Deep‐Water Fan‐Channel Conglomerates of Late Cretaceous Age, Southern Chile

Winn, Robert D.; Dott, Robert H.

doi:10.1002/9781444304473.ch43

Cited by 28 publications

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“…The conglomerates of this facies, previously termed the diamictites by Winn and Dott (1979), are interpreted to have resulted from composite mass-flow events, comprising a turbidity current, a gravelly hyperconcentrated flow, and a mud-rich debris flow (Sohn et al 2002). The erosional lower contact with well-developed flute and groove casts indicates an initial erosional event caused by a turbulent flow.…”

Section: Discussionmentioning

confidence: 99%

“…Previous studies suggest that the paleoflows in the LSC were directed dominantly toward the south (Scott 1966;Winn and Dott 1979;Beaubouef 2004). Measurement of the paleoflow directions by the authors on the basis of clast imbrication and sole marks reveals, however, that there are considerable variations in paleoflow directions among different facies and different outcrop localities.…”

Section: Spatial Variations Of Channel-fill Characteristics and Paleomentioning

confidence: 99%

“…The Cerro Toro Formation includes a lens of Lago Sofia conglomerate (LSC), which extends for more than 100 km from north to south of hemipelagic mudstones and thin interbeds of turbidite sandstones deposited during the late Cretaceous (Cenomanian-Campanian) (Cecioni 1957;Katz 1963). The formation is underlain by deep-water clastic sediments of the Punta Barosa Formation (Albian-Cenomanian) and overlain by a shallowing-upward clastic succession of the Tres Pasos Formation (Santonian-Maastrichtian) (Katz 1963;Scott 1966;Winn and Dott 1979;Shultz et al 2005). A study of foraminiferal assemblages indicates that the water depth in the Magallanes Basin was 1000−2000 m during the deposition of the Punta Barosa and Cerro Toro Formations (Natland et al 1974).…”

Section: Geological Settingmentioning

confidence: 99%

“…1B). Throughout the late Cretaceous, arc-and cordillera-derived clastic sediments, volcanic, plutonic, and metamorphic in origin, were dispersed axially along the foredeep trough, resulting in deposition of a thick (6.5−7.5 km) succession of deep-marine strata, including the Cerro Toro Formation (Cecioni 1957;Katz 1963;Scott 1966;Winn and Dott 1979). In the eastern part of the basin, shallow marine and slope environments persisted, which were relatively sediment-starved and prograded slowly to the southwest (Biddle et al 1986).…”

Section: Geological Settingmentioning

confidence: 99%

“…1), is deep-marine gravelly deposits, which are hundreds of meters thick, kilometers wide, and extend laterally for up to 100 km (Scott 1966). The LSC has been formerly interpreted as channel-levee complexes developed upon a submarine fan (Winn and Dott 1979). Recent studies debate on the nature of the channels whether they represent leveed-channel complexes (DeVries and Lindholm 1994; Beaubouef et al 1996;Beaubouef 2004) or backfilled erosional channel complexes without levees (Coleman 2000;Crane and Lowe 2001).…”

Section: Introductionmentioning

confidence: 99%

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Sedimentary Facies and Architecture of a Gigantic Gravelly Submarine Channel System in a Cretaceous Foredeep Trough (the Magallanes Basin, Southern Chile)

Cheo¹,

Kim²,

Jo³

et al. 2017

Ocean and Polar Research

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: The Lago Sofia conglomerate in southern Chile is a deep-marine gravelly deposit, which is hundreds of meters thick and kilometers wide and extends laterally for more than 100 km, filling the foredeep trough of the Cretaceous Magallanes Basin. For understanding the depositional processes and environments of this gigantic deep-sea conglomerate, detailed analyses on sedimentary facies, architecture and paleoflow patterns were carried out, highlighting the differences between the northern (Lago Pehoe and Lago Goic areas) and southern (Lago Sofia area) parts of the study area. The conglomerate bodies in the northern part occur as relatively thin (< 100 m thick), multiple units intervened by thick mudstone-dominated sequences. They show paleoflows toward ENE and S to SW, displaying a converging drainage pattern. In the southern part, the conglomerate bodies are vertically interconnected and form a thick (> 400 m thick) conglomerate sequence with rare intervening fine-grained deposits. Paleoflows are toward SW. The north-to-south variations are also distinct in sedimentary facies. The conglomerate bodies in the southern part are mainly composed of clast-supported conglomerate with sandy matrix, which is interpreted to be deposited from highly concentrated bedload layers under turbidity currents. Those in the northern part are dominated by matrix-to clast-supported conglomerate with muddy matrix, which is interpreted as the products of composite mass flows comprising a turbidity current, a gravelly hyperconcentrated flow and a mud-rich debris flow. All these characteristics suggest that the Lago Sofia conglomerate was formed in centripetally converging submarine channels, not in centrifugally diverging channels of submarine fans. The tributaries in the north were dominated by mass flows, probably affected by channel-bank failures or basin-marginal slope instability processes. In contrast, the trunk channel in the south was mostly filled by tractive processes, which resulted in the vertical and lateral accretion of gravel bars, deposition of gravel dunes and filling of scours and channels, similar to deposits of terrestrial gravel-bed rivers. The trunk channel developed along the axis of foredeep trough and its confinement within the trough is probably responsible for the thick, interconnected channel fills. The large-scale architecture of the trunk-channel fills shows an eastward offset stacking pattern, suggesting that the channel migrated eastwards most likely due to the uplift of the Andean Cordillera.

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Section: Discussionmentioning

confidence: 99%

Section: Spatial Variations Of Channel-fill Characteristics and Paleomentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Sedimentary Facies and Architecture of a Gigantic Gravelly Submarine Channel System in a Cretaceous Foredeep Trough (the Magallanes Basin, Southern Chile)

Cheo¹,

Kim²,

Jo³

et al. 2017

Ocean and Polar Research

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Influence of attenuated lithosphere and sediment loading on flexure of the deep-water Magallanes retroarc foreland basin, Southern Andes

2014

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Flexural subsidence in foreland basins is controlled by applied loads-such as topography, water/sediment, and subcrustal forces-and the mechanical properties of the lithosphere. We investigate the controls on subsidence observed within the Upper Cretaceous Magallanes retroarc foreland basin of southern South America to evaluate the impact of lateral variations in flexural rigidity due to Late Jurassic extension. Conventional elastic models cannot explain the observed basin deflection and thick accumulation of deep-water Cenomanian-Turonian basin strata. However, models in which the lithosphere has been previously thinned and deflects under topographic and sedimentary loads successfully reproduce regional subsidence patterns. Results satisfy paleobathymetric observations in the Magallanes Basin and suggest that lithospheric thinning is necessary to produce both long-wavelength and deep subsidence during Late Cretaceous basin evolution. Results indicate that elastic thickness decreases westward from~45-25 km in the distal foreland to~37-15 km beneath the foredeep. These findings are consistent with a westward reduction in crustal thickness associated with the Jurassic extensional history of the Patagonian lithosphere. Our results also show that sediment loading exerts an important control on regional deflection patterns and promotes a wider region of subsidence and reduced forebulge uplift. We propose that lateral variations in mechanical properties and large sediment loads restrict depocenter migration and may cause the foredeep to remain fixed for prolonged periods of time. These findings confirm that loading of thinned lithosphere imposes different mechanical controls on the flexural profile and have potential implications for other retroarc foreland basins characterized by earlier extensional histories.

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Sedimentation of submarine fan deposits in the Pindos foreland basin, from late Eocene to early Oligocene, west Peloponnesus peninsula, SW Greece

Konstantopoulos

Zelilidis

2012

Geological Journal

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Turbidite facies distribution and palaeocurrent analysis of submarine fan evolution in the Pindos foreland basin of west Peloponnesus peninsula (SW Greece) indicate that this part of the foreland was developed during Late Eocene to Early Oligocene in three linear sub‐basins (Tritea, Hrisovitsi and Finikounda). The basin fill conditions, with a multiple feeder system, which is characterized by axial transport of sediments and asymmetric stratigraphic thickness of the studied sediments, indicate that the Pindos Foreland Basin in this area was an underfilled foreland basin. Sediments are dominated by conglomerates, sandstones and mudstones. The flow types that controlled the depositional processes of the submarine fans were grain flows, debris flows and low‐ and high‐density turbidity currents. The sedimentary model that we propose for the depositional mechanisms and geometrical distribution of the turbidite units in the Tritea sub‐basin is a mixed sand‐mud submarine fan with a sequential interaction of progradation and retrogradation for the submarine fan development and shows a WNW main palaeocurrent direction. The Hrisovitsi sub‐basin turbidite system characterized by small‐scale channels was sediment starved, and the erosion during deposition was greater than the two other studied areas, indicating a more restricted basin topography with a NW main palaeocurrent direction. The Finikounda sub‐basin exhibits sand‐rich submarine fans, is characterized by the presence of distinct, small‐scale, thickening‐upward cycles and by the covering of a distal fan by a proximal fan. It was constructed under the simultaneous interaction of progradation and aggradation, where the main palaeocurrent direction was from NNW to SSE. Copyright © 2012 John Wiley & Sons, Ltd.

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Deep‐Water Fan‐Channel Conglomerates of Late Cretaceous Age, Southern Chile

Cited by 28 publications

References 0 publications

Sedimentary Facies and Architecture of a Gigantic Gravelly Submarine Channel System in a Cretaceous Foredeep Trough (the Magallanes Basin, Southern Chile)

Sedimentary Facies and Architecture of a Gigantic Gravelly Submarine Channel System in a Cretaceous Foredeep Trough (the Magallanes Basin, Southern Chile)

Influence of attenuated lithosphere and sediment loading on flexure of the deep-water Magallanes retroarc foreland basin, Southern Andes

Sedimentation of submarine fan deposits in the Pindos foreland basin, from late Eocene to early Oligocene, west Peloponnesus peninsula, SW Greece

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