Comments on Planktonic foraminiferal spine versus shell carbonate Na incorporation in relation to salinity

2019 ◽  
Author(s):  
Ralf Schiebel
Keyword(s):  
Shell Carbonate

scholarly journals On Correcting 14C Ages of Gastropod Shell Carbonate for Fractionation

Radiocarbon ◽  
2002 ◽  
Vol 44 (3) ◽  
pp. 755-760 ◽  
Author(s):  
Jeffrey S Pigati
Keyword(s):  
Isotopic Composition ◽  
Carbon Isotopic Composition ◽  
Iterative Approach ◽  
Shell Formation ◽  
Gastropod Shell ◽  
Carbon Isotopic ◽  
Soil Carbonate ◽  
Shell Carbonate ◽  
Atmospheric Carbon

Correcting the 14C age of a sample for fractionation is straightforward if the measured carbon was derived entirely from the atmosphere, either directly or through chemical and/or biological reactions that originated with atmospheric carbon. This correction is complicated in the case of gastropods that incorporate carbon from limestone or secondary carbonate (e.g. soil carbonate) during shell formation. The carbon isotopic composition of such gastropod shells is determined by fractionation, as well as mixing of carbon from sources with different isotopic values. Only the component of shell carbonate derived from atmospheric carbon should be corrected for fractionation. In this paper, the author derives a new expression for correcting the measured 14C activity of gastropod shells for fractionation, and describe an iterative approach that allows the corrected 14C activity and the fraction of shell carbonate derived from atmospheric carbon to be determined simultaneously.

Aminostratigraphic Correlation and Geochronology of Two Quaternary Loess Localities, Central Mississippi Valley

1994 ◽  
Vol 41 (3) ◽  
pp. 289-297 ◽  
Author(s):  
June E. Mirecki ◽  
Barry B. Miller
Keyword(s):  
Amino Acid ◽  
Kinetic Model ◽  
Mississippi Valley ◽  
River Section ◽  
Mollusc Shell ◽  
The Third ◽  
Shell Carbonate ◽  
Parabolic Kinetic

AbstractAmino acid epimeric (aIle/Ile) values from terrestrial molluscs are used to define and correlate three aminozones in loess sequences exposed across the central Mississippi Valley, in Arkansas and Tennessee. Three superposed aminozones are defined at Wittsburg quarry, Arkansas, primarily using aIle/Ile values from total hydrolysates of the gastropod genus Hendersonia: Peoria Loess (aIle/Ile = 0.07 ± 0.01), Roxana Silt (0.14 ± 0.02), and a third loess (0.28 ± 0.06). Loess units at Wittsburg quarry can be correlated on lithologic characteristics eastward across the Mississippi Valley to the Old River section, near Memphis, Tennessee; however, only one loess unit is fossil-bearing (Peoria Loess, aIle/Ile = 0.05) at that section. Radiocarbon analyses of charcoal from the upper Roxana Silt (ca. 26,000 to 29,000 yr old) and mollusc shell carbonate from the basal Roxana Silt (ca. 39,000 yr old) are used to calibrate amino acid epimeric data for the central Mississippi Valley. These data, applied to the apparent parabolic kinetic model of R. M. Mitterer and N. Kriausakul (1989, Quaternary Science Reviews 8, 353-357), suggest an Illinoian (>120,000 yr) age for the third loess in the central Mississippi Valley that is correlative with part of the Loveland Loess in Illinois and Iowa.

14C age anomalies in modern land snails shell carbonate from Southern Italy

2008 ◽  
Vol 3 (1-2) ◽  
pp. 68-75 ◽  
Author(s):  
Lea Romaniello ◽  
Gianluca Quarta ◽  
Giuseppe Mastronuzzi ◽  
Marisa D’Elia ◽  
Lucio Calcagnile
Keyword(s):  
Southern Italy ◽  
Land Snails ◽  
14C Age ◽  
Shell Carbonate

scholarly journals Carbon Isotope Analysis of Land Snail Shells: Implications for Carbon Sources and Radiocarbon Dating

Radiocarbon ◽  
1983 ◽  
Vol 25 (3) ◽  
pp. 810-830 ◽  
Author(s):  
Glenn A Goodfriend ◽  
Darden G Hood
Keyword(s):  
Exchange Rate ◽  
Organic Carbon ◽  
Radiocarbon Dating ◽  
Activity Patterns ◽  
Isotope Analysis ◽  
Carbon Sources ◽  
Isotopic Fractionation ◽  
Land Snail ◽  
Land Snails ◽  
Shell Carbonate

13C and 14C analyses were performed on a series of modern Jamaican land snails in order to quantitatively determine the sources of shell carbon. A model of these carbon sources, the pathways by which carbon reaches the shell, and the fractionation processes involved are presented. The contribution of limestone to shell carbonate is variable but may comprise up to 33% of the shell. About 25–40% of shell carbonate is derived from plants and about 30–60% from atmospheric CO2. Variation among populations and species with respect to 13C and 14C is attributed to the effects of limestone incorporation, snail size (as it affects CO2 exchange rate), physiological characteristics (presence of urease, respiration rate), and activity patterns of the snails. A formula for correction for isotopic fractionation of 14C of shell carbonate, based on 13C measurements, is derived. Bicarbonate-aragonite fractionation is apparently very minimal. Shell organic carbon appears to be derived largely from plants but also to a lesser extent from inorganic hemolymph carbon. This introduces the possibility of a small age anomaly of shell organic 14C due to limestone incorporation.

scholarly journals Coccolithophore response to climate and surface hydrography in Santa Barbara Basin, California, AD 1917–2004

2009 ◽  
Vol 6 (10) ◽  
pp. 2025-2039 ◽  
Author(s):  
M. Grelaud ◽  
A. Schimmelmann ◽  
L. Beaufort
Keyword(s):  
Southern Oscillation ◽  
California Current ◽  
Santa Barbara ◽  
Santa Barbara Basin ◽  
Enso Events ◽  
The Pacific ◽  
Hydrographic Conditions ◽  
Shell Carbonate ◽  
Relative Abundances ◽  
Counter Current

Abstract. The varved sedimentary AD 1917–2004 record from the depositional center of the Santa Barbara Basin (SBB, California) was analyzed with monthly to triannual resolution to yield relative abundances of six coccolithophore species representing at least 96% of the coccolithophore assemblage. Seasonal/annual relative abundances respond to climatic and surface hydrographic conditions in the SBB, whereby (i) the three species G. oceanica, H. carteri and F. profunda are characteristic of the strength of the northward flowing warm California Counter Current, (ii) the two species G. ericsonii and G. muellerae are associated with the cold equatorward flowing California Current, (iii) and E. huxleyi appears to be endemic to the SBB. Spectral analyses on relative abundances of these species show that all are influenced by the El Niño Southern Oscillation (ENSO) and/or by the Pacific Decadal Oscillation (PDO). Increased relative abundances of G. oceanica and H. carteri are associated with warm ENSO events, G. muellerae responds to warm PDO events and the abundance of G. ericsonii increases during cold PDO events. Morphometric parameters measured on E. huxleyi, G. muellerae and G. oceanica indicate increasing coccolithophore shell carbonate mass from ~1917 until 2004 concomitant with rising pCO2 and sea surface temperature in the region of the SBB.

Seasonality of Mollusk Collecting Determined from O-18 Profiles of Midden Shells

1981 ◽  
Vol 46 (1) ◽  
pp. 152-158 ◽  
Author(s):  
John S. Killingley
Keyword(s):  
Settlement Patterns ◽  
Baja California ◽  
Shell Carbonate ◽  
O 18 ◽  
Ancillary Information

Midden shell carbonate O-18 profiles are used to estimate the month of shellfish collection. Fourteen molluscan shells from a coastal midden in Baja California were analyzed to demonstrate the potential of the technique for reconstructing settlement patterns. Ancillary information on paleotemperatures is also recovered from the O-18 values.

scholarly journals High-resolution nitrogen stable isotope sclerochronology of bivalve shell carbonate-bound organics

2017 ◽  
Vol 200 ◽  
pp. 55-66 ◽  
Author(s):  
David P. Gillikin ◽  
Anne Lorrain ◽  
Aurélie Jolivet ◽  
Zita Kelemen ◽  
Laurent Chauvaud ◽  
...  
Keyword(s):  
High Resolution ◽  
Stable Isotope ◽  
Nitrogen Stable Isotope ◽  
Shell Carbonate ◽  
Bivalve Shell
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