Paleomagnetismo y fechamiento 40Ar/39Ar de una secuencia de coladas de lava Pliocénicas en el Cáucaso Menor: Registro de una rotación y análisis de la variación paleosecular

  1. Ana Caccavari 1
  2. Manuel Calvo-Rathert 2
  3. Avto Gogichaishvili 1
  4. He Huaiyu 3
  5. Goga Vashakidze 4
  6. Néstor Vegas 5
  1. 1 Universidad Nacional Autónoma de México
    info

    Universidad Nacional Autónoma de México

    Ciudad de México, México

    ROR https://ror.org/01tmp8f25

  2. 2 Universidad de Burgos
    info

    Universidad de Burgos

    Burgos, España

    ROR https://ror.org/049da5t36

  3. 3 Chinese Academy of Sciences
    info

    Chinese Academy of Sciences

    Pekín, China

    ROR https://ror.org/034t30j35

  4. 4 Tbilisi State University
    info

    Tbilisi State University

    Tiflis, Georgia

    ROR https://ror.org/05fd1hd85

  5. 5 Universidad del País Vasco/Euskal Herriko Unibertsitatea
    info

    Universidad del País Vasco/Euskal Herriko Unibertsitatea

    Lejona, España

    ROR https://ror.org/000xsnr85

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Journal:
Latinmag Letters

ISSN: 2007-9656

Year of publication: 2013

Volume: 3

Issue: PC03

Pages: 1-9

Type: Article

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More publications in: Latinmag Letters

Abstract

A paleomagnetic,rock magnetic investigation, 40Ar/39Ar dating and electronic microscope studieshas been carried out on a Pliocene lava flow sequence in the Djhavakheti Highland, central LesserCaucasus, Georgia.A ChRM direction could be isolated in all studied 39 lava flows, yielding reverse-polarity directionsin all cases. Mean direction D = 202.2°, I = -60.6° (N = 39;α95 = 2.0°; k = 138.6). Thermomagneticexperiments suggested low-Ti titanomagnetites and low Curie-temperature titanomagnetites withhigher titanium content as the main carriers of remanence, which is carried by a mixture of single-domain and multi-domain grains. 40Ar/39Ar dating yielded an age of 1.73 ± 0.03 Ma as the eruptionage of uppermost lava flow of the sequence.While the inclination obtained in the sequence agrees well with the expected one, the declinationshows an eastward deviation of 19.2º ± 5.8º. Thus, a significant 19º clockwise vertical-axis rotationtook place in the Saro sequence during the last 1.7 MaAnalysis of the scatter of virtual geomagnetic poles (VGPs) from all 39 lava flows yields an angularscatter SB = 16.5 (Sup = 19.5, Slow = 14.3), while a value SB = 19.0º (Sup = 25.4, Slow = 15.2) is obtainedwith 14 directional groups. In both cases SB agrees well with the angular dispersion predicted forlatitude 41º by Model G-fits to data of paleosecular variation of lavas from the last 5 Ma.