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dc.contributor.advisorSager, William W.en_US
dc.creatorTominaga, Masakoen_US
dc.date.accessioned2006-10-30T23:33:09Z
dc.date.available2006-10-30T23:33:09Z
dc.date.created2005-08en_US
dc.date.issued2006-10-30
dc.identifier.urihttp://hdl.handle.net/1969.1/4418
dc.description.abstractThe Jurassic Quiet Zone (JQZ) is a region of low amplitude, difficult-to-correlate magnetic anomalies located over Jurassic oceanic crust. We collected 1200 km of new deep-tow magnetic anomaly profiles over the Pacific JQZ that complement 2 deep-tow profiles reported in Sager et al. (1998). Our primary goals were to extend the correlation of deep-tow magnetic anomalies farther back in time, to evaluate the correlatability and repeatability of anomalies, and to refine the Jurassic geomagnetic polarity reversal time scale (GPTS). Correlations of anomalies were excellent over M34 and over supposedly older seafloor to the south of ODP Site 801. In contrast, the correlation in the region between M34 and Site 801 was difficult. Using anomaly correlation models, we made magnetic polarity block models to establish a revised Jurassic GPTS extending until 169.4 Ma. Age calibration was accomplished with radiometric dates from two ODP holes. Systematic changes in anomaly amplitudes occur along the survey lines with the amplitudes decreasing backward in time and then increasing again in the oldest part of survey area. The zone of the most difficult to correlate anomalies corresponds to a period of ~4 m.y. that appears to have an abrupt end. This low amplitude zone suggests unusual magnetic behavior during the Jurassic. It has been said that many of the larger anomalies are likely caused by changes in polarity, whereas smaller anomalies may be intensity fluctuations. Although it is impossible to identify which anomalies are caused by reversals and which are not, magnetization structures observed in ODP Hole 801C suggest that many of the smallest anomalies, particularly around Hole 801C indicate polarity reversals. We concluded that (1) the new data demonstrates repeatability and correlatability of the JQZ magnetic anomalies implying that they are seafloor spreading lineations and (2) good correlations made new GPTS models extending back to 169.4 Ma; and (3) the origin of the JQZ may be a combination of rapid polarity reversals in the Jurassic low magnetic dipole field and closely spaced, tilted magnetization structure in the oceanic crust.en_US
dc.format.extent1869676 bytes
dc.format.mediumelectronicen_US
dc.format.mimetypeapplication/pdf
dc.language.isoen_USen_US
dc.publisherTexas A&M Universityen_US
dc.subjectJurassic Quiet Zoneen_US
dc.subjectGeomagnetic Polarity Time Scaleen_US
dc.titleDeep-tow study of magnetic anomalies in the Pacific Jurassic Quiet Zoneen_US
dc.typeBooken
dc.typeThesisen
thesis.degree.departmentOceanographyen_US
thesis.degree.disciplineOceanographyen_US
thesis.degree.grantorTexas A&M Universityen_US
thesis.degree.nameMaster of Scienceen_US
thesis.degree.levelMastersen_US
dc.contributor.committeeMemberFox, P. Jeffen_US
dc.contributor.committeeMemberHilde, Thomas W. C.en_US
dc.type.genreElectronic Thesisen_US
dc.type.materialtexten_US
dc.format.digitalOriginborn digitalen_US


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