Pedosedimentary development of part of a Late Quaternary loess‐palaeosol sequence in northwest Argentina

Abstract

The field properties, magnetic susceptibility, particle size, calcium carbonate content, soil micromorphology and optical luminescence ages of the upper 6.1 m and lowermost 4.7 m of the 45 m loess-palaeosol sequence at El Lambedero in the Tafí del Valle region of Tucumán Province (Sierras Pampeanas, northwest Argentina) have been used to set up a partial stratigraphy and chronology, as well as a basic pedosedimentary model of loess accumulation, palaeosol development, reworking and erosion for the site. The minimum ages derived from the basal part of the section suggest that loess began to accumulate some time before 165 ka. A thick and well-developed pedocomplex in the upper profile is correlated with at least the latter part of marine isotope stage (MIS) 5, whereas the overlying palaeosol may be attributable to pedogenic activity during MIS 3. The absence of material younger than 33 ka close to the surface of this rounded spur landform is probably the result of either non-deposition or erosional stripping in response to climatic change, or episodic uplift in this seismically active region.

Chronology of late Pleistocene Pampa loess from the Córdoba area in Argentina

“…In the upper part of this sequence, a pedocomplex including three Bt b horizons is intercalated in the loess between 6 and 4 m below the surface. The uppermost Bt b horizon of the lower pedocomplex yielded an OSL age estimate of 96 AE 5 ka and was correlated to MIS 5a by Kemp et al (2004b). At the El Lambedero section, an upper pedocomplex including three Bt b horizons is intercalated in the sediment succession between 3.00 and 0.80 m below the surface.…”

“…OSL ages on fine-silt quartz seem to be significantly age underestimated above 100 ka, as evidenced for samples taken from below the Brunhes/ Matuyama polarity change Sayago, 1999, 2001;Kemp et al, 2003;Schellenberger et al, 2003;Schellenberger and Veit, 2006). The El Lambedero section situated about 10 km to the north of La Mesada in the Tafi del Valle region (Tucumán province) was studied by Kemp et al (2004b), establishing an OSL-based chronology for the loess/palaeosol sequence. In the upper part of this sequence, a pedocomplex including three Bt b horizons is intercalated in the loess between 6 and 4 m below the surface.…”

New morphostratigraphic and chronological constraints for the Quaternary paleosurfaces of the Molise Apennine (southern Italy)

“…This is also indicated in the upper horizons by vertic features, moderate clay translocation, the latter being typical of Quaternary interglacials or mild interstadials within glacial periods in mid-latitude areas (e.g. Catt 1989; Kemp et al 2004;Scarciglia et al 2006), and secondary CaCO 3 precipitation. The modest extent of clay illuviation, the occurrence of carbonate concretion and the complete lack of rubification better support drier (and possibly colder) conditions of glacial phases rather than interglacials.…”

“…In fact, the abundant clay coatings of surface soil horizons (in profile P1) may have been superimposed throughout various interglacials younger than OIS 11 (OISs 9 to 7 or 5). Another major erosion surface is indicated by the truncation of the upper paleosol in question, as highlighted by the lack of organic-mineral or albic horizons and the exposure of typical deep (argillic) ones at the topographic surface (Kemp et al 2004;Robustelli et al 2009). …”

The Quaternary record of Reithrodon auritus (Rodentia: Cricetidae) in northwestern Argentina and its paleoenvironmental meaning

“…In this note, we summarize the known Pleistocene and early Holocene fossil record of R. auritus in northwestern Argentina, provide new paleontological sites for the species, and make comments concerning the paleoenvironmental implications of its presence at such lower altitudes. The fossil remains were exhumed from loessic sediments assigned to middle-late Pleistocene and early Holocene, referable to the Taf í del Valle Formation (Kemp et al 2003, 2004, Schellenberger et al 2003, Sayago et al 2005, Carter -Stiglitz et al 2006, Ortiz et al 2011b ). However, in spite of lithological similarities with the stratotype in the Taf í valley, the assignation of the sediments from the El Rodeo area to this geologic unit is tentative (Sayago et al 2005 ).…”