Publikationsdatum:
2011-11-07
Beschreibung:
Stable isotope analyses of 61 diagenetically unaltered belemnite rostra from the Middle to Late Jurassic of the Kachchh Basin of western India suggest stable paleotemperatures across the Callovian-Oxfordian boundary (~14°C). Only at the end of the Middle Oxfordian water temperatures drop for more than 3°C before reaching again higher values during the Kimmeridgian (~12.3°C). The data do not support polar glaciations proposed for the Middle to Late Jurassic transition, which necessarily would have led to a global temperature and sea-level minimum at the boundary. Callovian to Oxfordian rocks in the Kachchh Basin point to a gradual shallowing corresponding to a slight fall in relative sea level. However, the magnitude of this regression is comparatively small, and the sea-level minimum is reached in the late Early Oxfordian and not close to the boundary. Results from the Kachchh Basin therefore, imply almost stable climatic conditions during the Middle to Late Jurassic transition and do not show any evidence for polar glaciations. Content Type Journal Article Category Original Article Pages 1-18 DOI 10.1007/s10347-011-0278-9 Authors Matthias Alberti, GeoZentrum Nordbayern, Fachgruppe PaläoUmwelt, Friedrich-Alexander-Universität Erlangen-Nürnberg, Loewenichstraße 28, 91054 Erlangen, Germany Franz T. Fürsich, GeoZentrum Nordbayern, Fachgruppe PaläoUmwelt, Friedrich-Alexander-Universität Erlangen-Nürnberg, Loewenichstraße 28, 91054 Erlangen, Germany Dhirendra K. Pandey, Department of Geology, University of Rajasthan, Jaipur, 302004, India Mu. Ramkumar, Department of Geology, Periyar University, Salem, 636011 India Journal Facies Online ISSN 1612-4820 Print ISSN 0172-9179
Print ISSN:
0172-9179
Digitale ISSN:
1612-4820
Thema:
Geographie
,
Geologie und Paläontologie
