Leg 169S-Saanich Inlet

Co-Chiefs: Brian BornholdStaff Scientist: John Firth
Cruise Dates: 19-21 August 1996Operations Superintendent: Eugene Pollard
Engineer: Leon Holloway


An improved understanding of the climate-ocean system, and in particular the global carbon cycle, will require ultra-high-resolution studies of rapidly deposited sediments in a variety of geographic settings. Because such sites record climatic and oceanographic conditions on an annual or seasonal basis, they will permit calibration and refinement of fully ocean-coupled general circulation models as well as lead to a better appreciation of the links among oceanographic processes, climatic parameters, terrestrial vegetation, and marine biota in coastal areas of the world.

Sediments from Saanich Inlet, British Columbia, contain a virtually continuous record of Holocene climatic and oceanographic change with seasonal resolution, together with a possible record of the paleoseismicity associated with the Cascadia convergent margin. Situated in a fjord near Victoria, British Columbia, the proposed sites record both terrestrial floral change since deglaciation (9000 to 11,000 m.y. ago) as well as marine biological productivity variations in a temperate-latitude coastal setting. The Saanich Inlet sites will provide an important complement to the high-resolution record obtained at Site 893 in the Santa Barbara Basin during Leg 146.

Leg Objectives

The objectives of ODP coring in Saanich Inlet are:

  1. To obtain an ultra-high-resolution record of Holocene climate, oceanography, marine productivity, ecology, and terrestrial vegetation;
  2. To attempt to establish the frequency of earthquakes (particularly very large events, which are greater than magnitude 8 in this region of the Cascadia convergent margin);
  3. To advance the understanding of diagenesis in organic-rich sedimentary basins, especially the role of microbial processes. The predominantly finely laminated (varved) sediments that are thought to have accumulated in the inlet since deglaciation will be cored at two sites in the deeper axial region of the fjord. These two sites (at 200 and 225 m water depth) have significantly different organic contents and accumulation rates.

Operations Update

Approximately 100 to 125 m of Holocene diatomaceous silts and clays and upper Pleistocene glaciomarine muds will be cored with the advanced hydraulic piston corer (APC) to refusal at two sites. Both sites will be triple cored with the APC. Only cores from Hole A at each site will be measured using the multisensor track (MST), split, and photographed on board. Core from Holes B and C at each site will be measured with the MST during Leg 169, and then they will be taken to the Gulf Coast Repository for further work. Temperature measurements will be made in the lowermost part of Site SI-02B if time permits.

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