A relative geomagnetic paleointensity stack from Ontong‐Java Plateau sediments for the Matuyama

Kok, Yvo S.; Tauxe, Lisa

doi:10.1029/1999jb900186

Cited by 42 publications

(65 citation statements)

References 24 publications

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“…Useful insight on the origin of tiny wiggles can however be gained from the few available highresolution magnetostratigraphic paleointensity studies covering the past few Myr (see for instance, [25] for the Brunhes period; [26] for the Matuyama period; [27] for the Matuyama and late Gauss periods; [9] for the past 2 Myr; [8] for the past 4 Myr; [28] for chrons 5n; [29] for chrons 6Bn to 13n; [30] for chrons 12r to 13r). These studies have shown that the magnetic polarity time scale mainly determined from marine magnetic anomalies is almost complete and that only a few tiny wiggles detected so far can be ascribed to additional short polarity intervals (e.g.…”

Section: Discussionmentioning

confidence: 99%

Geomagnetic field variations between chrons 33r and 19r (83–41 Ma) from sea-surface magnetic anomaly profiles

Bouligand

Dyment

Gallet

et al. 2006

Earth and Planetary Science Letters

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Sea-surface magnetic profiles exhibit coherent short wavelength "micro-anomalies" (or "tiny wiggles") superimposed to the main anomalies due to reversals. In this study, we investigate the nature and distribution of these tiny wiggles on oceanic crust formed during the ∼42 Myr-long period following the Cretaceous Normal Superchron. To this end, we compute stacks of anomaly profiles from different areas in the Indian and Pacific oceans.Using a simple method based on upward continuation, we demonstrate that, the tiny wiggles are consistent worldwide although their patterns exhibit different resolutions at different spreading rates. They are therefore confidently ascribed to past fluctuations of the geomagnetic dipole moment. A high resolution record of these fluctuations is obtained by selecting and stacking profiles from areas with the highest spreading rates. Modeling the micro-anomalies as short magnetic polarity intervals yields durations for these intervals generally shorter than 10 kyr, likely too short to be indeed "true" subchrons. Moreover, the number of detected tiny wiggles clearly depends on the spreading rate. These results support geomagnetic intensity fluctuations as being the cause of most tiny wiggles, as also Preprint submitted to Elsevier Science suggested by recent magnetostratigraphic data. The tiny wiggles are uniformly distributed within chrons, indicating that paleointensity fluctuations are neither inhibited after, nor enhanced before, a reversal beyond a "blind" zone of about 10 km (corresponding to 80 to 250 kyr depending on the spreading rate) for which the anomalies due to reversals prevent the detection of tiny wiggles. Most tiny wiggles probably represent a filtered record of a uniform secular variation regime, as suggested by their uniform spatial distribution over the whole investigated period.

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Section: Discussionmentioning

confidence: 99%

Geomagnetic field variations between chrons 33r and 19r (83–41 Ma) from sea-surface magnetic anomaly profiles

Bouligand

Dyment

Gallet

et al. 2006

Earth and Planetary Science Letters

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“…Moreover, from the Santa Rosa I dome ( Fig. 1 40 Ar/ 36 Ar intercept was 281.8 þ 9.4, signi¢cantly lower than the atmospheric value of 295.5, which is di⁄cult to explain for terrestrial volcanic rocks [18]. From a split of the same sanidine separate analyzed by Doell et al [17] from the Santa Rosa I rhyolite, Izett and Obradovich [3] obtained total fusion measurements from six multigrain aliquots that de¢ne a weighted mean age of 930 þ 17 ka.…”

Section: Geologic Setting and Previous Workmentioning

confidence: 99%

“…Following three additional minutes of clean up on a single SAES C-50 getter, the gas from each heating step was expanded into a Mass Analyser Products-215-50 spectrometer ¢tted with a Nier type ion source, the mass range 40^36 was scanned eight times in static mode using a Balzers SEV-17 electron multiplier, and its initial composition determined by regression analysis. System blanks were measured before every fourth sample and for 40 Ar were one to two orders of magnitude smaller than the samples (V10 317 mol), whereas for 36 Ar blanks typically comprised 10^90% of the signal (V10 319 mol), but were stable during analytical periods of several hours per session.…”

Section: Paleomagnetic Andmentioning

confidence: 99%

The Santa Rosa Event: 40Ar/39Ar and paleomagnetic results from the Valles rhyolite near Jaramillo Creek, Jemez Mountains, New Mexico

Singer

Brown

2002

Earth and Planetary Science Letters

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The Jaramillo Event was originally defined by Doell and Dalrymple in 1966 on the basis of K^Ar ages from sanidine in the normally, transitionally and reversely magnetized rhyolite domes named Cerro del Abrigo, Cerro Santa Rosa I and Cerro Santa Rosa II, respectively, that erupted following collapse of the archetypal Valles Caldera, New Mexico. We have collected new paleomagnetic data from the three domes and new 40 Ar/ 39 Ar laser fusion and furnace incremental heating experiments on sanidine crystals from the Cerro Santa Rosa I rhyolite.Step-wise alternating field and thermal demagnetization techniques applied to 52 samples from seven sites indicate that the original paleomagnetic results of Doell and Dalrymple [Science 152 (1966) 1060^1061] are valid. Cerro del Abrigo is normally magnetized, whereas the Santa Rosa I dome is transitional with an inclination of 363 ‡ toward the east and the Santa Rosa II dome is of reversed polarity. Twenty-five laser fusion experiments on sanidine crystals from the the Cerro Santa Rosa I dome, together with the saddle-shaped spectrum obtained by incrementally heating the sanidine in a furnace reveal that this rhyolite contained a small but significant component of excess argon prior to eruption. Our preferred age of 936 þ 8 ka ( þ 2c) for the Santa Rosa I rhyolite is based on the concordant laser fusion isochron and incremental heating plateau ages. This age is significantly older than was inferred on the basis of earlier laser fusion 40 Ar/ 39 Ar results that suggested a trapped component characterized by a 40 Ar/ 36 Ar ratio lower than the atmospheric value of 295.5. Our new age distinguishes the Santa Rosa I dome by 65 kyr from the termination of the Jaramillo normal subchron 1001 þ 10 ka and by 37 kyr from basaltic lavas at Haleakala and Tahiti, which record the Kamikatsura Event 899 þ 6 ka. Moreover, this determination is a factor of three more precise than the best previous estimate for a proposed geomagnetic event in this time period. The Cerro Santa Rosa I rhyolite dome, once intimately linked with the end of the Jaramillo Event and the acceptance of plate tectonic theory, now defines a highly resolved feature, the Santa Rosa Event, in a terrestrial geomagnetic reversal time scale that is consistent with the global record of magnetic field intensity from marine sediments. ß

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“…A rapid progress in paleointensity estimation using marine sediment cores in 1990s resulted in the establishment of the global paleointensity stack during the Brunhes chron: the Sint-800 of Guyodo and Valet (1999). Efforts have been made to extend the paleointensity record to older periods, and an increasing number of records in the Matuyama chron have been published (Valet and Meynadier, 1993;Meynadier et al, 1994;Sato et al, 1998;Kok and Tauxe, 1999;Channell et al, 2002;Yamazaki andOda, 2002, 2005;Carcaillet et al, 2003;Horng et al, 2003). However, agreement among the records is not very good (Yamazaki and Oda, 2005).…”

Section: Introductionmentioning

confidence: 99%

A relative paleointensity record of the geomagnetic field since 1.6 Ma from the North Pacific

Yamazaki

Kanamatsu

2007

Earth Planet Sp

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A paleomagnetic study was conducted on a sediment core KR0310-PC1 taken from the central North Pacific in order to obtain a relative paleointensity record in the Matuyama chron from this region. The core reached to about 1.6 Ma. The age control is based on the correlation of the S ratio (S −0.1T ) variations with a global oxygen-isotope stack. Isothermal remanent magnetization (IRM) was used as the normalizer of the relative paleointensity estimation; anhysteretic remanent magnetization (ARM) was not adopted because ARM is sensitive to magnetostatic interaction among magnetic particles, which is evidenced in these sediments by an inverse correlation between the ratio of ARM to saturation IRM (SIRM) and SIRM without significant magnetic grain-size changes. For the last 350 kyrs, the record of core NGC65, which was obtained at practically the same site as KR0310-PC1 and covers the Brunhes chron (Yamazaki, 1999), was incorporated because the upper part of KR0310-PC1 was physically disturbed. In the record of NGC65/KR0310-PC1, the average paleointensity in the late Matuyama chron is not lower than that during the Brunhes chron, which does not support the conclusion of Valet et al. (2005) based on their Sint-2000 stack. A spectral analysis on the NGC65/KR0310-PC1 paleointensity record shows a power at the ∼100 kyr eccentricity period. The relative paleointensity and magnetic properties of NGC65/KR0310-PC1 were compared with those of MD982185 from the western equatorial Pacific (Yamazaki and Oda, 2002, 2005). The two sites belong to different oceanographic regimes. Coherent variations in the relative paleointensity despite incoherent changes in the magnetic properties suggest that rock-magnetic contamination to the relative paleointensity is small, if any, and the ∼100 kyr period in the relative paleointensity records would reflect the geomagnetic field behavior.

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A relative geomagnetic paleointensity stack from Ontong‐Java Plateau sediments for the Matuyama

Cited by 42 publications

References 24 publications

Geomagnetic field variations between chrons 33r and 19r (83–41 Ma) from sea-surface magnetic anomaly profiles

Geomagnetic field variations between chrons 33r and 19r (83–41 Ma) from sea-surface magnetic anomaly profiles

The Santa Rosa Event: 40Ar/39Ar and paleomagnetic results from the Valles rhyolite near Jaramillo Creek, Jemez Mountains, New Mexico

A relative paleointensity record of the geomagnetic field since 1.6 Ma from the North Pacific

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