TY - JOUR
T1 - Lacustrine turbidites produced by surficial slope sediment remobilization
T2 - A mechanism for continuous and sensitive turbidite paleoseismic records
AU - Moernaut, Jasper
AU - Van Daele, Maarten
AU - Strasser, Michael
AU - Clare, Michael A.
AU - Heirman, Katrien
AU - Viel, Matías
AU - Cardenas, Javiera
AU - Kilian, Rolf
AU - Ladrón de Guevara, Bruno
AU - Pino, Mario
AU - Urrutia, Roberto
AU - De Batist, Marc
N1 - Publisher Copyright:
© 2015 Elsevier B.V.
PY - 2017/2/1
Y1 - 2017/2/1
N2 - Turbidite records along ocean margins and in lake basins are increasingly used as paleoseismic proxies. However, the slope remobilization processes that formed the earthquake-related turbidity currents are poorly understood and, therefore, it is difficult to assess the consistency of turbidite paleoseismic records. We analyzed the sedimentary imprint of the giant AD 1960 (Mw 9.5) Chile earthquake in four South-Central Chilean lakes. Mass-transport deposits and turbidites were compared by interpreting reflection-seismic profiles, sedimentary facies, volume balances and proxies for turbidite composition (i.e. grain size, radionuclides, sediment color, organic matter). Sediment lightness was used as a proxy for organic matter content. Comparison of lightness of turbidites and the underlying sediments shows that earthquake-triggered turbidites in the four lakes result from remobilization of a thin veneer (on average about 5 cm) of slope sediments and do not result from disintegration of subaquatic landslides. Statistical analysis of 34 turbidites in a new 5200 year sedimentary record does not show any correlation between inter-event time and turbidite thickness (and thus volume). This means that inter-event slope recharging is not a dominant factor governing turbidite recurrence and that initiation of turbidity currents by remobilization of surficial sediments is different to slope failure related to subaquatic landslides. We conclude that surficial slope sediment remobilization forms a valid mechanism that explains why turbidite paleoseismic records can be of excellent continuity and high sensitivity. Moreover, based on correlations between seismic intensity, turbidite volume and stratigraphic remobilization depth, we propose that surficial slope sediment remobilization allows for turbidite records containing information about paleo-earthquake intensity.
AB - Turbidite records along ocean margins and in lake basins are increasingly used as paleoseismic proxies. However, the slope remobilization processes that formed the earthquake-related turbidity currents are poorly understood and, therefore, it is difficult to assess the consistency of turbidite paleoseismic records. We analyzed the sedimentary imprint of the giant AD 1960 (Mw 9.5) Chile earthquake in four South-Central Chilean lakes. Mass-transport deposits and turbidites were compared by interpreting reflection-seismic profiles, sedimentary facies, volume balances and proxies for turbidite composition (i.e. grain size, radionuclides, sediment color, organic matter). Sediment lightness was used as a proxy for organic matter content. Comparison of lightness of turbidites and the underlying sediments shows that earthquake-triggered turbidites in the four lakes result from remobilization of a thin veneer (on average about 5 cm) of slope sediments and do not result from disintegration of subaquatic landslides. Statistical analysis of 34 turbidites in a new 5200 year sedimentary record does not show any correlation between inter-event time and turbidite thickness (and thus volume). This means that inter-event slope recharging is not a dominant factor governing turbidite recurrence and that initiation of turbidity currents by remobilization of surficial sediments is different to slope failure related to subaquatic landslides. We conclude that surficial slope sediment remobilization forms a valid mechanism that explains why turbidite paleoseismic records can be of excellent continuity and high sensitivity. Moreover, based on correlations between seismic intensity, turbidite volume and stratigraphic remobilization depth, we propose that surficial slope sediment remobilization allows for turbidite records containing information about paleo-earthquake intensity.
KW - Limnogeology
KW - Sediment remobilization
KW - South-Central Chile
KW - Subaquatic landslide
KW - Turbidite paleoseismology
UR - http://www.scopus.com/inward/record.url?scp=84947734413&partnerID=8YFLogxK
U2 - 10.1016/j.margeo.2015.10.009
DO - 10.1016/j.margeo.2015.10.009
M3 - Article
AN - SCOPUS:84947734413
SN - 0025-3227
VL - 384
SP - 159
EP - 176
JO - Marine Geology
JF - Marine Geology
ER -