Predominance of arid climates indicated by mammals in the pampas of Argentina during the Late Pleistocene and Holocene

Rock magnetic study of fluvial Holocene soil from Buenos Aires province (Argentina)

“…Two 14 C dating analyses on shell samples using mass accelerator spectrometry (AMS) revealed that a small piece of unidentified mollusk from level II contains more 14 C than the 1950 atmosphere; this sample is therefore "modern"-<1950 AD-which is coincident with the age of the artificial landfill. 14 C dating of a specimen of the micro-faunal mollusk (Mactra isabelleana) belonging to the lower part of level III revealed an age of 4900±110 years BP (OS-24330), which is coincident with radiocarbon dates obtained from M. isabelleana collected from other sites in the region (Tonni et al, 1999). This micromollusc is a typical fossil found in Holocene deposits from Buenos Aires (Aguirre, 1988(Aguirre, , 1993.…”

“…The period spanning ∼8.5-3.5 kybp consisted primarily of a humid subtropical and tropical climate, with Brazilian fauna characterized by pedogenesis and fluvial dynamics (Iriondo and García, 1993). Although there is no consensus on the subject of climate (see Tonni et al, 1999), between ∼7.5-5 kybp the spectrum of mammals reflect a humid climate (Prado and Alberdi, 1999). Most scholars currently agree that there was a climate change in Buenos Aires province during 5 kybp (Iriondo and García, 1993;Iriondo, 1995;Prieto, 1996;Prado and Alberdi, 1999;among others) and that a humid regime may have existed at the time of the Holocene marine transgression during a period of high sea level at ∼5-6 kybp (Isla, 1989).…”

“…There is a currently fully developed soil that is suggestive of a period of non-deposition and landscape stability (Holliday 1985;Kraus and Brown 1986). According to Favier Duvois (personal communication), the deposit at LM is similar to the Guerrero member of the Luján formation, which is a useful horizon marker for late Pleistocene and early Holocene sediments (Cione and Tonni 1995;Tonni et al, 1999Tonni et al, , 2003.…”

Geoarchaeological and Paleoenvironmental context of the human settlement in the Eastern Tandilia Range, Argentina

“…Cueva Tixi profile indicates colder conditions to the early Holocene (zone III) than Loberia I site 1. The presence of cold weather and dry conditions has also been reported for the early Holocene-Pleistocene by regional studies of other proxies (Prado, et al, 1987;Bonadonna, et al, 1995;Tonni, et al, 1999).…”

“…Based upon information from sites located in the adjacent Interserrana Plain, Politis, et al (2004), Martínez (2001), and Grill M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT et al (2007) postulated that initial population took place under arid to semi-arid climatic conditions. The human populations that would have lived in this area c. 11,000-10,000 BP would therefore done so under colder, dry sub-humid conditions (Quattrocchio et al, 2008;Tonni and Cione, 1994;Prieto, 1996;Tonni et al, 1999Tonni et al, , 2003. Between c. 10,500 and 9000 BP a change in these dry conditions towards higher rainfall levels and temperatures has been indicated by numerous proxy records from the Pampas region (Tonni and Fidalgo, 1978;Prado et al, 1987;Alberdi et al, 1989;Tonni y Cione, 1994;Prieto, 1996;Zárate et al, 1995Zárate et al, , 2000Zarate, 1997;Borrero et al, 1998;Bonadonna et al, 1999;Tonni et al, 1999;Martinez, 1999Martinez, , 2001Martinez, , 2007Prieto et al, 2004;Grill et al, 2007;Gutierrez y Martínez, 2008;Gutierrez et al, 2010).…”