Freshwater control of ice-rafted debris in the last glacial period at Mono Lake, California, USA |
| |
Authors: | Susan R.H. Zimmerman Crystal Pearl Sidney R. Hemming Kathryn Tamulonis N. Gary Hemming Stephanie Y. Searle |
| |
Affiliation: | aDept. of Earth and Environmental Sciences, Columbia University, New York, NY 10027, USA;bSchool of Earth and Environmental Sciences, Queens College, City University of New York, Flushing, NY 11367, USA;cDept. of Earth and Environmental Sciences and Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964, USA;dDept. of Geology, Dickinson College, Carlisle, PA 17013, USA;eSchool of Earth and Environmental Sciences, Queens College, City University of New York, Flushing, NY 11367, USA;fDept. of Earth and Environmental Sciences, Columbia University, New York, NY 10027, USA |
| |
Abstract: | The type section silts of the late Pleistocene Wilson Creek Formation at Mono Lake contain outsized clasts, dominantly well-rounded pebbles and cobbles of Sierran lithologies. Lithic grains > 425 μm show a similar pattern of variability as the > 10 mm clasts visible in the type section, with decreasing absolute abundance in southern and eastern outcrops. The largest concentrations of ice-rafted debris (IRD) occur at 67–57 ka and 46–32 ka, with strong millennial-scale variability, while little IRD is found during the last glacial maximum and deglaciation.Stratigraphic evidence for high lake level during high IRD intervals, and a lack of geomorphic evidence for coincidence of lake and glaciers, strongly suggests that rafting was by shore ice rather than icebergs. Correspondence of carbonate flux and IRD implies that both were mainly controlled by freshwater input, rather than disparate non-climatic controls. Conversely, the lack of IRD during the last glacial maximum and deglacial highstands may relate to secondary controls such as perennial ice cover or sediment supply. High IRD at Mono Lake corresponds to low glacial flour flux in Owens Lake, both correlative to high warm-season insolation. High-resolution, extra-basinal correlation of the millennial peaks awaits greatly improved age models for both records. |
| |
Keywords: | Mono Lake Late Pleistocene IRD Lake level Paleoclimate Ice rafting Great Basin |
本文献已被 ScienceDirect 等数据库收录! |
|