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| Natura: | Artículo científico |
| Lingua: | en |
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Universidad Nacional Autónoma de México
2006
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| Accesso online: | https://www.redalyc.org/articulo.oa?id=56845201 |
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Sommario:
- Late Pleistocene to Holocene environmental changes from ¿13C determinations in soils at Teotihuacan, Mexico E. Lounejeva Baturina P. Morales Puente H. V. Cabadas Báez E. Cienfuegos Alvarado S. Sedov E. Vallejo Gómez E. Solleiro Rebolledo Ciencias de la Tierra paleosols Teotihuacan Central Mexico carbon stable isotope archeological records Stable carbon isotopic signature (δ13C) of soil organic matter (SOM) is used as a high-spatial resolution tool to inferenvironmental changes during late Pleistocene to Present in the Teotihuacan valley, Mexico. Interpretation was based on climaticpreferences of C3, CAM and C4 plant groups. δ13C values of modern plant types are clearly distinguished. C3 plants displayvalues around 27, while C4 and CAM plants have values around13. Data from soil profiles range from -25.7 to -15.5. Cerro Gordo site δ13C varyies around -20, indicating long-term, time-stable co-existence between C3 and C4 or CAMplants. The more depleted signatures (-23 ± 2 ) are, dominated by carbon from C3 vegetation of late Pleistocene swamppaleosols in the Tepexpan profile of the Lake Texcoco. Younger paleosols from lower valley sites, have less depleted values(-17 ± 1) , dominated by C4 and CAM carbon. Late Holocene and modern soils present slightly more negative values (1-2 )with respect to δ13C of underlying soils. Our results show 1) an increase of 10-70 % depending on the site, during the transitionfrom the late Pleistocene to early Holocene, and 2) a dominance of C4 vegetation, up to 84%, in valley environment during themiddle Holocene. These data support a climatic change from cold and wet conditions in the Last Glacial Maximum and latePleistocene, to warm and dry conditions in middle Holocene. A slight rise in moisture availability during late Holocene isinferred based on the 4-10% increase in C3 plant carbon in soils from the valley. Conditions remained generally warm and dry,much as they are at present, favouring the development of agriculture in the valley. Our interpretation agrees with results ofpaleoenvironmental studies at Texcoco Lake based on diatom and pollen analyses in lake. 2006 artículo científico 0016-7169 https://www.redalyc.org/articulo.oa?id=56845201 en http://www.redalyc.org/revista.oa?id=568 Geofísica Internacional application/pdf Universidad Nacional Autónoma de México Geofísica Internacional (México) Num.2 Vol.45