Benthic foraminifera as paleo-sea-ice indicators in the western Arctic Ocean DISSERTATION

236 Pages·2014·9.15 MB·English

Benthic foraminifera as paleo-sea-ice indicators in the western Arctic Ocean

DISSERTATION

Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy
in the Graduate School of The Ohio State University

By
Kelly Best Lazar
Graduate Program in Geological Sciences

The Ohio State University
2014

Dissertation Committee:
William I. Ausich, Advisor
Leonid Polyak
Lawrence A. Krissek
Matthew R. Saltzman
Copyright by
Kelly Best Lazar
2014
Abstract

As global climate continues to warm, the Arctic Ocean is becoming increasingly
vulnerable, largely due to a fast retreat of sea ice. Knowledge of paleo-sea-ice conditions
is essential for comprehending the changing Arctic system. This study combines
micropaleontological (foraminiferal) data with existing litho- and chronostratigraphic
results to construct a more resolved stratigraphic record and history of sea-ice change
during the Quaternary in the western Arctic Ocean.
Benthic foraminiferal assemblages were investigated in four sediment cores from
the Northwind, Mendeleev, and Lomonosov Ridges (western Arctic Ocean). A uniquely-
preserved sediment core from the Northwind Ridge was found to contain the longest
calcareous foraminiferal record in the Arctic Ocean, estimated to extend to the early
Pleistocene, ca. 1.5 Ma. This record was divided into two assemblage zones, representing
distinct changes in foraminiferal composition with respect to ecological groups (polar vs.
phytodetrital species) and extinct taxa. The distribution of polar and phytodetrital species
yields significant information related to sea ice (perennial vs. seasonal) and associated
climatic conditions. A principal faunal and sedimentary turnover occurred near the early-
middle Pleistocene boundary (estimated ca 0.7-0.8 Ma), indicating an advance of
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perennial sea ice along with an increase in glacial inputs from the Laurentide ice sheet at
the end of the Mid-Pleistocene Transition (MPT).
Foraminiferal groups identified in the Northwind Ridge record were then
translated to other western Arctic cores in order to better understand sea-ice change over
the entire region. Foraminiferal abundances and assemblage composition show
stratigraphically consistent changes, with major transitions estimated at the end of the
MPT (ca. 0.7-0.8 Ma) and later near the bottom of Marine Isotope Stage 7 (ca. 0.25 Ma).
These foraminiferal records, interpreted in terms of sea-ice conditions, indicate an overall
expansion of year-round Arctic ice cover during the Pleistocene. The Holocene part of
the record is not yet adequately resolved due to mostly insufficient sedimentation rates.
To evaluate the stratigraphic significance of the morphological change between
foraminifers Cassidulina teretis and C. neoteretis, suggested by an earlier study for the
North Atlantic region, their tests were investigated in two sediment cores from the
Northwind Ridge. Unlike the North Atlantic, where a clear, although time-transgressive
transition between these test types is present in the early Pleistocene, they coexist
throughout most of the western Arctic record, except for its youngest (late Pleistocene)
part. This pattern suggests that these morphologies respond to changing ecological
conditions, possibly related to sea-ice history, over a considerable period of time.
Therefore, the use of C. teretis/C. neoteretis transition as a biostratigraphic marker should
be applied with caution at specific localities and cannot be used over the entirety of the
Arctic and sub-Arctic.

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Dedication

Dedicated to my parents, John and Denice Best, and my husband, Kevin Lazar.

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Acknowledgments

I am immensely appreciative for the guidance and support from my research
advisor, Leonid Polyak. I would like to thank him as well as Bill Ausich, Larry Krissek,
Peter Webb, and Matt Saltzman for their time spent helping me successfully complete
this project. Special thanks to Kevin Crawford for showing me the ropes when I first
arrived, and to Rachael Gray and Tracie Kline for help in processing samples. Thanks to
Harunur Rashid, Geoff Dipre, and Kirstin Werner for providing helpful discussion and
advice during this journey.
Funding for this dissertation was provided by several sources: the Ed Picou
Fellowship Grant from the Gulf Coast SEPM Foundation, Sigma Xi Grants-In-Aid (Ohio
State Chapter), Geological Society of America (GSA) Graduate Student Grant, the
Friends of Orton Hall Fund, a Career Development Grant from the Council of Graduate
Students (OSU), and several travel grants from the North-Central section of GSA. This
project would have been significantly more difficult without this support, and I am
sincerely grateful.
Special thanks to Katie McDowell Peek for her unwavering friendship and to
Kevin, for his love, patience, support, and for picking up his life and moving to Ohio so I
could pursue this doctorate.
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Vita

March 9, 1985 ................................................Born-Anchorage, Alaska
2007................................................................B.S. Geology, North Carolina State
University
2010................................................................M.S. Geological Sciences, East Carolina
University
2010-2012 .....................................................Graduate Research Associate, Byrd Polar
Research Center, The Ohio State University
2012-2014 ......................................................Graduate Teaching Associate, School of
Earth Sciences, The Ohio State University

Publications

Polyak, L., Best, K.M., Crawford, K.A., Council, E.A., and St-Onge, G., 2013.
Quaternary history of sea ice in the western Arctic Ocean based on foraminifera.
Quaternary Science Reviews 79: 145-156.

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Abstracts
Lazar, K.B. and Polyak, L., 2014. Quaternary sea-ice regime change in the western Arctic
Ocean based on benthic foraminifers. In: Geological Society of America, Abstracts with
Programs, Annual Meeting, Vancouver, British Columbia, Canada (October 2014).

Polyak, L., Best, K.M., Cronin, 2013. Evolution of glaciations and sea ice in the western
Arctic in the Early to Middle Pleistocene. In: Proceedings of the “Past Gateways” First
International Conference and Workshop, St. Petersburg, Russia (May 2013).

Best, K.M., Polyak, L., Crawford, K.A., 2012. Extinct foraminifera of the western Arctic
Ocean: Correlation to the global deep-sea extinction of the mid-Pleistocene Transition.
In: Geological Society of America, Abstracts with Programs, Annual Meeting, Charlotte,
NC (November 2012).

Best. K.M., Polyak, L., Crawford, K.A., and Gray, R.E., 2011. A long record of
foraminifera helps resolve Quaternary western Arctic stratigraphy. In: Geological Society
of America, Abstracts with Programs, Annual Meeting, Minneapolis, MN (October
2011).

Best, K.M., Polyak, L., Crawford, K.A., and Gray, R.E., 2011. Calcareous foraminifers in
Northwind Ridge sediments offer a new perspective on Quaternary paleoenvironments in
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the western Arctic Ocean. In: Arctic Workshop Abstract Volume, Annual Meeting,
Montreal, Quebec, Canada (March 2011).

Polyak, L.V., Best, K.M., Gray, R., Haley, B.A., Council, E.A., and Ortiz, J., 2011. A
Paleo Perspective on the Role of Pacific Water in the Arctic Ocean System. In: American
Geophysical Union Abstracts, Annual Meeting, San Francisco, CA (December 2011).

Polyak, L., Crawford, K.A., Gray, R.E., Best, K.M., + 5 others, 2010. Extended
Quaternary Record of Sea-Ice Conditions and Glaciation of the Western Arctic Ocean.
In: American Geophysical Union Abstracts, Annual Meeting, San Francisco, CA
(December 2010).

Fields of Study

Major Field: Geological Sciences

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Table of Contents

Abstract ............................................................................................................................... ii 
Dedication .......................................................................................................................... iv 
Acknowledgments............................................................................................................... v 
Publications .................................................................................................................... vi 
Fields of Study ................................................................................................................. viii 
List of Tables ................................................................................................................... xiv 
List of Figures ................................................................................................................... xv 
Chapter 1: Introduction and summary of previous work on Arctic Ocean oceanographic
conditions, sediment stratigraphy, and the foraminiferal record ........................................ 1 
Introduction ..................................................................................................................... 1 
Objectives, Material, and Methods of this Study .......................................................... 10 
Summary of papers resulting from this work ................................................................ 11 
Chapter 2: Quaternary history of sea ice in the western Arctic Ocean based on
foraminifera ....................................................................................................................... 15 
Abstract ......................................................................................................................... 15 
Introduction ................................................................................................................... 16 
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