| Popis: |
Saanich Inlet, a fjord on the eastern side of Vancouver Island, has HsS in the bottom waters during most of the year. Recent marinc sediments in the inlet include three clistinctly different types. Black, fine-graincd, varved clayey silts containing H& and large amounts of diatom frusEulcs and carbonaceous organic materials occur in the central part of the inlet. Olive-gray silts with moderate concentrations of organic materials and rcducing capacities occur on the sill at the entrance to the inlet. The nearshorc sands and gravels have low organic contents and low reducing capacity. Carbonate-rich sediments occur near a limestone quarry and cement factory. A carbon-nitrogen ratio of 7 is typical of the sediments in the inlet. Five sources of sediment can bc distinguished: ( 1) carbonaceous and siliceous organic matter from marinc organisms, principally planktonic diatoms, (2) suspcndcd scdimcnt in low-salinity water brought from the Fraser and Cowichan rivers, (3) material eroded from adjacent shorelines, (4) streams discharging into the inlet, and (5) the cement plant and limestone quarry at: Bambcrton. The varvcd sediments in the central basin consist of olive-gray laminac, apparently formed during the peak diatom production in spring or summer and olive-black laminac, containing larger mounts of terrigenous sediment, probably formed during the autumn and winter, Zones of nonlaminated sediment may be formed by terrigenous material or by the disruption of the laminated sediment by other physical processes. No evidence of burrowing organisms has been detected. Four to 6 mm of wet sediment are deposited each year in the southern portion of t]lc inlet. If this rate is typical of the basin as a whole, approximately 10G metric tons of s&imcnt are deposited each year. At least 25-35s of this sediment is dcrivcd from nlarinc organisms. |
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