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Climate of the Past An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/cp-2018-34
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
27 Mar 2018
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Climate of the Past (CP).
Mid-Cretaceous paleoenvironmental changes in the western Tethys
Cinzia Bottini and Elisabetta Erba Dipartimento di Scienze della Terra "A. Desio", Università degli Studi di Milano, 20133 Milan, Italy
Abstract. We present a continuous record of surface water temperature and fertility variations through the latest Barremian–Cenomanian interval (ca. 27 My) based on calcareous nannofossil abundances from the western Tethys. The nannofossil temperature index, calibrated with TEX86-Sea Surface Temperatures, suggests that warmest (34–36 °C) conditions were reached during Oceanic Anoxic Event (OAE) 1a onset, the Aptian/Albian boundary interval hyperthermals (113, Kilian Level and Urbino Level-OAE 1b), and during a ca. 4 My-long phase in the middle Albian. Coolest temperatures (29 °C) correspond, instead, to the late Aptian. Generally warm conditions characterized the Albian followed by a progressive cooling trend started in the latest Albian (at the Marne a Fucoidi/Scaglia Bianca Formation transition). Temperate conditions occurred in the Cenomanian with frequent short-term variations highlighted by abundance peaks of cold-water nannofossil species E. floralis and R. parvidentatum. Mid-Cretaceous surface water fertility was rather fluctuating and mostly independent from climatic conditions as well as from black shales intervals. Intense warming and fertility spikes resulted to be systematically associated only to black shales of OAE 1a and of the Aptian/Albian boundary hyperthermals. The Albian–Cenomanian rhythmic black shales are, in fact, associated with varying long-term climatic/fertility conditions. The similarity of western Tethys climatic/fertility fluctuations during OAE 1a, OAE 1b, the middle Albian and OAE 1d with nannofossil-based records from other basins indicated that these paleoenvironmental conditions were affecting the oceans at supra-regional to global scale.
Citation: Bottini, C. and Erba, E.: Mid-Cretaceous paleoenvironmental changes in the western Tethys, Clim. Past Discuss., https://doi.org/10.5194/cp-2018-34, in review, 2018.
Cinzia Bottini and Elisabetta Erba
Cinzia Bottini and Elisabetta Erba
Cinzia Bottini and Elisabetta Erba

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Short summary
The mid-Cretaceous (ca. 121 to 94 Ma) was characterized by generally warm climate punctuated by supra-regional to global phenomena of wide-spread ocean anoxia. In this work we present the first complete record of temperature and fertility variations through the mid-Cretaceous in the western Tethys based on calcareous nannofossils. The new record indicates that temperatures and fertility were rather fluctuating but mostly independently and they were not systematically associated with anoxia.
The mid-Cretaceous (ca. 121 to 94 Ma) was characterized by generally warm climate punctuated by...
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