Juan Morales

Juan Morales
Universidad Nacional Autónoma de México | UNAM · Department of Geomagnetism and Geophysical Exploration

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217
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Publications

Publications (217)
Article
In order to obtain the first absolute chronology data, a detailed rock-magnetic, archaeomagnetic and radiocarbon investigation was performed on some in situ features of the El Cerrito pyramid. Archaeomagnetic sampling was carried out on two rectangular fire pits and one burned soil located at the piedmont of the pyramid. Marked irreversibility betw...
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An approach that has acquired popularity in the last decade to ensure the quality of paleointensity determinations is the use of multimethodological analysis, especially when comparing intensity values obtained by methods with different physical bases such as the conventional Thellier-type experiments against the Shaw-family methods and the most re...
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Se reportan los resultados del estudio paleomagnético y de magnetismo de rocas provenientes de 12 sitios de la Sucesión Volcánica Carmichael localizada en el bloque Jalisco, cuya base está formada por brecha, lava, toba lítica de composición andesítica y tobas de composición riolítica. La unidad superior está compuesta por toba cristalina y toba so...
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We present new radiometric ages and full-vector paleomagnetic data from São Vicente Island, Cape Verde. Samples were obtained from a sequence of 11 nephelinitic flows. A K-Ar age determination was performed on the lowermost flow of the sequence, yielding an upper Miocene age of 6.07 ± 0.16 (2σ) Ma. Considering the normal polarity observed in all fl...
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Two sediment cores, collected from the center of the Lake Melincué (Santa Fe, Argentina), were analyzed using rock magnetic results, element composition, Total Organic and Inorganic Carbon (TOC and TIC) and Total Nitrogen (TN) to reconstruct the environmental variations in the last three centuries, associated with climatic changes and/or human acti...
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We present new radiometric ages and full-vector paleomagnetic data from São Vicente Island, Cape Verde. Samples were obtained from a sequence of 11 nephelinitic flows. A K-Ar age determination was performed on the lowermost flow of the sequence, yielding an upper Miocene age of 6.07 ± 0.16 (2σ) Ma. Considering the normal polarity observed in all fl...
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El conjunto de tumbas subterráneas de Tierradentro (Colombia), talladas en roca blanda de origen volcánico, contiene múltiples manifestaciones artísticas elaboradas con pintura roja. A pesar de su enorme importancia arqueológica y patrimonial, aún existe una fuerte controversia sobre la edad de estos hipogeos. La magnetización remanente pictórica,...
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We report a detailed rock-magnetic and paleomagnetic investigation on seventeen volcanic units (160 standard paleomagnetic cores) belonging to essentially Plio-Pleistocene Azufres Volcanic Field, located in the central part of the Trans-Mexican Volcanic Belt. Titanium-poor titanomagnetite is responsible for thermoremanence in most lava flows, while...
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Teotihuacan is considered as the best planned and largest pre-Hispanic city in Mesoamerica. One of the causes, related to the decline of the Teotihuacan, is the so-called “Big Fire”. However, associated chronological constraints are still poorly defined. Here, we report new archaeomagnetic dates of three burned walls located in the Plaza de la Luna...
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Revealing the evolution of the past geomagnetic field is of double interest. It is crucial to estimate the conditions of the Earth's deep interiors, while it offers a reliable absolute dating tool of burned archaeological artifacts. Although a substantial effort was paid during the last decade to construct a reference archaeomagnetic curve for Meso...
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La disponibilidad de edades radiométricas para el Campo Volcánico Michoacán-Guanajuato permite obtener un registro detallado de las variaciones del campo magnético de la Tierra durante los últimos 5 Ma. En el presente trabajo, analizamos 112 direcciones paleomagnéticas confiables respaldadas por igual número de edades radiométricas absolutas. Luego...
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Cueva de la Huachizca is located in the humid forests of the Municipio of Santa Clara del Cobre, Michoacán. During the Postclassic period (1300−1520 ad), Santa Clara del Cobre was a part of the Tarascan Señorio. Ethnographic accounts describe the use of Cueva de la Huachizca as a place of refuge during the Cristero Rebellion (1921−1926). Recent inv...
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The Altos de Jalisco region is still poorly understood in terms of its cultural dynamics. Extensive relationships have been identified with other nearby cultural areas, especially with the Bajío and the Lerma-Santiago River Basin. Much of the settlements so far discovered in this region belong to the Epiclassic period (600-900 AD) whose settlement...
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We report an archeomagnetic study from the Early Iron Age archeological site of Cerro de San Vicente (Salamanca, Spain). The studied materials were sampled from one roundhouse and its central fireplace, a surrounding burnt floor, and slags with a twofold objective. First, to archeomagnetically determine the last use of the central fireplace, becaus...
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s A detailed magnetic mineralogy and archaeomagnetic investigation was performed on thirty-two red mural painting samples belonging to the colonial Santo Domingo Convent in Oaxaca (Southern Mesoamerica). Systematic magnetic experiments included continuous thermomagnetic curves, hysteresis cycles, acquisition of isothermal remanence and step-wise al...
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A comprehensive archaeomagnetic investigation was carried out on seven ceramic fragments recovered at the "El Caracol" lava flow in the Zacapu Malpaís –Michoacan state, Mexico –. A full set of magnetic-mineralogy experiments (encompassing thermomagnetic curves, hysteresis loops, backfield curves, and isothermal remanent magnetization acquisition me...
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Dating analysis of potsherds from three of the six units recently excavated in the Tingambato archaeological site, central-western Mexico, was carried out employing two regional intensity Paleosecular Variation Curves (PSVC) and the global model SHA.DIF.14k. A complete evaluation of the ceramic fragments' magnetic characteristics was done to determ...
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We report paleointensity results obtained with the multispecimen method (MSP) over the Pliocene sequence of Apnia (Georgia) which records a polarity reversal. Paleointensity determinations with the multispecimen technique were performed on 12 flows with the original (MSP‐DB) and the domain‐state corrected (MSP‐DSC) protocol. Eight MSP‐DSC determina...
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El graben de Chapala-Acambay se caracteriza por el registro de yacimientos de diatomitas del Cuaternario con espesores variables, donde domina flora indicativa de lagos profundos. El depósito de diatomita de 6.70 m de espesor de la cuenca de represamiento de Agostitlán contiene un registro paleoambiental que marca la transición de condiciones menos...
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El Ocote es un sitio arqueológico que se localiza en el estado de Aguascalientes dentro de la parte alta del Cerro los Tecuanes. Gracias a recientes trabajos de investigación por parte del Instituto Nacional de Antropología y Historia, se han encontrado diversos vestigios culturales, pertenecientes a grupos sedentarios del Epiclásico (650 a 900 d.C...
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We report a detailed aeromagnetic, field magnetometry and paleomagnetic survey from the most recent volcano on the American continent that emerged in February of 1943. Paleomagnetic measurements were performed to determine the characteristic remanent magnetization directions, considering that the Geomagnetic Field observed in nearby existing observ...
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We report new results from frontier research that relates the methodology and knowledge of geophysics (geomagnetism) with archeology and the data will represent a valuable contribution to both disciplines. A detailed magnetic survey was performed on limekilns from the northern Yucatan peninsula. We used Attenuated Total Reflection Fourier Transform...
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Las investigaciones arqueológicas realizadas en el sector oeste de la comisaría de Tamanché, Yucatán, localizada al norte de Mérida, nos proporcionaron las muestras para realizar dataciones arqueomagnéticas de dos hornos de cal excavados en el sitio. Los hornos se hallaban en la periferia del sitio arqueológico, al suroeste del núcleo principal de...
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Sixteen rhyolitic and dacitic Cretaceous and Paleocene‐Eocene lavas from the Lesser Caucasus have been subjected to paleomagnetic and multimethod paleointensity experiments to analyze the variations of the Earth's magnetic field. Paleointensity experiments were performed with two methods. Thellier‐type experiments with the IZZI method on 65 specime...
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Well-exposed lava sequences with available geochronological information may provide invaluable information on the fine characteristics of the Earth's magnetic field variation. A paleomagnetic study has been performed on twenty Pleistocene age, sub-horizontal lava flows in the Javakheti Highland (Lesser Caucasus). The sequence is formed by calc-alka...
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The radiometric data available in the Trans-Mexican Volcanic Belt enables a quasi-continuous record of the Earth's magnetic field over the last million years to be obtained. Here, we analyze 149 well-defined paleomagnetic directions supported by an equal number of isotope ages. Eleven new paleomagnetic directions from the Tacambaro-Puruaran area (t...
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Abstract 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. Paleomagnetic samples from six lava flows were subjected to paleointensity analysis with...
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Elemental concentrations measured in 482 street dust samples from different urban and conurbated areas of Mexico City obtained using a portable energy-dispersive X-ray fluorescence spectrometer are reported. The data quality of eight different elements commonly used in pollution studies is evaluated, calculating the data precision and accuracy obta...
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Lime production structures and their combustion were investigated in the western Yucatan Peninsula (Mexico). Limekilns were excavated and the specific calcination temperature for each kiln was calculated using Fourier transform infrared spectroscopy (FTIR). A temperature range of 750–850 °C was estimated for the furnaces used for lime production. T...
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This work presents the results of a detailed paleomagnetic and rock-magnetic study carried out in the igneous units associated with the Tepic-Zacoalco Rift (western Trans-Mexican Volcanic Belt). Standard paleomagnetic drilled cores were collected from 21 sites distributed over the Rift extension, all of them with available radiometric ages between...
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A rock magnetic, paleomagnetic and absolute intensity study was conducted on 21 basic dike swarms situated in the Zapicán area (Lavalleja, Uruguay). Paleomagnetic directions revealed mostly normal polarity magnetizations with few intermediate and reverse polarity dikes. Combining data from a previous study, a mean paleodirection obtained is Dec = 3...
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En este estudio se reportan los resultados más recientes de la investigación arqueológica llevada a cabo en el norte de Sudamérica, particularmente en la depre-sión momposina-región colombiana ampliamente conocida por su extensa modificación del paisaje en tiempos prehispánicos-, y cuyo objetivo fue estudiar la intensidad del campo geomagnético ant...
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Industrial and vehicular emissions of particles cause multiple damages to human health due to concentration, size, and composition. These emissions contain magnetic particles; therefore, low-cost properties allow tracking and monitoring them. This study is aimed at identifying the primary sources ofmagneticmaterial in 100 samples of urban road dust...
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An amendment to this paper has been published and can be accessed via a link at the top of the paper.
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Systematic archeological research on the central and western Travesías region in Argentina are in permanent development. Although earth ovens or botijos are continuously identified in the archeological record in these territories, specific studies on these elements are still scarce. We have recently initiated a multi-proxy study in western San Luis...
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La relevancia del estudio de la cerámica arqueológica en los estudios prehispánicos de Mesoamérica es central, pues a partir de ella se configuraron las primeras interpretaciones, tanto de orden espacial como temporal. Durante mucho tiempo, sus atributos y características, a la par de su contextualización estratigráfica, permitieron el establecimie...
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Most detailed archaeometric studies come from central and southern Mesoamerica while many important sites belonging to the western regions are not yet rigorously studied. Here we report a detailed rock-magnetic and archaeomagnetic study from the El Coporo archaeological site at the northern border of Mesoamerica. Our study of more than 100 oriented...
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First archaeointensity reference paleosecular variation curve for South America and its implications for geomagnetism and archaeology – Corrigendum - Avto Goguitchaichvili, Catriel Greco, Rafael Garcia Ruiz, Lucas Pereyra Domingorena, Ruben Cejudo, Juan Morales, Claudia Gogorza, Cristina Scattolin, Myriam Tarragó
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Los hornos para la producción de cal excavados en el área maya pueden considerarse artefactos idóneos para los estudios arqueomagnéticos debido a que el proceso de producción requiere temperaturas generalmente superiores a 700 °C. Este hecho garantiza que las paredes y los pisos de los hornos sean portadores de la magnetización termorremanente esta...
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The progressive southward reoccupation of territories of the Iberian Peninsula by the Christian kingdom against the Muslims from the eighth century AD onwards is a well-known process. However, there are few well-dated sites of this period, especially in the northern plateau of Spain. Here we report the full vector archaeomagnetic dating of two hear...
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The geomagnetic field variations on the continent of Africa are still largely undeciphered for the past two millennia. In spite of archaeological artefacts being reliable recorders of the ancient geomagnetic field strength, only few data have been reported for this continent so far. Here we use the Thellier-Coe and calibrated pseudo-Thellier method...
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The radiocarbon technique is widely used to date Late Pleistocene and Holocene lava flows. The significant difference with palaeomagnetic methods is that the 14C dating is performed on the organic matter carbonized by the rock formation or the paleosols found within or below the lava flow. On the contrary, the archaeomagnetic dating allows to date...
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Abstract Three lava flows (Buenavista, Xalitzintla and Nealtican) and pyroclastic density currents (Lorenzo and Pink Pumice) from two Popocatepetl Plinian eruptions were sampled for paleomagnetic dating. A detailed rock-magnetic characterization of the lavas, scoria clasts and pottery shards intercalated between the volcanic deposits was also carri...
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We report the results of a paleomagnetic study conducted in a swarm of basic dikes located around the village of Nico Pérez and Zapicán, in the department of Lavalleja, Oriental Republic of Uruguay. The Paleomagnetic directions have normal, intermediate and reverse polarities, with an average direction of Dec = 183.7°, Inc = 50.5°, α95 = 9.5°, N =...
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While southern and central Mesoamerica have attracted numerous high-standard archaeological and archaeometric investigations, most of the sites belonging to the western regions and especially to the north remain understudied. The absence of detailed absolute chronology is considered a major weakness of these sites. Until recently, the history of Ag...
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We study seven out of the thirteen lava flows associated to El Metate shield volcano using paleomagnetic, absolute intensity and rock-magnetic experiments. Characteristic paleomagnetic directions were successfully determined from most of the flows. A combined mean direction of D = 346.4° and I = 32.1° (N = 34, R = 33.73, k = 121.74, α95 = 2.2) was...
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Las investigaciones arqueológicas realizadas en el Valle de Colima en los últimos años han tenido como una de sus principales limitantes la falta de una secuencia cronológica sustentada en dataciones absolutas. A partir de una revisión de la cronología propuesta por Isabel Kelly, el presente escrito da cuenta de los esfuerzos enfocados en comenzar...
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Colombia is located along so-called intermediate area between two major American civilizations: Mesoamerica and Central Andes. Despite impressive archaeological sites throughout whole Colombian territory and great cultural heritage, still no regional geomagnetic secular variation curve is available. Here, we report first, systematic archaeointensit...
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This paper analyzed the chemical composition of archaeological pottery produced by hunter-gatherers and horticulturist populations of the late Holocene of the lower Paraná basin. An energy dispersive X-ray fluorescence spectrometer was used to analyze the chemical composition of the sherds. The results obtained indicated that the analyzed samples,...
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The study of well-dated archeological potsherds and heated structures (i.e. kilns, floors, etc.) yields the opportunity for a better knowledge of the geomagnetic field variations at archeological timescales. We present the first archeointensity results obtained on Uruguayan ceramics prepared by indigenous societies on the coast of the Uruguay River...
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The Xitle volcano is part of the Quaternary Chichinautzin volcanic field, located in the southern portion of the Valley of Mexico. The Xitle lavas were emplaced on the archaeological site of Cuicuilco, one of the first urban settlements of the Preclassic period in Mexico. This eruption had a great impact, since it caused great economic and social c...
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In this paper we present the magnetic dating results of five independent lava flows belonging to the Ceboruco volcanic field in Jalisco, western Mexico, using the SHADIF14K geomagnetic field prediction model. Five lava flows corresponding to well-documented eruptive events were studied. The ages of these flows have already been established by radio...
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The present study employs petrology, rock magnetics, and paleointensity on four lava flows (seven sites) of the El Jorullo volcano; a historical (1759–1766 AD) cinder cone in the Michoacán-Guanajuato Volcanic Field. El Jorullo lava flows cover an extensive area of ∼10.8 Km ² , and a volume ∼0.35 Km ³ . Rock-magnetic experiments and microscopic obse...
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An integrated magnetic survey was carried out on key places within the La Quemada archaeological complex, built over a hill on the northern frontier of Classic period Mesoamerica. Samples were collected from the Plaza of Sacrifices and Hall of Columns in an attempt to precisely determine the age intervals corresponding to the decline and abandonmen...
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We report comprehensive rock-magnetic and archaeointensity investigations from 21 well-constrained pottery fragments from the Catamarca province of northwest Argentina. The absolute ages of the studied sites are ascertained by several high-quality radiometric ages and range between 1940 to 1140 ¹⁴ C yr BP. Magnetic mineralogy experiments indicates...
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Detailed records of the Earth's magnetic field have shown that it has occasionally reversed its polarity. Several cases have also been found when the Earth Magnetic Field has significantly deviated for a relatively short time from its usual position defining a geomagnetic excursion, a kind of aborted reversal. Although many transitional paleodirect...
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We report detailed rock-magnetic and paleomagnetic results from a 27-m-long sedimentary core collected at depocenter of Lake Chapala, western Trans-Mexican Volcanic Belt. Rock-magnetic parameters point to PSD grain-size titanomagnetites as the dominant magnetic mineralogy. Observed variations, in both concentration and grain-size dependent magnetic...
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In absence of organic remains suitable for radiocarbon dating, archaeomagnetic dating can contribute significantly to the better understanding and rescue of our past and cultural heritage. Nowadays, in the archaeological research is fundamental to obtain as much information as possible, including precise dates of the archaeological sites; indeed, t...