Section 20
Chapter 19,974

Sedimentation dynamics in the Santa Monica-San Pedro Basin off Los Angeles; radiochemical, sediment trap and transmissometer studies

Huh, C.-An; Small, L.F.; Niemnil, S.; Finney, B.P.; Hickey, B.M.; Kachel, N.B.; Gorsline, D.S.; Williams, P.M.

Continental Shelf Research 10(2): 137-164


ISSN/ISBN: 0278-4343
DOI: 10.1016/0278-4343(90)90027-j
Accession: 019973133

A large number of sediment cores and sediment trap samples collected from different parts of the Santa Monica-San Pedro (SM-SP) Basin during 1985–1988 were studied for radionuclides, trace metals and other sedimentary components. The radiochemical data are presented here to give a basin-wide view of the sedimentation dynamics.210Pb stratigraphy indicated that sedimentation rates were higher and more variable (30–80 mg cm2y1) in the more dynamic slope region, but were uniformly low (13.4–18.8 mg cm2y1) in the flat, deep basin. From the sediment record, it was suggested that sedimentation rates were decreasing and the area of anoxia had been expanding, at least during the past one to two centuries. Turbidite layers found in the sediment cores suggested higher frequency and more recent occurrence toward the basin margins.210Pb geochronologies indicated that the recent turbidites might be related to major storms which occurred during the past two decades.

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