A calcareous nannofossil and organic geochemical study of marine palaeoenvironmental changes across the Sinemurian/Pliensbachian (early Jurassic, ~191Ma) in Portugal

Plancq, J. , Mattioli, E., Pittet, B., Baudin, F., Duarte, L.V., Boussaha, M. and Grossi, V. (2016) A calcareous nannofossil and organic geochemical study of marine palaeoenvironmental changes across the Sinemurian/Pliensbachian (early Jurassic, ~191Ma) in Portugal. Palaeogeography, Palaeoclimatology, Palaeoecology, 449, pp. 1-12. (doi: 10.1016/j.palaeo.2016.02.009)

Abstract

The Sinemurian/Pliensbachian boundary (~ 191 Ma) is acknowledged as one of the most important steps in the radiation of planktonic organisms, especially primary producers such as dinoflagellates and coccolithophores. To date, there is no detailed study documenting changes in planktonic assemblages related to palaeoceanographic changes across this boundary. The aim of this study is to characterize the palaeoenvironmental changes occurring across the Sinemurian/Pliensbachian boundary at the São Pedro de Moel section (Lusitanian Basin, Portugal) using micropalaeontology and organic geochemistry approaches. Combined calcareous nannofossil assemblage and lipid biomarker data document for a decrease in primary productivity in relation to a major sea-level rise occurring above the boundary. The Lusitanian Basin was particularly restricted during the late Sinemurian with a relatively low sea level, a configuration that led to the recurrent development of black shales. After a sharp sea-level fall, the basin became progressively deeper and more open during the earliest Pliensbachian, subsequently to a major transgression. This sea-level increase seems to have been a global feature and could have been related to the opening of the Hispanic Corridor that connected the Tethys and palaeo-Pacific oceans. The palaeoceanographic and palaeoclimatic changes induced by this opening may have played a role in the diversification of coccolithophores with the first occurrence or colonization of Tethyan waters by placolith-type coccoliths.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Plancq, Dr Julien
• Authors: Plancq, J., Mattioli, E., Pittet, B., Baudin, F., Duarte, L.V., Boussaha, M., and Grossi, V.
• College/School: College of Science and Engineering > School of Geographical and Earth Sciences
• Journal Name: Palaeogeography, Palaeoclimatology, Palaeoecology
• Publisher: Elsevier BV
• ISSN: 0031-0182
• ISSN (Online): 1872-616X
• Copyright Holders: Copyright © 2016 Elsevier B.V.
• First Published: First published in Palaeogeography, Palaeoclimatology, Palaeoecology 449:1-12
• Publisher Policy: Reproduced in accordance with the copyright policy of the publisher.