Pleistocene marine kettle-fill deposits near Ottawa, Canada

1980 ◽  
Vol 17 (9) ◽  
pp. 1236-1245 ◽  
Author(s):  
M. Hayward ◽  
H. M. French
Keyword(s):  
Marine Environment ◽  
Debris Flows ◽  
Slope Instability ◽  
Turbidity Currents ◽  
Ice Melt ◽  
Sand And Gravel

Exposures at several localities in the Ottawa region reveal Champlain Sea deposits filling depressions on what were formerly submerged surfaces of Wisconsin sand and gravel ridges. The deposits, referred to as "kettle fill," constitute materials eroded from the ridges in a marine environment and redeposited in ice-melt depressions or kettle holes. Processes responsible for the deposition of the sediment appear to include debris flows and small turbidity currents initiated by wave washing and slope instability. The dimensions of the depressions, their depth in relation to the falling wave base, and the steepness of the flanks were important factors controlling sedimentation. The kettle-fill facies comprise diamicton (pebbly mud), gravel, sand, and lutite.

scholarly journals Aveiro Canyon Head (Portugal) Submarine Slope Instability Assessment

2020 ◽  
Vol 10 (24) ◽  
pp. 9038
Author(s):  
Nuno Lapa ◽  
Fernando M. F. S. Marques ◽  
Aurora Rodrigues
Keyword(s):  
Marine Environment ◽  
Regional Scale ◽  
Slope Angle ◽  
Area Under The Curve ◽  
Roc Curves ◽  
Information Value ◽  
Slope Instability ◽  
Landslide Inventory ◽  
Spatial And Temporal Variability ◽  
Sedimentary Dynamics

Mass wasting events are the main processes of sedimentary dynamics that affect the marine environment and which, due to their spatial and temporal variability, are difficult to study and evaluate. Affecting the marine floor, between the coastline and the abyssal plain, these processes are triggered by multiple causes, having different magnitudes and causing drastic changes and impacts on the marine environment and human activities. In this paper, the submarine landslide susceptibility affecting the upper course of the Aveiro canyon (West Iberian Margin) is addressed using statistical models which are based on the statistical relations between a landslide inventory and the landslide predisposing factors bathymetry, sediment cover, slope angle, aspect and curvature. The statistical methods were the widely proven bivariate information value (IV) and the multivariate logistic regression (LR). The model results were validated against the landslide inventory using receiver operating characteristic (ROC) curves and the corresponding area under the curve (AUC), which provided satisfactory results, with IV AUC = 0.79 and LR AUC = 0.83, in spite of the limitations of the databases used in this study. The results obtained suggest that these methods may be useful for the preliminary assessment of sea floor slope instability at a regional scale of analysis, enabling the selection of sites to be studied with much more detailed and expensive methods.

Sedimentary facies on the rises and slopes of passive continental margins

1980 ◽  
Vol 294 (1409) ◽  
pp. 169-176 ◽  
Keyword(s):  
Sediment Transport ◽  
Debris Flows ◽  
Thermohaline Circulation ◽  
Dominant Role ◽  
Sedimentary Facies ◽  
Turbidity Currents ◽  
Continental Margins ◽  
Passive Margins ◽  
New Evidence

JOIDES drilling results provide new evidence concerning facies patterns on evolving passive margins that strengthens and extends hypotheses constructed from studies of morphology, seismic reflexion data and shallow samples on modern margins, and from field geologic studies of uplifted ancient margins. On the slopes and rise, gravity-controlled mechanisms - turbidity currents, debris flows, slides and the like - play the dominant role in sediment transport over the long term, but when clastic supplies are reduced, as for example during rapid transgressions, then oceanic sedimentation and the effects of thermohaline circulation become important. Sedimentary facies models used as the basis of unravelling tectonic complexities of some deformed margins, for example in the Mesozoic Tethys, may be too simplistic in the light of available data from modern continental margins.

scholarly journals Effects of ground freezing and snow avalanche deposits on debris flows in alpine environments

2004 ◽  
Vol 4 (4) ◽  
pp. 519-530 ◽  
Author(s):  
E. Bardou ◽  
R. Delaloye
Keyword(s):  
Debris Flows ◽  
Soil Aggregates ◽  
Base Flow ◽  
Slope Instability ◽  
Snow Avalanche ◽  
Extreme Weather Events ◽  
Precipitation Event ◽  
High Mountain ◽  
Ground Freezing ◽  
The Impact

Abstract. Debris flows consist of a mixture of water and sediments of various sizes. Apart from few exceptions, the water is usually contributed directly from precipitation. In a high mountain environment like the Alps, it appears necessary to consider infiltration of water into the ground during rainfall events, the runoff characteristics and the potential supply of sediment as a function of a multitude of climatic and hydrogeological factors. This paper outlines several new processes - either linked to ice formation in the ground before an event, or to the presence of snow avalanche deposits - that change the probability of observing an event. These processes were identified during field observations connected with extreme weather events that occurred recently in the Valais Alps (south-western Switzerland): they can be seen as factors either amplifying or reducing the potential of slope instability caused by the precipitation event. An intense freezing of the ground during the week preceding the exceptional rainfall event in mid-October 2000 amplified the probability of triggering debris flows between roughly 1800 and 2300m asl. Both growth of ice needles and superficial ground freezing destroyed soil aggregates (increasing the availability of sediments) and/or, a deeper ground freezing resulted in decreased infiltration rate (increased runoff) during the first hours of heavy rainfall. The presence of snow avalanche deposits in a gully could be simultaneously an amplifying factor (the snow deposits increase the base flow and create a sliding plane for the sediments, mainly at the time of summer storms) or a reducing factor (reduction in the impact energy of the raindrops, mainly at the time of winter storms) of the risk of triggering debris flows. If it is not currently possible to establish rainfall threshold values for debris flow triggering, the knowledge and the implementation of these processes in the analysis of the potential triggering (for example by comparing the catchment hypsometric curve with the meteo-climatic situation) would nevertheless make the analysis of debris flows and forecasting more efficient.

Slow build-up of turbid currents triggered by a moderate earthquake in the Sea of Marmara

2020 ◽  
Author(s):  
Pierre Henry ◽  
M Sinan Özeren ◽  
Nurettin Yakupoğlu ◽  
Ziyadin Çakir ◽  
Emmanuel de Saint-Léger ◽  
...  
Keyword(s):  
Pressure Sensor ◽  
Debris Flows ◽  
Background Level ◽  
Signal Strength ◽  
Normal Operation ◽  
Turbidity Currents ◽  
Central Basin ◽  
Sea Of Marmara ◽  
Moderate Earthquake ◽  
Mud Flow

<p>Earthquake-induced submarine slope destabilization is known to cause debris flows and turbidity currents. These also interact with currents caused by tsunami and seiches resulting in deposits with specific sedimentological characteristics, turbidite-homogenites being a common example. Data on the deep-sea hydrodynamic events following earthquakes are, however, limited. An instrumented frame deployed at the seafloor in the Sea of Marmara Central Basin recorded some of the consequences of a magnitude 5.8 earthquake that occurred Sept 26, 2019 at 10-12 km depth without causing any significant tsunami. The instrumentation comprises a Digiquartz® pressure sensor recording at 5 s interval and a 1.9-2 MHz Doppler recording current meter set 1.5 m above the seafloor and recording at 1-hour interval. The device was deployed at 1184 m depth on the floor of the basin near the outlet of a canyon, 5 km from the epicenter. Chirp sediment sounder profiles indicate a depositional fan or lobe is present at this location. The passing of the seismic wave was recorded by the pressure sensor, but little other perturbation is recorded until 25 minutes later when the instrument, probably hit by a mud flow, tilts by 65° in about 15 seconds. Over the following 10 hours the tilted instrument records bursts of current of variable directions. The last burst appears to be the strongest with velocities in the 20-50 cm/s range, causing enough erosion to free the device from the mud and allowing the buoyancy attached to the upper part of the frame to straighten it back to its normal operation position. Then, the current, flowing down along the canyon axis, progressively decays to background level (≈2 cm/s) in 8 hours. Doppler signal backscatter strength is a proxy for turbidity, sensitive to sand-size suspended particles. Signal strength increased to high values during the event (max -7.6 dB from a background value of -40dB) and decayed over the next three days. These observations show that even a moderate earthquake can trigger a complex response involving mud flows and turbidity currents. We infer simultaneous slope failures at various locations may produce complex current patterns and cause build-up of kinetic energy over several hours.</p>

Silurian microbial associations from the Alexander terrane, Alaska

1993 ◽  
Vol 67 (5) ◽  
pp. 728-738 ◽  
Author(s):  
Constance M. Soja ◽  
Robert Riding
Keyword(s):  
Debris Flows ◽  
Turbidity Currents ◽  
Diverse Population ◽  
Microbial Assemblage ◽  
Microbial Associations ◽  
Transport And Mixing ◽  
Shelf Margin ◽  
Water Carbonate ◽  
Carbonate Deposits ◽  
Alexander Terrane

Silurian calcareous algae, cyanobacteria, and microproblematica are abundantly preserved in the Alexander terrane of southeastern Alaska. They represent a diverse population of calcified microbes that contributed to the formation of a variety of shallow- and deep-water carbonate deposits. Five associations are recognized on the basis of recurring groups of microbial taxa. These include a Girvanella-Tuxekanella association that formed oncoids and thick encrustations on skeletal grains in shelf environments. A Renalcis association predominated in a stromatoporoid-coral reef that developed at the incipient shelf margin on a crinoid-solenoporid shoal (“Solenopora” association). Other organic buildups are characterized by a Ludlovia association, which constructed skeletal stromatolite reefs, and by an Epiphyton-Sphaerina association that contributed to the formation of a stromatolitic mud mound. A mixed microbial assemblage reflects transport and mixing of shallow-water microbial biotas that were deposited by turbidity currents, debris flows, and slumps in a slope environment.

scholarly journals THE OCCURRENCE OF PALAEOZOIC CONGLOMERATIC ROCKS IN EAST JOHOR, PENINSULAR MALAYSIA

2015 ◽  
Vol 1 (2) ◽  
Author(s):  
Sugeng Sapto Surjono ◽  
Mohd Shafeea Leman ◽  
Kamal Roslan Mohamed ◽  
Che Aziz Ali
Keyword(s):  
Marine Environment ◽  
Debris Flows ◽  
Depositional Environment ◽  
River System ◽  
Peninsular Malaysia ◽  
Late Carboniferous ◽  
Braided River ◽  
Late Permian ◽  
Shallow Marine ◽  
Shallow Marine Environment

Conglomeratic rocks in East Johor are found in the separately three formations that are the Murau, Tanjung Leman and Linggiu Formations. The Murau Formation is characterized by cobble to boulder grained breccia with very angular to angular and disorganized clasts. It was deposited by fan-delta system in the sub-aerial to shallow marine environment. The Tanjung Leman Formation consists of pebble to cobble grained conglomerate with rounded to subrounded and organized clasts. It was deposited by braided river system in the sub-aerial environment. Both formations outcropped in eastern coastal of Johor. The rudaceous rocks of the Linggiu Formation consist of pebble to cobble-sized clasts with sub angular and disorganized texture. It present as subordinate rocks within sandstone dominant in the central part of East Johor and was deposited by debris flows in the shallow marine environment. All these rudaceous rocks were interpreted as Palaeozoic in age ranging from Late Carboniferous to Late Permian. Those rudaceous rocks indicated that since Late Carboniferous, palaeogeography of East Johor was a continent with subaerial to shallow marine depositional environment. Keywords: Conglomerate, Palaeozoic, East Johor, subaerial, shallow marine.

Debris Flows vs. Turbidity Currentsa Modeling Comparison of Their Dynamics and Deposits

2000 ◽  
Author(s):  
Lincoln F. Pratson ◽  
Jasim Imran ◽  
Gary Parker ◽  
James P. M. Syvitski ◽  
Eric Hutton
Keyword(s):  
Debris Flows ◽  
Turbidity Currents
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