| Autor: |
De Brodtkorb, M. K., Barbieri, M., Zak, K., Hladikova, J., Tassinari, C., Ametrano, S., Etcheverry, R., De Barrio, R. E., Blanco, M. Del, Danieli, J. C. |
| Zdroj: |
International Geology Review; April 1997, Vol. 39 Issue: 4 p307-316, 10p |
| Abstrakt: |
Stratabound barite and celestite deposits, related mainly to three evaporitic sequences, occur in the Mesozoic Neuquen Retroarc Basin, developed to the east of the Andean Cordillera of western Argentina. This basin is filled with Jurassic and Cretaceous marine to continental sediments that unconformably overlie basement rocks of Paleozoic to Triassic age.Celestite deposits formed by initial precipitation from seawater, with later crystallization during diagenesis and recrystallization related to Eocene intrusive activity. This is supported by evidence of evaporitic associations, textures, and Sr and S-isotope data. The barite deposits were deposited in a near-shore environment and could have formed as a result of interaction between barium absorbed in clay minerals (derived from weathering of basement rocks) and hypersaline seawater. This genetic model is supported by evidence such as the stratabound setting, textures, and Sr and S-isotope data.Carbon and oxygen-isotopic compositions of carbonates, which are interbedded with celestites, are in the range expected for marine carbonates. Lead-isotopic compositions of galenas from bedded and vein barite deposits of Upper Jurassic and Lower Cretaceous ages are consistent with Pb remobilization from a source located at high levels of the upper crust, possibly the basement rocks. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
|
