ISSN:
1573-0417
Keywords:
sediments
;
14C
;
210Pb
;
diatoms
;
geochemical analyses
;
coastal paleoenvironments
;
paleolimnology
;
Nodularia
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Geosciences
Notes:
Abstract An investigation of Holocene sediments within Lake Alexandrina, a shallow coastal lake at the mouth of the Murray River, South Australia, is presented based on a multidisciplinary approach.14C and210Pb radiometric dating methods are used to establish a geochronological framework for the last 7000 yr BP, and diatoms, sand-siltclay ratios, organic carbon, phosphorus and copper concentrations are used to infer paleoenvironmental changes. The diatom assemblages indicate a change from marine-brackish to oligosaline-freshwater conditions between 7000 and 6000 yr BP, with sea-level stabilisation and continuous barrier formation across the Murray mouth. Sand pulses after 2300 yr BP document sand spit formation in the lake and the commencement of extensive lacustrine sedimentation. In the past 100 years which include the advent of European settlement in the region, the short-term210Pb-based mass accumulation rate of 0.063 g cm−2 yr−1 is greater than that of the longer-term mean14C-based rate (0.023 g cm−2 yr−1), and high concentrations of phosphorus and copper correspond to historical records of blue-green algal blooms.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00678024
