scholarly journals Pliocene diatom and sponge spicule oxygen isotope ratios from the Bering Sea: isotopic offsets and future directions

2014 ◽  
Vol 10 (5) ◽  
pp. 1837-1842 ◽  
Author(s):  
A. M. Snelling ◽  
G. E. A. Swann ◽  
J. Pike ◽  
M. J. Leng
Keyword(s):  
Oxygen Isotope ◽  
Bering Sea ◽  
Diatom Species ◽  
Sponge Spicule ◽  
Future Directions ◽  
Oxygen Isotope Ratios ◽  
Sponge Spicules ◽  
Isotope Analyses ◽  
Regional Water ◽  
The Bering Sea

Abstract. Oxygen isotope analyses of different size fractions of Pliocene diatoms (δ18Odiatom) from the Bering Sea show no evidence of an isotope offset and support the use of bulk diatom species samples for palaeoceanographic reconstructions. Additional samples containing concentrations of sponge spicules produce δ18O values several per mille (‰) lower than δ18Odiatom with a calculated mean offset of 3.9‰ ± 1.5. This difference is significantly greater than modern-day variations in water δ18O through the regional water column. Despite the potential for oxygen isotope disequilibrium within δ18Osponge, there appears to be some similarity between δ18Osponge and a global stacked benthic δ18Oforam record. This highlights the potential for δ18Osponge in palaeoenvironmental research at sites where carbonates are not readily preserved.

scholarly journals Pliocene diatom and sponge spicule oxygen isotope ratios from the Bering Sea: isotopic offsets and future directions

2014 ◽  
Vol 10 (3) ◽  
pp. 2087-2104 ◽  
Author(s):  
A. M. Snelling ◽  
G. E. A. Swann ◽  
J. Pike ◽  
M. J. Leng
Keyword(s):  
Oxygen Isotope ◽  
Bering Sea ◽  
Diatom Species ◽  
Sponge Spicule ◽  
Future Directions ◽  
Oxygen Isotope Ratios ◽  
Sponge Spicules ◽  
Isotope Analyses ◽  
Regional Water ◽  
The Bering Sea

Abstract. Oxygen isotope analyses of different size fractions of Pliocene diatoms (δ18Odiatom) from the Bering Sea show no evidence of an isotope offset and support the use of bulk diatom species samples for palaeoceanographic reconstructions. Additional samples containing concentrations of sponge spicules produce δ18O values several per mille lower than δ18Odiatom with a calculated mean offset of 3.6‰ ± 0.7. This difference is significantly greater than modern day variations in water δ18O through the regional water column. Despite the potential for oxygen isotope disequilibrium within δ18Osponge, there appears to be some similarity between δ18Osponge and a global stacked benthic δ18Oforam record. This highlights the potential for δ18Osponge in palaeoenvironmental research at sites where carbonates are not readily preserved.

Biogenic opal production changes during the Mid-Pleistocene Transition in the Bering Sea (IODP Expedition 323 Site U1343)

2014 ◽  
Vol 81 (1) ◽  
pp. 151-157 ◽  
Author(s):  
Sunghan Kim ◽  
Kozo Takahashi ◽  
Boo-Keun Khim ◽  
Yoshihiro Kanematsu ◽  
Hirofumi Asahi ◽  
...  
Keyword(s):  
Bering Sea ◽  
North Pacific ◽  
Accumulation Rate ◽  
Diatom Species ◽  
Biogenic Opal ◽  
Export Production ◽  
Wavelet Transform Analysis ◽  
Climate Cooling ◽  
Mass Accumulation ◽  
The Bering Sea

AbstractBiogenic opal content and mass accumulation rate (MAR) at IODP Expedition 323 Site U1343 were found to fluctuate consistently, generally being high under warm conditions and low under cold conditions during the last 2.4 Ma. Continuous wavelet transform analysis of the normalized biogenic opal content indicates that export production in the Bering Sea varied predominantly at 41-ka periodicity before 1.25 Ma, and shifted to 100-ka periodicity at the onset of the Mid-Pleistocene Transition (MPT; 1.25–0.7 Ma). The 100-ka cycles dominated until the Holocene. Export production in the Bering Sea decreased markedly in the Bering Sea two times during the MPT: the first occurred at the beginning of the MPT (1.25 Ma) and the second in the middle of the MPT (0.9 Ma). These decreases coincided with both increases in the relative abundance of sea-ice diatoms and decreases in the warm-water diatom species Neodenticula seminae, indicating that reductions in export production in the Bering Sea during the MPT were associated with climate cooling. Decreases in export production in the Bering Sea during the MPT were most likely associated with the increased influence of polar/Arctic domains on the high-latitude North Pacific.

Holocene Climate Inferred from Oxygen Isotope Ratios in Lake Sediments, Central Brooks Range, Alaska

2001 ◽  
Vol 55 (3) ◽  
pp. 313-321 ◽  
Author(s):  
Lesleigh Anderson ◽  
Mark B. Abbott ◽  
Bruce P. Finney
Keyword(s):  
Oxygen Isotope ◽  
Late Holocene ◽  
Area Ratio ◽  
Lake Area ◽  
Brooks Range ◽  
The Past ◽  
Oxygen Isotope Ratios ◽  
Effective Moisture ◽  
Moisture Balance ◽  
Isotope Analyses

AbstractAnalyses of sediment cores from two lakes in the central Brooks Range provide temperature and moisture balance information for the past ∼8500 cal yr at century-scale resolution. Two methods of oxygen isotope analysis are used to reconstruct past changes in the effective moisture (precipitation minus evaporation) and temperature. Effective moisture is inferred from oxygen isotope ratios in sediment cellulose from Meli Lake (area ∼0.13 km2, depth 19.4 m). The lake has a low watershed-to-lake-area ratio (7) and significant evaporation relative to input. Summer temperature shifts are based on oxygen isotope analyses of endogenic calcite from Tangled Up Lake (area ∼0.25 km2, depth 3.5 m). This basin has a larger watershed-to-lake-area ratio (91) and less evaporation relative to input. Sediment oxygen isotope analyses from the two sites indicate generally more arid conditions than present prior to ∼6000 cal yr B.P. Subsequently, the region became increasingly wet. Temperature variability is recorded minimally at centennial scale resolution with values that are generally cool for the past ∼6700 cal yr. The timing and direction of climate variability indicated by the oxygen isotope time series from Meli and Tangled Up lakes are consistent with previously established late Holocene glacier advances at ∼5000 cal yr B.P. in the central Brooks Range, and high lake-levels at Birch Lake since ∼5500 cal yr B.P. This unique use of oxygen isotopes reveals both moisture balance and temperature histories at previously undetected high-resolution temporal scales for northern Alaska during the middle to late Holocene.

Preliminary isopach map of the Bering Sea basin

1976 ◽  
Author(s):  
Alan K. Cooper ◽  
K.A. Bailey ◽  
M. S. Marlow ◽  
D. W. Scholl ◽  
C.E. Carpenter
Keyword(s):  
Bering Sea ◽  
Isopach Map ◽  
The Bering Sea
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