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| Titel |
Holocene environmental changes in the highlands of the southern Peruvian Andes (14° S) and their impact on pre-Columbian cultures |
| VerfasserIn |
K. Schittek, M. Forbriger, B. Mächtle, F. Schäbitz, V. Wennrich, M. Reindel, B. Eitel |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 11, no. 1 ; Nr. 11, no. 1 (2015-01-07), S.27-44 |
| Datensatznummer |
250117116
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| Publikation (Nr.) |
 copernicus.org/cp-11-27-2015.pdf |
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| Zusammenfassung |
High-altitude peatlands of the Andes still remain relatively unexploited
although they offer an excellent opportunity for well-dated
palaeoenvironmental records.
To improve knowledge about climatic and environmental changes in the western
Andes of southern Peru, we present a high-resolution record of the Cerro
Llamoca peatland for the last 8600 years. The 10.5 m long core consists of
peat and intercalated sediment layers and was examined for all kinds of
microfossils. We chose homogeneous peat sections for pollen analysis at
decadal to centennial resolution. The inorganic geochemistry was analysed in
2 mm resolution (corresponding >2 years) using an ITRAX X-ray
fluorescence core scanner.
We interpret phases of relatively high abundances of Poaceae pollen in our
record as an expansion of Andean grasslands during humid phases. Drier
conditions are indicated by a significant decrease of Poaceae pollen and
higher abundances of Asteraceae pollen. The results are substantiated by
changes in arsenic contents and manganese/iron ratios, which turned out to be
applicable proxies for in situ palaeoredox conditions.
The mid-Holocene period of 8.6–5.6 ka is characterised by a series of
episodic dry spells alternating with spells that are more humid. After a
pronounced dry period at 4.6–4.2 ka, conditions generally shifted towards a
more humid climate. We stress a humid/relatively stable interval between
1.8 and 1.2 ka, which coincides with the florescence of the Nasca culture in
the Andean foothills. An abrupt turn to a sustained dry period occurs at
1.2 ka, which is contemporaneous with the demise of the Nasca/Wari society
in the Palpa lowlands. Markedly drier conditions prevail until 0.75 ka,
providing evidence of the presence of a Medieval Climate Anomaly. Moister
but hydrologically highly variable conditions prevailed again after 0.75 ka,
which allowed re-expansion of tussock grasses in the highlands, increased
discharge into the Andean foreland and resettling of the lowlands during
this so-called late Intermediate Period (LIP).
On a supraregional scale, our findings can ideally be linked to and proved
by the archaeological chronology of the Nasca–Palpa region as well as other
high-resolution marine and terrestrial palaeoenvironmental records. Our
findings show that hydrological fluctuations, triggered by the changing
intensity of the monsoonal tropical summer rains emerging from the Amazon
Basin in the north-east, have controlled the climate in the study area. |
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