Department or Program

Geology

Abstract

Samples of the marine bivalve, Arctica islandica, collected on the island of Ingøya in Finnmark, Norway, were used to produce a high-resolution annual and seasonal record of marine environmental conditions. This study site may provide unique regional insights into oceanic and atmospheric circulation patterns as it is influenced by three major currents: the North Atlantic Current, the Norwegian Coastal Current, and the Arctic Current. Shells were collected from a 3 meter high stratigraphic section, referred to as the Molo section, where several distinctive units comprised of disarticulated shells, shell hash, sand and pebbles are exposed. Ages were determined for 21 A. islandica shells collected throughout this section using new low-precision AMS radiocarbon dating method. Two long-lived shells were also chosen for standard-precision AMS radiocarbon dating. Ages of samples run using both techniques were not within 1-sigma error of one another, though they did fall just outside of this range. Ages from both types of dating techniques were used to construct a floating, crossdated record. The 14C ages determined from different shells taken from throughout the Molo in addition to a relative sea level curve constructed from raised beaches located at Kuhelleran were used to reconstruct the depositional history of the exposure. The phases of deposition found correspond to three distinct periods of sea level on the island. Trends from both the 400-year crossdated record and theδ18O records indicate large-scale variation occurring in this marine environment. Morlet and DOG Wavelet analyses are used to investigate cyclical trends in the 400-year record. Periodicities of 50, 35, 10-20, and 5-7 years were found, ranging in significance. MTM spectral analyses found additional periodicities of 164, 5.5, and 2-3 years. The 50 year periodicity has been interpreted as AMO-like variation, the 35 year cycles of low-frequency NAO-like variation, the 10 and 20 year periods as reflective of solar cycles, and the 2-3, 5.5, and 5-7 year periods as high-frequency NAO-like variation. Sub-annual δ18O records displayed seasonal cyclicity, with a mean seasonal variation of 4.68˚C. This seasonal variation indicates an increase in seasonal variability through the Holocene, as mid-Holocene (~6,000 calendar year BP) values indicate a smaller degree of seasonality while modern values indicate a larger degree of seasonality.

Level of Access

Open Access

First Advisor

Retelle, Michael

Date of Graduation

Spring 5-2016

Degree Name

Bachelor of Science

Number of Pages

74

Components of Thesis

1 pdf file

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