Start |Grid View | Author Index | View Uploaded Presentations | Meeting Information

North-Central Section - 54th Annual Meeting - 2020

Paper No. 39-1
Presentation Time: 1:35 PM

RECONSTRUCTION OF PALEOENVIRONMENTAL CONDITIONS AND TEMPORAL PATTERNS OF ANCIENT MINING ON ISLE ROYALE USING BIOGEOCHEMICAL ANALYSES OF LAKE SEDIMENT


VALL, Kathryn G., MineraLogic LLC, Duluth, MN 55802; Earth and Environmental Sciences, University of Minnesota Duluth, Duluth, MN 55805, STEINMAN, Byron A., Department of Earth and Environmental Sciences and Large Lakes Observatory, University of Minnnesota Duluth, 1114 Kirby Drive Heller Hall 229, Duluth, MN 55812, POMPEANI, David P., Department of Geography, Kansas State University, 1002 Seaton Hall, 920 N. 17th Street, Manhattan, KS 66506, SCHREINER, Kathryn, Large Lakes Observatory and Department of Chemistry & Biochemistry, University of Minnesota Duluth, 2205 E 5th St, Duluth, MN 55812 and DEPASQUAL, Seth, Cultural Resources, Isle Royale National Park, Houghton, MI 49931

Isle Royale and the Keweenaw Peninsula of Michigan are home to some of the oldest examples of native North American metalworking and land use. The overarching objective of this research is to produce a reconstruction of the timing, spatial patterns, and environmental impacts of mining activities on Isle Royale through sedimentological and biogeochemical analysis of lacustrine sediments. We also seek to produce a parallel record of paleoenvironmental conditions in order to assess the potential impacts of environmental change on ancient mining cultures.

In 2016, we collected a 7.5 m long sediment core sequence from Lily Lake on Isle Royale, MI. Lily Lake lies approximately 100 m above the current water level of Lake Superior, and formed approximately ~11,000 years before present following the retreat of the Laurentide ice sheet. Lily Lake has been exposed to very little human land use change relative to other lakes on Isle Royale (e.g. there are no ancient pit mines in the immediate catchment), and thus is well suited for reconstructing past environmental changes. We analyzed weakly sorbed metal concentrations using ICP-MS to test hypotheses on the timing and transport mechanisms of potential metal pollution derived from ancient mining activities. In addition, we conducted EA-IRMS analysis (including carbon/nitrogen ratios, and the isotopic composition of organic C and N) on bulk organic sediment to provide a record of natural paleoenvironmental changes.

Results from the metals analysis provide evidence of Middle Archaic mining activity that is temporally consistent with radiocarbon dated artifacts and similar evidence from other lakes located adjacent ancient pit mines on Isle Royale and the Keweenaw Peninsula of Michigan. Additional work is required to assess the relative influence of natural versus anthropogenic processes that may have influenced metal concentrations in Lily Lake sediment and to determine a transport mechanism for the putative mining related pollution.

Session No. 39

T24. Lakes as Sentinels of Environmental Change
Tuesday, 19 May 2020: 1:30 PM-5:30 PM
Lake Superior Ballroom MN (Duluth Entertainment Convention Center)
Geological Society of America Abstracts with Programs. Vol. 52, No. 5
doi: 10.1130/abs/2020NC-348279
© Copyright 2020 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.
Back to: T24. Lakes as Sentinels of Environmental Change
Previous Abstract | Next Abstract >>