Shallow-water facies setting around the Kac ˇa ´k Event: a multidisciplinary approach P. KO ¨ NIGSHOF 1 *, A. C. DA SILVA 2 , T. J. SUTTNER 3 , E. KIDO 3 , J. WATERS 4 , S. K. CARMICHAEL 4 , U. JANSEN 1 , D. PAS 2 & S. SPASSOV 5 1 Senckenberg Research Institute and Natural History Museum, Senckenberganlage 25, 60325 Frankfurt, Germany 2 Sedimentary Petrology, B 20, University of Liege, Sart-Tilman, B-4000 Lie `ge, Belgium 3 University of Graz, Institute of Earth Sciences, Heinrichstraße 26, A-8010 Graz, Austria 4 Department of Geology, Appalachian State University, Boone, NC 28608, USA 5 Geophysical Centre, Royal Meteorological Institute of Belgium, 1 rue du Centre Physique, B 5670 Dourbes (Viroinval), Belgium *Corresponding author (e-mail: peter.koenigshof@senckenberg.de) Abstract: In the Eifel area (western Rheinisches Schiefergebirge), a shallow- to deep-subtidal sequence of mixed carbonates and siltstones around the Kac ˇa ´k Event Interval close to the Eife- lian – Givetian stage boundary was studied. An overall transgressive trend is inferred by the micro- facies evolution. The stratigraphic variations of magnetic susceptibility in carbonates and in shale intervals show an overall decreasing evolution towards the top, which fits well with the transgres- sive trend. In addition, carbon and oxygen isotopes, and major, trace and rare earth element (REE) analysis have been used to get a better understanding of palaeoenvironmental variations in a shallow-water realm in the late Eifelian (kockelianus and ensensis conodont biozones): for example, the d 13 C excursion and Ce anomaly are interpreted to be the local representation of the beginning of the Kac ˇa ´k Event Interval, which is also consistent with the stratigraphy and microfacies analyses. Black shales at the Eifelian – Givetian boundary sec- tions are very common in Europe and elsewhere (summarized in House 1996), representing a global (eustatic) sea-level rise. The Kac ˇa ´k Event (Budil 1995; House 2002) occurs just below the Eife- lian – Givetian Stage boundary at the Jebel Mech Irdane section in Morocco, the Global Stratotype Section and Point (GSSP). The Kac ˇa ´k Event is a typical black shale event, connected with the global rise in sea level at the base of the transgressive– regressive (T–R) Cycle Ie of Brett et al. (2011). The sea-level rise is connected with increasing d 13 C values of about 2‰ at the Eifelian–Givetian boundary (e.g. Buggisch & Mann 2004; van Geldern et al. 2006), and the positive excursion can be at- tributed to an increased burial of isotopically light organic carbon or increased riverine weathering flux (Kump et al. 1999; Saltzman 2002). This event is characterized by a biotic turnover that is primarily recorded in pelagic faunas, such as conodonts, cephalopods and dacryoconarids (e.g. Chlupa ´c ˇ& Kukal 1986; Bultynck 1987, 1989; Becker & House 2000). The dacryoconarid Nowakia otomari is con- sidered to be an indicator of the Kac ˇa ´k Event or the otomari Event sensu Walliser (1985). In Germany, the otomari Event was described in pelagic carbonates of, for instance, the Odershausen Formation in the eastern Rheinisches Schieferge- birge (eastern RSG) in the Kellerwald area (e.g. Walliser 1985; Scho ¨ne 1997) (Fig. 1). The Eife- lian – Givetian boundary interval in the Eifel area (western RSG) is characterized by shallow-water successions. The otomari Event has been placed at the boundary between the Nims and Giesdorf mem- bers by Struve et al. (1997), whereas Scho ¨ne et al. (1998) suggested placing this event at the boundary between the Junkerberg and Freilingen formations (see Table 1). A detailed stratigraphic correlation of sections in the eastern RSG with those of the Eifel area is difficult owing to the different deposi- tional settings (deep-water facies setting v. shallow- water facies setting) and correlation problems: for example, the lack of the dacryoconarid Nowakia otomari in the shallow-water setting. The effects of anoxic events in Earth’s history on shallow-water realms are still poorly documented. In this paper, we describe a shallow-water sequence around the Kac ˇa ´k Event Interval, with special focus on a comparison of magnetic susceptibility data, facies analysis and geochemical data in order to From:Becker, R. T., Ko ¨ nigshof, P. & Brett, C. E. (eds) Devonian Climate, Sea Level and Evolutionary Events. Geological Society, London, Special Publications, 423, http://doi.org/10.1144/SP423.4 # 2015 The Geological Society of London. For permissions: http://www.geolsoc.org.uk/permissions. Publishing disclaimer: www.geolsoc.org.uk/pub_ethics by guest on June 10, 2015 http://sp.lyellcollection.org/ Downloaded from