K/Ar radiometric dating on rocks from the northern part of the Ditró syenite massif and its petrogenetic implications
Several opinions have been published on the date of the formation of the Ditro syenite massif. Direct contact of this massif and sedimentary rocks can not be found. It is probable that the syenite massif lithostratigraphically formed during the time between the Saalic and the Laramian orogenic cycle...
Elmentve itt :
| Szerzők: | |
|---|---|
| Dokumentumtípus: | Cikk |
| Megjelent: |
University of Szeged, Department of Mineralogy, Geochemistry and Petrology
Szeged
1995
|
| Sorozat: | Acta mineralogica-petrographica
36 |
| Kulcsszavak: | Kőzettan, Ásványtan, Földtan |
| Tárgyszavak: | |
| Online Access: | http://acta.bibl.u-szeged.hu/24826 |
| Tartalmi kivonat: | Several opinions have been published on the date of the formation of the Ditro syenite massif. Direct contact of this massif and sedimentary rocks can not be found. It is probable that the syenite massif lithostratigraphically formed during the time between the Saalic and the Laramian orogenic cycles. Valuable radiometric data (less than 30) gained by different methods (Pb/Pb, K/Ar, Rb/Sr) have mainly been related to the syenites and nepheline syenites (STRECKEISEN and HUNZIKER, 1974; MiNZATU, 1980 in JAKAB et al., 1987; JAKAB and POPESCU, 1979; JAKAB and POPESCU, 1984; JAKAB and POPESCU, 1985 in JAKAB et al., 1987). Although valuable data for hornblendites (BAGDASARIAN, 1972) differ from those of syenites, most researches dated the formation of the massif as a whole to the Jurassic on the basis of the radiometric data for the syenites and the nepheline syenites. In this work 25 K/Ar radiometric data of the rocks (hornblendites, diorites, granites, nepheline syenites, syenites, alkaline feldspar syenites) are evaluated and based on it, devising of a petrogenetic model is attempted. K/Ar radiometric age of the hornblendites is Middle and Upper Triassic (Ladinian and Carnian), and that of the granites is Upper Triassic (Rhaetian) - Lower Jurassic (Hettangian), the diorites indicate mixed age - Upper Triassic (Rhaetian) and Middle Jurassic (Bajocian), age of the nepheline syenites is Middle Triassic (Ladinian), and that of the syenites and the alkaline syenites is Middle Jurassic (Aalenian) - Lower Cretaceous (Albian). These data indicate two great geological events (intrusions). One happened in the age of the Upper Triassic - Lower Jurassic, and the other was formed in the Middle Jurassic - Lower Cretaceous. These events partly coincide with each other. It is proved by the mixed age of the diorites, which were probably formed by a hybridization of the hornblendites and the syenites during the second event. |
|---|---|
| Terjedelem/Fizikai jellemzők: | 101-116 |
| ISSN: | 0365-8066 |