9-10), pp.2245-2266
ISSN
0016-7606
Publisher
Geological Society of America
Start Page
2245
End Page
2266
Journal / Book Title
Geological Society of America Bulletin
Volume
134
Issue
9-10
Copyright Statement
© 2022 Geological Society of America
Identifier
https://pubs.geoscienceworld.org/gsa/gsabulletin/article/doi/10.1130/B36076.1/610673/Tectonic-controls-on-Quaternary-landscape
Subjects
Geology
0402 Geochemistry
0403 Geology
0404 Geophysics
Publication Status
Published online
Date Publish Online
2021-10-26