| 1. |
- Rosén, Peter, et al.
(författare)
-
Universally applicable model for the quantitative determination of lake sediment composition using fourier transform infrared spectroscopy
- 2011
-
Ingår i: Environmental Science and Technology. - : ACS Publications. - 0013-936X .- 1520-5851. ; 45:20, s. 8858-8865
-
Tidskriftsartikel (refereegranskat)abstract
- Fourier transform infrared spectroscopy (FTIRS) can provide detailed information on organic and minerogenic constituents of sediment records. Based on a large number of sediment samples of varying age (0-340 000 yrs) and from very diverse lake settings in Antarctica, Argentina, Canada, Macedonia/Albania, Siberia, and Sweden, we have developed universally applicable calibration models for the quantitative determination of biogenic silica (BSi; n = 816), total inorganic carbon (TIC; n = 879), and total organic carbon (TOC; n = 3164) using FTIRS. These models are based on the differential absorbance of infrared radiation at specific wavelengths with varying concentrations of individual parameters, due to molecular vibrations associated with each parameter. The calibration models have low prediction errors and the predicted values are highly correlated with conventionally measured values (R = 0.94-0.99). Robustness tests indicate the accuracy of the newly developed FTIRS calibration models is similar to that of conventional geochemical analyses. Consequently FTIRS offers a useful and rapid alternative to conventional analyses for the quantitative determination of BSi, TIC, and TOC. The rapidity, cost-effectiveness, and small sample size required enables FTIRS determination of geochemical properties to be undertaken at higher resolutions than would otherwise be possible with the same resource allocation, thus providing crucial sedimentological information for climatic and environmental reconstructions.
|
|
| 2. |
- Gebhardt, Andrea Catalina, et al.
(författare)
-
Seismic evidence of up to 200 m lake-level change in Southern Patagonia since Marine Isotope Stage 4
- 2012
-
Ingår i: Sedimentology. - : Wiley. - 0037-0746 .- 1365-3091. ; 59:3, s. 1087-1100
-
Tidskriftsartikel (refereegranskat)abstract
- Maar lake Laguna Potrok Aike is located north of the Strait of Magellan (south-eastern Patagonia). Seismic reflection profiles revealed a highly dynamic palaeoclimate history. Dunes were identified in the eastern part of the lake at approximately 30 to 80 m below the lake floor, overlying older lacustrine strata, and suggest that the region experienced dry conditions probably combined with strong westerly winds. It is quite likely that this can be linked to a major dust event recorded in the Antarctic ice cores during Marine Isotope Stage 4. The dunes are overlain by a series of palaeo-shorelines indicating a stepwise water-level evolution of a new lake established after this dry period, and thus a change towards wetter conditions. After the initial, rapid and stepwise lake-level rise, the basin became deeper and wider, and sediments deposited on the lake shoulder at approximately 33 m below present-day lake level point towards a long period of lake-level highstand between roughly 53.5 ka cal. bp and 30 ka cal. bp with a maximum lake level some 200 m higher than the desiccation horizon. This highstand was then followed by a regressional phase of uncertain age, although it must have happened some time between approximately 30 ka cal. bp and 6750 yrs cal. bp. Dryer conditions during the Mid-Holocene are evidenced by a dropping lake level, resulting in a basin-wide erosional unconformity on the lake shoulder. A second stepwise transgression between ca 5.8 to 5.4 ka cal. bp and ca 4.7 to 4 ka cal. bp with palaeo-shorelines deposited on the lake shoulder unconformity again indicates a change towards wetter conditions.
|
|
| 3. |
|
|
| 4. |
- Kliem, Pierre, et al.
(författare)
-
Lithology, radiocarbon chronology and sedimentological interpretation of the lacustrine record from Laguna Potrok Aike, southern Patagonia
- 2013
-
Ingår i: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791 .- 1873-457X. ; 71, s. 54-69
-
Tidskriftsartikel (refereegranskat)abstract
- The 106 m long composite profile from site 2 of ICDP expedition 5022 (PASADO) at Laguna Potrok Aike documents a distinct change in sedimentation patterns from pelagic sediments at the top to dominating mass movement deposits at its base. The main lithological units correspond to the Holocene, to the Lateglacial and to the last glacial period and can be interpreted as the result of distinct environmental variations. Overflow conditions might have been achieved during the last glacial period, while signs of desiccation are absent in the studied sediment record. Altogether, 58 radiocarbon dates were used to establish a consistent age-depth model by applying the mixed-effect regression procedure which results in a basal age of 51.2 cal. ka BP. Radiocarbon dates show a considerable increase in scatter with depth which is related to the high amount of reworking. Validation of the obtained chronology was achieved with geomagnetic relative paleointensity data and tephra correlation.
|
|
| 5. |
- Smith, Rebecca E., et al.
(författare)
-
Refining the Late Quaternary tephrochronology for southern South America using the Laguna Potrok Aike sedimentary record
- 2019
-
Ingår i: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791 .- 1873-457X. ; 218, s. 137-156
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a detailed record of volcanism extending back to similar to 80 kyr BP for southern South America using the sediments of Laguna Potrok Aike (ICDP expedition 5022; Potrok Aike Maar Lake Sediment Archive Drilling Project - PASADO). Our analysis of tephra includes the morphology of glass, the mineral componentry, the abundance of glass-shards, lithics and minerals, and the composition of glass-shards in relation to the stratigraphy. Firstly, a reference database of glass compositions of known eruptions in the region was created to enable robust tephra correlations. This includes data published elsewhere, in addition to new glass-shard analyses of proximal tephra deposits from Hudson (eruption units H-1 and H-2), Aguilera (A(1)), Reclus (R-1, R2-3), Mt Burney (MB1, MB2, MBx, MB1910) and historical Lautaro/Viedma deposits. The analysis of the ninety-four tephra layers observed in the Laguna Potrok Aike sedimentary sequence reveals that twenty-five tephra deposits in the record are the result of primary fallout and are sourced from at least three different volcanoes in the Austral Andean Volcanic Zone (Mt Burney, Reclus, Lautaro/Viedma) and one in the southernmost Southern Volcanic Zone (Hudson). One new correlation to the widespread H-1 eruption from Hudson volcano at 8.7 (8.6-9.0) cal ka BP during the Quaternary is identified. The identification of sixty-five discrete deposits that were predominantly volcanic ashes (glass and minerals) with subtle characteristics of reworking (in addition to three likely reworked tephra, and one unknown layer) indicates that care must be taken in the analysis of both visible and invisible tephra layers to decipher their emplacement mechanisms.
|
|
