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Published in "Swiss Journal of Geosciences 111(1–2): 1–11, 2018" which should be cited to refer to this work. New biostratigraphical data for the Burdigalian Montchaibeux Member at the locality Courrendlin-Sole´ (Canton of Jura, Switzerland) Je´roˆme Prieto1,2 • Damien Becker3,4 • Gae¨tan Rauber3 • Claudius M. Pirkenseer4,5 Abstract Geological surveys were carried out in the Abbreviations Miocene deposits at the place known as ‘‘En Sole´’’ east of CRD-SOL Courrendlin-Sole´ the village Courrendlin (Dele´mont Basin, Canton of Jura, M/m Upper/lower molar Switzerland). This resulted in the discovery of new Mio- MJSN JURASSICA Museum (old Muse´e jurassien cene small mammal assemblages. The association of the des Sciences naturelles) rodents Megacricetodon aff. collongensis and Melissiodon MN Mammal Neogene sp. allows to biochronostratigraphically correlate for the NAFB North Alpine Foreland Basin first time the so-called ‘‘Rote Mergel des Mont Chaibeux’’ OMM Obere Meeresmolasse (Upper Marine representing the lower part of the Montchaibeux Member Molasse) of the Bois de Raube Formation to the regional M. col- OSM Obere Su¨sswassermolasse (Upper Freshwater longensis–Keramidomys interval zone (MN 4; early Molasse) Miocene). P/p Upper/lower premolar Keywords Switzerland Á Canton of Jura Á Miocene Á Biostratigraphy Á Micromammals 1 Introduction From 2003 to 2008 geological surveys and sampling were carried out in Miocene deposits during the construction of the motorway A16 (Transjurane) between kilometres 42.500 and 42.840 of section 8 at the place known as ‘‘En http://doc.rero.ch & Claudius M. Pirkenseer [email protected] Sole´’’ east of the village Courrendlin (Dele´mont Basin, Canton of Jura, Switzerland; Fig. 1). These recent inves- 1 Department of Earth and Environmental Sciences, tigations led to the documentation of a sedimentary series Palaeontology & Geobiology, Ludwig-Maximilians-University composed mainly of small mammal-bearing red marl, Munich, Richard-Wagner-Str. 10, 80333 Munich, Germany nearly reaching 10 m measured at the construction site of 2 SNSB, Bayerische Staatssammlung fu¨r Pala¨ontologie und the motorway A16 just east of the Birse River (Fig. 2). Geologie, Richard-Wagner-Str. 10, 80333 Munich, Germany We report here the description and the identification of 3 JURASSICA Museum, Re´publique et Canton du Jura, Route new Miocene small mammal assemblages discovered at the de Fontenais 21, 2900 Porrentruy, Switzerland locality Courrendlin-Sole´. The general stratigraphic con- 4 Department of Geosciences, Earth Sciences, University of text of the Bois de Raube Formation provided by Ka¨lin Fribourg, Chemin du Muse´e6,Pe´rolles, 1700 Fribourg, Switzerland (1997) is emended. Additionally, the biochronostrati- graphical position of the so-called ‘‘Rote Mergel des Mont 5 Pale´ontologie A16, Office de la Culture, Re´publique et Canton du Jura, Rue de la Chaumont 13, 2900 Porrentruy, Chaibeux’’ sensu Liniger (1925) representing the lower Switzerland part of the Montchaibeux Member of the Bois de Raube 1 Fig. 1 The small mammal locality Courrendlin-Sole´ (red square). Dele´mont Basin. c Position of sampling sites at Courrendlin-Sole´ a The geographic position in Switzerland. b Simplified geologic map near the entrance of the future Choindez tunnel of the NW Switzerland, with the position of the locality in the Formation, is established for the first time in the Dele´mont Fig. 2 a Simplified lithostratigraphy of the northern Jura, with the c Basin. stratigraphic position of Courrendlin-Sole´ (bold red line). Timescale after GTS 2012, MN5-8 biozones adapted according to Ka¨lin and Kempf (2009) and Reichenbacher et al. (2013). b Synthetic log of the Courrendlin-Sole´ section, with range chart of small mammal taxa. http://doc.rero.ch 2 Geological setting Sample sites and logs refer to numbers in Fig. 1 The Dele´mont Basin lies at the palaeogeographic junction limestone of the Calcaires dele´montiens). Marine sands and between the Cenozoic tectonic and sedimentary provinces gravels of the Upper Marine Molasse (‘‘Obere Meeres- of the Upper Rhine Graben and the North Alpine Foreland molasse’’, (abbreviated OMM) occur only to the south and Basin (Berger et al. 2005a; Sissingh 2006). The simplified the east of the research area (e.g., Liniger 1925; Becker synthetic post-Mesozoic stratigraphic column of the 2003); they seem to be absent at Courrendlin-Sole´. northern Jura (Ajoie and Dele´mont Basin; Fig. 2a) extends Historically the ‘‘Rote Mergel des Mont Chaibeux’’ west from the Late Eocene laterites (Side´rolithique) to the of the Birse River have been discussed either as a lithos- supposed Pliocene fluviatile clastics (Sundgauschotter, tratigraphic unit directly related to the overlying Argiles de Bonfol; not depicted here) (Berger et al. 2005b). ‘‘Dinotheriensande’’ with no distinct limit and abundant The fluvio-lacustrine sediments of the Miocene Bois de reworked material derived from older units (Calcaires Raube Formation were deposited after a long hiatus (e.g., dele´montiens, OMM), or equivalent to red marls directly Becker 2003) discordantly on different substrates (e.g., overlying the OMM sediments recorded in the eastern part Chattian fluviatile sediments of the upper Molasse alsaci- of the Dele´mont Basin. ‘‘Dinotheriumsande’’-equivalent enne or latest Chattian-earliest Aquitanian freshwater deposits seem to be missing further to the east (Corban) and 2 http://doc.rero.ch 3 southeast (Vermes), but red marls comparable to the ‘‘Rote (47.34303°N, 7.38189°E) and C22 (47.34330°N, Mergel des Mont Chaibeux’’ are present in both localities 7.38192°E) represent inclined logs that have been corrected (Greppin 1855; Rollier 1898, 1910; Liniger 1925; Waibel for vertical thickness (Fig. 2b). The relative stratigraphic 1925; Engesser et al. 1981) but are situated below the Ver- position of the unlogged sample digs A21 (47.34318°N, mes limestone (Upper Freshwater Molasse; ‘‘Obere Su¨ss- 7.38198°E), A175 (47.34362°N, 7.38352°E) and S27 wassermolasse’’, abbreviated OSM). Effectively, Liniger (47.34299°N, 7.38202°E) is indicated in Fig. 2b. (1925) described the red marly deposits situated below the Several hundred kilograms of red marls were screen- church of Corban as ‘‘Rote Mergel von Corban’’, whereas in washed down to 125 lm mesh size. Residues larger than the Vermes area located at the southeastern end of the 250 lm were systematically screened for small mammal Dele´mont Basin similar red marls are sandwiched between teeth. The analysed material consists of 109 small mammal the Molasse alsacienne, the Calcaires dele´montiens and teeth and fragments. The measuring of Megacricetodon marine remnants (‘‘poudingues polygeniques’’ of the Upper teeth adheres to the method described in Prieto et al. Marine Molasse) below and lacustrine marls and limestones (2016). The referred small mammal teeth are stored in the above (Rollier 1910; Waibel 1925; Engesser et al. 1981). collection PAL A16 of the JURASSICA Museum in Por- Ka¨lin (1997) revised the lithostratigraphy of the regional rentruy (Canton of Jura, Switzerland). Miocene clastic sediments by the erection of the Bois-de- The chrono- and biostratigraphic correlations follow Raube Formation. Within the Dele´mont Basin, the formation Prieto and Rummel (2016), adapted from Ka¨lin and Kempf was subdivided in a basal Montchaibeux Member (including (2009), Abdul Aziz et al. (2010) and Reichenbacher et al. the ‘‘Rote Mergel und Dinotheriensande des Mont Chaibeux’’ (2013). In this work, and in contrast to Reichenbacher et al. of Liniger 1925 as well as similar sediments recorded in the (2013), we do not divided the MN 4 into two ‘‘subzones’’. Dele´mont Basin), a middle conglomeratic Bois de Raube The use of the MN-system has been shown to be prob- Member (‘‘Vogesenschotter des Bois de Raube’’ of Liniger lematic for the time range considered herein and allows 1925) and a mixed upper Ajoie Member (‘‘Hipparionsande only for an approximate long distance correlation (e.g., van von Charmoille’’ of Liniger 1925). The latter is exclusively der Meulen et al. 2011). We refer to Ka¨lin and Kempf recorded in Ajoie district and differs by a markedly different (2009) for the correlation of the Swiss local biozonation to heavy mineral spectrum and pebble content. the MN-system. Given the stratigraphic range considered Furthermore, Ka¨lin (1997), due to the constrained herein, we implement some clarification regarding the biostratigraphic range of the Vermes assemblages (Ka¨lin correlation between the Swiss and German regional scales 1993) and the lack of a proper dating of the ‘‘Rote Mer- around the MN 4–MN 5 transition. This transition is tra- gel’’, stated a concordant superposition of the Mon- ditionally linked in the NAFB to the Oberkulm-Sa¨mlen/ tchaibeux Member on the Middle Miocene freshwater Ta¨gernaustrasse assemblages in Switzerland and to the limestones of the Vermes locality, which is contrary to OSM A/OSM B in Germany (e.g., Reichenbacher et al. Engesser et al. (1981; see above). 2013). Prieto and Rummel (2016) conclude that the first Liniger (1925) interpreted the maximum contemporary occurrence of the eomyid rodent Keramidomys is the only thickness of the lower part of the Montchaibeux Member at taxon, which allows to clearly discriminate the Oberkulm- its type locality to reach 10–20 m (‘‘Rote Mergel’’), which Sa¨mlen assemblage on one hand and the OSM B on the is overlain by 80 m of sandy deposits of the ‘‘Dinothe- other; the lack of the eomyid rodent Ligerimys cannot be http://doc.rero.ch riensande’’. The typical red marls found at Courrendlin- used as a definitive argument for a primitive faunal imprint Sole´ can accordingly be attributed to the lower part of because of possible sampling bias. As a result, some Ger- the Montchaibeux Member. In detail, the sediments at man localities lacking Eomyidae are difficult to assign Courrendlin-Sole´ range from ochre or red marls to simi- [assigned to OSM A or B in Prieto and Rummel (2016), but larly coloured siltstones, partly bearing abundant calcare- traditionally correlated to OSM B].

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