Reconstructing a 350ky history of sea level using planktonic Mg/Ca and oxygen isotope records from a Cocos Ridge core

Oxygen isotope profiles along the growth axis of fossil bivalve shells of Macoma calcarea were established to reconstruct hydrographical changes in the eastern Laptev Sea since 8400 cal yr B.P. The variability of the oxygen isotopes (δ18O) in the individual records is mainly attributed to variations in the salinity of bottom waters in the Laptev Sea with a modern ratio of 0.50‰/salinity. The high-resolution δ18O profiles exhibit distinct and annual cycles from which the seasonal and annual salinity variations at the investigated site can be reconstructed. Based on the modern analogue approach oxygen isotope profiles of radiocarbon-dated bivalve shells from a sediment core located northeast of the Lena Delta provide seasonal and subdecadal insights into past hydrological conditions and their relation to the Holocene transgressional history of the Laptev Sea shelf. Under the assumption that the modern relationship between δ18Ow and salinity has been constant throughout the time, the δ18O of an 8400-cal-yr-old bivalves would suggest that bottom-water salinity was reduced and the temperature was slightly warmer, both suggesting a stronger mixture of riverine water to the bottom water. Reconstruction of the inundation history of the Laptev Sea shelf indicates local sea level ∼27 m below present at this time and a closer proximity of the site to the coastline and the Lena River mouth. Due to continuing sea level rise and a southward retreat of the river mouth, bottom-water salinity increased at 7200 cal yr B.P. along with an increase in seasonal variability. Conditions comparable to the modern hydrography were achieved by 3800 cal yr B.P.

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Sea-level and reef accretion history of Marine Oxygen Isotope Stage 7 and late Stage 5 based on age and facies of submerged late Pleistocene reefs, Oahu, Hawaii

Quaternary Research ◽

10.1016/j.yqres.2013.11.001 ◽

2014 ◽

Vol 81 (1) ◽

pp. 138-150 ◽

Cited By ~ 7

Author(s):

Clark E. Sherman ◽

Charles H. Fletcher ◽

Ken H. Rubin ◽

Kathleen R. Simmons ◽

Walter H. Adey

Keyword(s):

Oxygen Isotope ◽

Sea Level ◽

Late Stage ◽

Sea Levels ◽

Reef Accretion ◽

Oxygen Isotope Stage ◽

Accommodation Space ◽

History Of ◽

Mis 5

AbstractIn situ Pleistocene reefs form a gently sloping nearshore terrace around the island of Oahu. TIMS Th–U ages of in situ corals indicate that most of the terrace is composed of reefal limestones correlating to Marine Oxygen Isotope Stage 7 (MIS 7, ~ 190–245 ka). The position of the in situ MIS 7 reef complex indicates that it formed during periods when local sea level was ~ 9 to 20 m below present sea level. Its extensiveness and geomorphic prominence as well as a paucity of emergent in situ MIS 7 reef-framework deposits on Oahu suggest that much of MIS 7 was characterized by regional sea levels below present. Later accretion along the seaward front of the terrace occurred during the latter part of MIS 5 (i.e., MIS 5a–5d, ~ 76–113 ka). The position of the late MIS 5 reefal limestones is consistent with formation during a period when local sea level was below present. The extensiveness of the submerged Pleistocene reefs around Oahu compared to the relative dearth of Holocene accretion is due to the fact that Pleistocene reefs had both more time and more accommodation space available for accretion than their Holocene counterparts.

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The Late Weichselian sea level history of the Kullen Peninsula in northwest Skåne, southern Sweden

Boreas ◽

10.1080/03009480120569 ◽

2001 ◽

Vol 30 (2) ◽

pp. 115-130

Author(s):

Per Sandgren, Ian Snowball

Keyword(s):

Sea Level ◽

Southern Sweden ◽

History Of ◽

Late Weichselian

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Phanerozoic Oxygen

10.23943/princeton/9780691145020.003.0011 ◽

2017 ◽

Author(s):

Donald Eugene Canfield

Keyword(s):

Oxygen Consumption ◽

Organic Carbon ◽

Sea Level ◽

Time Scale ◽

Atmospheric Oxygen ◽

Sea Level Change ◽

Oxygen Production ◽

Level Change ◽

History Of ◽

Geologic Processes

This chapter discusses the modeling of the history of atmospheric oxygen. The most recently deposited sediments will also be the most prone to weathering through processes like sea-level change or uplift of the land. Thus, through rapid recycling, high rates of oxygen production through the burial of organic-rich sediments will quickly lead to high rates of oxygen consumption through the exposure of these organic-rich sediments to weathering. From a modeling perspective, rapid recycling helps to dampen oxygen changes. This is important because the fluxes of oxygen through the atmosphere during organic carbon and pyrite burial, and by weathering, are huge compared to the relatively small amounts of oxygen in the atmosphere. Thus, all of the oxygen in the present atmosphere is cycled through geologic processes of oxygen liberation (organic carbon and pyrite burial) and consumption (weathering) on a time scale of about 2 to 3 million years.

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