Relative paleointensity of the geomagnetic field during the past 0.8 Ma from Nihewan Basin, Hebei Province, China

2004 ◽  
Vol 49 (9) ◽  
pp. 948-952 ◽  
Author(s):  
Yong Wang ◽  
Zhenqing Chi ◽  
Tehquei Lee ◽  
Longrui Min ◽  
Huiyair Chu
Keyword(s):  
Geomagnetic Field ◽  
Hebei Province ◽  
The Past ◽  
Nihewan Basin ◽  
Relative Paleointensity

Preliminary paleomagnetic results from PS97 cores from the Drake Passage for the past 110 ka

2020 ◽  
Author(s):  
Jiabo Liu ◽  
Norbert Nowaczyk ◽  
Xufeng Zheng ◽  
Qinsong Liu ◽  
Helge Arz
Keyword(s):  
Southern Ocean ◽  
Geomagnetic Field ◽  
Sediment Cores ◽  
Drake Passage ◽  
Mono Lake ◽  
The Past ◽  
Asymmetric Pattern ◽  
Relative Paleointensity ◽  
Globally Distributed ◽  
Northern And Southern Hemispheres

<p>Paleomagnetic records reconstructed from globally distributed marine sediments have greatly improved our understanding of long-term paleosecular variations and geomagnetic excursions. Nevertheless, questions regarding to the development of the geomagnetic field anomaly in the Southern Atlantic Ocean and the asymmetric geomagnetic field between Northern and Southern Hemispheres are not yet satisfactorily resolved. Paleomagnetic data, particularly from the Southern Hemisphere, is needed to better define the global geomagnetic field configurations spanning paleosecular variations and excursions. In this study, three sediment cores (PS97-085, PS97-84, PS97-079) recovered from the Drake Passage, Southern Ocean were subjected to detailed rock magnetic and paleomagnetic investigations. Preliminary age models were obtained by correlating their magnetic susceptibility to the ẟ<sup>18</sup>O master record from Dome C, Antarctica. In addition, rock magnetic records of the studied PS97 cores were further correlated to that of core PS67/197-1 with AMS <sup>14</sup>C age constraints. The results from PS97 cores are thus continuously covering the past about 110 ka. Rock magnetic results indicate titanomagnetite is the dominant magnetic carrier in the studied PS97 cores. Relative paleointensities (RPI) derived from these PS97 cores are comparable with the regional relative paleointensity records and the South Atlantic paleointensity stack (SAPIS). Additionally, anomalous inclinations at about 41 ka and 35 ka, observed in core PS97-085, are coeval with the Laschamps and the Mono Lake excursions, respectively. This study provides new paleomagnetic records from the Southern Ocean, though further age constrains are needed to consolidate the paleomagnetic interpretations. The up to now obtained paleomagnetic records, together with previous studies from the Southern Ocean, are aiming to clarify the asymmetric pattern of non-dipole geomagnetic field between Northern and Southern Hemispheres.</p>

scholarly journals ORBITAL NOISE OF THE EARTH CAUSES INTENSITY FLUCTUATION IN THE GEOMAGNETIC FIELD

2003 ◽  
Vol 03 (01) ◽  
pp. L63-L72 ◽  
Author(s):  
H. S. LIU ◽  
R. KOLENKIEWLCZ ◽  
C. WADE
Keyword(s):  
Geomagnetic Field ◽  
Noise Spectrum ◽  
Outer Core ◽  
The Past ◽  
The Earth ◽  
Spectral Peaks ◽  
Relative Paleointensity ◽  
Intensity Fluctuations ◽  
Composite Curve ◽  
Insight Into

Orbital noise of Earth's obliquity can provide an insight into the core of the Earth that causes intensity fluctuations in the geomagnetie field. Here we show that noise spectrum of the obliquity frequency have revealed a series of frequency periods centered at 250-, 100-, 50-, 41-, 30-, and 26-kyr which are almost identical with the observed spectral peaks from the composite curve of 33 records of relative paleointensity spanning the past 800 kyr (Sint–800 data). A continuous record for the past two million years also reveals the presence of the major 100 kyr periodicity in obliquity noise and geomagnetic intensity fluctuations. These results of correlation suggest that obliquity noise may power the dynamo, located in the liquid outer core of the Earth, which generates the geomagnetic field.

scholarly journals Magnetic anomalies possibly linked to local low seismicity

2009 ◽  
Vol 9 (5) ◽  
pp. 1567-1572 ◽  
Author(s):  
F. Masci ◽  
P. Palangio ◽  
M. Di Persio
Keyword(s):  
Geomagnetic Field ◽  
Central Italy ◽  
Low Frequency ◽  
Magnetic Anomalies ◽  
Tectonic Activity ◽  
The Past ◽  
Tectonic Events ◽  
The City ◽  
Network Station ◽  
The Magnetic Field

Abstract. During the last twenty years a time-synchronized network of magnetometers has operated in Central Italy along the Apennine chain to monitor the magnetic field anomalies eventually related to the tectonic activity. At present time the network consists of five stations. In the past only few anomalies in the local geomagnetic field, possibly associated to earthquakes, has been observed, not least because the network area has shown a low-moderate seismic activity with the epicentres of the few events with Ml≥5 located away from the network station. During 2007 two Ml≈4 earthquakes occurred in proximity of two stations of the network. Here we report the magnetic anomalies in the geomagnetic field that could be related with these tectonic events. To better investigate these two events a study of ULF (ultra-low-frequency) emissions has been carried out on the geomagnetic field components H, D, and Z measured in L'Aquila Observatory during the period from January 2006 to December 2008. We want to stress that this paper refers to the period before the 2009 L'Aquila seismic sequence which main shock (Ml=5.8) of 6 April heavily damaged the medieval centre of the city and surroundings. At present time the analysis of the 2009 data is in progress.

Relative paleointensity of the geomagnetic field over the last 200,000 years from ODP Sites 883 and 884, North Pacific Ocean

1997 ◽  
Vol 152 (1-4) ◽  
pp. 11-23 ◽  
Author(s):  
Andrew P. Roberts ◽  
Benoı̂t Lehman ◽  
Robin J. Weeks ◽  
Kenneth L. Verosub ◽  
Carlo Laj
Keyword(s):  
Pacific Ocean ◽  
North Pacific ◽  
Geomagnetic Field ◽  
North Pacific Ocean ◽  
Relative Paleointensity

scholarly journals Correlation based snapshot models of the archeomagnetic field

2020 ◽  
Vol 223 (1) ◽  
pp. 648-665
Author(s):  
S Mauerberger ◽  
M Schanner ◽  
M Korte ◽  
M Holschneider
Keyword(s):  
Model Uncertainty ◽  
Geomagnetic Field ◽  
A Priori ◽  
Field Vector ◽  
Parametric Approach ◽  
Full Field ◽  
The Past ◽  
Uncertainty Estimates ◽  
Improved Model ◽  
Field Estimate

SUMMARY For the time stationary global geomagnetic field, a new modelling concept is presented. A Bayesian non-parametric approach provides realistic location dependent uncertainty estimates. Modelling related variabilities are dealt with systematically by making little subjective a priori assumptions. Rather than parametrizing the model by Gauss coefficients, a functional analytic approach is applied. The geomagnetic potential is assumed a Gaussian process to describe a distribution over functions. A priori correlations are given by an explicit kernel function with non-informative dipole contribution. A refined modelling strategy is proposed that accommodates non-linearities of archeomagnetic observables: First, a rough field estimate is obtained considering only sites that provide full field vector records. Subsequently, this estimate supports the linearization that incorporates the remaining incomplete records. The comparison of results for the archeomagnetic field over the past 1000 yr is in general agreement with previous models while improved model uncertainty estimates are provided.

scholarly journals Archaeointensity results spanning the past 6 kiloyears from eastern China and implications for extreme behaviors of the geomagnetic field

2016 ◽  
Vol 114 (1) ◽  
pp. 39-44 ◽  
Author(s):  
Shuhui Cai ◽  
Guiyun Jin ◽  
Lisa Tauxe ◽  
Chenglong Deng ◽  
Huafeng Qin ◽  
...  
Keyword(s):  
Geomagnetic Field ◽  
Dipole Moments ◽  
Eastern China ◽  
Published Data ◽  
Reference Curve ◽  
The Holocene ◽  
The Past ◽  
Deep Interior ◽  
Archaeomagnetic Dating ◽  
Data Points

Variations of the Earth’s geomagnetic field during the Holocene are important for understanding centennial to millennial-scale processes of the Earth’s deep interior and have enormous potential implications for chronological correlations (e.g., comparisons between different sedimentary recording sequences, archaeomagnetic dating). Here, we present 21 robust archaeointensity data points from eastern China spanning the past ∼6 kyr. These results add significantly to the published data both regionally and globally. Taking together, we establish an archaeointensity reference curve for Eastern Asia, which can be used for archaeomagnetic dating in this region. Virtual axial dipole moments (VADMs) of the data range from a Holocene-wide low of ∼27 to “spike” values of ∼166 ZAm2(Z: 1021). The results, in conjunction with our recently published data, confirm the existence of a decrease in paleointensity (DIP) in China around ∼2200 BCE. These low intensities are the lowest ever found for the Holocene and have not been reported outside of China. We also report a spike intensity of 165.8 ± 6.0 ZAm2at ∼1300 BCE (±300 y), which is either a prelude to or the same event (within age uncertainties) as spikes first reported in the Levant.

A comparison of geomagnetic secular variation as recorded by historical, archaeomagnetic and palaeomagnetic measurements

1982 ◽  
Vol 306 (1492) ◽  
pp. 103-112 ◽  
Keyword(s):  
Magnetic Field ◽  
Lake Sediments ◽  
Secular Variation ◽  
Geomagnetic Field ◽  
Secular Change ◽  
Mathematical Approach ◽  
Geomagnetic Secular Variation ◽  
The Past ◽  
Palaeomagnetic Data ◽  
Field Behaviour

Palaeomagnetic methods can extend the documentary record of changes in the Earth’s magnetic field far into the past. Tolerable agreement is found between various methods, demonstrating the geophysical value of palaeomagnetic experiments. Combining results from the different approaches of investigating secular change can lead to a better perspective and to superior models of geomagnetic field behaviour. Lake sediments have recently been found to hold remarkably detailed signatures of past field changes. A mathematical approach to formulating an empirical description of global geomagnetic field behaviour is proposed and applied to palaeomagnetic data spanning the last 10 ka.

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