Signatur:
ZSP-202-77
In:
Research report / Cold Regions Research and Engineering Laboratory, 77
Beschreibung / Inhaltsverzeichnis:
Abstract: A deep rotary core drilling project in 1957 at Site 2 on the Greenland ice sheet (76°59'N, 56°04'W provided ice core to a depth of 411 m. The vertical variation in bulk density, macroscopic structure, oxygen isotope ratios, ionic constituents, and extraterrestrial dust (black spherules) were analyzed using both field and laboratory techniques . These data permit the direct estimate of annual accumulation layers in the core. Continuous stratigraphic measurements and observations were made over the upper 110 m of the profile and detailed physical and chemical analyses were made on continuous lo 3 to 3.9-m core increments at 100, 200, 300 and 411-m depths. The average total ionic concentration in the ice sheet ranges between 0.65 and 1.35 mg/liter. The annual global mass deposit of black spherules as calculated from these studies varies from 2.10 x 10^5 metric tons in 700 year old ice to 6.57 x 10^5 metric tons in 12 year old firn. The oxygen isotope ratio variation provides the best means of estimating accumulation at depth. Results of the investigations indicate rates of net snow accumulation of 42.3, 34.2, 37.4, 41.1 and 41.6 g/cm^2 -yr at the surface, A.D. c. 1773, c. 1513, c. 1233 and c. 934 respectively. Accumulation data and other physical and chemical evidence allow climatological inferences to be made over the 10-century profile. The ice core record shows that snow accumulation and temperature in A. D. 934 were similar to today, followed by a gradual decrease in accumulation to a minimum around the late 18th century and an increase in both accumulation and temperature from A. D. 1773 to 1957 and following.
Materialart:
Schriftenreihen ausleihbar
Seiten:
vi, 130 Seiten
,
Illustrationen
Serie:
Research report / Cold Regions Research and Engineering Laboratory 77
URL:
https://hdl.handle.net/11681/5934
Sprache:
Englisch
Anmerkung:
CONTENTS
Preface
Summary
1. lntroduction
General background
Previous work
The Greenland Ice sheet
Present work
Ice core studies
ll. Field procedures
General background
Subsurface snow laboratory
Core reference datum
Core handling and processing
Ill. Macroscopic stratigraphy
General background
Polar stratigraphy
General observations and results
Discussion of results and conclusions above 100 m
IV. Detailed stratigraphic studies
General background
Macroscopic stratigraphy at 100 m
Results of analysis and discussion
Summary and conclusions
V. Oxygen isotope studies
General background
Previous work
Deep ice core 0-isotope stratigraphy
Results of analyses
Summary and conclusions
Vl. Chemical composition studies
General background
Previous work
Factors influencing the chemistry of glaciers
Deep core stratigraphy using chemical variations
Results of analyses and discussion
Summary and interpretation of the 300 m results
Geochemistry of the ice sheet
Results of analyses and discussion
Summary and conclusions
Vll. Cosmic dust studies
General background
Previous work
Origin of extraterrestrial dust
Deep ice core and near surface studies
Results of analyses
Discussion of results
Summary and conclusions
VIII. Climatological implications
General background
Recent history of the inland ice
Past history from the deep core
Summary and conclusions-
IX. Summary and conclusions
Discussion
Post Site l deep drilling programs
Selected bibliography
Appendix A. Sorge's law
Appendix B. Thinning of layers
Appendix C. Statistical terms
Appendix D. Average density determinations for meter increments from the surface to 411.21 meters , Site 2, Greenland
Standort:
AWI Archiv
Zweigbibliothek:
AWI Bibliothek
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