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Late Holocene Climate Inferred From Varved Sediments, Blue Lake, Brooks Range, Alaska

Osgood, Barbara Gabriele (2005) Late Holocene Climate Inferred From Varved Sediments, Blue Lake, Brooks Range, Alaska. Master's Thesis, University of Pittsburgh. (Unpublished)

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Geomorphologic evidence provided by late Holocene glacial advances demonstrates the sensitivity of central Brooks Range to changes in temperature and moisture balance over decadal to centennial timescales. High-resolution climate proxy records covering the middle to late Holocene are sparse from this region. One exception is Blue Lake, a small (<0.5 km2), shallow (4.7 m), glacier-fed lake set on the crest of the Brooks Range (68º05.3' N, 150º27.8' W) in north-central Alaska at an altitude of 1265 m. The 4 km2 watershed contains a small cirque glacier located on the north face of the 1890 m high headwall, on the north side of the continental divide. Field observations and air photos indicate that melt-water from the glacier contributes a substantial quantity of fine-grained sediment to the lake. Sediment cores recovered in August of 1999 contain millimeter-scale laminations comprised of lamina couplets, which exhibit the classic mode of varve formation in a glacial basin consisting of a succession of fine sands to silts deposited during the summer months, followed by a well-defined winter clay cap. In addition to annual variability in varve thickness, long-term trends in thickness were identified and compared with the historical climate record. Blue Lake records the glacial response to late Holocene climate phenomena, such as the Little Ice Age (cooling), Medieval Climatic Anomaly (warming), and the 20th century warming trend.Varve measurements from Blue Lake correlate well with regional cooling and warming trends described for the late Holocene from other proxy records across the Arctic.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Osgood, Barbara
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairAbbott, Markmabbott1@pitt.eduMABBOTT1
Committee MemberJones, Charlescejones@pitt.eduCEJONES
Committee MemberRosenmeier, Mikemrosenme@pitt.eduMROSENME
Date: 2 February 2005
Date Type: Completion
Defense Date: 19 August 2004
Approval Date: 2 February 2005
Submission Date: 9 December 2004
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Institution: University of Pittsburgh
Schools and Programs: Dietrich School of Arts and Sciences > Geology and Planetary Science
Degree: MS - Master of Science
Thesis Type: Master's Thesis
Refereed: Yes
Uncontrolled Keywords: clastic varves; paleoclimates; paleolimnology; proglacial varves; thin-section
Other ID:, etd-12092004-173041
Date Deposited: 10 Nov 2011 20:09
Last Modified: 15 Nov 2016 13:54


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