Metoda datowania kosmogenicznym izotopem 36Cl - nowe dane do chronologii glacjalnej Tatr Wysokich
Abstract
Prezentowana metoda polega na pomiarze zawartości izotopu 36Cl, powstałego w przypowierzchniowej warstwie skały pod wpływem promieniowania kosmicznego. Przy określonym tempie produkcji ilość akumulowanego w pobranej próbce izotopu zależy od czasu ekspozycji i stałej rozpadu. Dzięki długiemu czasowi połowicznego rozpadu (301000 lat) izotopem 36Cl można datować formy powierzchni ziemi, powstałe w przedziale wiekowym od kilku tysięcy do kilkuset tysięcy lat. Wyniki datowania 37 próbek i form rzeźby lodowcowej w Tatrach metodą 36Cl zostały przedstawione na szerszym tle paleogeograficznym. Otrzymano daty z przedziału czasowego od 21 do 6,5 tysięcy lat. Według dat „chlorowych” najstarsze są moreny w okolicach Brzezin (21–15,3 ka), a najmłodsze z okolic Morskiego Oka (9,9–7,3 ka). Wyniki datowania za pomocą 36Cl stanowią istotny głos w dyskusji nad chronologią glacjalną Tatr.
THE METHOD OF DATING BY COSMOGENIC 36CL – NEW DATA IN GLACIAL CHRONOLOGY OF THE HIGH TATRA MTS.
Summary
The cosmogenic 36CI method of dating of Quaternary deposits and the first results of dating of moraines in selected regions of the Polish Tatra Mts. are presented. The method is based on measuring the concentration of 36CI that is produced and accumulated in rocks exposed to cosmic rays. The concentration of 36CI in the rock depends on the production rate, decay constant and the time of exposure. Due to the long half-life of 36CI (301,000 yr), the method can be used to determine ages of landforms and sediments in the age range from a few thousand to a few hundred thousand years. Thirty seven samples from glacial deposits and land forms have been dated and the results are presented in paleogeographical context.
The obtained dates show that these glacial features are of Vistulian and Holocene age (21-6.5 ky). The oldest moraines (21-15.3 ky) are in the vicinity of Brzeziny, and the youngest (9.9-7.3 ka) are near Morskie Oko Lake. These results of 36Cl dating are an important contribution to the discussion of glacial chronology of this mountain range.
THE METHOD OF DATING BY COSMOGENIC 36CL – NEW DATA IN GLACIAL CHRONOLOGY OF THE HIGH TATRA MTS.
Summary
The cosmogenic 36CI method of dating of Quaternary deposits and the first results of dating of moraines in selected regions of the Polish Tatra Mts. are presented. The method is based on measuring the concentration of 36CI that is produced and accumulated in rocks exposed to cosmic rays. The concentration of 36CI in the rock depends on the production rate, decay constant and the time of exposure. Due to the long half-life of 36CI (301,000 yr), the method can be used to determine ages of landforms and sediments in the age range from a few thousand to a few hundred thousand years. Thirty seven samples from glacial deposits and land forms have been dated and the results are presented in paleogeographical context.
The obtained dates show that these glacial features are of Vistulian and Holocene age (21-6.5 ky). The oldest moraines (21-15.3 ky) are in the vicinity of Brzeziny, and the youngest (9.9-7.3 ka) are near Morskie Oko Lake. These results of 36Cl dating are an important contribution to the discussion of glacial chronology of this mountain range.