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Dating an 800,000 year Antarctic ice...

Princeton University.

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Dating an 800,000 year Antarctic ice core record using the isotopic composition of trapped air.

紀錄類型:	書目-語言資料,印刷品 : Monograph/item
正題名/作者:	Dating an 800,000 year Antarctic ice core record using the isotopic composition of trapped air./
作者:	Dreyfus, Gabrielle Boissier.
面頁冊數:	239 p.
附註:	Advisers: Michael L. Bender; Jean Jouzel.
Contained By:	Dissertation Abstracts International69-10B.
標題:	Atmospheric Sciences. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3332421
ISBN:	9780549847953

Dating an 800,000 year Antarctic ice core record using the isotopic composition of trapped air.
Dreyfus, Gabrielle Boissier.

Dating an 800,000 year Antarctic ice core record using the isotopic composition of trapped air. - 239 p.

Advisers: Michael L. Bender; Jean Jouzel.

Thesis (Ph.D.)--Princeton University, 2008.

Here we measure the isotopic composition of air trapped in the European Project for Ice Coring in Antarctica Dome C (EDC) ice core, and use this geochemical information to improve the ice core agescale and our understanding of air enclosure processes.

ISBN: 9780549847953Subjects--Topical Terms:

1019179
Atmospheric Sciences.

Dating an 800,000 year Antarctic ice core record using the isotopic composition of trapped air.
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100 1 $a Dreyfus, Gabrielle Boissier. $3 1019178
245 1 0 $a Dating an 800,000 year Antarctic ice core record using the isotopic composition of trapped air.
300 $a 239 p.
500 $a Advisers: Michael L. Bender; Jean Jouzel.
500 $a Source: Dissertation Abstracts International, Volume: 69-10, Section: B, page: 6001.
502 $a Thesis (Ph.D.)--Princeton University, 2008.
520 $a Here we measure the isotopic composition of air trapped in the European Project for Ice Coring in Antarctica Dome C (EDC) ice core, and use this geochemical information to improve the ice core agescale and our understanding of air enclosure processes.
520 $a A first result is the detection of a flow anomaly in the bottom 500m of the EDC ice core using the delta18O of atmospheric oxygen (noted delta18Oatm). By tuning the measured delta18Oatm to the orbital precession signal, we correct the EDC agescale over 400-800 ka for flow-induced distortions in the duration of events. Uncertainty in delta 18Oatm phasing with respect to precession limits the accuracy of the tuned agescale to +/-6 ka.
520 $a We use this improved agescale to date two 10Be peaks detected in the EDC ice core and associated with the Matuyama-Brunhes geomagnetic boundary. While the ice age of the "precursor" event agrees within uncertainty with the age of radioisotopically dated lavas, the volcanic age for the younger reversal is approximately 10 ka older than the mid-point of the 10 Be peak in the ice. Since 80% of the lavas recording the Matuyama-Brunhes reversal are located in the Central Pacific, the observed age difference may indicate that the magnetic field orientation at this location changed prior to the dipole intensity minimum recorded by the ice core 10Be, as suggested by recent geodynamo modeling.
520 $a A particular challenge for ice core dating is accurately accounting for the age difference between the trapped air and surrounding ice. This gas age - ice age difference (noted Deltaage) depends on the age of the ice at the bottom of the firn. delta15N of N2 is constant in the atmosphere over the timescales considered here, so any deviation from atmospheric composition reflects fractionation processes in the firn. We show that delta15N is positively correlated with the ice deuterium content, a proxy for temperature, over the entire EDC record, and propose an accumulation-permeability-convection mechanism. While temporal resolution and noise in the available data limit our ability to constrain glacial Deltaage, these data suggest that delta15N may be used as a gas-phase climate proxy at EDC.
590 $a School code: 0181.
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650 4 $a Geochemistry. $3 539092
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710 2 $a Princeton University. $3 645579
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