Landscape evolution and climate changes in the Late Pleistocene–Holocene, southern Pampa (Argentina): Evidence from palynology, mammals and sedimentology

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• 作者：Mirta E. Quattrocchio ; Ana M. Borromei ; Cecilia M. Deschamps ; Silvia C. Grill ; Carlos A. Zavala
• 关键词：Single-base mutation detection ; Reverse molecular beacon ; T4 DNA ligase ; RNA-templated
• 刊名：Quaternary International
• 出版年：2008
• 出版时间：April 2008
• 年：2008
• 卷：181
• 期：1
• 页码：123-138
• 全文大小：1490 K

文摘

The cumulative grain-size plots show that the sediments were transported by both aeolian saltation and aeolian suspension. Most of them have coarser and more heterogeneous grain size distributions than typical loess of the northern hemisphere, indicating a larger and more fluctuating wind energy than is required for the formation of typical loess. Deposits in the upper and middle basins were deposited in two main aeolian episodes which can be related to the dry periods of the Late Pleistocene and the Late Holocene recorded in southern Buenos Aires province. In some thin profiles of the middle and lower basins, the large clay content of the calcic C horizon was probably inherited from one or more previous pedogenic events. There is a systematic increase of particle size towards the lower basin, which may be related to an increase of energy towards the lower basin or to the influence of littoral dune fields along much of the Atlantic coastal zone.

tyle=""line-height:150 % "">The main goal of this paper is to highlight regional and temporal variation in the presence and exploitation of faunal resources during the Late Pleistocene and Early Holocene (ca. 12 000–7000 uncalibrated ¹⁴C yr BP) in the Pampean region (Argentina, South America). The main issues discussed are a summary of archeological and zooarchaeological evidence (sites, location, chronology, lithic technology, faunal distribution and diversity, etc.) both on regional and areal scales. The topics included in order to characterize subsistence strategies are the climatic changes that operated on and influenced the species, differential species extinction and survival, exploited species diversity, procurement and processing techniques, and intensity of faunal exploitation. It is proposed that the Late Pleistocene–Early Holocene period is characterized by a generalized regional economy, as has also been recently proposed for North America. In general terms, a broad spectrum of resources would have been exploited by humans as suggested by the presence and diversity of consumed species. Given the fluctuating climatic conditions during the Pleistocene-Holocene transition, a subsistence pattern composed of a broad diet would have been a suitable strategy to promote in unstable environments. Both taxonomic diversity and richness are greater when compared with the following time period (Middle Holocene), characterized by a specialized regional economy.

tyle=""line-height:150 % "">A paleoenvironmental reconstruction of the southeast coast of Buenos Aires province, Argentina, is made mainly on the basis of paleontological and paleoichnological studies, supported by sedimentological analyses and radiocarbon dating. Continental late Pleistocene and continental, transitional, and marine Holocene stratigraphic units are identified. The former comprises fossil mammals and ichnites of 16000–12,000 BP. The continental early Holocene time, ca. 8100 BP, is represented by an interdune paleoenvironment in which shallow brackish ponds were colonized by diatoms, fish, rodents, and birds. A transitional paleoenvironment in the middle Holocene—6930–6570 BP—is recorded by deposits formed by estuarine crabs. During the late Holocene, between 5000 and 4800 BP, a marine transgression was recorded by a rich mollusc fauna.

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Resumen

El objetivo del presente trabajo es la reconstrucción paleoambiental de un sector de la costa sudeste de la Provincia de Buenos Aires, basado en el estudio paleontológico, paleoicnológico, análisis sedimentológicos y dataciones radiocarbónicas. Fueron identificadas unidades estratigráficas continentales del Pleistoceno tardío y continentales, de transición y marinas de edad holocena. Para el Pleistoceno tardío, se registran restos fósiles e icnitas de mamíferos y aves con rango estratigráfico entre 16,000–12,000 años A.P. Durante el Holoceno temprano, hacia 8100 años A.P.,se registran ambientes de lagunas salobres someras de interduna colonizadas por diatomeas, peces, roedores y aves. En el Holoceno medio, 6930–6570 A.P. se registra un ambiente de transición, con depósitos formados por cangrejos estuarinos. En el Holoceno tardío, 5000–4800 años A.P. se registra una transgresión marina con una fauna rica de moluscos. Se destaca la variabilidad paleoambiental observada en una reducida extensión de costa de la Provincia de Buenos Aires, Argentina.