Radiocarbon “Wiggles” in Great Lakes Wood at About 10,000 to 12,000 BP

High-resolution radiocarbon calibration for the last 14,000 cal yr has been developed in large part using European oaks and pines. Recent subfossil wood collections from the Great Lakes region provide an opportunity to measure 14C activity in decadal series of rings in North America prior to the White Mountains bristlecone record. We developed decadal 14C series from wood at the classic Two Creeks site (∼11,850 BP) in east-central Wisconsin, the Liverpool East site (∼10,250 BP) in northwestern Indiana, and the Gribben Basin site (∼10,000 BP) in the Upper Peninsula of Michigan. Initial AMS dates on holocellulose produced younger-than-expected ages for most Two Creeks subsamples and for a few samples from the other sites, prompting a systematic comparison of chemical pretreatment using 2 samples from each site, and employing holocellulose, AAA-treated holocellulose, alpha-cellulose, and AAA-treated whole wood. The testing could not definitively reveal the source of error in the original analyses, but the “best” original ages together with new AAA-treated holocellulose and α-cellulose ages were visually fitted to the IntCal04 calibration curve at ages of 13,760–13,530 cal BP for the Two Creeks wood, 12,100–12,020 cal BP for Liverpool East, and 11,300–11,170 cal BP for Gribben Basin. The Liverpool East age falls squarely within the Younger Dryas (YD) period, whereas the Gribben Basin age appears to postdate the YD by ∼300 yr, although high scatter in the decadal Gribben Basin results could accommodate an older age nearer the end of the YD.

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Significance of Organic Detritus in the Diet of Larval Lampreys in the Great Lakes Basin

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f94-239 ◽

1994 ◽

Vol 51 (11) ◽

pp. 2380-2387 ◽

Cited By ~ 72

Author(s):

Trent M. Sutton ◽

Stephen H. Bowen

Keyword(s):

Great Lakes ◽

Feeding Rate ◽

Assimilation Efficiency ◽

Dry Mass ◽

Great Lakes Basin ◽

Organic Detritus ◽

Upper Peninsula ◽

Sea Lampreys ◽

Gut Fullness ◽

Upper Peninsula Of Michigan

Larval sea lamprey (Petromyzon marinus) and northern brook lamprey (Ichthyomyzon fossor) were collected monthly from three streams in the Upper Peninsula of Michigan from May 1992 through May 1993 and larval sea lampreys were collected during summer months from sites throughout the Great Lakes basin. Organic detritus made up most of the diet ash-free-dry-mass (AFDM) throughout the year, averaging 97.79%, with algae (2.12%) and bacteria (0.09%) making up the remainder of the diet AFDM. Assimilation efficiency for AFDM averaged 72% during warmer months and 53% during cooler months (annual mean = 61%). Gut fullness (amount of AFDM in the anterior one-tenth of the intestine) was low (mean = 0.10 mg diet AFDM∙g−1 ammocoete). There were no significant differences in these measures between ammocoetes collected from the Upper Peninsula and those collected throughout the Great Lakes basin. From a laboratory-determined relationship between gut fullness and feeding rate, feeding rate in the field was estimated to be extremely slow, ranging from 4.2 to 5.5 mg diet AFDM∙g−1 ammocoete∙d−1. These observations indicate that larval lampreys efficiently utilize a diet of organic detritus during warmer months when stream temperatures and food quality are more favorable for feeding, digestion, and growth.

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Statement from civil society & religious organisations of east & central Afrca regarding the escalating violent conflict in the great lakes region

Review of African Political Economy ◽

10.1080/03056249808704338 ◽

1998 ◽

Vol 25 (77) ◽

pp. 533-534

Keyword(s):

Civil Society ◽

Great Lakes ◽

Violent Conflict ◽

Great Lakes Region ◽

East Central

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Inland dunes on the abandoned bed of Glacial Lake Chicago indicate eolian activity during the Pleistocene-Holocene transition, southwestern Michigan, USA

Quaternary Research ◽

10.1017/qua.2016.13 ◽

2017 ◽

Vol 87 (1) ◽

pp. 66-81 ◽

Cited By ~ 5

Author(s):

Patrick M. Colgan ◽

William H. Amidon ◽

Sara A. Thurkettle

Keyword(s):

Great Lakes ◽

Younger Dryas ◽

Fine Sand ◽

Optically Stimulated Luminescence ◽

Glacial Lake ◽

Great Lakes Region ◽

Limited Effect ◽

Westerly Winds ◽

Western Great Lakes ◽

Inland Dunes

AbstractInland dune fields have recently emerged as a source of data for reconstructing paleoenvironments and climate in the western Great Lakes region of North America during the Pleistocene-Holocene transition. We employ optically stimulated luminescence (OSL) methods, radiocarbon ages, soils, and landform relationships to determine the age of inland dunes in Ottawa County, Michigan. These dunes rest on the abandoned bed of Glacial Lake Chicago, which is thought to have been exposed after ~13.6 ka. OSL analyses from two inland dunes yield ages ranging from 13.3±1.1 to 11.6±0.9 ka (uncertainty=2σ). Fine sand in the parabolic dunes suggests deflation of exposed glaciolacustrine nearshore sand by northwesterly and westerly winds. These new data add to a growing number of studies that demonstrate widespread eolian activity in the western Great Lakes region during the Pleistocene-Holocene transition. OSL ages from dune fields in the western Great Lakes indicate peak eolian activity and dune stabilization occurred during or following the Younger Dryas and Preboreal events. Northwesterly and westerly winds suggest the limited effect of hypothesized easterly anticyclonic winds during the Pleistocene-Holocene transition. Rapidly changing climate and newly deglaciated surfaces provided an ideal environment for dune formation.

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Geology and geochemistry of granitoid rocks in the Archean Northern complex, Michigan, U.S.A.

Canadian Journal of Earth Sciences ◽

10.1139/e92-132 ◽

1992 ◽

Vol 29 (8) ◽

pp. 1674-1685 ◽

Cited By ~ 4

Author(s):

Richard T. Wilkin ◽

Theodore J. Bornhorst

Keyword(s):

Great Lakes ◽

Alkali Feldspar ◽

Superior Province ◽

Tectonic Zone ◽

Upper Peninsula ◽

Tectonic Model ◽

Granitoid Rocks ◽

Deformation Event ◽

Upper Peninsula Of Michigan ◽

Granite Suite

The Northern complex, located in the Upper Peninsula of Michigan, is an Archean greenstone–granite terrane that lies at the southern margin of the Superior Province. The origin of the plutonic suites in the Northern complex can be interpreted within a plate tectonic model proposed for the Superior Province and related to northward-directed subduction and subsequent collision along the Great Lakes tectonic zone. The following plutonic suites are recognized based on intrusive relationships, as well as textural and compositional differences: (i) gneissic tonalite suite; (ii) foliated tonalite suite; (iii) trondhjemite–granite suite; (iv) hornblendite–syenite suite; and (v) late granite dike suite. Rocks in the gneissic and foliated tonalite suites have lithologic and geochemical characteristics typical of Archean trondhjemite–tonalite–granodiorite assemblages exposed elsewhere in the Superior Province. They were emplaced during a primary deformation event and are interpreted to represent partial melts that formed during north-directed subduction of oceanic crust just prior to collision along the Great Lakes tectonic zone. During a second deformation event, stocks and plugs of the trondhjemite–granite suite, derived by intracrustal melting of amphibolite associated with collision and tectonic thickening, intruded both interior and exterior to a preexisting volcanic portion of the Northern complex. The hornblendite–syenite suite, composed of hornblende-rich syenites to monzodiorites with geochemical features that include high Mg numbers, and elevated Cr and Ni content, was derived from partial melting of the mantle during collision along the Great Lakes tectonic zone. The late granite dike suite, comprising late-stage, muscovite- and biotite-bearing quartz – alkali feldspar pegmatite and finer grained granitic lithologies, represents the last magmatic event in the Northern complex emplaced after collision.

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