Magnetic Polarity Transition Zones at the Brunhes/Matuyama and Upper Olduvai Boundaries: Preliminary Results from ODP Leg 104

The youngest geomagnetic polarity reversal, the Matuyama–Brunhes boundary (MBB), which occurred 780 kyr ago, is a “golden spike” in the age calibration of sediment sequences. The use of palaeomagnetic method as a stratigraphic tool in the study of loess sequences from Ukraine originated some 50 years ago. One major problem in using the available data is the contradictory position of the MBB in different stratigraphic units, which affected historic evolution of thechronostratigraphic models of the Quaternary in Ukraine. The most important units in this regard are the Shyrokyne and Martonosha units, in which the MBB had been defined most often. This paper provides the careful analysis of the previous magnetostratigraphic data and new preliminary results from key loess-palaeosol sections in Central Ukraine. Shyrokyne palaeosol complex in four loesspalaeosol sections located in the Middle Dnieper and Podolia regions has been palaeomagnetically studied. It is shown that the transition zone of the Matuyama–Brunhes palaeomagnetic reversal is most likely located at the base of the soil complex. In the Vyazivok section the MBB has been found in the lowermost part of Shyrokyne palaeosol sh1. Preliminary palaeomagnetic studies of theStari Kaydaky section reveal that the MBB cannot be defined at least above sh1 subunit. Medzhybizh and Holovchyntsi sections were deposited after the Matuyama–Brunhes reversal; however, the palaeomagnetic informativeness of the part of studied strata is doubtful. Magnetostratigraphic position of the Shyrokyne unit below the MBB in some previous studies is explained by methodological reasons and inconsistent chronostratigraphic models. The paper substantiates that normal magnetic polarity zone in the Pryazovya loess and upper part of the Shyrokyne soil is not associated with the influence of secondary processes on the palaeomagnetic record.

Download Full-text

A numerical study on magnetic polarity transition in an MHD dynamo model

Earth Planets and Space ◽

10.1186/bf03352729 ◽

2007 ◽

Vol 59 (7) ◽

pp. 665-673 ◽

Cited By ~ 18

Author(s):

Futoshi Takahashi ◽

Masaki Matsushima ◽

Yoshimori Honkura

Keyword(s):

Numerical Study ◽

Magnetic Polarity ◽

Dynamo Model ◽

Mhd Dynamo ◽

Polarity Transition

Download Full-text

Cosmic Ray Spectra and the Solar Magnetic Polarity: Preliminary Results from 1994–2002

10.1063/1.1618673 ◽

2003 ◽

Cited By ~ 3

Author(s):

J. W. Bieber

Keyword(s):

Cosmic Ray ◽

Magnetic Polarity ◽

Preliminary Results

Download Full-text

Soil recovery following landslides at Whatawhata Research Station, Waikato, New Zealand: preliminary results

NZGA: Research and Practice Series ◽

10.33584/rps.16.2016.3227 ◽

2016 ◽

Vol 16 ◽

pp. 179-184

Author(s):

A.M. Noyes ◽

M.R. Balks ◽

V.G. Moon ◽

D.J. Lowe

Keyword(s):

New Zealand ◽

Soil Carbon ◽

Transition Zone ◽

Shear Zones ◽

Research Station ◽

Landslide Area ◽

Transition Zones ◽

Preliminary Results ◽

Accumulation Zone ◽

Soil Recovery

This research investigates soil recovery following landslides at the Whatawhata Research Station 20 km west of Hamilton. Six landslides were studied, ranging in age from pre-1953 to 2014. The landslides were divided into four zones: shear zones (mean of 25% of landslide area), intact accumulation zones (20%), transition zones (40%), and re-deposition zones (15%), along with a control. Soils were well-developed in the control and intact accumulation zones and least recovered in the shear and re-deposition zones. Mean A horizon depths ranged from 2 cm in the shear and re-deposition zones to 7 cm in the transition zone, 17 cm in the intact accumulation zone, and 20 cm in the control. Mean soil carbon contents were lower (P

Download Full-text

A magnetic polarity transition recorded in a 41m granitic core from Takasegawa valley, Nagano prefecture, Japan.

Journal of geomagnetism and geoelectricity ◽

10.5636/jgg.41.137 ◽

1989 ◽

Vol 41 (1) ◽

pp. 137-145

Author(s):

Haruaki ITO ◽

Kanichi MOMOSE ◽

Katsuyasu TOKIEDA ◽

Yukio NOTSU

Keyword(s):

Magnetic Polarity ◽

Nagano Prefecture ◽

Polarity Transition

Download Full-text

Magnetization and suitability for paleomagnetic field intensity measurements of selected samples from sites 332, 334, and 335 of Leg 37 DSDP

Canadian Journal of Earth Sciences ◽

10.1139/e77-072 ◽

1977 ◽

Vol 14 (4) ◽

pp. 745-755 ◽

Cited By ~ 1

Author(s):

C. M. Carmichael

Keyword(s):

Field Intensity ◽

Single Unit ◽

Thick Layer ◽

Magnetic Polarity ◽

Small Samples ◽

Visual Examination ◽

Field Reversal ◽

Intensity Measurements ◽

Polarity Transition ◽

Partial Reversal

The magnetic properties of 31 small samples from sites 332, 334, and 335 of Leg 37 DSDP were measured, and attempts were made to determine paleomagnetic field intensity. Values of paleointensity of 0.5 and 0.7 times the present field were obtained using one sample from site 332 and one from Site 335 respectively. All of the remaining samples proved unsuitable for paleointensity determinations owing to alteration on heating. This alteration is of two types: (1) destruction of maghemite, which reduces the magnetization of the samples, and (2) a process that markedly increases their thermal and saturation remanences and which may involve precipitation of new small magnetic grains out of glass. A 19 m thick layer at a depth of about 600 m in hole 332B, which appears to be a single unit on the basis of visual examination and chemical analysis of samples, contains a magnetic polarity transition. This may be due to a field reversal, or a partial reversal, while the unit was being implaced. Only samples from site 335 have a magnetization that can account for the surface anomaly by the remanence of the layers drilled.

Download Full-text

The O–C diagrams of minor planets − a new approach to modelling the rotation

International Astronomical Union Colloquium ◽

10.1017/s0252921100031407 ◽

1999 ◽

Vol 173 ◽

pp. 185-188

Author(s):

Gy. Szabó ◽

K. Sárneczky ◽

L.L. Kiss

Keyword(s):

Error Analysis ◽

Time Dependence ◽

Theoretical Work ◽

Minor Planet ◽

Minor Planets ◽

New Approach ◽

Preliminary Results ◽

Ccd Observations

AbstractA widely used tool in studying quasi-monoperiodic processes is the O–C diagram. This paper deals with the application of this diagram in minor planet studies. The main difference between our approach and the classical O–C diagram is that we transform the epoch (=time) dependence into the geocentric longitude domain. We outline a rotation modelling using this modified O–C and illustrate the abilities with detailed error analysis. The primary assumption, that the monotonity and the shape of this diagram is (almost) independent of the geometry of the asteroids is discussed and tested. The monotonity enables an unambiguous distinction between the prograde and retrograde rotation, thus the four-fold (or in some cases the two-fold) ambiguities can be avoided. This turned out to be the main advantage of the O–C examination. As an extension to the theoretical work, we present some preliminary results on 1727 Mette based on new CCD observations.

Download Full-text

Cyclic Evolution of Sunspots: Gleaning New Results from Old Data

International Astronomical Union Colloquium ◽

10.1017/s0252921100064411 ◽

2000 ◽

Vol 179 ◽

pp. 163-165

Author(s):

S. K. Solanki ◽

M. Fligge ◽

P. Pulkkinen ◽

P. Hoyng

Keyword(s):

Sunspot Number ◽

Sunspot Cycle ◽

Preliminary Results ◽

Butterfly Diagram

AbstractThe records of sunspot number, sunspot areas and sunspot locations gathered over the centuries by various observatories are reanalysed with the aim of finding as yet undiscovered connections between the different parameters of the sunspot cycle and the butterfly diagram. Preliminary results of such interrelationships are presented.

Download Full-text