Abstract
Biogenic Silica (BSi) has been one of the most important proxies for determining the palaeoclimate from Lake Baikal over glacial-interglacial cycles. Concentrations (calculated through a 1% Na2CO3 wet-alkaline digestion) at a site in the north basin, however, reveal consistently low values during MIS 3 compared to greater than tenfold changes in diatom concentrations and biovolumes from c. 53.3–51.5 kyr BP. With similar glacial trends present at other low sedimentation sites, we suggest that significant amounts of BSi are removed from diatoms during glacials due to a relative increase in diatom dissolution at the sediment–water interface. This contrasts with existing results from other, higher sedimentation, sites such as those within the Selenga Delta, which display a strong relationship between diatoms and BSi. Site selection is therefore essential when searching for Heinrich and other glacial millennial-scale events in Lake Baikal, and we recommend that both BSi and diatom concentrations be calculated together in future studies.
Highlights
An increasingly recognised feature in glacial lacustrine and marine sediments are the presence of abrupt climate events, such as Heinrich and/or smaller amplitude Dansgaard/Oeschger (D/O) events (Heinrich 1988; Dansgaard et al 1993)
Similar to the biogenic silica (BSi) record, diatom concentrations are low throughout the sequence (c. < 1 x 107 valves/g dry wt) except from c. 53.3-51.5 kyr BP when concentrations increase from 0.056 x 107 valves/g dry wt. to 3.026 x 107 valves/g dry wt. (Fig. 2), reflecting a warm interval terminated by Heinrich event 5 (Swann et al 2005)
A notable feature of the Continent Ridge record is the lack of an increase in BSi from c. 0.9-1.5 wt.% as SiO2 during the interval from c. 53.3-51.5 kyr BP when diatom concentrations increase to 3.026 x 107 valves/g dry wt. and biovolume measurements rise to c. 11,000 μm3/g dry wt. (Fig. 2)
Summary
An increasingly recognised feature in glacial lacustrine and marine sediments are the presence of abrupt climate events, such as Heinrich and/or smaller amplitude Dansgaard/Oeschger (D/O) events (Heinrich 1988; Dansgaard et al 1993). Obtaining reliable information from such sites is important since their reduced oceanic control permits associations to be made to hemispheric climatic processes and their global teleconnections. These sites provide information concerning the rates of environmental change during these events in addition to their impact and regional leads and lags. Measurements of biogenic silica (BSi) have been extensively used to obtain palaeoclimatic information over glacial-interglacial cycles (e.g., Colman et al 1995, 1999; Williams et al 1997). 98% of all sedimentary BSi (Granina et al 1992), BSi profiles essentially represent a record of diatom palaeoproduction. BSi, though, is often a more practical measurement than diatom species analysis since it inherently accounts for diatom size and biovolume with significantly reduced analytical time
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
