Sea-level responses to rapid sediment erosion and deposition in Taiwan

Abstract

Numerous studies have shown that sediment deposition can perturb sea level by several meters over millennial timescales by modifying the gravity field, crustal elevation, and sediment thickness. Relatively few studies have focused on the complementary role of erosion on sea-level change despite its effects on the same quantities, partly because many rapidly eroding mountains are too far from shorelines to strongly perturb sea level at the coast. Taiwan, a mountainous island eroding rapidly within tens of km of the coast, offers an opportunity to investigate the joint influences of rapid onshore erosion and rapid offshore deposition on sea-level change. Here we develop a sediment loading history for Taiwan since the previous interglacial (~120 ka) by compiling published erosion and deposition rate measurements and by applying a geometric marine sediment deposition and compaction model for sites without deposition rate measurements. We use the resulting sediment redistribution history to drive sea-level responses in a gravitationally self-consistent sea-level model. Our simulations show that the effects of rapid onshore erosion outweigh the effects of rapid offshore deposition along Taiwan's east coast.

Holocene relative sea-level changes along the Caribbean and Pacific coasts of northwestern South America

“…A relatively recent publication suggests an RSL fall of ~15 m since the last interglacial (122 ka) at deltas along the Caribbean and Pacific of NW South America due to sediment isostasy (Pico, 2020). Also, crustal uplift can be associated with erosional unloading via sediment isostasy and tectonic uplift, resulting in another source of RSL fall (Ruetenik et al, 2020).…”

Influence of reef isostasy, dynamic topography, and glacial isostatic adjustment on sea-level records in Northeastern Australia

“…Crustal loading due to local processes can also cause the vertical displacement of observed sea-level indicators through isostatic adjustment. For example, sediment loading can cause regional sea level to depart significantly from the global mean along major deltaic systems [18,64,27,64,71,26,88]. Karst erosion is another mechanism that induces isostatic adjustment, through mass unloading, causing a net crustal uplift.…”