Diploptene in varved sediments of Saanich Inlet: indicator of increasing bacterial activity under anaerobic conditions during the Holocene

Saanich Inlet has been a highly productive fjord since the last glaciation. During ODP Leg 169S, nearly 70 m of Holocene sediments were recovered from Hole 1034 at the center of the inlet. The younger sediments are laminated, anaerobic, and rich in organic material (1-2.5 wt.% C sub(org)), whereas t...

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Bibliographic Details
Published in:Marine geology 2001-03, Vol.174 (1-4), p.371-383
Main Authors: Elvert, M, Whiticar, M.J, Suess, E
Format: Article
Language:English
Subjects:
Brackish
Canada
Marine
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Summary:Saanich Inlet has been a highly productive fjord since the last glaciation. During ODP Leg 169S, nearly 70 m of Holocene sediments were recovered from Hole 1034 at the center of the inlet. The younger sediments are laminated, anaerobic, and rich in organic material (1-2.5 wt.% C sub(org)), whereas the older sediments below 70 mbsf are non-laminated, aerobic, with glacio-marine characteristics and have a significantly lower organic matter content. This difference is also reflected in the changes of interstitial fluids, and in biomarker compositions and their carbon isotope signals. The bacterially-derived hopanoid 17 alpha (H),21 beta (H)-hop-22(29)-ene (diploptene) occurs in Saanich Inlet sediments throughout the Holocene but is not present in Pleistocene glacio-marine sediments. Its concentration increases after similar to 6000 years BP up to present time to about 70 mu g/g C sub(org), whereas terrigenous biomarkers such as the n-alkane C sub(31) are low throughout the Holocene (
ISSN:0025-3227
DOI:10.1016/S0025-3227(00)00161-4