Effects of mass-wasting on the stratigraphic architecture of a fjord-valley fill: Correlation of onshore, shear-wave seismic and marine seismic data at Trondheim, Norway

An integrated interpretation of on‐ and offshore stratigraphical records at Leirfjorden, north Norway, reveals new aspects of the area's palaeoenvironmental history. The study is based on marine sparker data and well‐exposed sections on land that were analysed for their sediment facies, mineralogy and fossil assemblages. Existing research and new radiocarbon dates provide a chronological framework for the interpretation. The late Younger Dryas Nordli substage type locality in the Leirfjorden catchment is revised and found to reflect local glacial activity, maybe a collapse of stagnant ice rather than glacier advance, while late Younger Dryas to Preboreal glacier re‐advances south of Leirfjorden and near Ranfjorden are here named the Bardal substage. The stratigraphical record includes pre‐Younger Dryas, valley‐crossing, glacial striae and old till with provenance of resistant bedrock typical of more elevated mountain areas. It differs from younger till units representing topographically controlled glacier movement. Part of the Leirfjorden fjord‐valley system is located between the main glacial and fluvial drainage paths affecting the sediment supply. As a result, highstand deposits are indistinct and fluvial sediments form only a minor part of the forced‐regressive systems tract. Instead, the valley fill overlying till and subtill sediments is dominated by the deglacial transgressive tract and a forced‐regressive systems tract with composite marine deposits and various marine erosion surfaces. A special event bed is interpreted as a possible tsunami deposit caused by seismicity and/or mass‐wasting in the fjord following glacier retreat. The study highlights the stratigraphical complexity of interconnected fjord and sound systems in a low accretion setting.

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“…Hansen et al . ). The Leirfjorden study shows several types of erosion surfaces in the stratigraphical record.…”

Section: Discussionmentioning

confidence: 97%

Stratigraphical signatures of glacier activity, marine processes and a possible tsunami in the Leirfjorden fjord‐valley system, north Norway

Hansen

Bøe

Sveian

et al. 2018

Boreas

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“…Syvitski, 1989). The deep and calm sedimentary environments in these seas are characterized by the slow settling of fine-grained sediments that fill the lower topography (Elverhøi et al, 1983;Mullins and Hinchey, 1989;Syvitski and Lee, 1997;Mullins and Halfman, 2001;Boyd et al, 2008;Hjelstuen et al, 2009;Stocker et al, 2009;Cowan et al, 2010;Forwick and Vorren, 2010;Waldman et al, 2010;Heirman et al, 2012;Turner et al, 2012;Hansen et al, 2013;Kempf et al, 2013;Van Daele et al, 2013). The rhythmicity and medium amplitude of the reflections in U2b indicate a low-impedance contrast of the sediments interbedded with thin layers of higher contrast.…”

Section: Acoustic Stratigraphymentioning

confidence: 99%

Morphological signatures of deglaciation and postglacial sedimentary processes in a deep fjord‐lake (Grand Lake, Labrador)

Trottier

Lajeunesse

Gagnon-Poiré

et al. 2020

Earth Surf Processes Landf

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High‐resolution multibeam bathymetric data and acoustic sub‐bottom profiles were recently collected in Grand Lake (Labrador), one of the deepest lake basins in eastern North America, to reconstruct: (1) the retreat of the Laurentide Ice Sheet (LIS) west of Lake Melville and (2) the history of sedimentation since deglaciation in this 54 km‐long, 3 km‐wide fjord‐lake. Our results provide a morphostratigraphical framework that brings new insights to the style and pattern of retreat of the LIS in the region, as well as deglacial and postglacial sedimentary dynamics. Terrestrial glacial lineations observed on a digital elevation model (DEM) provide evidence of a previously undocumented ice stream in the Grand Lake area. This newly mapped ice stream suggests that the calving bay formed in Lake Melville triggered a reorganization of the regional drainage pattern of the LIS. The sedimentary infill of Grand Lake consists of a sequence of deglacial to postglacial sediments that contain deposits related to a series of mass movements. The 8.2 cal ka BP cold event is recorded in Grand Lake by a series of closely spaced moraines deposited at the outlet of the fjord‐lake to form a morainic complex similar to the Cockburn morainic complex on Baffin Island. During deglaciation, a dense dendritic network of proglacial gullies incised into the steep sidewalls of the lake. Since deglaciation, paraglacial and postglacial sedimentation has led to the deposition of large prograding deltas at the fjord head, where density currents remain active today and have formed a series of sediment waves on the frontal slopes and a prodeltaic environment. © 2019 John Wiley & Sons, Ltd.

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“…These studies have shown that turbidity flows can deposit upstream and above MTDs (e.g., Bernhardt et al 2012;Ortiz-Karpf et al 2015;Corella et al 2016), or, instead, can be erosive to create large-scale scours above MTDs (e.g., Shultz et al 2005). Furthermore, turbidity flows can be diverted by topographic highs created by MTDs, leading to the generation of new sediment routes (Hansen et al 2013;Masalimova et al 2015;Kertznus 2009;Corella et al 2016). Large-scale mass-wasting events can therefore modify the geometry of sedimentary basins and result in rapid shifts in the location of slope depocenters (Lucente and Pini 2008).…”

Section: Introductionmentioning

confidence: 99%

“…Previous studies focused mainly on the location and pathways of channels influenced by MTDs (e.g., Kertznus 2009;Hansen et al 2013;Masalimova et al 2015;Kneller et al 2016;Corella et al 2016), but less attention has been paid to the initiation and development submarine-channels affected by MTD-related topography. The presence of MTDs at the base of channel systems has been documented on both seismic (e.g., Deptuck et al 2003;Mayall et al 2006) and outcrop data (e.g., Macauley and Hubbard 2013;Bain and Hubbard 2016), leading some authors to suggest that seafloor roughness produced by mass-wasting processes can capture and accelerate turbidity flows, facilitating the formation of channels (e.g., Deptuck et al 2003;Gee et al 2007;Abdurrokhim and Ito 2013).…”

Section: Introductionmentioning

confidence: 99%

The Role of Mass Wasting In the Progressive Development Of Submarine Channels (Espírito Santo Basin, Se Brazil)

Qin

Alves

Constantine

et al. 2017

Journal of Sedimentary Research

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ABSTRACT:A Pliocene-Quaternary submarine channel system, influenced by a localized mass wasting, is investigated in this work using high-resolution 3D seismic data from offshore Espírito Santo Basin, SE Brazil. Three abandoned channels, a channel belt and an mass-transport deposit (MTD) are recognized in the channel system within a confluence region confined by salt diapirs. In this confluence region, the cross-sectional area (CSA) of the channel system can be up to 1.2 km 2 , i.e., 4 to 10 times larger than CSA in other parts of the channel system. Such significant changes in the architecture and morphology of the channel system resulted from the interaction between mass-wasting processes and turbidity flows. We postulate that a basal erosional scar was created by mass-wasting processes and was filled with an MTD. This basal scar was then used as a preferential pathway for turbidity flows, which were captured by its headwall and lateral margins. The interpreted data shows that the captured turbidity flows greatly widened the basal scar, but caused only small modifications in scar height. Part of the MTD within the basal scar was removed downslope by turbidity flows, and was replaced by channel-fill deposits. This paper shows a flow-capture process occurred in a confluence region on continental slope. Basal scars can capture turbidity flows and facilitate flow channelization, which is a key process for submarine-channel initiation. The replacement of MTD by channel-fill deposits has profound implications for reservoir volumes and net-to-gross ratios in channel systems and partly depends on the turbidity-flows properties, such as their erosive ability and frequency. The more erosive and frequent flows are captured by the basal scar, the larger is the accommodation space created for succeeding sand-prone turbidites.

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Effects of mass-wasting on the stratigraphic architecture of a fjord-valley fill: Correlation of onshore, shear-wave seismic and marine seismic data at Trondheim, Norway

Cited by 16 publications

References 33 publications

Stratigraphical signatures of glacier activity, marine processes and a possible tsunami in the Leirfjorden fjord‐valley system, north Norway

Stratigraphical signatures of glacier activity, marine processes and a possible tsunami in the Leirfjorden fjord‐valley system, north Norway

Morphological signatures of deglaciation and postglacial sedimentary processes in a deep fjord‐lake (Grand Lake, Labrador)

The Role of Mass Wasting In the Progressive Development Of Submarine Channels (Espírito Santo Basin, Se Brazil)

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