All issues
Successor
Volume 32 (1980)
- Issue 12 Pages 721-
- Issue 11 Pages 671-
- Issue 10 Pages 585-
- Issue 9 Pages 507-
- Issue 8 Pages 431-
- Issue 7 Pages 365-
- Issue 6 Pages 309-
- Issue 5 Pages 265-
- Issue 4 Pages 181-
- Issue 3 Pages 129-
- Issue 2 Pages 67-
- Issue 1 Pages 1-
- Issue Supplement3 Pag･･･
- Issue Supplement2 Pag･･･
- Issue Supplement1 Pag･･･
Volume 38, Issue 12
Displaying 1-13 of 13 articles from this issue
- |<
- <
- 1
- >
- >|
-
M. Kono, R. S. Coe, J. Shaw1986 Volume 38 Issue 12 Pages 1257
Published: 1986
Released on J-STAGE: August 11, 2011
JOURNAL FREE ACCESSDownload PDF (90K) -
M. E. EVANS1986 Volume 38 Issue 12 Pages 1259-1267
Published: 1986
Released on J-STAGE: September 14, 2010
JOURNAL FREE ACCESSPaleointensity estimates from three archeological sites are reported; field magnitudes (F) of 71.3±3.7μT and 75.3±1.2μT are obtained from two 1st century A. D. kilns, whilst a 3rd century B. C. kiln yields F=79.7±1.3μT. The present geomagnetic field in the area has a magnitude of 44.7μT. A modern kiln, investigated by the same technique, yields F=45.7±0.7μT. These results employ the correction factor suggested by KONO (1978) to compensate for mineralogical and magnetic changes occurring during laboratory heating of the samples. The validity of this scheme is scrutinized in the light of a brief summary of relevant experimental data. The evidence currently available supports Kono's proposal, but the magnitude of changes it can effectively monitor is poorly defined.View full abstractDownload PDF (773K) -
T. C. ROLPH, J. SHAW1986 Volume 38 Issue 12 Pages 1269-1277
Published: 1986
Released on J-STAGE: September 14, 2010
JOURNAL FREE ACCESSA collection of well dated historical lavas has been obtained from Mt. Etna, Sicily. Standard palaeomagnetic analysis has yielded the directions of magnetisation in the lavas; the equivalent field intensities have been derived using an adaption (ROLPH and SHAW, 1985) of the SHAW (1974) palaeointensity technique. These results are in excellent agreement with data derived for Sicily from a geomagnetic field model (BLOXHAM and GUBBINS, 1985).View full abstractDownload PDF (662K) -
I. TUNYI1986 Volume 38 Issue 12 Pages 1279-1295
Published: 1986
Released on J-STAGE: September 14, 2010
JOURNAL FREE ACCESSThe palaeointensity of the geomagnetic field has been derived from selected rock types of the Czechoslovakian West Carpathians using Thellier's and Van Zijl's methods. Igneous rocks of three geologic time periods were studied. The following values were determined for the ratio of the intensity of the geomagnetic field at the place and time of origin of the rock to the intensity of the laboratory magnetic field (parameter K): a) basaltic rocks (Upper Miocene to Quaternary) K=0.21-2.11; b) monchiquite (Lower Cretaceous) K=0.61; c) quartz porphyry (Middle Silurian) K=0.50.View full abstractDownload PDF (1217K) -
M. KOVACHEVA, M. KANARCHEV1986 Volume 38 Issue 12 Pages 1297-1310
Published: 1986
Released on J-STAGE: September 14, 2010
JOURNAL FREE ACCESSThis paper describes the process of accumulation of the new archaeointensity results from Bulgaria after 1978. The methods of laboratory treatments are discussed. Beside the difficulties connected with the experimental determination of the ancient intensity, the main obstacle for a better elucidation of its variations is inaccurate dating, especially in the prehistoric past. The conclusion is drawn that the relative chronology of prehistoric cultures has to be preserved.
The revised archaeointensity results are systematized as site averages and a weight is given to each individual result. Data are given in terms of the ratio FA/FD, where FD is the geomagnetic field intensity at the site due to an axial geocentric dipole with the present-day moment.
A first attempt for computer processing of the experimental data is shown. A second order polynomial is taken as a local model in a running window of 5 points. In the Appendix the theoretical basis is described and the weights given to experimental site mean values are explained. To obtain the continuous curve of smooth values of the intensity a spline cubic interpolation with a step of 10 years is used.View full abstractDownload PDF (783K) -
Q. Y. WEI, D. J. LI, G. Y. CAO, W. X. ZHANG, S. F. WEI1986 Volume 38 Issue 12 Pages 1311-1322
Published: 1986
Released on J-STAGE: September 14, 2010
JOURNAL FREE ACCESSThe total intensity of geomagnetic field for the period 4500 B. C.-A. D. 1500 was determined with archaeological samples collected from the southern part of China by the Thellier's stepwise heating method. Results indicate that the total intensity of geomagnetic field in this area (28°-32°N, 111°-120°E) varied between 38-90μT during the period 4500 B. C.-A. D. 1500. The high value occurred during the first centuries of Anno Domini with subsequent decreasing while the relative low value was at about 900 B. C. Earlier than 1000 B. C. the average value of the total intensity of geomagnetic field was close to the present day level with evident fluctuations.View full abstractDownload PDF (527K) -
H. SAKAI, K. HIROOKA1986 Volume 38 Issue 12 Pages 1323-1329
Published: 1986
Released on J-STAGE: September 14, 2010
JOURNAL FREE ACCESSA further 172 determinations of the geomagnetic field strength in western Japan between 5000 B. C. to 1800 A. D., combined with previous results, indicate that the strength of the field was consistently weaker than at present between 5000 and 1000 B. C., it then rose to a peak at about 600 A. D., since which it has been declining, except for a brief rise around 1300 A. D. Chemical demagnetization was efficient at removing secondary chemical remanences, particularly from some of the older pottery.View full abstractDownload PDF (492K) -
Graham J. SHERWOOD, John SHAW1986 Volume 38 Issue 12 Pages 1331-1338
Published: 1986
Released on J-STAGE: September 14, 2010
JOURNAL FREE ACCESSMeasurements have been made on a collection of New Zealand lavas, from 18 to 6 Ma in age, to determine the intensity of the ancient geomagnetic field. The predicted geocentric virtual dipole moment (VDM) derived from the New Zealand rocks (2.24×1022Am2) is much lower than that obtained from Icelandic rocks of similar age (7.11×1022Am2). The offset dipole model is discussed as a possible explanation for this discrepancy.View full abstractDownload PDF (516K) -
Masaru KONO, Naoko UENO, Yoshio ONUKI1986 Volume 38 Issue 12 Pages 1339-1348
Published: 1986
Released on J-STAGE: September 14, 2010
JOURNAL FREE ACCESSThe changes in geomagnetic field intensity in Peru in the last 1500 years was investigated by the Thelliers' method applied to ceramics excavated near Cajamarca, northern Peru. The age interval spanned by these samples is from 1500 B. C. to 1300 A. D., which is subdivided into seven different cultural periods. Ages of the individual periods were determined by combining C-14 data, stratigraphy, and the stylistic evolution of the ceramics in the pre-Inca cultures of northern Peru. Thirteen good and 7 acceptable results were obtained among the 24 samples subjected to the experiments. The results are in broad agreement with the ones already reported for the period 1500 B. C.-500 A. D., and a maximum at about 700 B. C. and a minimum at about 0 A. D. are well defined by the present data. The large scatter in the previous results are concluded to be due to the errors in the assignment of ages to the ceramics. The importance is stressed of using materials with well defined ages for archeomagnetic experiments.View full abstractDownload PDF (777K) -
D. WALTON1986 Volume 38 Issue 12 Pages 1349-1352
Published: 1986
Released on J-STAGE: September 14, 2010
JOURNAL FREE ACCESSExperimental evidence is presented for a process of mineral alteration at elevated temperatures in which the change in moment due to alteration is a constant fraction of the moment induced by a laboratory field. Alteration of this nature will result in a linear Arai plot, and has probably escaped detection in the past. A method for estimating its magnitude is outlined, and applied to results obtained using well-dated sherds from Tel-el-Amarna. Removal of the effect of alteration reduces the scatter in the data from 29% to 6%.View full abstractDownload PDF (297K) -
Reliability CriteriaM. J. AITKEN, A. L. ALLSOP, G. D. BUSSELL, M. WINTER1986 Volume 38 Issue 12 Pages 1353-1363
Published: 1986
Released on J-STAGE: September 14, 2010
JOURNAL FREE ACCESSThe Thellier technique is discussed, specifically in respect of small (3×3mm) samples measured using a cryogenic magnetometer. It is concluded that as long as stringent criteria are imposed the technique gives reliable results. Agreement with the Shaw technique is noted, as also with observatory-based values. Consequently the high values found for Western Asia around 1000 BC are substantiated.View full abstractDownload PDF (1056K) -
C. RADHAKRISHNAMURTY1986 Volume 38 Issue 12 Pages 1365-1368
Published: 1986
Released on J-STAGE: September 14, 2010
JOURNAL FREE ACCESSThe selection of basalt samples for the determination of paleointensity, proposed by SENANAYAKE et al. (1982) based mainly on the low-temperature susceptibility variation, may not be adequate for the purpose. Besides the Type 2 basalts in their classification, the magnetic mineral Fe2.9Ti0.1O4 (TM10), which occurs commonly in basalts, also shows an increase in the susceptibility at low temperatures. It is shown that these two could be distinguished from each other by using an extra criterion like coercive force or Curie temperature and the TM10 bearing basalts, not quite suitable for paleointensity measurements, could be separated.View full abstractDownload PDF (402K) -
S. P. BURLATSKAYA, P. MARTON, E. MARTON1986 Volume 38 Issue 12 Pages 1369-1372
Published: 1986
Released on J-STAGE: September 14, 2010
JOURNAL FREE ACCESSDownload PDF (251K)
- |<
- <
- 1
- >
- >|