Document Type

Open Access Thesis

Embargo Period

12-1-2014

Degree Program

Geosciences

Degree Type

Master of Science (M.S.)

Year Degree Awarded

2014

Month Degree Awarded

September

Advisor Name

Julie

Advisor Last Name

Brigham-Grette

Co-advisor Name

Steven

Co-advisor Middle Initial

T

Co-advisor Last Name

Petsch

Abstract

Sea level regression during the Last Glacial Maximum exposed the Bering Land Bridge, and cut off the connection between the North Pacific and Arctic Ocean, ending the exchange of North Pacific Water through the Bering Strait. Exchange of North Pacific Water comprises a major portion of fresh water input to the Arctic Ocean, and is of vital importance to North Atlantic Deep Water formation, a vital component of Atlantic Meridional Overturning Circulation. Bering Strait throughflow thus plays an integral role in global climate stability. A suite of four cores was selected, three in the Bering Sea and one in the Chukchi Sea, to bracket the Bering Strait in order to elucidate changes in sediment delivery, productivity and regional oceanography as the Bering Land Bridge flooded and modern ocean circulation was established during the last deglaciation. The arrival of nutrient rich North Pacific Water in the Chukchi Sea is recorded around 8 ka by organic carbon isotope depletion and an increase in total organic carbon and organic nitrogen, reflecting an increasingly marine isotopic signal and increased productivity. In the Bering Sea, the early deglaciation is marked by depleted organic carbon isotopes that indicate increasing terrestrial input, and increased total organic carbon. Principal component analysis of sedimentologic, geochemical and isotopic data clearly captures discrete sediment populations that correspond to key climatic intervals, representing changes in sediment delivery, productivity and circulation during the last deglaciation. In the Bering Sea we observe that deglaciation began in earnest around 18–17 ka, but lack of confidence in our age control does not allow for a precise date. Our results suggest that modern circulation through the Bering Strait, and thus for the Bering and Chukchi Seas, was established ~8 ka. Prior to 8 ka there is an interval of sediment that appears record a possible reversal of flow through the Bering Strait corresponding to the 8.2 ka event.

ReadmePelto.txt (16 kB)
Describes the data files included here

3JPC_Geotek.csv (807 kB)
3JPC_GS.csv (5 kB)
3JPC_iso.csv (18 kB)
3JPC_XRF.csv (1620 kB)
24JPC_Geotek.csv (427 kB)
24JPC_GS.csv (2 kB)
24JPC_iso.csv (10 kB)
24JPC_XRF.csv (1035 kB)
17JPC_Geotek.csv (168 kB)
17JPC_GS.csv (1 kB)
17JPC_iso.csv (2 kB)
17JPC_XRF.csv (403 kB)
51JPC_Geotek.csv (163 kB)
51JPC_GS.csv (1 kB)
51JPC_iso.csv (5 kB)
51JPC_XRF.csv (400 kB)
28JPC_Geotek.csv (45 kB)
28JPC_GS.csv (1 kB)
28JPC_XRF.csv (910 kB)
JPC3_Sec1_R_1350-1441cm.tif (83262 kB)