A 22,000 14C year BP sediment and pollen record of climate change from Laguna Miscanti (23°S), northern Chile

Grosjean, Martín; Leeuwen, Jacqueline F. N. van; Knaap, W.O. van der; Geyh, Mebus A.; Ammann, Brigitta; Tanner, W. F; Messerli, Bruno; Núñez, Láutaro; Garcés, Blas Lorenzo Valero; Veit, Heinz

doi:10.1016/s0921-8181(00)00063-1

Cited by 165 publications

(162 citation statements)

References 19 publications

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“…It is not clear what mechanisms might have been able to increase regional precipitation to this extent, even during peak Tauca phase. Proxies at this time indicate perhaps a doubling of modern precipitation from ~300 to ~600 mm/yr (e.g., Grosjean et al, 2001;Maldonado et al, 2005;Gayo et al, 2012). The indication by the new cosmogenic ages that the extensive moraines in these areas do not date to Tauca phase may place peak glaciation in the arid Andes during a colder period such as mid-global LGM, when temperatures were likely 5-7º colder, and therefore less precipitation would be needed to glaciate the region than previously modeled.…”

Section: Discussionmentioning

confidence: 80%

“…Upper elevations of the Puna Plateau and surrounding area receive between 200 and 350 mm/yr of water-equivalent precipitation (Grosjean et al, 2001), with high interannual variability (e.g., Garreaud and Aceituno, 2001;Houston, 2006). Much of this precipitation falls during austral summer (Garreaud et al, 2003) and is derived from moist air transported from the east, arriving from the tropical Atlantic via the Amazon Basin.…”

Section: Modern Regional Climatementioning

confidence: 99%

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Across the Arid Diagonal: deglaciation of the western Andean Cordillera in southwest Bolivia and northern Chile

Ward

Thornton

Cesta

2017

CIG

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Section: Discussionmentioning

confidence: 80%

Section: Modern Regional Climatementioning

confidence: 99%

Across the Arid Diagonal: deglaciation of the western Andean Cordillera in southwest Bolivia and northern Chile

Ward

Thornton

Cesta

2017

CIG

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“…Identifications were based on our own reference collection and on published atlases and keys (Heusser, 1971;Markgraf and D'Antoni, 1978;Graf, 1979;Hooghiemstra, 1984;Sandoval et al, 2010;Torres et al, 2012). Pollen and non-pollen palynomorphs data were subjected to numerical zonation using binary splitting techniques (Hammer et al, 2001), which highlighted five main zones.…”

Section: Methodsmentioning

confidence: 99%

“…microenvironments that have varied with climatic changes, resulting in significant responses of vegetation zonation, geomorphodynamics and other variations in biotic and abiotic systems (Grosjean et al, 2001;Garreaud et al 2003;Grosjean and Veit, 2005).…”

Section: K Schittek Et Al: Holocene Environmental Changes In the Himentioning

confidence: 99%

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Holocene environmental changes in the highlands of the southern Peruvian Andes (14° S) and their impact on pre-Columbian cultures

et al. 2015

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Abstract. 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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Pressure Dependence in the Methyl Vinyl Ketone+OH and Methacrolein+OH Oxidation Reactions: An Electronic Structure Study

Ochando-Pardo¹,

Nebot–Gil²,

González‐Lafont³

et al. 2005

ChemPhysChem

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High-level electronic structure calculations were carried out for the study of the reaction pathways in the OH-initiated oxidations of methyl vinyl ketone (MVK) and methacrolein (MACR). For the two conformers of MVK (called synperiplanar and antiperiplanar), the addition channels of OH to the terminal and central carbon atom of the double bond dominate the overall rate constant, whereas the abstraction of the methyl hydrogen atoms has no significant kinetic role. In the case of MACR, only the antiperiplanar conformer is important in its reactivity. In addition, the lower Gibbs free energy barrier for MACR corresponds to the aldehydic hydrogen abstraction reaction, which will be somewhat more favorable than the addition processes. The subtle balance between the different pathways (additions versus abstractions) serves to give an understanding of the pressure dependence of the rate constants of these tropospheric oxidation processes.

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A 22,000 14C year BP sediment and pollen record of climate change from Laguna Miscanti (23°S), northern Chile

Cited by 165 publications

References 19 publications

Across the Arid Diagonal: deglaciation of the western Andean Cordillera in southwest Bolivia and northern Chile

Across the Arid Diagonal: deglaciation of the western Andean Cordillera in southwest Bolivia and northern Chile

Holocene environmental changes in the highlands of the southern Peruvian Andes (14° S) and their impact on pre-Columbian cultures

Pressure Dependence in the Methyl Vinyl Ketone+OH and Methacrolein+OH Oxidation Reactions: An Electronic Structure Study

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