Zhan, Wenhuan
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Zhan, Wenhuan
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Zhan, Wenhuan
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Item-typ:Veröffentlichung, Incision of Submarine Channels Over Pockmark Trains in the South China SeaThe genesis of submarine channels is often controlled by gravity flows, but channels can also be formed by oceanographic processes. Using multibeam bathymetry and two-dimensional seismic data from the western South China Sea, this study reveals how pockmarks can ultimately form channels under the effect of bottom currents and gravity-driven sedimentary processes. We demonstrate that alongslope and across-slope channels were initiated by pockmark trains on the seafloor. Discrete pockmarks were elongated due to the erosion of gravity-driven sedimentary processes and bottom currents, and later coalesced to form immature channels with irregular thalwegs. These gradually evolved into mature channels with continuous overbanks and smooth thalwegs. Submarine channel evolution was significantly influenced by seafloor topography since the Late Miocene. The evolutionary model documented here is a key to understanding how channels are formed in deep-water environments.Wissenschaftlicher ArtikelBand:48Heft:e2021GL092861179 190 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Channel inception through bottom‐current erosion of pockmarks revealed by numerical simulation(2023-04-23); ; ; ; In deep-marine environments, the inception of channels can be induced by the interaction between bottom currents and rough topography. However, it is still unclear under which conditions such features can form and what happens in the earliest phase of channel development. In this study, based on the morphological, sedimentary and oceanographic settings of a pockmark field in the NW South China Sea, we reveal the process of channel inception through the erosion of pockmarks by bottom currents. Using numerical simulations, we show that an appropriate current velocity can induce the erosion of pockmark trains in cohesive sediments, leading to the coalescence of discrete pockmarks and the formation of a channel with a rough thalweg. The interaction of bottom currents with the pockmarks induces a significant erosion along the pockmarks axis. Bottom current erosion is strongest at the downstream edges of pockmarks, where the horizontal velocity reaches a maximum and an upwelling forms. Erosion increases as the distance between pockmarks reduces. In our simulation results, a channel is only formed by the coalescence of pockmarks if the distance between pockmarks is <6 times the diameter of the pockmark. This study provides evidence of the formation of channels by bottom currents, which helps reconstruct paleoceanographic conditions based on sediment architecture. It also shows the complex hydrodynamics at these structures that strongly control sedimentary processes and may affect distribution of benthic ecosystems in marine environments.Wissenschaftlicher Artikel209 235