Revised Pacific M-anomaly geomagnetic polarity timescale


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dc.contributor.author Tominaga, Masako
dc.contributor.author Sager, William W.
dc.date.accessioned 2010-06-28T15:58:58Z
dc.date.available 2010-06-28T15:58:58Z
dc.date.issued 2010-05-12
dc.identifier.citation Geophysical Journal International 182 (2010): 203-232 en_US
dc.identifier.uri http://hdl.handle.net/1912/3699
dc.description Author Posting. © The Authors, 2010. This article is posted here by permission of John Wiley & Sons for personal use, not for redistribution. The definitive version was published in Geophysical Journal International 182 (2010): 203-232, doi:10.1111/j.1365-246X.2010.04619.x. en_US
dc.description.abstract The current M-anomaly geomagnetic polarity timescale (GPTS) is mainly based on the Hawaiian magnetic lineations in the Pacific Ocean. M-anomaly GPTS studies to date have relied on a small number of magnetic profiles, a situation that is not ideal because any one profile contains an uncertain amount of geologic 'noise' that perturbs the magnetic field signal. Compiling a polarity sequence from a larger array of magnetic profiles is desirable to provide greater consistency and repeatability. We present a new compilation of the M-anomaly GPTS constructed from polarity models derived from magnetic profiles crossing the three lineation sets (Hawaiian, Japanese and Phoenix) in the western Pacific. Polarity reversal boundary locations were estimated with a combination of inverse and forward modelling of the magnetic profiles. Separate GPTS were established for each of the three Pacific lineation sets, to allow examination of variability among the different lineation sets, and these were also combined to give a composite timescale. Owing to a paucity of reliable direct dates of the M-anomalies on ocean crust, the composite model was time calibrated with only two ages; one at each end of the sequence. These two dates are 125.0 Ma for the base of M0r and 155.7 Ma for the base of M26r. Relative polarity block widths from the three lineation sets are similar, indicating a consistent Pacific-wide spreading regime. The new GPTS model shows slightly different spacings of polarity blocks, as compared with previous GPTS, with less variation in block width. It appears that the greater polarity chron irregularity in older models is mostly an artifact of modelling a small number of magnetic profiles. The greater averaging of polarity chron boundaries in our model gives a GPTS that is statistically more robust than prior GPTS models and a superior foundation for Late Jurassic–Early Cretaceous geomagnetic and chronologic studies. en_US
dc.description.sponsorship This work was supported by the Jane & R. Ken Williams'45 Chair of Ocean Drilling Science and Technology. en_US
dc.format.mimetype application/pdf
dc.language.iso en_US en_US
dc.publisher John Wiley & Sons en_US
dc.relation.uri http://dx.doi.org/10.1111/j.1365-246X.2010.04619.x
dc.subject Magnetic anomalies: modelling and interpretation en_US
dc.subject Reversals: process, time scale, magnetostratigraphy en_US
dc.subject Marine magnetics and palaeomagnetics en_US
dc.title Revised Pacific M-anomaly geomagnetic polarity timescale en_US
dc.type Article en_US
dc.identifier.doi 10.1111/j.1365-246X.2010.04619.x

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