CELESTIAL FORCING AS A POSSIBLE DRIVER OF CYCLIC HOLOCENE CLIMATE AND MARINE PRODUCTIVITY IN THE NE PACIFIC

Marine-laminated sediments from anoxic basins in several fjords along the British Columbia coast provide an archive of Holocene climate variability and marine productivity at annual to millennial scales. Sediments from freeze and piston cores recovered from the Seymour-Belize Inlet Complex (SBIC) on the mainland coast and from Effingham Inlet, Vancouver Island were deposited under primarily anoxic conditions. In these inlets diatom-dominated laminae are deposited when marine productivity is higher in the spring to fall, and darker clay-dominated laminae are laid down under the higher precipitation conditions of winter. Wavelet transform and other time series analyses methods were applied to sediment color (i.e. gray-scale values) line scans obtained from x-ray images and compared with global records of cosmogenic nuclides (14C and 10Be), as well as the Ice Drift Index (hematite-stained grains) record to detect cycles, trends and non-stationarities in the sedimentary record. We carried out similar analyses on foraminifera, diatom, dinoflagellate and fish scale records recovered from these same cores. The results indicate that the marine productivity and sedimentary record of the NE Pacific responded to abrupt changes and long-term variability in climate that can be linked to external forcing (e.g. solar and cosmic irradiance). For example, a strong cooling in the NE Pacific at ~ 3550 yBP can be correlated to a weakening of high-frequency (50-150) year pulses in solar activity at the Gleissberg cycle band, similar to what occurred during the “Little Ice Age” about AD1630. Episodes of low sun activity are characterized in the sedimentary record (e.g. 2350, 2750 and 3350 yBP) of the cores by intervals of clay-rich and thick laminae that were deposited under unusually wet conditions. These intervals of higher precipitation may have been related to a regional intensification of the Aleutian Low (AL) caused by an eastward migration of the Center of Action (COA) of the AL, which occurs during intervals of solar minima. Dryer conditions prevail in the region when the COA of the AL migrates westward and the COA of the North Pacific High (NPH) migrates northward during intervals of solar maxima. These NPH and AL COA changes greatly impact the influence of open ocean upwelling in Effingham Inlet and estuarine circulation in the SBIC.