Premium
Flood‐triggered versus earthquake‐triggered turbidites: A sedimentological study in clastic lake sediments (Eklutna Lake, Alaska)
Author(s) -
Vandekerkhove Elke,
Van Daele Maarten,
Praet Nore,
Cnudde Veerle,
Haeussler Peter J.,
De Batist Marc
Publication year - 2020
Publication title -
sedimentology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.494
H-Index - 108
eISSN - 1365-3091
pISSN - 0037-0746
DOI - 10.1111/sed.12646
Subject(s) - turbidite , geology , turbidity current , varve , sedimentology , flood myth , clastic rock , sediment , structural basin , paleoseismology , geomorphology , paleontology , holocene , sedimentary depositional environment , archaeology , history
Abstract Lake sediments in Eklutna Lake, Alaska, reveal the presence of turbidites within varved sequences. These turbidites, which result from flood events and earthquakes, show a similar macroscopic appearance. In order to use turbidites to reconstruct flood variability and/or seismic history in the lake basin, it is crucial to determine the trigger of the turbidity currents. This study examined the turbidite caused by the ad 1964 Great Alaska earthquake as well as turbidites linked to historical flood events in order to differentiate between these earthquake‐triggered and flood‐triggered turbidites. In a suite of samples from throughout the lake, distinctive proxies are identified that can be associated with event‐specific flow characteristics. The study presents straightforward discrimination methods related to the sedimentology and geochemical components of the turbidites. These methods are also applicable to other lakes, particularly proglacial lakes where the sediment composition of onshore and offshore sources is similar. Finally, the discrimination of the turbidite trigger can be used to reconstruct the palaeoflood and seismic history.