Deep-water leveed-channel complexes of the Cerro Toro Formation, Upper Cretaceous, southern Chile

Beaubouef, R. T.

doi:10.1306/06210403130

Cited by 115 publications

(160 citation statements)

References 21 publications

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“…The presence of coarsegrained deposits at the base of sandstone beds probably represents lag deposits indicative of sediment bypass and throughgoing turbidity currents. The horizontal and vertical stacking of sandstone beds strongly suggests lateral migration of sandy channel belts in a deep-marine environment (e.g., Beaboef, 2004, Mayall et al, 2006Wynn et al, 2007). The outcrops do not allow for plan view of the sandstone geometries, but the associations have a strong resemblance to sinuous channel systems (e.g., Janocko et al, 2013;Li et al, 2016) (Fig.…”

Section: Discussionmentioning

confidence: 99%

Turbidite and conglomerate successions in an Ordovician back-arc basin, Mid-Norwegian Caledonides: a result of long-term staging followed by catastrophic release of sediments

Henriksen¹,

Roberts²,

Pedersen³

2018

NJG

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The Ordovician metasedimentary rocks in the Caledonian nappes in Mid Norway were deposited in a back-arc setting, following ophiolite obduction, uplift and erosion, related to continental uplift and changing directions of subduction during this period. Deep-water conditions were established in the basin and this accommodated a thick succession of variously coarse-grained, conglomeratic and argillaceous sediments. The conglomerates typically display the well-rounded clast material of variable igneous, volcanic, sedimentary and carbonate origin and alternate between being clast-supported and matrix-supported with interbedded sandstone beds. The rounded clasts suggest significant reworking and long-term storage of sediments in the source area before transport into the deeper part of the basin. The basal surface of conglomerates always shows an erosive contact with underlying shales or coarsening-upward sandstone successions. The basal surfaces probably represent sedimentary fairways, where several conglomerate units separated by erosional contacts are stacked on top of each other. The conglomerate successions likely result from episodic release of large quantities of sediments. Between each burst of release, sediments accumulated in alluvial fans, fan deltas and fluvial delta systems along the basin shoreline and carbonate reefs established on the outer shelf. Laterally accreting channel sandstone beds were probably important in setting up sedimentary fairways for the succeeding conglomerates. In the inferred deepest part of the basin, smaller channellised features and thin-bedded turbidites seem to dominate. Channel features and hummocky cross-stratification in shelf to upper slope sandstone beds are alternatively interpreted to result from unidirectional flows and constitute an integral part of the turbidite system. By including all the observed facies within the turbidite system we invoke a depositional model which does not require a eustacy-driven sequence-stratigraphic model for explanation. We rather suggest a tectonic model involving an elevated source area, either volcanic or continental, where erosional products are stored and reworked in the alluvial accommodation zone. These sediments are built up to a threshold level and flushed to the sea by a sudden availability of large amounts of water. The actual cause of this sudden availability of water remains uncertain, but the consequent mixture of water and sediments resulted in a super-concentrated high-energy density current. Turbidite and conglomerate successions in an Ordovician back-arc basin, Mid-Norwegian Caledonides: a result of long-term staging followed by catastrophic release of sediments IntroductionThe Caledonides of central Norway are especially well known for their fragmented ophiolite assemblages and, in some areas, the overlying, richly fossiliferous, Ordovician to inferred Early Silurian, low-grade metasedimentary rocks (Bergström, 1979(Bergström, , 1997Bruton & Bockelie, 1980;Ryan et al., 1980;Neuman & Bruton, 1989;Neuman et al., 1997). The...

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Section: Discussionmentioning

confidence: 99%

Turbidite and conglomerate successions in an Ordovician back-arc basin, Mid-Norwegian Caledonides: a result of long-term staging followed by catastrophic release of sediments

Henriksen¹,

Roberts²,

Pedersen³

2018

NJG

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“…The Lago Sofia conglomerate (LSC) is several tens to hundreds of meters thick and kilometers wide and encased by dark gray hemipelagic mudstones and thin-bedded turbidites. A group of workers (Scott 1966;DeVries and Lindholm 1994;Beaubouef et al 1996;Beaubouef 2004) presented a leveed-channel model to explain the stratigraphic relations of the LSC relative to the surrounding finegrained deposits, whereas another group of workers (Coleman 2000;Crane and Lowe 2001) suggested that the channels of the LSC are simple, erosional features cutting into the fine-grained deposits. This facies includes all the clast-supported conglomerates with sand matrix that are massive or very crudely stratified, planar-stratified, low-angle inclined-stratified or high-angle cross-stratified (Fig.…”

Section: Geological Settingmentioning

confidence: 99%

“…The conglomerate packages in this area were designated as channel-complex sets (CCS) 1 to 4 from base to top in a recent paper by Beaubouef (2004). The channel-complex sets consist of a number of channel fills and channel complexes, which are several tens of meters thick, 0.5−1.5 km wide, and variably amalgamated, making up conglomerate bodies that are as thick as 250 meters and extend laterally for more than several kilometers (Beaubouef 2004). These channel-complex sets are separated by several tens to hundreds of meter thick hemipelagic mudstones, of which the thickness varies depending on the degree of vertical amalgamation of channel fills.…”

Section: Lago Pehoe Areamentioning

confidence: 99%

“…The lowermost conglomerate package (LP 1) in the Lago Pehoe area (Fig. 5B), corresponding to part of CCS 1 of Beaubouef (2004), is up to about 50 m thick and extends laterally for about 10 km with meager variations in thickness, although it eventually pinches out toward the north and the south (Fig. 2).…”

Section: Lago Pehoe Areamentioning

confidence: 99%

“…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). The authors believe that an understanding of the nature of the overall LSC depositional system is necessary before an in-depth examination and debate on the characteristics and nature of the channel-fill units in the LSC depositional system.…”

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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The critical role of stratification in submarine channels: Implications for channelization and long runout of flows

Dorrell

Darby

Peakall

et al. 2014

J. Geophys. Res. Oceans

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Channelized submarine gravity currents travel remarkable distances, transporting sediment to the distal reaches of submarine fans. However, the mechanisms by which flows can be sustained over these distances remain enigmatic. In this paper we consider two shallow water models the first assumes the flow is unstratified whilst the second uses empirical models to describe vertical stratification, which effects depth averaged mass and momentum transfer. The importance of stratification is elucidated through comparison of modeled flow dynamics. It is found that the vertically stratified model shows the best fit to field data from a channelized field-scale gravity current in the Black Sea. Moreover, the stratified flow is confined by the channel to a much greater degree than the flow in the unstratified model. However, both models fail to accurately represent flow dynamics in the distal end of the system, suggesting current empirical stratification models require improvement to accurately describe field-scale gravity currents. It also highlights the limitations of weakly stratified small-scale experiments in describing field-scale processes. The results suggest that in real-world systems stratification is likely to enable maintenance of velocity and discharge within the channel, thus facilitating sediment suspension over distances of hundreds of kilometers on low seafloor gradients. This explains how flows can travel remarkable distances and transport their sediment to the distal parts of submarine fans.

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Deep-water leveed-channel complexes of the Cerro Toro Formation, Upper Cretaceous, southern Chile

Cited by 115 publications

References 21 publications

Turbidite and conglomerate successions in an Ordovician back-arc basin, Mid-Norwegian Caledonides: a result of long-term staging followed by catastrophic release of sediments

Turbidite and conglomerate successions in an Ordovician back-arc basin, Mid-Norwegian Caledonides: a result of long-term staging followed by catastrophic release of sediments

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

The critical role of stratification in submarine channels: Implications for channelization and long runout of flows

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