Use of a new 10Be and 26Al inventory method to date marine terraces, Santa Cruz, California, USA
Abstract
Marine terraces along active continental margins reflect the interplay between sea-level oscillations and rock uplift. Well-dated marine terraces record the timing of sea-level highstands and delimit both uplift and geomorphic rates. Cosmogenic radionuclides provide a new tool for dating previously undatable terraces. Because the five marine terraces north of Santa Cruz, California, are capped by well-developed soils formed in regressive marine sands, both predepositional cosmogenic radionuclide inheritance and bioturbation of the profile must be accounted for. We present a new cosmogenic radionuclide inventory method that uses the depth-integrated cosmogenic radionuclide concentration to determine the terrace age. This method yields terrace ages that correlate well with sea-level highstands of marine oxygen isotope stages 3, 5a, 5c, 5e, and 7. The implied uplift rate is steady at 1.1 mm/yr, and is two to three times higher than rates suggested by earlier studies.
- Publication:
-
Geology
- Pub Date:
- October 2001
- DOI:
- 10.1130/0091-7613(2001)029<0879:UOANBA>2.0.CO;2
- Bibcode:
- 2001Geo....29..879P