rock magnetic paleointensity

  • A rock-magnetic and paleointensity study of some .Traduire cette page

    The NRM fractions used for paleointensity determination range from 0.34 to 0.97 and the quality factors varies between 4.5 and 97.8, being normally greater than 5. The obtained virtual dipole moment values are higher than those recently reported for the past 5 .

  • Short reversals of the earth's magnetic field and its ... · Fichier PDF

    Therefore, calculation of different ratios of rock magnetic parameters such as ARM/IRM or ARM/κ LF are used to estimate relative grain size variations. If these are large, paleointensity estimates have to be restricted to intervals with minimum variations, or paleointensity estimates have to be corrected for grain size variations, a procedure not well developed up to now. Examples Fig. 3 ...

  • Studies on rock magnetic and paleointensity of .Traduire cette page

    The magnetic mineralogy of all the samples was dominated by ferrimagnetic mineral (magnetite/magnetite with low titanium content), which was suitable for paleointensity measurements. The geomagnetic paleointensity value obtained by subjecting them to modified Thellier and Thellier method, is found to be (48.81±0.15) μT.

  • Paleointensity of the Earth's magnetic field using SQUID ... · Fichier PDF

    SQUID microscopy has been used in previous paleomagnetic and rock magnetic studies (see Weiss et al., 2007 and references therein).Forthisstudy,weusedtheNRM/sIRMmethodas the first step for adapting SQUID microscopy to paleointensityexperiments.Thebasictechniquedescribed here should in the future be adaptable to more robust methods like that of Thellier.

  • Rock Magnetic Properties and Paleointensity .

    Other rock magnetic properties such as low-temperature measurements and thermomagnetic curves also indicate that the magnetic composition of the basalt varies from almost pure magnetite to titanomagnetite (x=0.4) within the same hole. Identification of magnetic minerals is important in order to assess the reliability of paleointensity and ...

  • Rock magnetic and paleointensity results from .Traduire cette page

    Updated mean paleomagnetic poles were calculated for the Upper Cretaceous Tovuz-Paravakar sections (65.6 degrees N, 162.2 degrees E, A(95) = 4.3, paleolatitude = 27.0 +/- 3.4 degrees) and the Upper Jurassic-Lower Cretaceous Kafan section (61.7 degrees N, 158.9 degrees E, A(95) = 4.8 degrees, paleolatitude = 24.7 +/- 3.8 degrees).

  • Rock‐magnetic artifacts on long‐term relative ...Traduire cette page

    Rock‐magnetic artifacts on long‐term relative paleointensity variations in sediments Rock‐magnetic artifacts on long‐term relative paleointensity variations in sediments Yamazaki, Toshitsugu; Yamamoto, Yuhji; Acton, Gary; Guidry, Emily P.; Richter, Carl 2013-01-01 00:00:00 1 Introduction Estimating the strength of the past geomagnetic field is fundamentally important for understanding ...

  • Rock magnetic and paleointensity results from .Traduire cette page

    Updated mean paleomagnetic poles were calculated for the Upper Cretaceous Tovuz-Paravakar sections (65.6 degrees N, 162.2 degrees E, A(95) = 4.3, paleolatitude = 27.0 +/- 3.4 degrees) and the Upper Jurassic-Lower Cretaceous Kafan section (61.7 degrees N, 158.9 degrees E, A(95) = 4.8 degrees, paleolatitude = 24.7 +/- 3.8 degrees).

  • A rock-magnetic and paleointensity study of .

    Eleven Late Quaternary lava flows were sampled in the Chichinautzin volcanic field of central Mexico to determine their magnetic characteristics and absolute paleointensity. The samples studied cover a geological time interval of approximately 0.39 My to 2000 years. Several rock-magnetic experiments were carried out in order to identify the magnetic carriers and to obtain information about ...

  • On the features of the geodynamo following reversals or ... · Fichier PDF

    magnetic curves. Altogether 54 samples from 21 flows yielded reliable paleointensity estimates. The mean paleointensity of the intermediate ... rocks which satisfy some specific rock-magnetic cri-teria can be used for absolute intensity determination (Kosterov and Prévot, 1999). Judging from scant available data, there is now a general agreement that the intermediate polarity geomagnetic ...

  • 2001), A rock-magnetic and paleointensity study .Traduire cette page

    The NRM fractions used for paleointensity determination range from 0.34 to 0.97 and the quality factors varies be-tween 4.5 and 97.8, being normally greater than 5. The obtained virtual dipole moment values are higher than those recently reported for the past 5 My and to .

  • Toward a robust normalized magnetic .

    15.11.2004 · Relative paleointensity techniques normalize the NRM by a room temperature magnetic parameter proportional to the amount of NRM carriers . An artificial remanence is preferable to magnetic susceptibility (e.g. [11] ) as meteorite remanence is often carried by a minor fraction of the total magnetic material in the meteorite, especially in case of metal-bearing meteorites.

  • A new rock‐magnetic approach to selecting .Traduire cette page

    A rock‐magnetic evaluation of LeBoeuf Lake sediments with these techniques indicates that these sediments are suitable for a relative plaeointensity study. The second approach to evaluating the DRM/ARM ratio as a measure of relative paleointensity is direct comparison with absolute paleointensity data. A comparison between the LeBoeuf Lake ...

    Cited by : 398
  • Palaeo- and rock magnetic investigations on Late ...Traduire cette page

    Palaeo- and rock magnetic investigations carried out on all samples from sediment cores M35003-4 and M78/1_235-1, Tobago Basin. Open in new tab Magnetic extracts and scanning electron microscopy Magnetic extracts were taken from two samples from core M35003-4 (43 and 264 cm depth) and three samples from core M78/1_235-1 (39, 95 and 141 cm depth).

    Cited by : 2
  • Rock magnetic and paleointensity results from .Traduire cette page

    23/01/2009 · Rock magnetic and paleointensity results from Mesozoic baked contacts of Armenia. Authors; Authors and affiliations; V. V. Shcherbakova; M. Perrin; V. P. Shcherbakov ; V. E. Pavlov; A. Ayvaz'yan; G. V. Zhidkov; Open Access. Article. First Online: 23 January 2009. 268 Downloads; 13 Citations; Abstract. Samples were obtained from three baked contacts and one lava flow along the .

    Cited by : 14
  • Rock magnetic properties of dusty olivine: .

    The mechanism of chondrule formation is an important outstanding question in cosmochemistry. Magnetic signals recorded by Fe-Ni nanoparticles in chondrules could carry clues to their origin. Recently, research in this area has focused on 'dusty olivine' in ordinary chondrites as potential carriers of pre-accretionary remanence. Dusty olivine is characterised by the presence of sub-micron Fe-Ni ...

  • Rock magnetic and paleointensity data from .Traduire cette page

    01/12/2005 · Here we examine the rock magnetic and paleointensity characteristics of the Jurassic Stormberg (Karoo) lavas of Lesotho. In the 1960's, van Zijl et al. (1962) reported evidence for a magnetic reversal transition from these lavas. Subsequent studies have confirmed the transition.

    Author : R. D. Cottrell, J. A. Tarduno, M. K. Watkeys
  • Paleomagnetism indicates that primary magnetite .

    New paleointensity and Pb-Pb radiometric age data from additional zircons meeting robust selection criteria provide further evidence for the fidelity of the magnetic record and suggest a period of high geomagnetic field strength at 4.1 to 4.0 billion years ago (Ga) that may represent efficient convection related to chemical precipitation in Earth's Hadean liquid iron core.

  • Rock-magnetic properties of single zircon crystals .Traduire cette page

    15/09/2015 · Although rock-magnetic properties of single zircon crystal are essential for future work establishing the reliable paleointensity method, systematic rock-magnetic studies have not been conducted for single zircon crystals, which is largely because of their small size and related weak magnetic moment.

    Cited by : 14
  • Low-temperature demagnetization of volcanic rocks ...

    KEY WORDS: Rock-magnetism, low-temperature demagnetization, domain structure. INTRODUCTION Reliable absolute paleointensity results are generally much more difficult to obtain than reliable directional data. Only volcanic rocks that satisfy certain specific magnetic criteria can be used for paleointensity determination (Kosterov and Prévot ...

  • Rock magnetic and paleointensity results from .

    Paleointensity determinations could be estimated from two of the upper Cretaceous and three of the Upper Jurassic-Lower Cretaceous baked contacts, corresponding to a 30% success rate. The mean virtual dipole moments obtained were low (1.7-5.5 x 10(22) A m(2)), which is in agreement with data published by Bol'shakov and Solodovnikov (1981a, 1983) for the same sections (3.0-4.4 x 10(22) A .

  • Reassessment of the eruptive chronology of El .

    01.02.2020 · Rock magnetism experiments in air were carried out to identify the remanence carriers and to evaluate the thermal stability of magnetic mineralogy and the suitability of the material to obtain paleointensity (PI) determinations by using a variable field translation balance (AVFTB) from Magnetic Measurements Ltd. These experiments included: (i) progressive isothermal remanence magnetization ...

  • A method paleointensity approach applied to .Traduire cette page

    13/07/2020 · An inclusive rock-magnetic and absolute paleointensity survey of the ~ 2-ka-old Xitle volcano (southerly Basin of Mexico) was undertaken to assess the faithfulness of the paleomagnetic log carried by fresh, widely exposed and well-preserved lava flows.

    Author : Juan Morales, Nayeli Pérez-Rodríguez, Avto Goguitchaichvili, Miguel Cervantes-Solano
  • Rock magnetic response to climatic changes in .Traduire cette page

    Rock magnetic results reveal magnetic uniformities in mineralogy, concentration and grain size along the two cores, thus relative paleointensity variations are acquired. The three normalizers-anhysteresis remanent magnetization (ARM), magnetic susceptibility (?

  • Application of an Anisotropy-Based Correction to .

    The relative continuity and ubiquity of the global sedimentary record makes sediments and sedimentary rocks an ideal target for studies of relative paleointensity (RPI) and the evolution of the Earth's magnetic field. However, processes including flocculation, contact with the substrate, bioturbation, and compaction disrupt this alignment, leading to shallowed remanent inclinations and biased ...

  • Rock magnetic properties and relative .

    15.08.2007 · 1. Introduction. Sedimentary sequences continuously record the past variations of the Earth magnetic field. Normalized records of sedimentary natural remanent magnetization (NRM) are interpreted as representing the relative paleointensity (RPI) of the geomagnetic field (King et al., 1983, Tauxe, 1993).The quality of individual RPI determinations is assessed in terms of mineralogic and rock ...

  • A rock-magnetic and paleointensity study of some Mexican ... · Fichier PDF

    The NRM fractions used for paleointensity determination range from 0.34 to 0.97 and the quality factors varies be- tween 4.5 and 97.8, being normally greater than 5. The obtained virtual dipole moment values are higher than those recently reported for the past 5 My and to .

  • Bulk magnetic domain stability controls paleointensity ... · Fichier PDF

    comprehensive rock magnetic and paleointensity data compila-tions, we quantify a stability trend in hysteresis data that charac-terizes the bulk domain stability (BDS) of the magnetic carriers in a paleomagnetic specimen. This trend is evident in both geological and archeological materials that are typically used to obtain pale- ointensity data and is therefore pervasive throughout most paleo ...

  • 2001), A rock-magnetic and paleointensity study .Traduire cette page

    The NRM fractions used for paleointensity determination range from 0.34 to 0.97 and the quality factors varies be-tween 4.5 and 97.8, being normally greater than 5. The obtained virtual dipole moment values are higher than those recently reported for the past 5 My and to .

  • SPECIAL TOPICS IN ROCK MAGNETISM · Fichier PDF

    PALEOINTENSITY FROM THERMOREMANENT MAGNETIZATION The development of thermoremanent magnetism in Chapter 3 focused on directional properties of TRM. But TRM is unique among forms of natural remanent magnetism in providing information about past intensi- ties of the geomagnetic field via a technique that is straightforward in principle.

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