Flow dynamics at the origin of thin clayey sand lacustrine turbidites: Examples from Lake Hazar, Turkey

Hage, Sophie; Hubert‐Ferrari, Aurélia; Lamair, Laura; Avşar, Ulaş; Ouahabi, Meriam El; Daele, Maarten Van; Boulvain, Frédéric; Bahri, Mohamed Ali; Seret, Alain; Plenevaux, Alain

doi:10.1111/sed.12380

Cited by 20 publications

(38 citation statements)

References 85 publications

(211 reference statements)

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“…Where sediments are disturbed by bioturbation the original structure may be obscured (McCall & Tevesz 1982). In particular, conventional optical microscopy of resin-embedded sediment may lack the necessary resolution to interpret microfabrics, for example Hage et al (2017) found it difficult to distinguish burrows from fluid escape features using optical microscopy. To aid microfabric analysis we used Back Scattered Electron Imagery (BSEI) (Krinsley et al 2005).…”

Section: Accepted Manuscriptmentioning

confidence: 99%

“…BSEI is effectively an ultra-thin section image showing a porosity and composition signal in resin embedded sediment, and so is more informative than the optical image that contains optical "noise" from the entire thickness of the thin section. While BSEI has been extensively used in the study of varved sediments (Dean et al, 1999), studies of event deposits have primarily used optical microscopy for the highest resolution observations (Schlolaut et al 2014;Hage et al 2017). Our new approach may serve as an example for the future development of subaquatic palaeoseismology.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

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Palaeoseismology from microfabric and geochemical analysis of lacustrine sediments, Windermere, UK

Fielding

Kemp

Bull

et al. 2018

JGS

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Lake sediments commonly contain detrital layers that record events such as floods or earthquakes but these may be disturbed or partially destroyed by bioturbation. Here we use a novel combination of techniques to relate microscopic sediment fabric features to lake-basin scale processes. X-radiography and micro-XRF of cores are complemented by backscattered electron imagery and energy dispersive X-ray microanalysis of resinembedded sediment. Together, the microfabric and geochemical methods enable the identification of clay-layer mass transport deposits despite bioturbational mixing of the original end members. Two cores with robust radionuclide chronologies contain correlative clay layers dated to 1979 (1974-1982) and 1979-1980 (1973-1986) respectively. These clay layers likely represent the distal turbidite generated by a major mass flow deposit identified from multibeam swath bathymetry and sediment grab sampling. A likely trigger for the mass flow and associated turbidity current is the 4.7 ML 1979 Carlisle earthquake. The lake basin slope was likely preconditioned for failure by increased sedimentary biogenic gas production and sediment in-wash as a result of anthropogenic activities, coupled with sediment disruption and dredging. This study highlights the effectiveness of microstratigraphic techniques in the recognition and characterisation of event layers in sediments where bioturbative disruption has occurred.

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Section: Accepted Manuscriptmentioning

confidence: 99%

Section: Accepted Manuscriptmentioning

confidence: 99%

Palaeoseismology from microfabric and geochemical analysis of lacustrine sediments, Windermere, UK

Fielding

Kemp

Bull

et al. 2018

JGS

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“…The grading in muddy parts (Bm or the upper part of Bs) is indicative of suspension/incremental deposition from a turbulent flow or a longitudinally segregated (graded) flow (Fig. C: Talling et al ., ; Hage et al ., ), regardless of high clay content in the muddy parts of the deposits (Fig. C).…”

Section: Formation Processes Of Event Depositsmentioning

confidence: 85%

“…The clay‐rich Gm deposits are massive and ungraded and are interpreted to be of cohesive laminar flow origin with en masse transport and deposition (Talling et al ., ; Hage et al ., ; Fig. A).…”

Section: Formation Processes Of Event Depositsmentioning

confidence: 89%

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From sink to volcanic source: Unravelling missing terrestrial eruption records by characterization and high‐resolution chronology of lacustrine volcanic density flow deposits, Lake Inawashiro‐ko, Fukushima, Japan

Kataoka

Nagahashi

2019

Sedimentology

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Eruption records in the terrestrial stratigraphy are often incomplete due to erosion after tephra deposition, limited exposure and lack of precise dating owing to discontinuity of strata. A lake system and sequence adjacent to active volcanoes can record various volcanic events such as explosive eruptions and subaqueous density flows being extensions of eruption triggered and secondary triggered lahars. A lacustrine environment can constrain precise ages of such events because of constant and continuous background sedimentation. A total of 71 subaqueous density flow deposits in a 28 m long core from Lake Inawashiro-ko reveals missing terrestrial volcanic activity at Adatara and Bandai volcanoes during the past 50 kyr. Sedimentary facies, colour, grain size, petrography, clay mineralogy, micro X-ray fluorescence analysis and chemistry of included glass shards characterize the flow event deposits and clarify their origin: (i) clay-rich grey hyperpycnites, extended from subaerial cohesive lahars at Adatara volcano, with sulphide/sulphate minerals and high sulphur content which point to a source from hydrothermally altered material ejected by phreatic eruptions; and (ii) clay-rich brown density flow deposits, induced by magmatic hydrothermal eruptions and associated edifice collapse at Bandai volcano, with the common presence of fresh juvenile glass shards and low-grade hydrothermally altered minerals; whereas (iii) non-volcanic turbidites are limited to the oldest large slope failure and the 2011 Tohoku-oki earthquake events. The high-resolution chronology of volcanic activity during the last 50 kyr expressed by lacustrine event deposits shows that phreatic eruption frequency at Adatara has roughly tripled and explosive eruptions at Bandai have increased by ca 50%. These results challenge hikers, ski-fields and downstream communities to re-evaluate the increased volcanic risks from more frequent eruptions and far-reaching lahars, and demonstrate the utility of lahar and lacustrine volcanic density flow deposits to unravel missing terrestrial eruption records, otherwise the recurrence rate may be underestimated at many volcanoes.

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An Atlas of Mass‐Transport Deposits in Lakes

Sammartini

Moernaut

Anselmetti

et al. 2019

Geophysical Monograph Series

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Flow dynamics at the origin of thin clayey sand lacustrine turbidites: Examples from Lake Hazar, Turkey

Cited by 20 publications

References 85 publications

Palaeoseismology from microfabric and geochemical analysis of lacustrine sediments, Windermere, UK

Palaeoseismology from microfabric and geochemical analysis of lacustrine sediments, Windermere, UK

From sink to volcanic source: Unravelling missing terrestrial eruption records by characterization and high‐resolution chronology of lacustrine volcanic density flow deposits, Lake Inawashiro‐ko, Fukushima, Japan

An Atlas of Mass‐Transport Deposits in Lakes

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