Palaeoenvironmental, palaeogeographic, and palaeoclimatic signals of a condensed horizon: The Upper Callovian-Oxfordian Dhosa Oolite of the Kachchh Basin, western India
Zusammenfassung der Projektergebnisse
The aim of the project was to reconstruct the palaeoenvironmental, palaeogeographic, and palaeoclimatic conditions in the Kachchh Basin during the Late Callovian and Oxfordian. This time interval is of special interest due to the proposal of a glacial phase by Dromart et al. (2003), and because of the highly condensed nature of the strata. The major results of the present project are the following: A detailed biostratigraphic framework for the Oxfordian of the Kachchh Basin based on the collection of more than 800 ammonites. Most of the zones and few subzones of the Oxfordian standard zonal scheme of Europe have been recognised. On Kachchh Mainland most of the Upper Oxfordian and Lower Kimmeridgian is represented by a hiatus. - A comprehensive taxonomic study of the Oxfordian ammonite fauna. So far, 50 taxa have been revised. - A detailed model explaining the formation of the highly condensed Dhosa Oolite mb. It includes two phases of subaerial exposure of large parts of the basin floor, which could be dated as late Early and Late Oxfordian. - The reconstructed sea-level curve for the Kachchh Basin does not support the existence of a pronounced sea-level minimum at the Callovian-Oxfordian boundary connected with an ice age as proposed by earlier workers. - Detailed studies on the petrography of the Oxfordian rocks and associated geochemical analyses have been used to infer an original calcareous origin of the allochthonous, ferruginous ooids and to corroborate/modify palaeoenvironmental reconstructions based on sedimentological data. - Stable isotope (δ18O, δ13C) analyses of belemnites, brachiopods, and oysters from the Kachchh Basin were used to reconstruct the temperature development in the area from the Late Callovian to Kimmeridgian. The results show comparatively warm conditions around the Middle to Late Jurassic transition and therefore do not support the existence of an ice age as earlier proposed. - The reconstructed Oxfordian temperature curve could be connected with strong upwelling currents dominating the northern Malagasy Gulf during the Late Jurassic as had been previously suggested by general circulation models. - A high-resolution stable isotope analysis of an oyster was used to reconstruct average seasonal temperatures over a consecutive time interval of ten years. The results of this study point to a comparatively low palaeo-seasonality of 1- 3°C, which can be explained by the subtropical latitude of the Kachchh Basin.
Projektbezogene Publikationen (Auswahl)
- Seasonality in low latitudes during the Oxfordian (Late Jurassic) reconstructed via high-resolution stable isotope analysis of the oyster Actinostreon marshi (J. Sowerby, 1814) from the Kachchh Basin, western India. International Journal of Earth Sciences
Alberti, M., Fürsich, F.T., Pandey, D.K.
(Siehe online unter https://doi.org/10.1007/s00531-013-0864-x) - 2011. Ammonites of the genus Peltoceratoides Spath, 1924 from the Oxfordian of Kachchh, western India. Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen 262: 1-18
Alberti, M., Pandey, D.K., Fürsich, F.T.
- 2012. Ammonites of the genus Perisphinctes Waagen, 1869 from the Oxfordian of Kachchh, western India. Revue de Paléobiologie 31: 483-587
Pandey, D.K., Alberti, M., Fürsich, F.T.
- 2012. Stable isotope analyses of belemnites from the Kachchh Basin, western India: paleoclimatic implications for the Middle to Late Jurassic transition. Facies 58: 261-278
Alberti, M., Fürsich, F.T., Pandey, D.K., Ramkumar, M.
(Siehe online unter https://doi.org/10.1007/s10347-011-0278-9) - 2012. The Oxfordian stable isotope record (δ18O, δ13C) of belemnites, brachiopods, and oysters from the Kachchh Basin (western India) and its potential for palaeoecologic, palaeoclimatic, and palaeogeographic reconstructions. Palaeogeography, Palaeoclimatology, Palaeoecology 344-345: 49-68
Alberti, M., Fürsich, F.T., Pandey, D.K.
(Siehe online unter https://doi.org/10.1016/j.palaeo.2012.05.018) - 2013. Deciphering condensed sequences: A case study from the Oxfordian (Upper Jurassic) Dhosa Oolite member of the Kachchh Basin, western India. Sedimentology 60: 574-598
Alberti, M., Fürsich, F.T., Pandey, D.K.
(Siehe online unter https://doi.org/10.1111/j.1365-3091.2012.01351.x)
