Abstracts with Programs - Geological Society of America
Abstracts with Programs - Geological Society of America
Abstracts with Programs - Geological Society of America
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SESSION NO. 24, 8:00 AM<br />
Friday, 3 May 2013<br />
T5. Quaternary Research in the Great Lakes Region II:<br />
The Holocene, Part I<br />
Fetzer Center, Putney Auditorium<br />
24-1 8:00 AM Hladyniuk, Ryan [218332]<br />
THE N-ALKANE AND CARBON-ISOTOPE SIGNATURES OF ORGANIC CARBON IN LAKE<br />
ONTARIO SINCE 14,000 CAL YR BP<br />
HLADYNIUK, Ryan, DILDAR, Nadia, and LONGSTAFFE, Fred J., Department <strong>of</strong> Earth<br />
Sciences, The University <strong>of</strong> Western Ontario, 1151 Richmond Street, Biological and<br />
<strong>Geological</strong> Sciences Building, London, ON N6A5B7, Canada, rhladyni@uwo.ca<br />
The n-alkane abundances and carbon-isotope compositions <strong>of</strong> organic matter (OM) from Lake<br />
Ontario sediments reveal a complex history <strong>of</strong> variation in both source and lacustrine productivity<br />
over the last 14,000 cal yr BP. Glacial sediments containing ~0.2-0.3 % organic carbon (OC) are<br />
dominated by C23 through C29 n-alkanes. These compositions most likely represent allochtonous<br />
contributions <strong>of</strong> peat, higher terrestrial plant matter and clay-associated OM delivered by glacial<br />
meltwaters from the periglacial environment. Subordinate amounts <strong>of</strong> C17-C19 n-alkanes<br />
may indicate limited primary lacustrine productivity at this time. Transition from glacial to postglacial<br />
conditions in the Lake Ontario basin was marked by a lowering <strong>of</strong> water levels, rising<br />
OC contents, and increased abundances <strong>of</strong> C17-19 n-alkanes. Little systematic carbon isotopic<br />
variation was found for individual n-alkanes in the glacial and transitional sediments: C17-C19,<br />
–30 per mil; C21, –33 to –30 per mil; and C23+, –33 to –32 per mil, which likely reflects wellmixed,<br />
multiple OM sources. Hydraulic closure <strong>of</strong> Lake Ontario beginning at about 12,300 cal yr<br />
BP produced its lowest recorded levels. Approximately equal abundances <strong>of</strong> C17-C19, C23-C25,<br />
and C27+ n-alkanes at this time are tentatively interpreted to indicate lacustrine, (submergent)<br />
macrophyte and terrestrial OM contributions. C17-C19 n-alkanes showed little carbon isotopic<br />
variation from the older sediments. However, a 2 per mil decrease in carbon-13 for C23 and<br />
enrichments <strong>of</strong> ≤8 per mil for C25+ n-alkanes (C25> C27> C29) occurred by the end <strong>of</strong> hydraulic<br />
closure. Increased littoral zone productivity may have been favoured by low lake levels. Warming<br />
beginning at 8,300 cal yr BP triggered a transition from cold/dry to warm/wet conditions, during<br />
which water levels gradually rose. OC in associated lake sediments reaches 2 % and contains the<br />
highest fraction <strong>of</strong> C27+ n-alkanes, which have carbon isotopic compositions <strong>of</strong> –33 to –30 per<br />
mil. These data suggest that Lake Ontario received significant terrestrial OM from its catchment<br />
at this time. The progressive 5 per mil depletion <strong>of</strong> carbon-13 in C17 and C25 n-alkanes upwards<br />
through this interval remains to be explained.<br />
24-2 8:20 AM Loope, Walter L. [218627]<br />
CAN PALEOECOLOGICAL PROXIES ADEQUATELY FORECAST SURFACE COVER ACROSS<br />
NORTH CENTRAL NORTH AMERICA? (A CAUTIONARY TALE)<br />
LOOPE, Walter L., United States <strong>Geological</strong> Survey, N8391 Sand Point Road, P.O. Box 40,<br />
Munising, MI 49862, wloope@usgs.gov<br />
Pollen stratigraphy provides the core body <strong>of</strong> paleoecological perspective across north central<br />
North <strong>America</strong>. Pollen based methodologies have matured over nearly a century and are<br />
now joined by a vast and vetted literature focused on paleolimnology, wetland dynamics, soil<br />
stratigraphy and landscape ecology. The COHMAP project <strong>of</strong> the 1970s and 80s placed these<br />
data sets in spatial context across the continent and more recent updates and refinements <strong>of</strong><br />
these maps have been developed. The utility and importance <strong>of</strong> paleoecological models are more<br />
apparent given recognition <strong>of</strong> anthropogenic climate forcing. Concurrent <strong>with</strong> their adoption and<br />
broad use in discussions <strong>of</strong> such forcing, however, caveats and limitations <strong>of</strong> paleoecological<br />
data, prominently voiced by their authors, must be honored. Linda Brubaker, a pioneer in the<br />
application <strong>of</strong> pollen stratigraphy to Upper Michigan, recognized in 1975 that patchy habitats<br />
<strong>of</strong>ten impose permanent control on vegetation pattern on varying spatial scales. The scale <strong>of</strong><br />
patchiness varies across landscapes and greatly complicates their classification as well as<br />
any assessment <strong>of</strong> their projected behavior. In broad and roughly uniform landscapes these<br />
complications may be minimal; in patchy landscapes, they may defy intuition and interpretation.<br />
As Brubaker pointed out, some <strong>of</strong> the more obvious drivers <strong>of</strong> patchiness in the upper Midwest<br />
are differences in soil texture and development and in the nature <strong>of</strong> regolith. These differences<br />
are invisible in broad pattern but detectable on a local level. Pollen-based maps <strong>of</strong> surface cover<br />
in eastern Upper Michigan prove inadequate in detecting the major climatic anomaly that drove<br />
hydrologic closure <strong>of</strong> the Upper Great Lakes ~10-8 ka. In contrast, an intensive study <strong>of</strong> 2 ponds<br />
<strong>with</strong>in a small sandy tract in Alger County clearly identifies this and other major droughts at that<br />
time, albeit on different scales. Maps <strong>of</strong> Quaternary vegetation at sub-continental scales are<br />
useful across uniform environments but may fail to portray important local and even regional<br />
differences. This has long been recognized and expressed by pollen practitioners but may be<br />
glossed over by modelers who need to summarize projected change across the continent.<br />
24-3 8:40 AM Yansa, Catherine H. [218716]<br />
A 8500-YEAR RECORD OF LAKE-EFFECT CLIMATE FROM MINER LAKE, SOUTHWESTERN<br />
LOWER MICHIGAN<br />
YANSA, Catherine H., Department <strong>of</strong> Geography, Michigan State University, 227 Geography<br />
Building, East Lansing, MI 48824-1117, yansa@msu.edu and RAWLING, J. Elmo III,<br />
Geography/Geology, University <strong>of</strong> Wisconsin Platteville, 1 University Plaza, Platteville, WI<br />
53818<br />
Miner Lake (42.7°N, 85.8°W) in Allegan County, southwestern Lower Michigan, is located<br />
30 km east <strong>of</strong> Lake Michigan. Today, the local vegetation is comprised <strong>of</strong> primarily beech-maple<br />
forest and has a lake-mediated climate characterized by higher snowfall and warmer winter<br />
temperatures than inland locations. The objective <strong>of</strong> our research was to test whether the lakeeffect<br />
climate in the past was a more dominant influence on the local climate <strong>of</strong> the Miner Lake<br />
area than regional paleoclimate patterns. We did this by analyzing sediment cores from Miner<br />
Lake for pollen, plant macr<strong>of</strong>ossils and sedimentology (particle size, % organic matter (OM), and<br />
% calcium carbonate (CaCO )), and compared these data to paleoclimate data from two lakes<br />
3<br />
from inland locations <strong>with</strong> similar latitudes.<br />
Over the past 8500 cal yr BP, the sedimentology and paleobotany <strong>of</strong> Miner Lake indicate that<br />
there has been little environmental change in the area. In general, the %OM increases from ~25<br />
to 40%, %CaCO decreases from ~20 to 10% and the median grain size ranges from ~10 to 25<br />
3<br />
microns. The high %OM and CaCO , and fine median grain size in the sediments <strong>of</strong> Miner Lake<br />
3<br />
SESSION NO. 24<br />
suggest that this lake received little influx <strong>of</strong> clastic material. The pollen and plant macr<strong>of</strong>ossil<br />
records indicate four intervals <strong>of</strong> vegetation change. A pine-oak forest characterizes Zone I<br />
(~8500 to 7000 cal yr BP), prior to the arrival <strong>of</strong> beech in the region. Zone II (~7000-3200 cal yr<br />
BP) is that <strong>of</strong> a beech-maple forest <strong>with</strong> oak patches. Percentages <strong>of</strong> beech and maple are higher<br />
than in the two comparative pollen records, indicating that moisture provided by the lake-effect<br />
climate prevailed in the Miner Lake area during the peak Holocene warmth. Zone III (~3200-200<br />
cal yr BP) is characterized by cooler and moister conditions, as suggested by expansion <strong>of</strong> the<br />
beech-maple forest. Median grain size is most variable in Zone III. Zone IV (last 200 years) is<br />
distinguished by a spike in disturbance weeds, a sharp decrease in %OM, a dramatic increase<br />
in %CaCO 3 , and a sharp decrease in median grain size, likely resulting from agriculture. In<br />
summary, the paleoclimate record <strong>of</strong> Miner Lake was, for the most part, invariant during the past<br />
several millennia, which suggests that a “lake effect” climate induced by nearby Lake Michigan<br />
was a more dominant control than the regional climate for this site.<br />
24-4 9:00 AM Sonnenburg, Elizabeth [218504]<br />
PALEOENVIRONMENTAL RECONSTRUCTION OF THE ALPENA-AMBERLEY RIDGE<br />
SUBMERGED LANDSCAPE DURING THE LAKE STANLEY LOWSTAND (CA. 8.4-9 KA CAL<br />
BP), LAKE HURON<br />
SONNENBURG, Elizabeth, Museum <strong>of</strong> Anthropology, University <strong>of</strong> Michigan, Ruthven<br />
Museums Building 4016, 1109 Geddes Avenue, Ann Arbor, MI 48109, esonnenb@umich.edu<br />
The Great Lakes basin has high potential for submerged archaeological sites due to considerable<br />
water level changes during deglaciation and as a result <strong>of</strong> Holocene climate change. The<br />
Holocene period in the Great Lakes basin (ca. last 12,000 years) was marked by several phases<br />
<strong>of</strong> drier climate and low lake levels (lowstands) including major events between ca. 11,300-8,400<br />
cal BP recorded in sediments in Lake Huron and Georgian Bay (Lake Hough and Lake Stanley<br />
lowstands). During the Lake Stanley phase water levels in the Lake Huron basin were up to<br />
70-100 m below present and large areas <strong>of</strong> the lake bed were exposed terrestrial landscapes.<br />
In 2007 and 2008, a 300 meter-long series <strong>of</strong> boulders was discovered on the Alpena-Amberley<br />
Ridge in 30 m <strong>of</strong> water in Lake Huron during a side-scan sonar survey. The boulders, when<br />
mapped, resembled caribou drive lanes which are well-documented in the Arctic. During the Lake<br />
Stanley lowstand phase, the Ridge was a sub-aerially exposed causeway separating the lake into<br />
two basins, and the discovery <strong>of</strong> the potential drive lanes provides compelling albeit circumstantial<br />
evidence that the Ridge supported human habitation during the early Holocene. Little is known<br />
about the paleogeography and environment <strong>of</strong> the Ridge since there is limited sedimentation,<br />
and most lake-level and paleoenvironmental research in Lake Huron has focused on the more<br />
sediment loaded basins <strong>of</strong> the Georgian and Saginaw Bays. In 2011 and 2012, a total <strong>of</strong> sixtyseven<br />
core, sediment and rock samples were collected by divers and ponar sampler on an<br />
ROV. Thirty-six surface sediment grab samples and six short (10-25 cm) cores were obtained<br />
for analysis <strong>of</strong> microdebitage, micr<strong>of</strong>ossils, grain size, and organic content. Cores were subsampled<br />
at 2 cm intervals for analysis, lith<strong>of</strong>acies logged in detail and photographed. Preliminary<br />
paleoenvrionmental reconstructions based on results from these samples indicate that during the<br />
last Lake Stanley phase, the Ridge was a relatively stable landscape <strong>with</strong> sub-artic vegetation,<br />
small shallow ponds, sphagnum bogs, wetlands and rivers, and would have provided numerous<br />
potential resources for both caribou and pre-historic hunter-gathers.<br />
24-5 9:40 AM Thompson, Todd A. [218327]<br />
THE ELEVATION OF THE PEAK NIPISSING PHASE (MID HOLOCENE) AT OUTLETS OF THE<br />
UPPER GREAT LAKES<br />
THOMPSON, Todd A., Indiana <strong>Geological</strong> Survey, Indiana University, 611 North Walnut<br />
Grove, Bloomington, IN 47405-2208, tthomps@indiana.edu, JOHNSTON, John W.,<br />
Department <strong>of</strong> Physical and Chemical Sciences, University <strong>of</strong> Toronto Mississauga,<br />
3359 Mississauga Road N, Mississauga, ON L5L 1C6, Canada, and LEPPER, Kenneth,<br />
Department <strong>of</strong> Geosciences, North Dakota State University, P.O. Box 6050, Dept. #2745,<br />
Fargo, ND 58108-6050<br />
The Nipissing phase <strong>of</strong> ancestral Lakes Michigan, Huron, and Superior was the last pre-modern<br />
highstand <strong>of</strong> the upper Great Lakes. Reconstructions <strong>of</strong> past lake-level change and glacial<br />
isostatic adjustment (GIA), as well as activation and abandonment <strong>of</strong> outlets is dependent on<br />
an understanding <strong>of</strong> the elevation <strong>of</strong> the lake at each outlet. More than one hundred years <strong>of</strong><br />
study has established the gross elevation <strong>of</strong> the Nipissing phase at each outlet, but the mixing<br />
<strong>of</strong> geomorphic and sedimentologic data has produced interpreted outlet elevations varying by<br />
least several meters. Vibracore facies, optically stimulated luminescence and radiocarbon age<br />
control, and ground-penetrating radar transects from new and published studies were collected to<br />
determine peak Nipissing water-level elevations for the Port Huron (Lake Huron), Chicago (Lake<br />
Michigan), and Sault (Lake Superior) outlets. These data and published relative hydrographs<br />
were combined to produce one residual hydrograph for the Port Huron outlet from 6,000 to<br />
3,500 calendar years ago that best defines the rise, peak, and rapid fall <strong>of</strong> the Nipissing phase.<br />
Establishing accurate elevations at the only present-day unregulated outlet <strong>of</strong> the Great Lakes<br />
and the only ancient outlet that has played a critical role in draining the upper Great Lakes<br />
since the middle Holocene is a critical step to better understand GIA and water-level change<br />
geologically and historically. The geologic context may provide the insight required for water<br />
managers to make informed decisions to best manage the largest freshwater system in the world.<br />
24-6 10:00 AM Hanson, Paul R. [218692]<br />
IMPACT OF THE NIPISSING AND ALGOMA HIGH LAKE PHASES FROM OSL DATING OF<br />
BAYMOUTH BARRIER SYSTEMS IN THE DOOR PENINSULA, WISCONSIN<br />
HANSON, Paul R., School <strong>of</strong> Natural Resources, University <strong>of</strong> Nebraska-Lincoln, 3310<br />
Holdrege Street, Lincoln, NE 68583, phanson2@unl.edu and RAWLING, J.E. III, Geography<br />
and Geology Program, University <strong>of</strong> Wisconsin-Platteville, Platteville, WI 53818<br />
This study focuses on the geomorphology and geochronology <strong>of</strong> three baymouth barrier systems<br />
at Clark, Europe and Kangaroo Lakes in the Door Peninsula <strong>of</strong> Wisconsin. The Lake Michigan<br />
shoreline in the peninsula contains abundant evidence for fluctuations in lake level as evidenced<br />
by strandplains and beach ridges that lie up to ~ 7 m above the present shoreline. Our study was<br />
conducted on three baymouth barriers that contain beach ridges that were buried by varying<br />
depths <strong>of</strong> eolian sand in the form <strong>of</strong> sandsheets, as well as parabolic and transverse dunes <strong>with</strong><br />
relief <strong>of</strong> up to 21 m. The purpose <strong>of</strong> this study was to document when the barriers were deposited<br />
and when the subsequent eolian activity occurred. Our chronology for barrier emplacement and<br />
dune development is based on 65 OSL samples which were collected from lacustrine sediment<br />
<strong>with</strong>in the barrier fills (n = 17) and the overlying eolian sand (n = 48). Sediment samples were<br />
collected using bucket augers or a vibracoring device at depths ranging from 0.5 to 4.1 m below<br />
the ground surface. Our OSL ages show that baymouth barriers in each <strong>of</strong> our study sites were<br />
constructed between ~ 5.9 to 3.9 ka, and most <strong>of</strong> our ages correspond closely to the Nipissing<br />
high lake level phase. Both geomorphic and geochronological evidence from the Kangaroo Lake<br />
site shows portions <strong>of</strong> this barrier were re-occupied after the Nipissing phase. Our OSL ages<br />
from lacustrine sediment taken from <strong>with</strong>in the barrier suggest this occurred at 3.3 to 2.5 ka,<br />
2013 GSA North-Central Section Meeting 55