21. LATEST QUATERNARY PALEOCLIMATIC AND RADIOCARBON CHRONOLOGY, HOLE 1017E, SOUTHERN CALIFORNIA MARGIN¹

ABSTRACT

Oxygen isotopic (¹⁸O) climatic stratigraphy and radiocarbon chronology, at high resolution, have been used to establish an age model for Ocean Drilling Program Hole 1017E, a continuous 25-m sequence of hemipelagic sediments from the continental slope (956 m water depth), east of Point Arguella, Southern California. The upper part of Hole 1017E from ~33 ka (7.445 mbsf) was dated using 13 calendar-corrected radiocarbon ages of mixed planktonic foraminiferal assemblages. Benthic oxygen isotopic stratigraphy records a continuous 130-k.y. sequence ranging from marine isotope Stage 6 to the present day. The benthic ¹⁸O curve, representing the last two interglacial and glacial cycles, closely resembles the well-dated, deep-sea reference sequence, providing a detailed chronologic framework. Sedimentation rates remained relatively constant throughout the sequence at ~18 cm/k.y. and were sufficiently rapid to provide considerable potential for high-resolution paleoceanographic/paleoclimatic investigations.

Planktonic foraminiferal oxygen isotopic stratigraphy based on the surface-dwelling form Globigerina bulloides defines an almost complete sequence of interstadial/stadial oscillations (Dansgaard/Oeschger cycles [D/O]). Combined use of radiocarbon chronology, deep-sea oxygen isotopic datums, and visual pattern matching has enabled us to identify the sequence of D/O cycles as described for the Greenland (GRIP2) ice core. This has strengthened the stratigraphic framework for the last 60 k.y. in the sequence as a basis for further paleoenvironmental investigations.

¹Lyle, M., Koizumi, I., Richter, C., and Moore, T.C., Jr. (Eds.), 2000. Proc. ODP, Sci. Results, 167 [Online]. Available from World Wide Web: <http://www-odp.tamu.edu/publications/167_SR/167sr.htm>. [Cited YYYY-MM-DD]

²Department of Geological Sciences and Marine Science Institute, University of California, Santa Barbara CA 93106, USA. Correspondence author: kennett@magic.geol.ucsb.edu

³Department of Geography, University of California, Berkeley CA 94720, USA.

⁴Present address: Department of Geology and Geophysics, University of California, Berkeley CA 94720, USA.

⁵Geological Institute, University of Tokyo, 7-3-1 Hongo, Tokyo 113, Japan.

Date of initial receipt: 28 October 1998
Date of acceptance: 3 May 1999
Ms 167SR-242