Constraining the Timespan of Fluvial Activity From the Intermittency of Sediment Transport on Earth and Mars
The timespan recorded in deposits from fluvial activity is a key gap in our understanding of ancient environments on Earth and Mars. Because riverine sediment transport occurs under time-variable water discharge, common models that represent sediment transport with a single bankfull discharge require an intermittency factor. For this reason, the ability to predict intermittency factor values based on environmental factors would improve estimates of time from fluvial deposits. To address this knowledge gap, we calculated intermittency factors from 201 modern rivers and six fans and deltas with depositional timespans of months to millions of years. Intermittency factors range from 0.0064–0.73; they are uncorrelated with averaging timescale, bed-material grainsize, or climate aridity, but are larger in river catchments with greater rates of denudation relative to precipitation. Application to ancient fluvial systems on Mars indicates long-lived depositional river systems for up to 10⁴–10⁶ years.
© 2021. American Geophysical Union. Issue Online: 18 August 2021; Version of Record online: 18 August 2021; Accepted manuscript online: 16 July 2021; Manuscript accepted: 24 May 2021; Manuscript revised: 01 May 2021; Manuscript received: 18 January 2021. This work was supported by NASA (grant NNX16AQ81G1960 to MPL and graduate fellowship support 80NSSC17K0492 to A. T. Hayden). The authors have no financial conflicts of interest. Data Availability Statement: Data from sedimentary deposits and modern rivers are at http://dx.doi.org/10.22002/D1.2023 and the supplement describes methods in additional detail. All survey data are available in the original publications: Emmett, 1972; Williams, 1978; Andrews, 1984; Elliott and Cartier, 1986; Castro and Jackson, 2001; McCandless and Everett, 2002; McCandless, 2003a, 2003b; Cinotto, 2003; Moody et al., 2003; Lawlor, 2004; Metcalf et al., 2009; Chaplin, 2005; Keaton et al., 2005; Sherwood & Huitger, 2005; Mistak and Stille, 2008; Agouridis et al., 2011; Wilkerson & Parker, 2011; Brockman et al., 2012; Foster, 2012. Original USGS streamgage data can be downloaded from https://waterservices.usgs.gov and McMurdo LTER streamgage data from https://mcm.lternet.edu/content/daily-summarized-seasonal-measurements-discharge-water-temperature-and-specific-conductiv-14.
Published - 2021GL092598.pdf
Supplemental Material - 2021gl092598-sup-0001-supporting_information_si-s01.docx