Zastosowanie datowania metodą K/Ar polihalitów wschodniego Przedkarpacia w celu wyjaśnienia ich genezy
Abstract
Mioceńskie potasowo-magnezowe utwory siarczanowe zapadliska przedkarpackiego występują w dwóch poziomach stratygraficznych. Niższy należy do eggenburgu, wiek wyższego jest dyskusyjny - ottnang lub baden. Określono metodą K/Ar radiometryczny wiek 15 próbek dwóch odmian genetycznych polihalitu. Zbadano polihalit z czerwonej skały polihalitowej, występujący w miejscach wyklinowywania złóż soli potasowych oraz polihalit z warstw polihalitowo-anhydrytowych, znajdujących się w brekcji solnej w pobliżu kontaktu ze złożami soli potasowych. Radiometryczne wieki polihalitów z czerwonej polihalitowej skały mieszczą się w granicach 8,314,7 Ma. Radiometryczne wieki próbek polihalitu z warstw polihalitowo-anhydrytowych są nieco niższe 5,7 12,3 Ma. Porównując wieki tych samych odmian polihalitu ze złoża stebnickiego (eggenburg) i kałusko-hołyńskiego (ottnang? baden?) nie widać istotnych różnic. Powstawanie polihalitu jest powiązane ze zjawiskami tektonicznymi w historii rozwoju geologicznego zapadliska przedkarpackiego. Duży rozrzut otrzymanych wieków dla próbek polihalitu z warstw polihalitowo-anhydrytowych świadczyć może o powstawaniu tych warstw w kilku etapach.
AN APPLICATION OF K/AR DATING OF POLYHALITES IN THE EASTERN PART OF THE CARPATHIAN FOREDEEP AS A METHOD FOR EXPLAINING THEIR ORIGIN
Summary
The Miocene K-Mg-sulfate deposits of the Carpathian Foredeep occur within two stratigraphic horizons. The lower belongs to Eggenburgian stage, whereas the age of the upper is debatable—either Ottnangian or Badenian. The radiometric age of 15 specimens assigned to two genetic varieties of polyhalite was determined using a K/Ar method. Both thepolyhalite from the red bedded polyhalite rock occurring near thinned potash salt deposits and that from the polyhalite-anhydrite beds located within a salt breccia close to the contact with potash salt deposits was investigated. The radiometric age data of polyhalite from the red polyhalite rock varies from 8.3 to 14.7 Ma. In turn, the radiometric age determined for polyhalite from the polyhalite-anhydrite beds turned out to be younger (from 5.7 to 12.3 Ma). The age comparison of the same polyhalite varieties from Stebnyk deposits (Eggenburgian) and Kalush-Holyn (Ottnangian?, Badenian?) shows no significant differences. The origin of polyhalite is connected with tectonic eventsthat took place during the geological development of the Carpathian Foredeep. The large dispersion of polyhalite dates obtained forpolyhalite-anhydrite beds may suggest that they were formed in several stages.
AN APPLICATION OF K/AR DATING OF POLYHALITES IN THE EASTERN PART OF THE CARPATHIAN FOREDEEP AS A METHOD FOR EXPLAINING THEIR ORIGIN
Summary
The Miocene K-Mg-sulfate deposits of the Carpathian Foredeep occur within two stratigraphic horizons. The lower belongs to Eggenburgian stage, whereas the age of the upper is debatable—either Ottnangian or Badenian. The radiometric age of 15 specimens assigned to two genetic varieties of polyhalite was determined using a K/Ar method. Both thepolyhalite from the red bedded polyhalite rock occurring near thinned potash salt deposits and that from the polyhalite-anhydrite beds located within a salt breccia close to the contact with potash salt deposits was investigated. The radiometric age data of polyhalite from the red polyhalite rock varies from 8.3 to 14.7 Ma. In turn, the radiometric age determined for polyhalite from the polyhalite-anhydrite beds turned out to be younger (from 5.7 to 12.3 Ma). The age comparison of the same polyhalite varieties from Stebnyk deposits (Eggenburgian) and Kalush-Holyn (Ottnangian?, Badenian?) shows no significant differences. The origin of polyhalite is connected with tectonic eventsthat took place during the geological development of the Carpathian Foredeep. The large dispersion of polyhalite dates obtained forpolyhalite-anhydrite beds may suggest that they were formed in several stages.