Wyniki wyszukiwania - Biblioteka Nauki

1

Low to middle Pleistocene paleoclimatic record from the Kraków-Częstochowa Upland (Poland) based on isotopic and calcite fabrics analyses

100%

Błaszczyk M. , Hercman H. , Pawlak J. , Gąsiorowski M. , Matoušková Š. , Aninowska M. , Kicińska D. , Tyc A.

|

2018

|

tom Vol. 45, no. 1

185--197

EN

The quality of paleoenvironmental reconstruction based on speleothem records depends on the accuracy of the used proxies and the chronology of the studied record. As far as the dating method is concerned, in most cases, the best solution is the use of the U-series method to obtain a precise chronology. However, for older periods (i.e., over 0.5 Ma), dating has become a serious challenge. Theoretically, older materials could be dated with the U-Pb dating method. However, that method requires a relatively high uranium content (minimum of several ppm), whereas typical speleothems from Poland (and all of Central Europe) have uranium concentrations below 0.1 ppm. Because the materials in Polish caves are problematic, we applied oxygen isotope stratigraphy (OIS) as a tool for speleothem dating. By using OIS as an alternative tool to create a chronology of our flowstone, it was found that the studied flowstone crystallized from 975 to 470 ka with three major discontinuities, so obtained isotopic record can be correlated with oxygen isotopic stages from MIS 24 to MIS 12. The observed isotopic variability was also consistent and confirmed with the petrographic observations of the flowstone.

2

An 854-year tree-ring chronology of scots pine for south-west Finland

86%

Helama S. , Holopainen J. , Timonen M. , Mielikainen K.

|

tom Vol. 31, Nr 1

61--68

EN

A near-millennial tree-ring chronology (AD 1147-2000) is presented for south-west Finland and analyzed using dendroclimatic methods. This is a composite chronology comprising samples both from standing pine trees (Pinus sylvestris L.) and subfossil trunks as recovered from the lake sediments, with a total sample size of 189 tree-ring sample series. The series were dendrochronologically cross-dated to exact calendar years to portray variability in tree-ring widths on inter-annual and longer scales. Although the studied chronology correlates statistically significantly with other long tree-ring width chronologies from Finland over their common period (AD 1520-1993), the south-west chronology did not exhibit similarly strong mid-summer temperature or spring/early-summer precipitation signals in comparison to published chronologies. On the other hand, the south-west chronology showed highest correlations to the North Atlantic Oscillation indices in winter/spring months, this association following a dendroclimatic feature common to pine chronologies over the region and adjacent areas. Paleoclimatic comparison showed that tree-rings had varied similarly to central European spring temperatures. It is postulated that the collected and dated tree-ring material could be studied for wood surface reflectance (blue channel light intensity) and stable isotopes, which both have recently shown to correlate notably well with summer temperatures.

3

Air temperature and water level inferences from northeastern Lapland (69°N) since the Little Ice Age

86%

Luoto T. P. , Kivilä, E. Henriikka , Kotrys B. , Płóciennik M. , Rantala M. V. , Nevalainen L. , Luoto T. P. , Kivilä, E. Henriikka , Kotrys B. , Płóciennik M. , Rantala M. V. , Nevalainen L.

|

nr 1

4

Wheeler's dilemma

86%

Archibald B. , Farrell B. D.

|

nr Suppl.

5

Ślady zmian klimatycznych plejstocenu oraz holocenu w profilach temperatury w głębokich otworach wiertniczych na Niżu Polskim

58%

Szewczyk J.

|

2002

|

tom Vol. 50, nr 11

1109-1114

PL

Zmiany klimatu jakie miały i mają miejsce na Ziemi mogą pozostawiać swoje ślady w postaci zmian temperatury obserwowanych obecnie w profilach otworów wiertniczych. Analiza głębokościowej zmienności tych temperatur może być źródłem informacji o warunkach klimatycznych jakie istniały na badanym obszarze w różnych okresach. Czynnik ten wpływa równocześnie na obserwowaną wielkość ziemskiego strumienia cieplnego i jego uwzględnienie może mieć istotny wpływ na poprawność wyznaczenia tego parametru. Na podstawie przedstawionych w pracy wyników analiz badań geotermicznych opartych zarówno na metodzie konstrukcji syntetycznych profilowań termicznych (Ts), jak i wykonanych modelowaniach geotermicznych przeanalizowano wpływ czynnika paleoklimatycznego związanego ze zlodowaceniem późnoplejstoceńskim na wartości temperatur obserwowanych obecnie w otworach wiertniczych na obszarze Niżu Polskiego. Wstępna interpretacja danych geotermicznych z ponad 30 głębokich otworów z tego obszaru pozwoliła między innymi na stwierdzenie obecności efektu paleoklimatycznego, a także naokreślenie średniej wartości temperatury warstwy przypowierzchniowej (GST) istniejącej na tym obszarze w okresie tego zlodowacenia. (-6.85 deg C).

EN

Past and current climatic changes on the Earth may be recorded in the subsurface temperature profiles observed in deep boreholes. Analysis of such profiles measured in boreholes few thousand metres deep may provide information on past climatic conditions existing in on the studied area. Terrestial heat flow data may be considerably influenced by this factor and should be corrected for all data accordingly. Results of analysis based both on constructions of synthetic thermal logs (Ts) and on the results of further modelling show that the last glaciation has left evident paleoclimatic temperature signals in nearly all observed subsurface temperature profiles in deep boreholes from the Polish Lowlands. Preliminary results on the average annual ground surface temperature for the Polish Lowlands in the Late Pleistocene have been obtained (GST = -6.8°C).

6

Fauna osadów interglacjalnych z Koczarek koło Mrągowa

58%

Skompski S.

|

tom Vol. 50, nr 7

615--619

PL

Analiza paleontologiczna 46 próbek z otworu wiertniczego w Koczarkach wykazała obecność różnorodnych szczątków zwierząt: mięczaków, małżoraczków, ryb i owadów. Na tej podstawie określono warunki paleoekologiczne i paleoklimatyczne w jakich powstawały osady z fauną oraz ich stratygrafię. Znalezione tu charakterystyczne gatunki mięczaków: Corbicula fluminalis i Lithoglyphus jahni oraz małżoraczka Scottia browniana pozwalają określić wiek osadów z fauną na interglacjał mazowiecki.

7

Climate-driven diversity changes of Mediterranean echinoids over the last 6 Ma

58%

Borghi E. , Garilli V.

|

tom 67

|

nr 4

8

Reconstruction of postglacial paleoproductivity in Long Lake, King George Island, West Antarctica

58%

Yoon H. , Khim B. , Lee K. , Park Y. , Yoo K.

|

nr 3

189-206

EN

A sediment core (LS-1) collected from Long Lake in King George Island, South Shetland Islands (West Antarctica) was analyzed for a variety of textural, geochemical, iso- topic and paleontological properties together with 14C age dates. These data combined with published records of other studies provide a detailed history of local/regional postglacial paleoproductivity variation with respect to terrestrial paleoclimate change. The lithologic contrast of a lower diamicton and an upper fine-grained sediment demonstrates glacial recession and subsequent lake formation. The upper fine-grained deposit, intercalated by mid-Holocene tephra-fallout followed by a tephra gravity flow, was formed in a lacustrine environment. Low total organic carbon (TOC) and biogenic silica (Sibio) contents with high C/N ratios characterize the diamicton, whereas an increase of TOC and Sibio contents characterize the postglacial lacustrine fine-grained sediments, which are dated at c. 4000 yrBP. More notable are the distinct TOC maxima, which may imply enhanced primary productivity during warm periods. Changes in Sibio content and S13C values, which support the increasing paleoproductivity, are in sympathy with these organic matter variations. The uniform and low TOC contents that are decoupled by Sibio contents are attributed to the tephra gravity flows during the evolution of the lake rather than a reduced paleoproductivity. A very recent TOC maximum is also characterized by high Sibio content and S13C values, clearly indicating increased paleoproductivity consequent upon gradual warming across King George Island. Comparable with changes in sediment geochemistry, the occurrence and abundance of several diatom species corroborate the paleoproductivity variations together with the lithologic development. However, the paleoclimatic signature in local terrestrial lake environment during the postglacial period (for example the Long Lake) seems to be less distinct, as compared to the marine environment.