Palaeolandforms and Volcanic Impact on the Environment of Prehistoric Cuicuilco, Southern Mexico City

Córdova, Carlos E.; Pozzo, Ana Lillian Martin-Del; Camacho, Javier López

doi:10.1006/jasc.1994.1058

Cited by 51 publications

(20 citation statements)

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“…The lava is composed of olivine basalt and is of considerable archeological interest because of its effect on the environment of the early urban centre of Cuicuilco. Numerous 14C analyses have been carried out since Libby (1955) to fix this impact in time (see review in Cordova et al, 1994): apparent ages cluster around 2400 BP and 2000 BP. These ages in part were obtained from samples taken from baked sediments at different depths below the lava flow and this may go some way in explaining the range of age determinations.…”

Section: The Xitle Lava Flowmentioning

confidence: 99%

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Variation of Rock Magnetic Parameters and Paleointensities over a Single Holocene Lava Flow.

Böhnel

Morales

Caballero

et al. 1997

J. geomagn. geoelec

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A recent (2000 BP) lava flow from central Mexico has been sampled along a vertical profile with 55 cores covering a total flow thickness of 6.6 m. A wide range of physical and magnetic parameters have been studied to characterise the samples: Curie temperature and saturation magnetisation as intrinsic properties; density, magnetic susceptibility and remanence intensity as bulk properties; Konigsberger Qfactor and hysteresis parameters as coercivity parameters. All parameters vary smoothly over the profile, most probably due to grain size variation of the magnetic minerals present in the samples. Optical observations indicate that the main opaque minerals are deuterically oxidised titanomagnetites (C3-C5) and ilmenites (R2-R3), which increase in size away from the edges of the flow. Paleointensity (PI) was determined using the double heating Thellier-Thellier method with pTRM checks. According to reliability parameters (f-, g-, and q-factor) the obtained PIs are of reasonable to good quality. PI shows marked variation with vertical position in the flow, across a range of about 25 to 125 MT, with most samples having a PI between 50 and 100 MT. The flow-mean PI of 72 µT is higher than the present day field, consistent with global data for this time-period. No obvious correlation could be found between PI and any other measured parameter. The variation of PI with vertical position in the flow may show some systematic behaviour. It is important, therefore, to sample a flow both horizontally and vertically in order to obtain a reliable paleointensity. IntroductionLavas are generally considered to be the best recorders of geomagnetic behaviour, paleomagnetically speaking. Yet individual flows may show considerable variability in their magnetic properties (Watkins and Haggerty, 1965;Ade-Hall et al., 1968a;Wilson et al., 1968; Lawley and Ade-Hall, 1971;Peterson, 1976;Herzog et al., 1988;Audunsson et al., 1992), and the extent to which this impacts on the paleomagnetic signal recorded in the flow will limit its potential resolution. Natural remanent magnetisation (NRM) intensity and stability have been shown to be far from uniform, NRM intensity in particular varying by more than a factor of 10 within individual flows. In most cases this variation seems related to high temperature (HT) deuteric oxidation of the remanence-bearing titanomagnetites, the development of which can be highly variable within any single flow giving rise to complex intra-flow NRM distributions (e.g. Wilson et al., 1968;Peterson, 1976;Herzog et al., 1988).NRM directions may also exhibit some variability. Samples with low NRM stability often show greater scatter about the flow-mean direction (e.g. Watkins and Haggerty, 1965;Wilson et al., 1968;Herzog et al., 1988). This is associated with the development of a magnetically soft secondary overprint and on alternating field demagnetization to relatively low fields (<40 mT) the directions converge with the flowmean value. Herzog et al. (1988) describe a flow showing large directional changes towards its ...

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Section: The Xitle Lava Flowmentioning

confidence: 99%

“…The lowermost part (cores 50-55) of the sampled profile is reddish and porous, resembling a scoriae in texture and colour. Above that part and up to about 4 m (cores 21-49), the lava Cordova et al (1994).…”

Section: The Xitle Lava Flowmentioning

confidence: 99%

Variation of Rock Magnetic Parameters and Paleointensities over a Single Holocene Lava Flow.

Böhnel

Morales

Caballero

et al. 1997

J. geomagn. geoelec

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“…(2) Another hypothesis (Pin Äa-Chan, 1967;Heizer and Bennyhoff, 1972;Haury, 1975;Sanders et al, 1979;Co Ârdova et al, 1994) explains the abandonment of Cuicuilco as a result of the rise of Teotihuaca Ân in the northern part of the Basin of Mexico. According to this hypothesis, Teotihuaca Ân absorbed a large part of the regional population and represented a neighbor hostile to Cuicuilco.…”

Section: Discussionmentioning

confidence: 99%

Age and archaeological implications of Xitle volcano, southwestern Basin of Mexico-City

Siebe

2000

Journal of Volcanology and Geothermal Research

151

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The Pedregal lavas are fresh, well-exposed basaltic¯ows erupted from the Xitle scoria-and-cinder cone in the southwestern part of the Basin of Mexico. These lavas cover an area of 70 km 2 and were emplaced over pyramids and other buildings (e.g. Cuicuilco and Copilco archaeological sites). Today, a part of Mexico-City (including the National University) is built on thē ows. Initial strombolian activity produced an ash fallout layer, which was immediately followed by effusive emplacement of lavā ows. The Xitle cone grew on the north-facing slope of Ajusco volcano, and lava¯owed down to the N±NE until it reached the basin¯oor.More than 30 radiocarbon dates have been obtained by several workers on charcoal samples from beneath the lava, and several ages for the eruption have been proposed from these dates. Most dated samples were not directly produced by Xitle's eruption but instead are artifacts of human activity that predates the eruption. Thus, these ages (mostly about 2000 bp) are older than the eruption. A new age of 1670^35 years bp (AD 245±315) obtained on charcoal samples collected just beneath the lavas is favored for the Xitle eruption. These samples originated by ignition of vegetation during the emplacement of hot scoriaceous tephra. The new age is within the Classic period of Mesoamerican archaeology, whereas the earlier reported ages are at the end of the Preclassic. The new age carries important implications for the timing of population shifts within the Basin of Mexico. q

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“…Por la presencia de grandes estructuras arquitectónicas, se le ha considerado, junto con Teotihuacán, uno de los centros urbanos regionales más importantes de la Cuenca de México (Sanders et al, 1979). El desarrollo de Cuicuilco tuvo lugar sobre una planicie deltaica, formada por los ríos provenientes del volcán Ajusco (Córdova et al, 1994;Siebe, 2000), la que fue posteriormente cubierta por las lavas del volcán Xitle.…”

Section: Cuicuilcounclassified

“…Córdova et al (1994) están a favor de esta hipótesis, basados en la existencia de depósitos detríticos expuestos durante las primeras excavaciones en Cuicuilco, originados por la acumulación de materiales provenientes de la degradación de las estructuras arquitectónicas. También, el fechamiento de carbón presente en la ceniza del mismo volcán implica que la erupción ocurrió 300 años más tarde que lo que previamente se pensaba, cuando las poblaciones habían ya migrado a Teotihuacán (Siebe, 2000).…”

Section: Cuicuilcounclassified

Patrimonio natural de la Reserva Ecológica del Pedregal de San Ángel y áreas cercanas: sitios de interés geológico y geomorfológico al sur de la Cuenca de México

Palacio-Prieto¹,

Guilbaud²

2015

BSGM

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227 ResumenLa Reserva Ecológica del Pedregal de San Ángel (REPSA) es un territorio de conservación creado en 1983 dentro del campus de la Universidad Nacional Autónoma de México (UNAM). El objetivo de la REPSA es conservar un espacio de alto valor biológico y cultural, único en su género por la diversidad y características de la biota que sostiene, y que contiene los últimos reductos de ecosistemas naturales del sur de la Cuenca de México. Además del interés en los aspectos biológicos, la REPSA es un espacio geológica y geomorfológicamente significativo para explicar la evolución del paisaje de la porción sur de la Cuenca de México. En este trabajo se identificaron y caracterizaron nueve geositios (dentro y cercanos a la REPSA) ejemplares de los procesos volcánicos en esta zona de la Cuenca de México. El interés de los sitios seleccionados incluye valores estratigráficos (secuencias de lavas y piroclastos), geológico-vulcanológicos (estructura de derrames de lavas, conos piroclásticos) y arqueológicos. Los sitios tienen también interés educativo, por lo que pueden incorporarse en esquemas de educación formal (como sitios de interés en cursos universitarios) e informales (como información para los visitantes no especializados) y contribuyen a la divulgación de las Ciencias de la Tierra, en particular de la geología y la geomorfología.Palabras clave: geositios, volcán Xitle, Sierra Chichinautzin, patrimonio geológico, flujos de lava. Abstract The Pedregal de San Angel Ecological Reserve (PSAER) is a conservation area created in 1983 within the campus of the Universidad Nacional Autónoma de México (UNAM). The objective of the reserve is to maintain an area of biological and cultural diversity containing the last remnants of natural ecosystems in the southern

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Palaeolandforms and Volcanic Impact on the Environment of Prehistoric Cuicuilco, Southern Mexico City

Cited by 51 publications

References 0 publications

Variation of Rock Magnetic Parameters and Paleointensities over a Single Holocene Lava Flow.

Variation of Rock Magnetic Parameters and Paleointensities over a Single Holocene Lava Flow.

Age and archaeological implications of Xitle volcano, southwestern Basin of Mexico-City

Patrimonio natural de la Reserva Ecológica del Pedregal de San Ángel y áreas cercanas: sitios de interés geológico y geomorfológico al sur de la Cuenca de México

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