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Tests for orbital influences on the ...

Xuan, Chuang.

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Tests for orbital influences on the geomagnetic field, and Quarternary magnetic records from North Atlantic and Arctic deep-sea sediments.

紀錄類型:	書目-語言資料,印刷品 : Monograph/item
正題名/作者:	Tests for orbital influences on the geomagnetic field, and Quarternary magnetic records from North Atlantic and Arctic deep-sea sediments./
作者:	Xuan, Chuang.
面頁冊數:	248 p.
附註:	Source: Dissertation Abstracts International, Volume: 71-08, Section: B, page: 4713.
Contained By:	Dissertation Abstracts International71-08B.
標題:	Geology. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3416748
ISBN:	9781124128733

Tests for orbital influences on the geomagnetic field, and Quarternary magnetic records from North Atlantic and Arctic deep-sea sediments.
Xuan, Chuang.

Tests for orbital influences on the geomagnetic field, and Quarternary magnetic records from North Atlantic and Arctic deep-sea sediments. - 248 p.

Source: Dissertation Abstracts International, Volume: 71-08, Section: B, page: 4713.

Thesis (Ph.D.)--University of Florida, 2010.

This dissertation investigated the possible connection between orbital variations and the Earth's magnetic field, and the origin of orbital periods in sedimentary relative paleointensity (RPI) records, using previously published data. Circular statistic methods were utilized to test whether there is any consistent relationship between the phase of orbital parameters and the timing of geomagnetic reversals or excursions. The results indicate no discernable tendency, disagreeing with orbital forcing on the geodynamo. Numerical simulations further indicate that precision of the current polarity timescales need to be improved for any firm relationship to be established. Wavelet analyses methods were employed to investigate the origin of orbital periods in the RPI records. In some records, significant coherence at orbital periods occurs between RPI and a particular magnetic grain-size proxy. Therefore, orbital periods in some RPI records are attributed to lithologic 'contamination' resulted from incomplete normalization of the natural remanent magnetization (NRM) record. Comparison of RPI records from different regions of the world in both the time and time-frequency domains imply that the 'contamination' does not debilitate most RPI records as a global signal that is primarily of geomagnetic origin. Calibrated RPI and oxygen isotope stack records (PISO-1500) were developed by simultaneously matching and stacking both RPI and oxygen isotope data for 13 pairs of high-resolution global records. Wavelet analyses on the PISO-1500 RPI stack record failed to show significant orbital periods, and no tendencies were found for RPI minima in the stack to occur at particular phases of orbital variations.

ISBN: 9781124128733Subjects--Topical Terms:

516570
Geology.

Tests for orbital influences on the geomagnetic field, and Quarternary magnetic records from North Atlantic and Arctic deep-sea sediments.
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245 1 0 $a Tests for orbital influences on the geomagnetic field, and Quarternary magnetic records from North Atlantic and Arctic deep-sea sediments.
300 $a 248 p.
500 $a Source: Dissertation Abstracts International, Volume: 71-08, Section: B, page: 4713.
500 $a Adviser: James E.T. Channell.
502 $a Thesis (Ph.D.)--University of Florida, 2010.
520 $a This dissertation investigated the possible connection between orbital variations and the Earth's magnetic field, and the origin of orbital periods in sedimentary relative paleointensity (RPI) records, using previously published data. Circular statistic methods were utilized to test whether there is any consistent relationship between the phase of orbital parameters and the timing of geomagnetic reversals or excursions. The results indicate no discernable tendency, disagreeing with orbital forcing on the geodynamo. Numerical simulations further indicate that precision of the current polarity timescales need to be improved for any firm relationship to be established. Wavelet analyses methods were employed to investigate the origin of orbital periods in the RPI records. In some records, significant coherence at orbital periods occurs between RPI and a particular magnetic grain-size proxy. Therefore, orbital periods in some RPI records are attributed to lithologic 'contamination' resulted from incomplete normalization of the natural remanent magnetization (NRM) record. Comparison of RPI records from different regions of the world in both the time and time-frequency domains imply that the 'contamination' does not debilitate most RPI records as a global signal that is primarily of geomagnetic origin. Calibrated RPI and oxygen isotope stack records (PISO-1500) were developed by simultaneously matching and stacking both RPI and oxygen isotope data for 13 pairs of high-resolution global records. Wavelet analyses on the PISO-1500 RPI stack record failed to show significant orbital periods, and no tendencies were found for RPI minima in the stack to occur at particular phases of orbital variations.
520 $a The generation of high-resolution paleomagnetic data is often associated with processing large volumes of measurement data. MATLAB(TM) software with graphical user interfaces was developed in this dissertation work to improve the efficiency of processing large volumes of paleomagnetic data and facilitates the calculation of paleomagnetic directions and RPI proxies. This new software incorporates new methods of analysis, particularly in the generation of RPI proxies.
520 $a U-channel NRM measurements at Integrated Ocean Drilling Program (IODP) Site U1304 yield continuous high resolution paleomagnetic records for the last &sim;1.5 Ma. Sediments from IODP Site U1304 clearly recorded the Brunhes/Matuyama boundary, the Jaramillo subchron, and the Cobb Mountain subchron, as well as the Kamikatsura excursion and the Gardar excursion. Age model for the site is established by correlating IODP Site U1304 RPI record to the PISO-1500 RPI stack using automated dynamic programming method with limited number of tie points. No significant orbital periods were detected in RPI record from the site. Various evidences indicate that the episodic deposits of laminated diatom ooze throughout the IODP Site U1304 sediments, appear to dilute the magnetic concentrations of the sediments with elevated sedimentation rates, but do not debilitate the reliability of the acquired paleomagnetic direction and intensity data.
520 $a Rock magnetic experiments carried out under various temperature ranges, along with scanning electron microscopy (SEM) and X-ray energy-dispersive spectroscopy (EDS) observations as well as X-ray diffraction (XRD) analyses, on bulk Arctic deep-sea sediments and magnetic extracts from seven cores collected by the Healy-Oden Trans-Arctic Expedition 2005 (HOTRAX05), indicate that (titano)magnetite and titanomaghemite are the magnetic remanence carriers. It appears that the titanomaghemite carries a chemical remanent magnetization (CRM) that is partially self-reversed relative to the detrital remanent magnetization (DRM) carried by the host titanomagnetite, causing the apparent magnetic 'excursions' in the Arctic deep-sea sediment records. The partial self-reversal could have been accomplished by ionic ordering during oxidation, thereby changing the balance of the magnetic moments in the ferrimagnetic sublattices that characterize titanomagnetite and titanomaghemite. The partial self-reversal process appears to have affected all the studied cores from different regions of the Arctic Ocean, with less alteration in core from the Yermak Plateau located at the edge of the Arctic Ocean.
590 $a School code: 0070.
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650 4 $a Geophysics. $3 535228
650 4 $a Marine Geology. $3 1674685
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