Counter-clockwise motion of paleomagnetic directions 24000 years ago at Mono Lake, California.

Denham, Charles R.

doi:10.5636/jgg.26.487

Cited by 67 publications

(25 citation statements)

References 23 publications

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“…The strength ratio falls in the range suggested by DENHAM (1974) for the source of the Mono Lake excursion, 24,000 years ago namely, p=0.12 to 0.21. Also it is somewhat greater than the absolute minimum value given in the finely tuned model of HARRISON and RAMIREZ (1975) for the Laschamp event (ps=-0.113).…”

Section: An Examplementioning

confidence: 94%

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Minimum-effect model of geomagnetic excursions applied to auroral zone locations.

Siscoe¹

1976

J. geomagn. geoelec

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The discovery of many brief but large excursions of the paleomagnetic field in the time period 10,000 to 30,000 years B.P. together with the observed absence of excursions in coetaneous records from different sites led to the construction of minimum-effect models of geomagnetic excursions utilizing dipole anomaly sources close to the observations sites. We investigate here the modification of the auroral zone resulting from a minimum-effect model consisting of a main, geocentric dipole (Me) and a radial dipole at the core-mantle boundary (MS) representing the source of the geomagnetic anomaly. The location and size of the auroral zone is found as a function of the location, strength and direction (in or out) of the source. The auroral zone is displaced toward a positive source (MS,Me>0) and reduced in size; and it is displaced away from a negative source (MS. Me<0) and enlarged. An example based on plausible model parameters shows that the auroral zone can be displaced equatorward by 150 to 200 in certain longitudes. If excursions mark times of a reduced main dipole field, an additional equatorward displacement of perhaps 100 can be expected.

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Section: An Examplementioning

confidence: 94%

“…according to DENHAM (1974) could have been produced by a source at about 230 geographic latitude drifting eastward with a positive ps. The geomagnetic latitude of the source would have a middle or low value depending on the orientation of the main dipole at the time.…”

Section: Discussionmentioning

confidence: 99%

Minimum-effect model of geomagnetic excursions applied to auroral zone locations.

Siscoe¹

1976

J. geomagn. geoelec

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“…Nevertheless, the Mono Lake study became well known because of a large amplitude departur e of declination from true north to about 120~ accompanied by abnormally high inclinations reaching nearly 90 ~ (down) as compared with the overall average value of about 55 ~ and the ADF value of 57 ~ This feature became known as the 'Mono Lake Excursion': its age was estimated to have run from 24 600 to 24 000 bp, during which time the NRM vector rotated in a counter-clockwise sense (with advancing time). Denham (1974) later observed the same phenomenon at another site which he correlated with the first site (Verosub, 1977); LAHONTAN = Lake Lahontan (Liddicoat, 1976); PYRAMID = Lake Pyramid (Verosub et al, 1980); MONODC and MONOL ---Mono Lake (Denham andCox 1971 andLiddicoat, 1976 respectively); BONNEVILLE = Lake Bonneville (Liddicoat, 1976). Timescale in thousands of years before present.…”

Section: Mono Lake Excursionmentioning

confidence: 99%

“…This was largely because radiocarbon did not provide an K.M.CREER , 1936); E = Lake Erie (Creer et al, 1976a); H = Lake Huron (Mothersill, 1981); M = Lake Michigan (Creer et al, 1976b;Vitorello and Van der Voo, 1977;Dodson et al, 1977); S = Lake Superior (Mothersill, 1979); K = Kylen Lake and SC = St. Croix Lake (Lund andBanerjee, 1979, 1983;Lund, 1981); A = Anderson's Pond (Lund, 1981;Lund and Banerjee, 1983); Bv = Lake Bonneville, Lh = Lake Lahontan (Liddicoat, 1976); Py = Pyramid Lake (Verosub et. al., 1980); Mo = Mono Lake (Denham and Cox, 1971;Denham, 1974;Liddicoat, 1976;Liddicoat and Coe, 1979); CI = Clear Lake (Verosub, 1977); Sp = speleothems (Latham et al, 1982); B = Bessette Creek (Turner et al, 1983).…”

Section: Great Lakesmentioning

confidence: 99%

Review of lake sediment palaeomagnetic data

Creer

1985

Geophysical Surveys

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Abstract. This first part of a two part review is essentially descriptive: palaeomagnetic data sets used to compile the publisheffreference curves of geomagnetic secular variations (SV) through Holocene time are critically examined, particularly with respect to coring techniques used for sampling, reliability of the measured directions of remanent magnetization and transformation to timescales. Also, progress made in extending SV records into Late Glacial time is reviewed. SV curves have been constructed for W. Europe and N. America going back respectively to 22000 and 31000 yr before the present (bp). The best quality SV records have invariably been obtained from homogeneous muds and clays which typically smooth the geomagnetic signal over intervals of a few hundred years. They show irregular oscillatory patterns in contrast with certain records obtained from some inhomogeneous sections which Show sequences of strongly aberrant palaeomagnetic directions. The latter have been interpreted by some authors as evidence of abnormal geomagnetic field behaviour but such evidence is, on the whole, found to be unconvincing. If geomagnetic excursions or aborted attempts at polarity reversal have occurred, they must have been so rapid as to have been smoothed out in the quasi-continuous records obtained from homogeneous muds. The second part of the review, to be published shortly in this journal, will deal with analyses and interpretations of the data presented here.

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“…High deposition rate sedimentary environments offer the best resolution availablè, as shown by paleomagnetic work on present day lacustrine sediments (Thompson, 1975;Creer, 1977), dry lake beds (Denham and Cox, 1971;Denham, 1974;Liddicoat and Coe, 1979), and marine sediments (Opdyke et al, 1972).…”

Section: Previous Workmentioning

confidence: 99%

Applications of time series analysis to geophysical data

Chave¹

1980

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Counter-clockwise motion of paleomagnetic directions 24000 years ago at Mono Lake, California.

Cited by 67 publications

References 23 publications

Minimum-effect model of geomagnetic excursions applied to auroral zone locations.

Minimum-effect model of geomagnetic excursions applied to auroral zone locations.

Review of lake sediment palaeomagnetic data

Applications of time series analysis to geophysical data

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