Sedimentation and climatic patterns in the Santa Barbara Basin during the 19th and 20th centuries

摘要

The thickness of annual sediment laminations in the Santa Barbara Basin is compared to southern California drought-resistant tree growth and to regional indices of rainfall and temperature. The rate of sedimentation was found to be independent of temperature, but it is highly correlated with rainfall and tree growth. We suggest that sedimentation, like tree growth, is a function of the amount of rainfall in the prior seasons as well as the current season. The natural filter displayed by the sedimentation and tree-growth records can be described by a simple mathematical model which, in the case of sedimentation, can be related to upstream aggradation or to distributional processes on the shelf. The pair of laminae that constitute a single year's sediment accumulation are directly related. This suggests that the process of detrital sediment delay and redistribution operates primarily in the marine environment. The density difference that distinguishes "winter" laminae and "summer" laminae is ascribed to the interaction of the seasonal rate of deposition and the growth of a mat-forming organism endemic to the surface sediment of the Santa Barbara Basin.