Open AccessMagnetic and geochemical signatures of flood layers in a lake system
Author(s) -
Støren Eivind W. N.,
Paasche Øyvind,
Hirt Ann M.,
Kumari Monika
Publication year - 2016
Publication title -
geochemistry, geophysics, geosystems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.928
H-Index - 136
ISSN - 1525-2027
DOI - 10.1002/2016gc006540
Subject(s) - geology , flood myth , sediment , spring (device) , hydrology (agriculture) , snow , oceanography , paleontology , geomorphology , archaeology , mechanical engineering , engineering , geotechnical engineering , history
River floods holds the capasity to erode and transport sediments that are deposited whenever the discharge is reduced. In catchments that are subjected to repeated flooding, downstream lakes can therefore contain a record of past events across multiple timescales. High‐resolution core scanning analyses, such as X‐ray fluorescence (XRF) scanning and magnetic susceptibility (MS) provide data that are frequently used to detect flood layers in soft sediment archives, such as lakes, fjords and ocean basins. Deposits of past floods also can potentially reveal information about the evolution of flood events as well as source area. Here we explore ways in which subtle variability in high‐resolution data can be utilized and subsequently vetted by high‐precision measurements in order to delineate the copious information that can be extracted from soft sediment records. By combining magnetic hysteresis measurements and first‐order reversal curves (FORCs) with inductively coupled plasma optical emission spectrometer (ICP‐OES) measurements of chemical elements on 36 samples, questions about flood dynamics and variability are raised, and also sources of noise in high‐resolution scanning techniques are discussed. Specifically, we show that a lake flood record from Southern Norway containing 92 floods distributed over 10,000 years can be subdivided into two groups of floods that were generated either by spring snow melting, intense summer rainstorms, or a combination of both. The temporal evolution of this pattern shows a marked shift toward spring floods around 2000 years ago compared to the earlier part of the record.