Stable isotope stratigraphy and paleoceanography of the last 170 K.Y.: Site 1014, Tanner Basin, California

摘要: Late Quaternary oxygen (δ 18 O) and carbon 13 C) isotopic records for the benthic foraminifer Uvigerina planktonic Globigerina bulloides are presented upper 20 meters composite depth sediment sequence of Ocean Drilling Program Site 1014, Tanner Basin, in outer California Borderland province. The record documents a continuous >160-k.y. from marine isotope Stage (MIS) 6 to present day. closely resembles other late North Pacific records, as well well-dated deep-sea (SPECMAP), thus provides detailed chronologic framework. 1014 useful response climate change it enters southern Borderland. Sedimentation rates relatively constant high (~11.5 cm k.y. –1 ). foraminiferal is preserved except during Substages 5b 5d, when normally G. abundance strongly diminished result dissolution. shift ~3‰ between last glacial maximum Holocene suggests surface water temperature <7°C, similar estimates Hole 893A (Leg 146) north. Unlike Santa Barbara δ O values interglacial (MIS 5) at were significantly higher than Holocene. In particular, Substage 5e (Eemian) was ~0.8‰ higher. This unlikely reflect cooler Eemian but instead preferential dissolution thin-shelled (low specimens this interval. mid-depth basin, large Termination I dramatic salinity changes switches source Intermediate Water. Although C disequilibria with seawater hence interpretations limited, exhibits several negative excursions found sites region (Sites 1017 893). indicates regional processes along margin. A general increase (–1.75‰ –0.75‰) Basin 200 overprinted smaller fluctuations correlated change. coolest intervals (MISs 2 4) exhibit lower values, which correlate global shifts. opposite relationship exhibited before 85 ka, associated warmer (marine 5c 5e) interglacial. These time also marked by decreased intermediate ventilation. Increased organic accumulation 5d anticorrelated record. results suggest that delicate balance has existed relative influences ventilation 1165-m 1014.