DOI: 10.1016/j.quascirev.2014.09.031
Scopus记录号: 2-s2.0-85027922446
论文题名: Testing the use of bulk organic δ13C, δ15N, and Corg: Ntot ratios to estimate subsidence during the 1964 great Alaska earthquake
作者: Bender A.M. ; Witter R.C. ; Rogers M.
刊名: Quaternary Science Reviews
ISSN: 2773791
出版年: 2015
卷: 113 起始页码: 134
结束页码: 146
语种: 英语
英文关键词: Alaska
; Paleoseismology
; Quaternary
; Sea level
; Stable isotopes
Scopus关键词: Earthquakes
; Errors
; Geophysics
; Isotopes
; Peat
; Regression analysis
; Sea level
; Sediments
; Silt
; Transfer functions
; Alaska
; Alaska earthquakes
; Intertidal sediments
; Mean higher high waters
; Microfossil assemblages
; Paleoseismology
; Quaternary
; Stable isotopes
; Subsidence
; biostratigraphy
; carbon isotope
; earthquake magnitude
; fossil assemblage
; intertidal environment
; microfossil
; mudflat
; nitrogen isotope
; paleoseismicity
; peat
; Quaternary
; sea level change
; seismology
; stable isotope
; subsidence
; transfer function
; Alaska
; Turnagain Arm
; United States
; Aves
英文摘要: During the Mw 9.2 1964 great Alaska earthquake, Turnagain Arm near Girdwood, Alaska subsided 1.7 ± 0.1 m based on pre- and postearthquake leveling. The coseismic subsidence in 1964 caused equivalent sudden relative sea-level (RSL) rise that is stratigraphically preserved as mud-over-peat contacts where intertidal silt buried peaty marsh surfaces. Changes in intertidal microfossil assemblages across these contacts have been used to estimate subsidence in 1964 by applying quantitative microfossil transfer functions to reconstruct corresponding RSL rise. Here, we review the use of organic stable C and N isotope values and Corg:Ntot ratios as alternative proxies for reconstructing coseismic RSL changes, and report independent estimates of subsidence in 1964 by using δ13C values from intertidal sediment to assess RSL change caused by the earthquake. We observe that surface sediment δ13C values systematically decrease by ~4‰ over the ~2.5 m increase in elevation along three 60- to 100-m-long transects extending from intertidal mud flat to upland environments. We use a straightforward linear regression to quantify the relationship between modern sediment δ13C values and elevation (n = 84, R2 = 0.56). The linear regression provides a slope-intercept equation used to reconstruct the paleoelevation of the site before and after the earthquake based on δ13C values in sandy silt above and herbaceous peat below the 1964 contact. The regression standard error (average = ±0.59‰) reflects the modern isotopic variability at sites of similar surface elevation, and is equivalent to an uncertainty of ±0.4 m elevation with respect to Mean Higher High Water. To reduce potential errors in paleoelevation and subsidence estimates, we analyzed multiple sediment δ13C values in nine cores on a shore-perpendicular transect at Bird Point. Our method estimates 1.3 ± 0.4 m of coseismic RSL rise across the 1964 contact by taking the arithmetic mean of the differences (n = 9) between reconstructed elevations for sediment above and below the 1964 earthquake subsidence contact. This estimate compares well with independent subsidence estimates derived from post-earthquake leveling in Turnagain Arm, and from microfossil transfer functions at Girdwood (1.50 ± 0.32 m). While our results support the use of bulk organic δ13C for reconstructing RSL change in southern Alaska, the variability of stable isotope values in modern and buried intertidal sediment required the analysis of multiple samples to reduce error. © 2014. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/59988
Appears in Collections: 过去全球变化的重建
There are no files associated with this item.
作者单位: U.S. Geological Survey, Alaska Science Center, Anchorage, AK, United States; Geological Science, Western Washington University, Bellingham, WA, United States; ENRI Stable Isotope Laboratory, University of Alaska, Anchorage, Anchorage, AK, United States
Recommended Citation:
Bender A.M.,Witter R.C.,Rogers M.. Testing the use of bulk organic δ13C, δ15N, and Corg: Ntot ratios to estimate subsidence during the 1964 great Alaska earthquake[J]. Quaternary Science Reviews,2015-01-01,113