Paleomagnetism and geochronology of St. Matthew Island, Bering Sea

1989 ◽  
Vol 26 (10) ◽  
pp. 2116-2129 ◽  
Author(s):  
Paul R. Wittbrodt ◽  
David B. Stone ◽  
Donald L. Turner
Keyword(s):  
Late Cretaceous ◽  
Bering Sea ◽  
Large Scale ◽  
Flow Units ◽  
Intrusive Rocks ◽  
Normal Polarity ◽  
Reversed Polarity ◽  
Shelf Region ◽  
Bering Sea Shelf ◽  
The Bering Sea

Oriented samples from a series of flow units, pyroclastics, tuffs, tuff breccias, and some intrusive rocks from St. Matthew Island were studied paleomagnetically in an attempt to constrain possible paleolatitudes of the Bering Sea shelf. The volcanic sequences have apparently stable magnetic directions and contain a reversed–normal–reversed–normal polarity succession.The Late Cretaceous paleolatitude deduced from the paleomagnetic data was 67°N, and the island has rotated in a clockwise sense by a nominal 10°. This implies that the rocks analyzed were formed about 12 °south of their present location with respect to cratonic North America. These data argue against tectonic models for the Bering Sea shelf region that require large-scale Late Cretaceous and Tertiary latitude changes.New K–Ar age dates combined with previously reported K–Ar ages give a best estimate of the age of the St. Matthew volcanic units of about 78.7 ± 0.4 Ma. The reversed–normal–reversed polarity changes are thought to represent part of the sequence seen between marine anomalies 32 and 33 that are usually assigned an age of about 74 Ma, which appears to be about 5 Ma too young.

scholarly journals Role of physical processes in formation of spring phytoplankton bloom in the Bering Sea

Trudy VNIRO ◽  
2020 ◽  
Vol 181 ◽  
pp. 206-222
Author(s):  
K.K. Kivva ◽  
◽  
J.V. Selivanova ◽  
M.N. Pisareva ◽  
A.A. Sumkina ◽  
...  
Keyword(s):  
Bering Sea ◽  
Phytoplankton Bloom ◽  
Physical Processes ◽  
Spring Phytoplankton Bloom ◽  
Eastern Bering Sea ◽  
Ice Retreat ◽  
Shelf Region ◽  
Sea Ice Retreat ◽  
Bering Sea Shelf ◽  
The Bering Sea

The main part of the annual primary production in the Arctic and Subarctic zones of the World Ocean is formed during the spring phytoplankton bloom. The timing of the bloom depends on combination of physical factors. Oscillating control hypothesis, proposed in [Hunt et al., 2002] for the Eastern Bering Sea, describes annual peculiarities of ecosystem development related to conditions of the spring phytoplankton bloom. We review propositions of this hypothesis on the reasons of phytoplankton bloom and its connection with physical processes for four local regions of the Bering Sea shelf. The regions include western, northern and south-eastern parts of the shelf. The analysis is based on ocean color and microwave remotely sensed data as well as on atmospheric reanalysis. The results allow for hypothesis improvement. An early phytoplankton bloom may be present in the surface layer in April or May along the eastern Bering Sea shelf even in situations of early sea ice retreat (e. g. February-March) or absence of ice during winter. However, such combinations were not observed in the western Bering Sea shelf region. In 1998–2018, early ice retreat in the western shelf region was always accompanied by relatively late phytoplankton bloom. The temporal lag between sea ice retreat and phytoplankton bloom may be substantial in some years along the southernmost position of the ice edge. On the other hand, the spring bloom in the northern part of the shelf usually follows the ice retreat. In case of early ice retreat, the timing of the bloom is determined not only by wind conditions, but also by heat balance at the surface of the sea. The results are proposed to be used in further analysis of ecosystem dynamics of the western Bering Sea shelf.

Magnétochronologie des formations rocheuses du Mont Mégantic et des environs, Québec méridional

1985 ◽  
Vol 22 (4) ◽  
pp. 487-497 ◽  
Author(s):  
Maurice K.-Seguin ◽  
B. St-Hilaire
Keyword(s):  
Late Cretaceous ◽  
The Other ◽  
Field Observations ◽  
Magnetization Component ◽  
Paleomagnetic Study ◽  
Intrusive Rocks ◽  
Normal Polarity ◽  
Reversed Polarity ◽  
Radiometric Ages ◽  
Devonian Age

A paleomagnetic study was made to elucidate the ambiguities of the radiometric ages of Mont Megantic intrusions in relation to field observations and to determine the magnetochronology of the intruded rocks. Some 179 samples (550 specimens) were collected over 58 sites, and their magnetization was cleaned by thermal and (or) alternating field treatment. The paleopoles obtained for the Compton Formation metasediments indicate an Early to Middle Devonian age and for the overlying Frontenac Formation metavolcanics indicate an age definitely different from that for the intrusive rocks. The baked contact test on the hornfels forming the contact metamorphic aureole is positive, and the magnetization component was acquired in the Early to Late Cretaceous interval. Syenite contains two components: one with normal polarity, the other with reversed polarity; their ages are Juro-Cretaceous. The gabbro contains only one magnetization component (reversed), which was acquired in the Early Cretaceous, whereas the granite bears one component with a mostly normal polarity; its intrusive age is Late Cretaceous.The paleomagnetic ages for the intrusive rocks support the multiple intrusion interpretation; it appears that the emplacement of the intrusive bodies is Juro-Late Cretaceous. [Journal Translation]

scholarly journals Calanus on the Bering Sea shelf: probable cause for population declines during warm years

2017 ◽  
Vol 39 (2) ◽  
pp. 257-270 ◽  
Author(s):  
K. O. Coyle ◽  
G. A. Gibson
Keyword(s):  
Bering Sea ◽  
Population Declines ◽  
Bering Sea Shelf ◽  
The Bering Sea

scholarly journals Air-sea CO<sub>2</sub> fluxes on the Bering Sea shelf

2011 ◽  
Vol 8 (5) ◽  
pp. 1237-1253 ◽  
Author(s):  
N. R. Bates ◽  
J. T. Mathis ◽  
M. A. Jeffries
Keyword(s):  
Bering Sea ◽  
Atmospheric Co2 ◽  
Net Community Production ◽  
Phytoplankton Primary Production ◽  
Co2 Partial Pressure ◽  
Small Areas ◽  
Co2 Sink ◽  
Bering Sea Shelf ◽  
Seawater Pco2 ◽  
The Bering Sea

Abstract. There have been few previous studies of surface seawater CO2 partial pressure (pCO2) variability and air-sea CO2 gas exchange rates for the Bering Sea shelf. In 2008, spring and summertime observations were collected in the Bering Sea shelf as part of the Bering Sea Ecological Study (BEST). Our results indicate that the Bering Sea shelf was close to neutral in terms of CO2 sink-source status in springtime due to relatively small air-sea CO2 gradients (i.e., ΔpCO2 and sea-ice cover. However, by summertime, very low seawater pCO2 values were observed and much of the Bering Sea shelf became strongly undersaturated with respect to atmospheric CO2 concentrations. Thus the Bering Sea shelf transitions seasonally from mostly neutral conditions to a strong oceanic sink for atmospheric CO2 particularly in the "green belt" region of the Bering Sea where there are high rates of phytoplankton primary production (PP)and net community production (NCP). Ocean biological processes dominate the seasonal drawdown of seawater pCO2 for large areas of the Bering Sea shelf, with the effect partly countered by seasonal warming. In small areas of the Bering Sea shelf south of the Pribilof Islands and in the SE Bering Sea, seasonal warming is the dominant influence on seawater pCO2, shifting localized areas of the shelf from minor/neutral CO2 sink status to neutral/minor CO2 source status, in contrast to much of the Bering Sea shelf. Overall, we compute that the Bering Sea shelf CO2 sink in 2008 was 157 ± 35 Tg C yr−1 (Tg = 1012 g C) and thus a strong sink for CO2.

Erratum to “Modelling phytoplankton succession on the Bering Sea shelf: role of climate influences and trophic interactions in generating Emiliania huxleyi blooms 1997–2000”

2005 ◽  
Vol 52 (5) ◽  
pp. 881-882
Author(s):  
Agostino Merico ◽  
Toby Tyrrell ◽  
Evelyn J. Lessard ◽  
Temel Oguz ◽  
Phyllis J. Stabeno ◽  
...  
Keyword(s):  
Trophic Interactions ◽  
Bering Sea ◽  
Emiliania Huxleyi ◽  
Phytoplankton Succession ◽  
Climate Influences ◽  
Bering Sea Shelf ◽  
The Bering Sea

Vertical Mixing on the Bering Sea Shelf

1985 ◽  
pp. 553-557 ◽  
Author(s):  
G. R. Stegen ◽  
P. J. Hendricks ◽  
R. D. Muench
Keyword(s):  
Bering Sea ◽  
Vertical Mixing ◽  
Bering Sea Shelf ◽  
The Bering Sea

scholarly journals A Study of the Fluctuations in Sea-Ice Extent of the Bering and Okhotsk Seas with Passive Microwave Satellite Observations (Abstract)

1987 ◽  
Vol 9 ◽  
pp. 236-236
Author(s):  
D.J. Cavalieri ◽  
C.L. Parkinson
Keyword(s):  
Sea Ice ◽  
Bering Sea ◽  
Sea Of Okhotsk ◽  
Large Scale ◽  
Phase Relationship ◽  
Kamchatka Peninsula ◽  
Sea Ice Extent ◽  
Atmospheric Circulation Patterns ◽  
Circulation Patterns ◽  
The Bering Sea

The seasonal sea-ice cover of the combined Bering and Okhotsk Seas at the time of maximum ice extent is almost 2 × 106 km2 and exceeds that of any other seasonal sea-ice zone in the Northern Hemisphere. Although both seas are relatively shallow bodies of water overlying continental shelf regions, there are important geographical differences. The Sea of Okhotsk is almost totally enclosed, being bounded to the north and west by Siberia and Sakhalin Island, and to the east by Kamchatka Peninsula. In contrast, the Bering Sea is the third-largest semi-enclosed sea in the world, with a surface area of 2.3 × 106 km2, and is bounded to the west by Kamchatka Peninsula, to the east by the Alaskan coast, and to the south by the Aleutian Islands arc.While the relationship between the regional oceanography and meteorology and the sea-ice covers of both the Bering Sea and Sea of Okhotsk have been studied individually, relatively little attention has been given to the occasional out-of-phase relationship between the fluctuations in the sea-ice extent of these two large seas. In this study, we present 3 day averaged sea-ice extent data obtained from the Nimbus-5 Electrically Scanning Microwave Radiometer (ESMR-5) for the four winters for which ESMR-5 data were available, 1973 through 1976, and document those periods for which there is an out-of-phase relationship in the fluctuations of the ice cover between the Bering Sea and the Sea of Okhotsk. Further, mean sea-level pressure data are also analyzed and compared with the time series of sea-ice extent data to provide a basis for determining possible associations between the episodes of out-of-phase fluctuations and atmospheric circulation patterns.Previous work by Campbell and others (1981) using sea-ice concentrations also derived from ESMR-5 data noted this out-of-phase relationship between the two ice packs in 1973 and 1976. The authors commented that the out-of-phase relationship is “... surprising as these are adjacent seas, and one would assume that they had similar meteorologic environments”. We argue here that the out-of-phase relationship is consistent with large-scale atmospheric circulation patterns, since the two seas span a range of longitude of about 60°, corresponding to a half wavelength of a zonal wave-number 3, and hence are quite susceptible to changes in the amplitude and phase of large-scale atmospheric waves.

Comparison of soundscapes across the Bering Sea shelf, a biological perspective

2013 ◽  
Vol 134 (5) ◽  
pp. 4147-4147 ◽  
Author(s):  
Jennifer L. Miksis-Olds
Keyword(s):  
Bering Sea ◽  
Biological Perspective ◽  
Bering Sea Shelf ◽  
The Bering Sea

scholarly journals The importance of episodic weather events to the ecosystem of the Bering Sea shelf

2005 ◽  
Vol 14 (2) ◽  
pp. 97-111 ◽  
Author(s):  
NICHOLAS A. BOND ◽  
JAMES E. OVERLAND
Keyword(s):  
Bering Sea ◽  
Weather Events ◽  
Bering Sea Shelf ◽  
The Bering Sea
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