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

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

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

Cited by 6 publications

(3 citation statements)

References 5 publications

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“…Clinoforms and incisions connecting this paleocanyon with the shelf were not observed. In the same region, but at the shelf‐edge, the Chuí megaslide occurs with ca.60 km of horizontal length, ca.414 m of wall height (ca.460 ms TWT) and ca.660 m of total vertical relief (ca.740 ms TWT; dos Reis et al., 2016).…”

Section: Resultsmentioning

confidence: 99%

“…Miocene RGC depositional evolution is therefore interpreted to be analogous to the modern Chuí megaslide and the megaslide complexes of the Amazon Fan (Figure 10; dos Reis et al., 2016; Silva et al., 2016). Another example of a large‐scale mass‐wasting comparable to the RGC is the Storegga Slide, where slope instability has been linked to the dissociation of gas hydrates (Mienert et al., 2005).…”

Section: Discussionmentioning

confidence: 97%

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Neogene evolution of the margin adjacent to the La Plata River Delta (Pelotas Basin): Sedimentary pathways and the origins of the Rio Grande Cone

Tagliaro,

Britzke,

Gama

et al. 2024

Basin Research

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Continental margins that exhibit high terrigenous input are generally located near deltas that are capable of transporting large quantities of sediments into the basin. However, in rare cases, high terrigenous sedimentation occurs in regions deprived of major riverine systems where the sedimentary pathway is enigmatic. One such case is the Neogene of the Pelotas Basin of Brazil and Uruguay, adjacent to the La Plata River mouth. Since the Miocene, anomalous sedimentation formed a giant progradational wedge, the Rio Grande Cone, one of the largest submarine fan‐like features on Earth. To understand the Neogene evolution of the margin and the origins of the Rio Grande Cone, here we present a seismic‐stratigraphic framework based on well‐logs and 2D seismic data. Three depositional environments are identified: (1) on the shelf, upper Miocene to Pliocene fluvial channels delivered sand deposits on the mud‐dominated shelf; (2) on the slope, sediment instability resulted in structural deformation and multiple phases of mass transport deposition and (3) on the lower slope and basin floor, large contourite drifts formed by sediment reworking. We classify the Rio Grande Cone as a megaslide complex, due to its depositional and structural setting. Local deltaic systems were active on the shelf in the Neogene, but the limited size of their paleo‐drainage systems in comparison to the volume of sedimentation in the margin suggests that an additional sedimentary pathway existed. In this sense, the demise of an epicontinental sea over the La Plata Basin during the Neogene likely enabled the input of large volumes of fine sediments into the margin, via the La Plata plume water. We suggest that the desiccation of this epicontinental sea and the intensification of ocean currents since the middle Miocene explains the anomalous Neogene terrigenous influx into the SW Atlantic margin.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 97%

Neogene evolution of the margin adjacent to the La Plata River Delta (Pelotas Basin): Sedimentary pathways and the origins of the Rio Grande Cone

Tagliaro,

Britzke,

Gama

et al. 2024

Basin Research

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“…Mass wasting deposits of smaller scale are observed near the feather edge of the GHSZ on the Rio Grande cone [53]. A megaslide complex is recognized to the south of the Rio Grande cone, with headwall scarps near the shelf-break and upper slope, although there is no clear association with gas hydrate systems in the area and gravity tectonics has been proposed as the main triggering mechanism [68]. Along most of the continental slope, gas hydrate stability has decreased since the last glacial maximum (LGM) due to the warming of South Atlantic bottom waters, by at least 3.5˚C at 657 m depth on the upper Rio Grande cone [69].…”

Section: Discussionmentioning

confidence: 99%

Gas Seeps at the Edge of the Gas Hydrate Stability Zone on Brazil’s Continental Margin

Ketzer

Praeg

Pivel³

et al. 2019

Preprint

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Gas hydrate provinces are present in at least in two areas along Brazil’s continental margin: (1) the Rio Grande Cone in the southeast, and (2) the Amazon deep-sea fan in the equatorial region. The occurrence of gas hydrates in these depocentres was first detected geophysically and has recently been proven by seafloor sampling of gas vents, detected as water column acoustic anomalies rising from seafloor depressions (pockmarks) and/or mounds, many associated with seafloor faults. The gas vents include typical features of cold seep systems, including shallow sulphate reduction depths (<4 m), authigenic carbonate pavements and chemosynthetic ecosystems. In both areas, gas sampled in hydrate and in sediments is dominantly formed by biogenic methane. Calculation of the methane hydrate stability zone for water temperatures in the two areas shows that gas vents occur along its feather edge (water depths between 510-760 m in the Rio Grande Cone and 500-670 m in the Amazon deep-sea fan) but also in deeper waters within the stability zone. Gas venting along the feather edge of the stability zone could reflect gas hydrate dissociation and release to the oceans, as inferred on other continental margins, or upward fluid flow through the stability zone facilitated by tectonic structures recording the gravitational collapse of both depocentres. The potential quantity of venting gas on the Brazilian margin under different scenarios of natural or anthropogenic change require further investigation. The studied areas provide a natural laboratory where these critical processes can be analysed and quantified.

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Active tectonic structures and submarine landslides offshore southern Apulia (Italy): a new scenario for the 1743 earthquake and subsequent tsunami

2017

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

Cited by 6 publications

References 5 publications

Neogene evolution of the margin adjacent to the La Plata River Delta (Pelotas Basin): Sedimentary pathways and the origins of the Rio Grande Cone

Neogene evolution of the margin adjacent to the La Plata River Delta (Pelotas Basin): Sedimentary pathways and the origins of the Rio Grande Cone

Gas Seeps at the Edge of the Gas Hydrate Stability Zone on Brazil’s Continental Margin

Active tectonic structures and submarine landslides offshore southern Apulia (Italy): a new scenario for the 1743 earthquake and subsequent tsunami

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

Cited by 6 publications

References 5 publications

Neogene evolution of the margin adjacent to the La Plata River Delta (Pelotas Basin): Sedimentary pathways and the origins of the Rio Grande Cone

Neogene evolution of the margin adjacent to the La Plata River Delta (Pelotas Basin): Sedimentary pathways and the origins of the Rio Grande Cone

Gas Seeps at the Edge of the Gas Hydrate Stability Zone on Brazil&rsquo;s Continental Margin

Active tectonic structures and submarine landslides offshore southern Apulia (Italy): a new scenario for the 1743 earthquake and subsequent tsunami

Contact Info

Product

Resources

About

Gas Seeps at the Edge of the Gas Hydrate Stability Zone on Brazil’s Continental Margin