Wisconsin Glaciation of the Sierra Nevada (79,000–15,000 yr B.P.) as Recorded by Rock Flour in Sediments of Owens Lake, California

• Published in: Quaternary research Vol. 55; no. 1; pp. 14 - 24
• Main Authors: Bischoff, James L., Cummins, Kathleen
• Format: Journal Article
• Language: English
• Published: New York, USA Cambridge University Press 01.01.2001; Elsevier Inc; Elsevier
• Subjects: America; Bgi / Prodig; Physical geography; United States of America; United States of America; California; USA, Wisconsin; AN, North Atlantic; INE, USA, California; USA, Nevada; USA, California, Searles L; USA, California, Owens L; rock flour; Wisconsin Glaciation; Owens Lake; Sierra Nevada; Glaciation; Geochronology; C 14 dating; Glacier fluctuation; Quaternary; Geochemistry; Lacustrine sediment; Grain size distribution; Th/U dating
• ISSN: 0033-5894; 1096-0287
• DOI: 10.1006/qres.2000.2183

Chemical analyses of the clay-sized fractions of 564 continuous sediment samples (200-yr resolution) from composite core OL90/92 allow quantification of an abundance of glacial rock flour. Rock flour produced during glacier advances is represented by clay-sized plagioclase, K-feldspar, and biotite in homogeneous internal composition. The abundance of rock flour is deemed proportional to the intensity of glacies advances. Age control for the composite section is provided by combining previously published radiocarbon dates on organics, U/Th dates on ostracode shells, and U/Th dates on saline minerals from nearby Searles Lake correlated to OL92 by pollen. The rock flour record displays three levels of variability: (1) a dominant one of about 20,000 yr related to summer insolation and precipitation; (2) an intermediate one of 3000–5000 yr, perhaps related to North Atlantic Heinrich events; and (3) a minor one of 1000–2000 yr, perhaps related to North Atlantic thermohaline-driven air-temperature variation.