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The Chuí Megaslide Complex: Regional-Scale Submarine Landslides on the Southern Brazilian Margin

2015; Springer Nature (Netherlands); Linguagem: Inglês

10.1007/978-3-319-20979-1_11

2213-6959

António Tadeu dos Reis, Cleverson Guizan Silva, Marcus Aguiar Gorini, Rafael Leão, Nara Pinto, R. Perovano, Marcos V. M. Santos, Josefa Varela Guerra, Izabel King Jeck, Ana Angélica A. Tavares,

earthquake and tectonic studies

The Brazilian Continental Shelf Survey Programme (LEPLAC) identified the occurrence of large-scale mass-transport deposits on the southernmost limit of the Brazilian margin, based mainly on analyses of acoustic imagery. The mass-transport deposits, named the Chuí Megaslide Complex, comprise a stack of large translational slides that spread from the shelf break ~650 km downslope to ~4,900 m water depth, cutting into Pliocene-Quaternary sedimentary successions and strongly affecting both the margin morphology and regional depositional processes. The main headwall scarp is U-shaped, 400–500 m high, and extends c. 80 km downslope as a large elongated evacuated scar, 50–85 km wide. Outside this main failure scar, external scarps evidence a large area of erosion and faulted blocks, indicating ongoing retrogressive sediment disruption. Slide masses occur as a combination of variably deformed failed masses and debris flows, covering an area of ~150,000 km2. Main preconditioning parameters and the possible triggering mechanism for the Chui Megaslide Complex are likely a combination of a series of causative factors such as slope failure structurally-induced by gravity tectonics and high sediment influx into the shelf-edge and upper slope during the Early Miocene-Quaternary.