45 Long Continental Records

Monday, 28 July 2003
8:00 AM - 12:00 PM

A 65 KA HIGH-RESOLUTION TERRESTRIAL CLIMATE RECORD FROM LAGUNA DE LAS TRANCAS, CENTRAL COAST, CALIFORNIA

Paper number: 45-11
Program: SYMPOSIA
Time: 10:50 AM – 11:10 AM

Authors

Abstract

Geochemical and mineral magnetic analysis of a 10m sediment record from Laguna de las Trancas, Central Coastal California, reveals alternation between aeolian and lacustrine sediment sources over the last 65 ka (age based on the 55-65 ka Olema ash at 9.8m). Down-core trends preserved in the stratigraphy from this small, landslip lake closely match the marine isotope record from the Santa Barbara Basin for this time interval.

Sediment deposited during MIS 1 and 3 contains abundant diatoms, pollen and plant macrofossils and reveals strong magnetosome activity, implying productive lacustrine conditions. The minor aeolian silt/sand component varies cyclically, reflecting fluctuations in either aeolian supply or lake productivity. MIS 2 and 4 are silt/sand dominated and possess strongly cyclical changes in composition.

The geochemical record shows striking similarity with neighbouring marine records - a comparison justified by the robust two-point dating framework. Strong cyclical variation (ca. 1000 year timescale) shows considerable similarity to the well-established offshore records inferred to be related to Dansgaard-Oeschger events. This has potentially great significance for both the Late Quaternary climate record and for determining land-sea climate coupling in this region.