DOI: 10.1016/j.palaeo.2015.08.030
论文题名: Bioturbation trends across the freshwater to brackish-water transition in rivers
作者: La Croix A.D. ; Dashtgard S.E. ; Gingras M.K. ; Hauck T.E. ; MacEachern J.A.
刊名: Palaeogeography, Palaeoclimatology, Palaeoecology
ISSN: 0031-0182
出版年: 2015
卷: 440 起始页码: 66
结束页码: 77
语种: 英语
英文关键词: Brackish water
; Brackish-water ichnological model
; Deltas
; Estuaries
; Freshwater
; Neoichnology
; Trace fossils
英文摘要: Most existing ichnological models predict an increase in burrow density and diversity from the zone of persistent brackish-water into the realm of persistent freshwater. Herein we compare the neoichnology of five tidal-fluvial channels with varying tidal magnitudes, saltwater incursion distances, and river discharge. The results indicate that there is a noticeable diminution in the sizes of marine traces and a corresponding decrease in their distribution (reduced abundance of burrowed versus unburrowed beds) with decreasing salinity. From the landward limit of saltwater incursion into the wholly freshwater tidal backwater, there is no concurrent increase in terrestrial or freshwater burrow forms; rather, burrow diversities remain low (range: 10 to 35% of the "open marine" signature) and burrow densities decrease from BI 0-3 to BI 0-1 in both sand and mud units. The five modern systems described in this study do not support the hypothesis that there is an increase in bioturbation from the brackish-water reaches of channels into freshwater reaches. In fact, freshwater channels, including those in the tidal backwater zone, are characterized by very low trace-fossil diversities (1 to 2 forms) as well as low and sporadically distributed bioturbation intensities (BI 0-1). © 2015 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/68753
Appears in Collections: 过去全球变化的重建
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作者单位: Applied Research in Ichnology and Sedimentology (ARISE) Group, Department of Earth Sciences, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada; Ichnology Research Group, Department of Earth and Atmospheric Sciences, University of Alberta, 1-26 Earth Sciences Building, Edmonton, AB, Canada; Alberta Geological Survey, 402 Twin Atria Building, 4999 98 Avenue, Edmonton, AB, Canada
Recommended Citation:
La Croix A.D.,Dashtgard S.E.,Gingras M.K.,et al. Bioturbation trends across the freshwater to brackish-water transition in rivers[J]. Palaeogeography, Palaeoclimatology, Palaeoecology,2015-01-01,440