Global radiolarian zonation for the Pliensbachian, Toarcian and Aalenian Elizabeth S. Carter a , Špela Goričan b, ⁎, Jean Guex c , Luis O'Dogherty d , Patrick De Wever e , Paulian Dumitrica f , Rie S. Hori g , Atsushi Matsuoka h , Patricia A. Whalen i a Department of Geology, Portland State University, Portland, OR 97207-0751, USA b Paleontološki inštitut Ivana Rakovca, ZRC SAZU, Novi trg 2, SI-1000 Ljubljana, Slovenia c Institut de Géologie et Paléontologie, Université de Lausanne, CH-1015 Lausanne, Switzerland d Departamento de Ciencias de la Tierra, Facultad de Ciencias del Mar, Universidad de Cádiz, Campus Río S. Pedro, 11510 Puerto Real, Cádiz, Spain e Département Histoire de la Terre, Muséum National d'Histoire Naturelle, 43 rue Buffon, F-75005 Paris, France f Dennigkofenweg 33, CH-3073 Guemligen, Switzerland g Department of Earth Sciences, Faculty of Science, Ehime University, Matsuyama 790-8577, Japan h Department of Geology, Faculty of Science, Niigata University, Niigata 950-2181, Japan i Department of Geosciences, University of Arkansas, 118 Ozark Hall, Fayetteville, AR 72701, USA abstract article info Article history: Received 21 January 2010 Received in revised form 14 August 2010 Accepted 29 August 2010 Available online 29 September 2010 Keywords: Radiolaria Lower Jurassic Middle Jurassic Biochronology Unitary Associations Jurassic radiolarians from 220 samples in Queen Charlotte Islands, B.C., Williston Lake, B.C., east-central Oregon, Baja California Sur, southern Spain, Austria, Slovenia, Turkey, Oman, Japan and Argentina were studied in order to construct global zonation for the Pliensbachian, Toarcian and Aalenian stages. Well- preserved faunas from continuous stratigraphic sections in Queen Charlotte Islands provide the most detailed record for this time interval, and all collections are tied to North American ammonite zones or assemblages. Collections from nearly all other areas lack independent dating except for early Toarcian carbon-isotope dating in Slovenia and late Aalenian ammonites in Spain. A database of 197 widely distributed updated taxonomic species was used to construct a Unitary Association (UA) zonation for the interval. A global sequence of 41 UAs was obtained for the top of the Sinemurian to the base of the Bajocian. The first and the last UAs represent the Late Sinemurian and the Early Bajocian respectively. The remaining 39 UAs were merged into nine zones (four Early Pliensbachian, one Late Pliensbachian, one Early Toarcian, one Middle–Late Toarcian, and two Aalenian) according to prominent radiolarian faunal breaks and ammonite data. The new zones are the Canutus tipperi – Katroma clara Zone (latest Sinemurian/earliest Pliensbachian); Zartus mostleri – Pseudoristola megaglobosa, Hsuum mulleri – Trillus elkhornensis and Gigi fustis – Lantus sixi zones (Early Pliensbachian); Eucyrtidiellum nagaiae – Praeparvicingula tlellensis Zone (Late Pliensbachian); Napora relica – Eucyrtidiellum disparile Zone (Early Toarcian); Elodium pessagnoi – Hexasaturnalis hexagonus Zone (Middle and Late Toarcian); Higumastra transversa – Napora nipponica Zone (early Aalenian); and Mirifusus proavus – Transhsuum hisuikyoense Zone (late Aalenian). These zones can be correlated worldwide and link previously established UA zonations for the Hettangian–Sinemurian and the Middle to Upper Jurassic. The new zonation allows high-resolution dating in the studied interval and provides a solid basis for analyzing faunal turnovers and the paleobiogeography of Jurassic radiolarians. © 2010 Elsevier B.V. All rights reserved. 1. Introduction The construction of a global radiolarian zonation for three Jurassic stages, the Pliensbachian, Toarcian and Aalenian, is essential for the future zonation of the entire Jurassic. Earliest Jurassic (Hettangian and Sinemurian) and Middle to Late Jurassic radiolarians have been studied extensively (Carter et al., 1998; Baumgartner et al., 1995 respectively) but Pliensbachian, Toarcian and Aalenian faunas are much less well known biochronologically. To address this need, a joint international project was initiated under the framework of INTERRAD (International Association of Radiolarian Paleontologists) during the 9th INTERRAD meeting in Blairsden, California in 2000. The first step for the Pliensbachian to Aalenian Working Group (PTA) was to establish a set of clearly defined and updated taxonomic species that would be used in the construction of the zonation and to agree upon the sections to be used. This was accomplished during meetings in 2001 and 2002 in Slovenia, and final editing in 2004 and 2005. The ‘Catalogue and systematics of Pliensbachian, Toarcian and Aalenian radiolarian genera and species’ is now complete (Goričan et al., 2006). Palaeogeography, Palaeoclimatology, Palaeoecology 297 (2010) 401–419 ⁎ Corresponding author. Tel.: + 386 1 4706371; fax: + 386 1 4257755. E-mail addresses: cartermicro@earthlink.net (E.S. Carter), spela@zrc-sazu.si (Š. Goričan), jean.guex@unil.ch (J. Guex), luis.odogherty@uca.es (L. O'Dogherty), pdewever@mnhn.fr (P. De Wever), Paulian.Dumitrica@unil.ch (P. Dumitrica), shori@sci.ehime-u.ac.jp (R.S. Hori), matsuoka@geo.sc.niigata-u.ac.jp (A. Matsuoka), micropaw14@ipa.net (P.A. Whalen). 0031-0182/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.palaeo.2010.08.024 Contents lists available at ScienceDirect Palaeogeography, Palaeoclimatology, Palaeoecology journal homepage: www.elsevier.com/locate/palaeo