Date of Award

Spring 1-1-2013

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Geological Sciences

First Advisor

Gifford H. Miller

Second Advisor

Aslaug Geirsdottir

Third Advisor

Thomas Marchitto

Abstract

Sediment records from Icelandic lakes are utilized to interpret past environmental change related to climate evolution and tephra deposition on the landscape. A multi-proxy high-resolution Holocene record from Vestra Gíslholtsvatn (VGHV) was used to describe ecosystem development and variability over the last ~11 ka. Principle component analyses (PCA) of proxies from VGHV indicate irreversible changes in the environmental state at ~5.5 ka and ~4.2 ka coinciding with onset and intensification of Neoglaciation in Iceland. Abundant tephra fall in VGHV contributed to transient variability throughout the Holocene record. PCA of ultrahigh-resolution multi-proxy records before and after four significant tephra fall events were used to compare ecosystem responses between four Icelandic lakes; VGHV, Hvítárvatn, Haukadalsvatn, and Torfadalsvatn. Rhyolitic tephra produced more substantial impacts than basaltic tephra. Climate state at the time of tephra fall also influenced the length and magnitude of ecosystem perturbations with more severe response in the cool Neoglacial.

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