High-resolution reconstruction of Holocene climate variability and environmental changes in the North Pacific using bivalve shells [Elektronische Ressource] / von Nadine Hallmann

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Informations

• Publié par: johannes_gutenberg-universitat_mainz
• Publié le: 01 janvier 2011
• Nombre de lectures: 7
• Langue: English
• Poids de l'ouvrage: 11 Mo

Extrait

High-resolution reconstruction of Holocene climate
variability and environmental changes in the North
Pacific using bivalve shells


TITLE PAGE


Dissertation
zur Erlangung des Grades
“Doktor der Naturwissenschaften“
im Promotionsfach Geologie/Paläontologie

am Fachbereich Chemie, Pharmazie und Geowissenschaften
der Johannes Gutenberg-Universität Mainz



von
Nadine Hallmann
geb. in Nauen



Mainz, 2011
(D77)
APPROVAL PAGE

















Dekan: Not displayed for reasons of data protection.

1. Berichterstatter: Not displayed for reasons of data protection.
2. Berichterstatter: Not displayed
3. Berichterstatter: Not displayed

Datum der mündlichen Prüfung: 09.06.2011

  iiDECLARATION





Ich erkläre hiermit, dass ich die vorliegende Arbeit
selbständig verfasst und keine anderen als
die angegebenen Quellen und Hilfsmittel benutzt habe.


Mainz, März 2011











  iii
  iv
CITATION






Denken und Tun, Tun und Denken, das ist die Summer aller Weisheit,
von jeher anerkannt, von jeher geübt, nicht eingesehen von einem jeden.
Beides muß wie Aus- und Einatmen sich im Leben ewig fort hin und wider
bewegen;
wie Frage und Antwort sollte eins ohne das andere nicht stattfinden.
-Johann Wolfgang von Goethe-


 
 
 
 
 
 
 
 
 
  v 
  viPREFACE

This thesis presents results from a three years and seven months research on bivalve shells as
climate proxy archives in the paleontological group of Prof. Dr. Bernd R. Schöne in Mainz. I
started my Ph.D. in August 2007 in this group. The aim of this project is the reconstruction of
Holocene climate variations in the North Pacific with a high spatial and temporal resolution
using marine bivalve shells and the technique of high-resolution isotope sclerochronology.
The purpose is to create a network of climate proxies based on bivalve shells to study large-
scale climate variations during the Holocene. High-resolution proxy data from the marine
environment of the mid- and high-latitudes are rare, therefore, this study contributes to the
understanding of past climate and the improvement of the prediction of future climate.
This research was conducted under the supervision of Prof. Dr. Bernd R. Schöne. The
accomplishment of this multidisciplinary project was made possible with the collaboration of
research groups in Canada, The United States of America and Japan. Within the framework of
this study a two-month research stay in Tokyo, Japan, from July to August 2009 permitted the
collection of modern and archaeological shells and to maintain contact with our Japanese
colleagues.
This thesis consists of three manuscripts, which are published in international peer-
reviewed journals. The first paper, published in Palaeogeography, Palaeoclimatology,
Palaeoecology, examines the reliability of the long-lived bivalve mollusk Panopea abrupta as
a climate archive to reconstruct temperatures of the oxygen isotope values of the shells is
tested. The second manuscript, published in the Journal of Archaeological Science, provides
new insights into the biology, geochemistry and seasonal growth of the short-lived bivalve
Saxidomus gigantea, which is crucial information for interpreting paleoenvironments and the
season of shellfish collection in archaeological contexts. A combined approach of
sclerochronology and stable isotope analysis helps to refine seasonality estimates and to
improve the understanding of the gathering strategies of pre-historic coastal communities of
hunter-gatherers. The third manuscript, published in PALAIOS, presents a model for
reconstructing water temperatures and salinity from shell growth rates of the butter clam
S. gigantea from south west Alaska, which allows us to disentangle the influence of
freshwater and temperature on shell oxygen isotope values. An integrated growth pattern and
isotope approach can be used to estimate salinity and temperature changes in freshwater-
  viiinfluenced environments through time. Therefore, this study allows for a better understanding
of hydrological changes related to the Alaska Coastal Current, and helps to interpret the
meaning of oxygen isotope data in estuarine settings.
I would like to use this preface to thank all the people that contributed to this study.
First of all, I am grateful to my supervisor Prof. Dr. Bernd R. Schöne for his guidance and
support during this time. I wish to acknowledge the German Research Foundation (DFG) who
funded this research project and the Japan Society for the Promotion of Science (JSPS) who
provided financial support during my stay at the University of Tokyo. I want to thank all the
numerous collaborators and providers of study material who made this project possible.

Mainz, 25 March 2011

Nadine Hallmann

 

  viiiABSTRACT

Bivalve mollusk shells are useful tools for multi-species and multi-proxy paleoenvironmental
reconstructions with a high temporal and spatial resolution. They are valuable proxy archives
to detect past environmental changes, since they record sensitive environmental information
in their carbonate shells, but also these data can be used to gain new insights into the
settlement and subsistence strategies of prehistoric people. Past environmental conditions can
be reconstructed from shell growth and stable oxygen and carbon isotope ratios, which
present an archive for temperature, freshwater fluxes and primary productivity. The purpose
of this thesis is the reconstruction of Holocene climate and environmental variations in the
North Pacific with a high spatial and temporal resolution using marine bivalve shells. This
thesis focuses on several different Holocene time periods and multiple regions in the North
Pacific, including: Japan, Alaska (AK), British Columbia (BC) and Washington State, which
are affected by the monsoon, Pacific Decadal Oscillation (PDO) and El Niño/Southern
Oscillation (ENSO). Such high-resolution proxy data from the marine realm of mid- and high-
latitudes are still rare. Therefore, this study contributes to the optimization and verification of
climate models. However, before using bivalves for environmental reconstructions and
seasonality studies, life history traits must be well studied to temporally align and interpret the
geochemical record. These calibration studies are essential to ascertain the usefulness of
selected bivalve species as paleoclimate proxy archives. This work focuses on two bivalve
species, the short-lived Saxidomus gigantea and the long-lived Panopea abrupta.
In the first part of this study, the sclerochronology and oxygen isotope ratios of
different shell layers of P. abrupta were studied in order to test the reliability of this species
as a climate archive and to reconstruct temperatures. The growing season lasts mainly during
the warm period of the year from March/April through November/December with maximum
growth rates in late spring and summer and negligible rates during the cold winter months.
Shell growth patterns are clearly discernable in umbonal shell portions, but less so in the outer
18shell layer near the ventral margin. The δ O values recorded from the inner and outer shell
layer are not the same. Temperatures reconstructed from the oxygen isotope values taken
from the outer shell layer compare well with instrumental water temperature, however, values
from the umbo differ by up to 3°C. The outer shell layer seems to be precipitated in isotopic
equilibrium with the seawater. In contrast, the precipitation of the inner shell layer appears to
  ixbe in isotopic disequilibrium with the seawater. Therefore, annual increment widths should be
measured in umbonal shell portions and a reliable reconstruction of paleotemperatures may
only be achieved by exclusively sampling the outer shell layer of multiple contemporaneous
specimens.
S. gigantea is one of the most commonly recovered bivalves from archaeological
midden deposits along the west coast of North America. The second part of this thesis
presents the first detailed analysis of life history traits and a stable isotope record of
S. gigantea, which provides new insights into the growth of this species. Shell growth records
and shell geochemistry can be used to reconstruct paleotemperature and paleoenvironmental
conditions as well as to identify the season of shellfish collection and proxy the season of site
occupation in archaeological contexts. However, this approach requires detailed knowledge of
the life history traits, including regional variation in both shell growth and stable isotope
values. Modern shells collected alive on a monthly basis for a period of one year in 1987-
1988 from Pender Island (southern BC) and additional specimens from Dundas Is