Blake polarity episode in two cores from the Greater Antilles Outer Ridge

Denham, Charles R.

doi:10.1016/0012-821x(76)90147-3

Cited by 92 publications

(47 citation statements)

References 26 publications

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“…But the morphology and age of the event still remain controversial. It seems to be characterised by two reversed polarity zones (Denham, 1976) or even by a single polarity zone (Tucholka et aI., 1987). Age and duration estimates vary signifi cantly in the literature.…”

Section: Introductionmentioning

confidence: 99%

“…Age and duration estimates vary signifi cantly in the literature. Extreme discrepancies for the onset of the Blake event have been given with 138 kyr BP and 100 kyr (Bleil and Card (1989), and Denham (1976), respectively), Duration estimates range between 20 and 35 kyr (Denham, 1976) with a minimum value of around 5 kyr introduced by Tucholka et al (1987). Studies on marine sediments suggest that this excursion occurred during marine isotope stage MI5 5, probably during sub stages SejSd .…”

Section: Introductionmentioning

confidence: 99%

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The Blake geomagnetic excursion recorded in a radiometrically dated speleothem

Osete

Martı́n-Chivelet

Rossi

et al. 2012

Earth and Planetary Science Letters

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Keywords:geomagnetic excursions speleothems radioisotope geochronology palaeointensity rock magnetism quaternary geochronologyOne of the most important developments in geomagnetism has been the recognition of polarity excursions of the Earth's magnetic field. Accurate timing of the excursions is a key point for understanding the geodynamo process and for magnetostratigraphic correlation. One of the best known excursions is the Blake geomagnetic episode, which occurred during marine isotope stage MIS 5, but its morphology and age remain controversial. Here we show, for the first time, the Blake excursion recorded in a stalag mite which was dated using the uranium-series disequilibrium techniques. The characteristic remanent magnetisation is carried by fine-graine d magnetite. The event is documented by two reversed intervals (Bl and B2). The age of the event is estimated to be between 116.5 + 0.7 kyr BP and 112.0 + 1.9 kyr BP, slightly younger (�3-4 kyr) than recent estimations from sedimentary records dated by astronomical tuning. Low values of relative palaeointensity during the Blake episode are estimated, but a relative maximum in the palaeofield intensity coeval with the complete reversal during the B2 interval was observed. Duration of the Blake geomagnetic excursion is 4.5 kyr, two times lower than single excursions and slightly higher than the estimated diffusion time for the inner core (�3 kyr).

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The Blake geomagnetic excursion recorded in a radiometrically dated speleothem

Osete

Martı́n-Chivelet

Rossi

et al. 2012

Earth and Planetary Science Letters

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“…However, at least one of them, the Blake Subchron at about 1.2 k.y. (Smith and Foster, 1969;Denham, 1976), is well documented in sedimentary sections (e.g., Denham, 1976;Creer et al, 1980;Tucholka et al, 1987;Trie et al, 1991).…”

Section: Introductionmentioning

confidence: 99%

Paleomagnetic Analyses of Short Normal Polarity Magnetic Anomalies in the Matuyama Chron

Gallet¹,

Gee²,

Tauxe³

et al. 1993

Proceedings of the Ocean Drilling Program

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We document three short normal intervals in the natural remanent magnetization of sediments within the Matuyama Chron. These three anomalous zones of magnetization between the Jaramillo and Olduvai subchrons were identified from continuous measurements of archive halves from Hole 803 A using the pass-through 2G cryogenic magnetometer at Scripps. The U-channel samples were taken from the three intervals, analyzed using the pass-through system, and then cut into discrete 1 -cm-thick samples. Measurements on discrete samples confirmed the presence of the upper normal polarity zone. Based on sedimentation rate calculations, this zone is confidently correlated with the Cobb Mountain Subchron. For the two other anomalous zones, complete thermal demagnetization revealed a high-stability component (250°-575°C) of reversed polarity. The intensity of the low-stability normal polarity component, normalized by susceptibility, remains roughly constant throughout the entire interval sampled, whereas the intensity of the high-stability reversed component is much lower within the normal zone than outside. We interpret these two normal zones, then, as periods of low (reversed polarity) geomagnetic field intensity resulting in low magnetization of the sediments; the periods of these low magnetization reversed polarity zones are completely masked by the component acquired viscously in a normal polarity field.

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“…Among the available data, anomalous paleomagnetic features in some deep-sea core sediments reported by WOLLIN et ad. (1971), DENHAM (1976), and DENHAM et al (1977 are candidates which may represent the same geomagnetic phenomenon as the Biwa I episode. In this section, we made a discussion about possibility of world-wide correlation of the Biwa I episode, especially from a climatostratigraphical view point.…”

Section: Comparisonmentioning

confidence: 97%

Reversed polarity episode in the Late Brunhes Epoch as confirmed on parallel sections of Pleistocene deposits in the Kinki district, central Japan.

Hayashida

1984

J. geomagn. geoelec

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Blake polarity episode in two cores from the Greater Antilles Outer Ridge

Cited by 92 publications

References 26 publications

The Blake geomagnetic excursion recorded in a radiometrically dated speleothem

The Blake geomagnetic excursion recorded in a radiometrically dated speleothem

Paleomagnetic Analyses of Short Normal Polarity Magnetic Anomalies in the Matuyama Chron

Reversed polarity episode in the Late Brunhes Epoch as confirmed on parallel sections of Pleistocene deposits in the Kinki district, central Japan.

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