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Comparing palaeolimnological and instrumental evidence of climate change for remote mountain lakes over the last 200 years 总被引:8,自引:1,他引:7
Richard W. Battarbee John-Arvid Grytnes Roy Thompson Peter G. Appleby Jordi Catalan Atte Korhola H.J.B. Birks Einar Heegaard Andrea Lami 《Journal of Paleolimnology》2002,28(1):161-179
This paper compares the palaeolimnological evidence for climate change over the last 200 years with instrumental climate data for the same period at seven European remote mountain lakes. The sites are Øvre Neådalsvatn (Norway), Saanajärvi (Finland), Gossenköllesee (Austria), Hagelseewli (Switzerland), Jezero v Ledvici (Slovenia), Estany Redó (Spain, Pyrenees), and Niné Terianske Pleso (Slovakia). We used multiple regression analysis to transfer homogenised lowland air temperature records to each of the sites, and these reconstructions were validated using data from on-site automatic weather stations. These data showed that mean annual temperature has varied over the last 200 years at each site by between 1 and 2 °C, typical of the high frequency variability found throughout the Holocene, and appropriate, therefore, to test the sensitivity of the various proxy methods used. Sediment cores from each site were radiometrically dated using 210Pb, 137Cs and 241Am and analysed for loss-on-ignition, C, N, S, pigments, diatoms, chrysophytes, Cladocera and chironomids. Comparisons between the proxy data and the instrumental data were based on linear regression analysis with the proxy data treated as response variables and the instrumental data (after smoothing using LOESS regressions) as predictor variables. The results showed few clear or consistent patterns with generally low or very low r2 values. Highest values were found when the data were compared after smoothing using a broad span, indicating that some of the proxy data were capturing climate variability but only at a relatively coarse time resolution. Probable reasons for the weak performance of the methods used include inaccurate dating, especially for earlier time periods, the influence of confounding forcing factors at some sites e.g., air pollution, earthquakes, and the insensitivity of some methods to low amplitude climate forcing. Nevertheless, there were trends in some proxy records at a number of sites that had a relatively unambiguous correspondence with the instrumental climate records. These included organic matter and associated variables (C and N) and planktonic diatom assemblages at the majority of sites and chrysophytes and chironomids at a few sites. Overall for longer term studies of the Holocene, these results indicate the need to be cautious in the interpretation of proxy records, the importance of proxy method validation, the continuing need to use reinforcing multi-proxy approaches, and the need for careful site and method selection. 相似文献
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Mathieu Duval Christophe Falguères Jean‐Jacques Bahain Rainer Grün Qingfeng Shao Maxime Aubert John Hellstrom Jean‐Michel Dolo Jordi Agusti Bienvenido Martínez‐Navarro Paul Palmqvist Isidro Toro‐Moyano 《第四纪科学杂志》2011,26(6):603-615
The palaeontological site of Venta Micena (Orce, Andalusia, Spain) lies in the eastern sector of the Guadix–Baza basin, one of the best documented areas in Europe for Plio‐Pleistocene biostratigraphy. The combination of biochronological and palaeomagnetic results, combined with the radiometric data obtained for Atapuerca Sima del Elefante, indicated that the Venta Micena stratum was formed between the Jaramillo and Olduvai palaeomagnetic events, most likely between 1.22 and 1.77 Ma. Five fossil teeth from two outcrops (sites A and B) were selected to assess the potential of combined uranium series–electron spin resonance (US‐ESR) dating of Early Pleistocene sites. Although the US‐ESR results of the first outcrop showed a large scatter between the three teeth, the mean age of 1.37 ± 0.24 Ma can be considered a reasonable age estimate for Venta Micena. The mean ESR age of 0.62 ± 0.03 Ma obtained for site B seems to be a severe underestimation when compared with the independent age control. This underestimation is attributed to a relative recent U‐mobilization event that led to some U‐leaching. The results show that any ESR age calculations of old samples are extremely sensitive to variations in the measured 230Th/234U ratios in dental tissues. Although the results demonstrate that ESR can in principle be applied to Early Pleistocene sites, they also reveal the complexity of dating such old teeth. It is necessary to continue research in several directions, such as study of the behaviour of ESR signals in old teeth and understanding recent U‐mobilization processes, to improve the reliability of the combined US‐ESR dating method applied to Early Pleistocene times, a period for which the number of available numerical dating techniques is very limited. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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Josep M. TRIGO‐RODRÍGUEZ Jií BOROVIKA Pavel SPURNÝ Jos L. ORTIZ Jos A. DOCOBO Alberto J. CASTRO‐TIRADO Jordi LLORCA 《Meteoritics & planetary science》2006,41(4):505-517
Abstract— The L6 ordinary chondrite Villalbeto de la Peña fall occurred on January 4, 2004, at 16: 46: 45 ± 2 s UTC. The related daylight fireball was witnessed by thousands of people from Spain, Portugal, and southern France, and was also photographed and videotaped from different locations of León and Palencia provinces in Spain. From accurate astrometric calibrations of these records, we have determined the atmospheric trajectory of the meteoroid. The initial fireball velocity, calculated from measurements of 86 video frames, was 16.9 ± 0.4 km/s. The slope of the trajectory was 29.0 ± 0.6° to the horizontal, the recorded velocity during the main fragmentation at a height of 27.9 ± 0.4 km was 14.2 ± 0.2 km/s, and the fireball terminal height was 22.2 ± 0.2 km. The heliocentric orbit of the meteoroid resided in the ecliptic plane (i = 0.0 ± 0.2°), having a perihelion distance of 0.860 ± 0.007 AU and a semimajor axis of 2.3 ± 0.2 AU. Therefore, the meteorite progenitor body came from the Main Belt, like all previous determined meteorite orbits. The Villalbeto de la Peña fireball analysis has provided the ninth known orbit of a meteorite in the solar system. 相似文献
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Josep Maria Trigo-Rodriguez Jeremie Vaubaillon José Luís Ortiz Alberto Castro-Tirado Jordi Llorca Esko Lyytinen Martin Jelínek Antonio de Ugarte Postigo Pablo Santos Sanz Francisco J. Aceituno Castro Albert Sánchez Caso Antonio Bernal González Juan Pastor Erades Francisco Ocaña 《Earth, Moon, and Planets》2005,97(3-4):269-278
Jupiter and Saturn produce important gravitational impulses on meteoroids released by comet 109P/Swift-Tuttle. The meteoroids from this comet once released follow retrograde orbits that during their periodic approaches to these planets (within 1.6 and 0.9 A.U., respectively) are impulsed gaining orbital energy. This perturbation effect is translated into a net inward shift in the node of the perturbed meteoroids. Such geometry with Jupiter occurred in 2004 over a meteoroid trail ejected by this comet during the 1862 A.D. return of the comet to perihelion. In order to study the predicted outburst produced by one-revolution meteoroids, the Spanish Photographic Meteor Network (SPMN) performed an extensive campaign. As a part of this observational effort here are presented 10 accurate meteoroid orbits. We discuss their origin by comparing them with the theoretical orbital elements of the dust trails intercepting the Earth during the 2004 Perseid return. 相似文献
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Reduction and analysis of photoelectric observations of stars by the Moon made between 1955–1978 permit to obtain corrections to the Watts' reference surface, using the recent values for the correction of the equinox. 相似文献
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Jordi LLORCA Ignasi CASANOVA Josep M. TRIGO‐RODRÍGUEZ José M. MADIEDO Julia ROSZJAR Addi BISCHOFF Ulrich OTT Ian A. FRANCHI Richard C. GREENWOOD Matthias LAUBENSTEIN 《Meteoritics & planetary science》2009,44(2):159-174
Abstract— Puerto Lápice is a new eucrite fall (Castilla‐La Mancha, Spain, 10 May 2007). In this paper, we report its detailed petrography, magnetic characterization, mineral and bulk chemistry, oxygen and noble gas isotope systematics, and radionuclide data. Study of four thin sections from two different specimens reveal that the meteorite is brecciated in nature, and it contains basaltic and granulitic clasts, as well as recrystallized impact melt and breccia fragments. Shock veins are ubiquitous and show evidence of at least three different shock events. Bulk chemical analyses suggest that Puerto Lápice belongs to the main group of basaltic eucrites, although it has a significantly higher Cr content. Oxygen isotopes also confirm that the meteorite is a normal member of the HED suite. Noble gas abundances show typical patterns, with dominant cosmogenic and radiogenic contributions, and indicate an average exposure age of 19 ± 2 Ma, and a Pu‐fission Xe age well within typical eucrite values. Cosmogenic radionuclides suggest a preatmospheric size of about 20–30 cm in diameter. 相似文献