Inversion of fluvial channels for paleorock uplift rates in Taiwan

Abstract

The transient response of erosion to changes in rock uplift rate leads to the preservation of rock uplift history in the long profiles of rivers. However, extracting this information is nontrivial as changes in channel steepness are the result of both spatial and temporal changes in rock uplift rate, as well as other factors such as climate and rock type. We exploit an analytical linear solution for river channel profile evolution in response to erosion and tectonic uplift to investigate the rock uplift history of Taiwan. The analytical approach allows us to solve the linear inverse problem, efficiently extracting rock uplift as a function of space and time, from digital elevation data. We assess the potential of fluvial topography to resolve rock uplift rates using three approaches: (1) a synthetic resolution test, (2) analysis of the forward model to demonstrate where in space and time the fluvial topography constrains rock uplift rate, and (3) interpretation of the model resolution matrix. Furthermore, the potential to analyze large data sets reduces the influence of stochastic processes such as landslides, small-scale river network reorganization, and also local lithological variability. In Taiwan, our analysis suggests that current rock uplift rates exceed erosion rates across much of the island and that there has been an increase in rock uplift rates since 0.5 Ma across the Central Range.

Landscape evolution models using the stream power incision model show unrealistic behavior when <i>m</i> ∕ <i>n</i> equals 0.5

“…The ratio m/n is also used to describe the relationship between slope and drainage area in describing stream long profiles (Flint, 1974). All models using SPIM, including studies on drainage reorganization and stability , tectonic histories of landscapes (Goren et al, 2014b;Fox et al, 2014), and persistent drainage migration (Pelletier, 2004), involve the specification of this ratio. In addition, the specific values of m and n are important (Tucker and Whipple, 2002).…”

River profile response to normal fault growth and linkage: an example from the Hellenic forearc of south-central Crete, Greece

“…4). Only basins draining ≥ 3 km 2 were analyzed because it has been shown that ephemeral streams, such as those on Crete, have difficulty responding to tectonic forcing at small drainage areas (e.g., Frankel and Pazzaglia, 2005). We delineated 21 drainage basins and labeled them 1 to 21 from west to east (Fig.…”

The CAIRN method: automated, reproducible calculation of catchment-averaged denudation rates from cosmogenic nuclide concentrations

“…Simulating nuclide concentrations in settings where denudation rates vary in space and time is possible (Mudd, 2016), but computationally intensive and one must have some confidence that one can accurately reconstruct the temporal evolution of denudation rates. Although recent progress has been made in deriving time series of denudation rates from current topography (e.g., Whittaker et al, 2008;Pritchard et al, 2009;Hurst et al, 2013;Goren et al, 2014;Fox et al, 2014;Croissant and Braun, 2014;Rudge et al, 2015), these methods still suffer from the fact that we lack devices for time travel and struggle to test such reconstructions.…”