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Sediment-magnetic signature of land-use and drought as recorded in lake sediment from south-central Minnesota, USA Christoph E. Geissa,*, Subir K. Banerjeeb, Phil Camillc, Charles E. Umbanhowar Jr.d aDepartment of Physics, Trinity College, Hartford, CT 06106, United States bDepartment of Geology and Geophysics, University of Minnesota, Minneapolis, MN 55455, United States cDepartment of Biology, Carleton College, Northfield, MN 55057, United States dDepartment of Biology, St. Olaf College, Northfield, MN 55057, United States Received 20 August 2003 Abstract Sediment magnetic properties of a short core from Sharkey Lake, MN, record the effects of Euroamerican settlement and climate change over the last 150 yr. The onset of European-style farming led to increased erosion, reflected in high values of concentration-dependent parameters such as magnetic susceptibility (j), Isothermal Remanent Magnetization (IRM), and Anhysteretic Remanent Magnetization (ARM). These high values are only partially due to increased supply of terrigenous material to the lake, and recent sediment contains an additional component of authigenic fine (single-domain) magnetite, most likely magnetosomes from magnetotactic bacteria. High organic productivity in the lake during the 1920s to 1940s drought increased this authigenic component resulting in highly magnetic fine-grained sediment. A comparison with older Holocene sediment from the same lake shows that, over time, most of the fine magnetic signal is lost after deposition, leading to decreases in magnetization and a bimodal grain size distribution of ultrafine, superparamagnetic grains and coarser multidomain particles, evident from measurements of ARM/IRM ratios, hysteresis measurements, and low-temperature analyses. The effects of dissolution and the superposition of climate and land-use signals complicate the use of recent sediments as modern analogs for sediment magnetic analyses. D 2004 University of Washington. All rights reserved. Keywords: Sediment magnetism; Holocene; Limnology; Drought; Reductive dissolution; Magnetotactic bacteria Introduction In recent years, sediment-magnetic investigations have played an increasingly important role in reconstructing paleoenvironmental and paleoclimatic change from con-tinental and marine records. Multi-proxy studies that include sediment-magnetic analyses have successfully reconstructed late Pleistocene and Holocene climate variations (e.g., Oldfield et al., 2003; Rosenbaum et al., 1996), have clarified sediment provenance (Reynolds et al., 1997), or established the fire history of a watershed (Gedye et al., 2000). Sediment-magnetic parameters are easily measured and allow for the rapid construction of high-resolution records of paleoclimate independent from other paleoclimate proxies, such as pollen or geochemistry. They are, however, no direct recorder of climate or environmental change. Interpretation of magnetic parameters in such terms requires identification of the underlying processes that influence the input, distribution, preservation, or neoformation of the minerals that make up the magnetic component of the sediment. Research described in this paper helps to improve the interpretation of sediment-magnetic parameters by compar-ing them to known climatic or environmental changes. Geiss et al. (2003) studied several lakes along the prairie-forest ecotone in Minnesota to determine the processes that 0033-5894/$ - see front matter D 2004 University of Washington. All rights reserved. doi:10.1016/j.yqres.2004.06.009 * Corresponding author. Department of Physics, Trinity College, 300 Summit Street, Hartford, CT 06106. E-mail addresses: christoph.geiss@trincoll.edu (C.E. Geiss)8 banerjee@umn.edu (S.K. Banerjee)8 pcamill@carleton.edu (P. Camill)8 ceumb@stolaf.edu (C.E. Umbanhowar). Quaternary Research 62 (2004) 117– 125 www.elsevier.com/locate/yqres
Object Description
Collection Title | Scholarly Publications by Carleton Faculty and Staff |
Journal Title | Quaternary Research |
Article Title | Sediment-magnetic signature of land-use and drought as recorded in lake sediment from south-central Minnesota, U.S.A. |
Article Author |
Camill, Phil Geiss, Christoph Banerjee, Subir Umbanhowar, Charles |
Carleton Author |
Camill, Phil |
Department | Biology |
Field | Science and Mathematics |
Year | 2004 |
Volume | 62 |
Publisher | Elsevier |
File Name | 002_Camill-Phil_Sediment-magneticSignatureOfLandUse.pdf; 002_Camill-Phil_Sediment-magneticSignatureOfLandUse.pdf |
Rights Management | This document is authorized for self-archiving and distribution online by the author(s) and is free for use by researchers. |
RoMEO Color | RoMEO_Color_Green |
Preprint Archiving | Yes (with link to journal home page) |
Postprint Archiving | Yes |
Publisher PDF Archiving | No |
Paid OA Option | Yes |
Contributing Organization | Carleton College |
Type | Text |
Format | application/pdf |
Language | English |
Description
Article Title | Page 1 |
FullText | Sediment-magnetic signature of land-use and drought as recorded in lake sediment from south-central Minnesota, USA Christoph E. Geissa,*, Subir K. Banerjeeb, Phil Camillc, Charles E. Umbanhowar Jr.d aDepartment of Physics, Trinity College, Hartford, CT 06106, United States bDepartment of Geology and Geophysics, University of Minnesota, Minneapolis, MN 55455, United States cDepartment of Biology, Carleton College, Northfield, MN 55057, United States dDepartment of Biology, St. Olaf College, Northfield, MN 55057, United States Received 20 August 2003 Abstract Sediment magnetic properties of a short core from Sharkey Lake, MN, record the effects of Euroamerican settlement and climate change over the last 150 yr. The onset of European-style farming led to increased erosion, reflected in high values of concentration-dependent parameters such as magnetic susceptibility (j), Isothermal Remanent Magnetization (IRM), and Anhysteretic Remanent Magnetization (ARM). These high values are only partially due to increased supply of terrigenous material to the lake, and recent sediment contains an additional component of authigenic fine (single-domain) magnetite, most likely magnetosomes from magnetotactic bacteria. High organic productivity in the lake during the 1920s to 1940s drought increased this authigenic component resulting in highly magnetic fine-grained sediment. A comparison with older Holocene sediment from the same lake shows that, over time, most of the fine magnetic signal is lost after deposition, leading to decreases in magnetization and a bimodal grain size distribution of ultrafine, superparamagnetic grains and coarser multidomain particles, evident from measurements of ARM/IRM ratios, hysteresis measurements, and low-temperature analyses. The effects of dissolution and the superposition of climate and land-use signals complicate the use of recent sediments as modern analogs for sediment magnetic analyses. D 2004 University of Washington. All rights reserved. Keywords: Sediment magnetism; Holocene; Limnology; Drought; Reductive dissolution; Magnetotactic bacteria Introduction In recent years, sediment-magnetic investigations have played an increasingly important role in reconstructing paleoenvironmental and paleoclimatic change from con-tinental and marine records. Multi-proxy studies that include sediment-magnetic analyses have successfully reconstructed late Pleistocene and Holocene climate variations (e.g., Oldfield et al., 2003; Rosenbaum et al., 1996), have clarified sediment provenance (Reynolds et al., 1997), or established the fire history of a watershed (Gedye et al., 2000). Sediment-magnetic parameters are easily measured and allow for the rapid construction of high-resolution records of paleoclimate independent from other paleoclimate proxies, such as pollen or geochemistry. They are, however, no direct recorder of climate or environmental change. Interpretation of magnetic parameters in such terms requires identification of the underlying processes that influence the input, distribution, preservation, or neoformation of the minerals that make up the magnetic component of the sediment. Research described in this paper helps to improve the interpretation of sediment-magnetic parameters by compar-ing them to known climatic or environmental changes. Geiss et al. (2003) studied several lakes along the prairie-forest ecotone in Minnesota to determine the processes that 0033-5894/$ - see front matter D 2004 University of Washington. All rights reserved. doi:10.1016/j.yqres.2004.06.009 * Corresponding author. Department of Physics, Trinity College, 300 Summit Street, Hartford, CT 06106. E-mail addresses: christoph.geiss@trincoll.edu (C.E. Geiss)8 banerjee@umn.edu (S.K. Banerjee)8 pcamill@carleton.edu (P. Camill)8 ceumb@stolaf.edu (C.E. Umbanhowar). Quaternary Research 62 (2004) 117– 125 www.elsevier.com/locate/yqres |