Magnetic properties and Archeointensity of Earth’s magnetic field recovered from El Opeño, earliest funeral architecture known in Western Mesoamerica

Abstract

Despite of the impressive cultural heritage and abundant archaeological sites, absolute geomagnetic intensity data from Mesoamerica are still sparse. Archeointensity determinations using the Coe variant of the Thellier and Thellier method have been carried out on some selected pottery fragments from the El Opeño archeological site which has the earliest funeral architecture known in western Mesoamerica. The El Opeño chronology is supported by six C 14 datings performed on carbon-bearing materials. Detailed rock magnetic experiments including susceptibility vs. temperature curves, hysteresis cycles and thermal demagnetization procedures were carried out in order to estimate the magnetic carriers and their stability. Cooling rate and anisotropy remanence corrected intensity values range from 25.0 ± 2.3 to 40.2 ± 3.0 µT and corresponding virtual axial dipole moments (VADM) range from 5.6 ± 0.5 to 8.9 ± 0.7  10 22 Am 2 . In addition, we present here a new compilation and analysis of existing absolute intensity data in order to try to estimate the variation of the Earth's magnetic field over the past three millennia. The mean archeointensity obtained in the present study agrees reasonably well with the predicted absolute intensities retrieved from the CALS7K main field model. Other available Mesoamerican data, however, differ from this model. Most of available archeointensity data from Mesoamerica agree reasonably well with the ARCH3K main field model prediction. The broad peak defined at about 50 A.D. by our data is also predicted by the CALS3k.3 main field model but slightly displaced to the right M. Pineda Duran et al. 576 Stud. Geophys. Geod., 54 (2010) while two smaller peaks are observed on the ARCH3K curve for the same time interval. The intensity value obtained at about 200 B.C. is a clear outlier and thus its geomagnetic significance should be confirmed by further investigations. K e y w o r d s : archeointensity, Mesoamerica, magnetic properties, El Opeño, Michoacán, Mexico

High paleointensities for the Canary Islands constrain the Levant geomagnetic high

“…7b), although the mean VADMs per site are consistently below the 10-point moving average through the Levant-data -at least until 723 BC. For the period between ∼1050-500 BC, paleointensity data from other parts of the world are sparse; for Mexico VADMs of ∼82 (Pétronille et al, 2012) and ∼105 ZAm 2 (Duran et al, 2010) are suggested and Yu (2012) and Hong et al (2013) report VADMs of ∼80-90 ZAm 2 for Japan and South Korea, respectively, around ∼750 BC. All reported values are much lower than the values reported for the Middle East (>150 ZAm 2 ) and the Canary Islands (∼125 ZAm 2 ).…”

First Full Vector Archeomagnetic Data From Northern Mexico

“…One‐third of the initial Mexican data set was accepted: six lava flows (Alva‐Valdivia et al., 2019; Gratton et al., 2005; Mahgoub, Juárez‐Arriaga, Böhnel, Siebe, & Pavón‐Carrasco, 2019; Morales et al., 2006; Pérez Rodriguez et al., 2019) and 39 baked clays (Alva‐Valdivia et al., 2021; Hervé, Perrin, Alva‐Valdivia, Tchibinda Madingou, et al., 2019; Mahgoub, Juárez‐Arriaga, Böhnel, Manzanilla, & Cyphers, 2019). Other high‐quality archeomagnetic data exist in Mexico, but they are either beyond the 2,000 km limit (e.g., Fanjat et al., 2013) or older than 2 kyrs (e.g., Duran et al., 2010; Hervé, Perrin, Alva‐Valdivia, Rodríguez‐Trejo, et al., 2019). For Western North America, 47% of the data set passed the selection criteria, with one lava flow (Champion, 1980) and 23 data on ceramics (Bowles et al., 2002; Jones et al., 2020; Sternberg, 1982).…”

Secular Variation of the Intensity of the Geomagnetic Field in Mexico During the First Millennium BCE

“…Over the 194 available in Mexico, only 14 data, eight from Duran et al (), three from Rodriguez‐Ceja et al (), and three from Rodriguez‐Ceja et al (), fulfilled the quality criteria for the period between 2000 BCE and 200 CE. Intensities of Rodriguez‐Ceja et al (, ) calculated on a secondary or two overlapping components of magnetization were not considered.…”