A post-glacial isotope record of primary production and accumulation in the organic sediments of Saanich Inlet, ODP Leg 169S

Changes in palaeoproduction in Saanich Inlet, British Columbia, were examin ed from sediments using total organic carbon contents and stable carbon iso tope ratios. Sediments were obtained from Holes 1033B and 1034B of Ocean Dr illing Program Leg 169S. These cores contain two distinct zones: (1) carbon poor (%C-org < 0.5 wt.%) glaciomarine muds from the upper Pleistocene, and (2) carbon rich (%C(org)1-3 wt.%), well-laminated sediments from the Holoc ene, A slight monotonic rise in %C-org and <delta>C-13(org) throughout the Holocene suggests that primary production in the inlet has been steadily in creasing. Some influence of changes in local land vegetation is also eviden t. Sharp decreases in %C-org and delta C-13(org) in the early Holocene prob ably represent material deposited from a major flood, Differences in organi c delta C-13(org) between light and dark laminae are related to seasonal va riations in species composition temperature and nutrient conditions. (C) 20 01 Elsevier Science B.V. All rights reserved.