The Upper Limit of Denudation Rate Measurement From Cosmogenic ¹⁰Be(Meteoric)/⁹Be Ratios in Taiwan

Abstract

Tectonically active regions produce disproportionately high sediment (physical erosion) (Milliman & Syvitski, 1992) and dissolved (chemical weathering) (Gaillardet et al., 1999) fluxes to the oceans, and therefore play an important role in the global carbon cycle. As an active mountain belt, the Taiwan orogen alone bears eight of the world's 13 rivers with sediment yield >10 4 t/km 2 /yr (Milliman & Farnsworth, 2011) that results from active tectonics and frequent typhoon events. Rates of mineral weathering from silicates and sulfides (Blattmann et al., 2019;Bufe et al., 2021) and rates of organic carbon transport and oxidation (Hemingway et al., 2018;Hilton et al., 2012) in the Taiwan orogen are among the highest worldwide as these processes are driven by rapid denudation. Hence, knowledge of denudation rates that integrate over time scales

Molybdenum Isotopic Fingerprints in Taiwan Rivers: Natural versus Anthropogenic Sources

“…The upper part of the Liwu catchment consists of Miocene to Eocene slate of the Backbone Range, with schists and marble of the Tailuko Belt in the middle and lower reaches [37]. The landslide-dominated Liwu River accounts for 22%, 56%, and 22% of slate, schist, and marble of the total drainage area [41]. No marble outcrops have been reported in the upper reaches of the Waheir and Dasha Rivers and their tributaries, as they drain completely through the Paleozoic-Mesozoic schist of the Tailuko Belt.…”

“…The data shows that the midstream Liwu River had a high SO 4 2− concentration, high Sr concentration, and relatively high (Ca + Mg) concentrations with lighter δ 98/95 Mo and a low Mo concentration, and vice versa downstream. The middle reaches, in particular, the Dasha and Waheir tributary, drain schist and slate with disseminated calcites [41,58]. The enhanced dissolution of disseminated calcites in these low-grade metamorphic terranes is 350 times faster than plagioclase and may be responsible for the release of high (Ca + Mg), Sr, and SO 4 2− content in the middle reaches of the Liwu River [53,59], while the Mo concentration reported in carbonates was very low <0.1 µg/g [60].…”

Landslide-Induced Weathering in Tectonically Active Mountains: Evidence From Dissolved Radiogenic Uranium Isotopes

“…Understanding this linkage requires effective tracers of landslide-induced weathering fluxes (e.g., Li et al, 2018;Li S. et al, 2019), which have received less attention. Studies have used total dissolved solids (TDS, Emberson et al, 2016), elemental composition (Jin et al, 2016), and 10 Be (meteoric)/ 9 Be (Deng et al, 2021) to examine landslide-induced weathering, but we are still lacking tracers of the weathering of fresh bedrock exposed during landsliding. In the previously used tracers, TDS and elemental concentrations are sensitive to lithologic variations and are easily influenced by rainfall-related dilution effects (e.g., Gaillardet et al, 1999;Torres et al, 2015).…”