Ichnological Analysis of the Bidart and Sopelana Cretaceous/Paleogene (K/Pg) Boundary Sections (Basque Basin, W Pyrenees): Reﬁning Eco-Sedimentary Environment

Sedimentary Geology 234 (2011) 42–55

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Ichnological analysis of the Bidart and Sopelana Cretaceous/Paleogene (K/Pg) boundary sections (Basque Basin, W Pyrenees): Reﬁning eco-sedimentary environment

F.J. Rodríguez-Tovar a,⁎, A. Uchman b, X. Orue-Etxebarria c, E. Apellaniz c, Juan I. Baceta c a Departamento de Estratigrafía y Paleontología, Facultad de Ciencias, Universidad de Granada, 18002 Granada, Spain b Jagiellonian University, Institute of Geological Sciences, Oleandry Str. 2a, PL-30-063 Kraków, Poland c Departamento de Estratigrafía y Paleontología, Facultad de Ciencia y Tecnología, Universidad del País Vasco, E-48080 Bilbao, Spain article info abstract

Article history: Ichnological analysis of two Cretaceous–Paleogene boundary sections at Bidart (SE France) and Sopelana (N Received 12 August 2010 Spain) has been conducted in order to refining eco-sedimentary environment, and to a make comparison with Received in revised form 23 October 2010 previous interpretations based on microfossils. In both sections, trace fossil assemblage is low diverse, Accepted 22 November 2010 consisting of Chondrites, Planolites, Thalassinoides, Trichichnus, Zoophycos, and ?Phycosiphon, ascribed to the Available online 1 December 2010 Zoophycos ichnofacies, however, with distinct differences. In the Bidart section, early Danian dark-filled trace Editor: M.R. Bennett fossil assemblage is more abundant in large Thalassinoides, Zoophycos and larger Chondrites, and less abundant in Trichichnus and small Chondrites in comparison to the Sopelana section. Sopelana is thus interpreted as a Keywords: more offshore, deeper section than Bidart although both were located in the upper bathyal zone of the basin. Trace fossils Oxygenation below the sediment–water interface was enough to favour a generalized total bioturbation of Cretaceous/Paleogene boundary sediments. The presence of chemichnia and trace fossils which tracemakers sequestered sediments from the Zoophycos ichnofacies sea floor in deep burrows (Zoophycos) suggests at least periodical food deficiency. The distribution and Eco-sedimentary conditions content of trace fossils across the K/Pg boundary do not change significantly, revealing minor incidence of the Bidart K/Pg boundary event on the macrobenthic environment. The K/Pg boundary transition, including the Sopelana boundary layer, is nearly totally bioturbated; hence a redistribution of microbiotic and abiotic components by tracemakers is possible. © 2010 Elsevier B.V. All rights reserved.

1. Introduction 1984; Ekdale and Stinnesbeck, 1998). However, in the last years ichnological analyses conducted in several K/Pg sections, reveal that The Cretaceous–Paleogene (K/Pg) boundary event is one of the the boundary layer is bioturbated, containing diverse trace fossils, most spectacular phenomenon in the Phanerozoic history of the which help to refine several aspects in the interpretation of the Earth causing a global major extinction. In pelagic environments it is palaeoenvironmental conditions that prevailed during sedimenta- recorded in the so-called boundary layer, which is a thin, usually 5– tion of the K/Pg boundary event interval (Rodríguez-Tovar, 2005; 10 cm thick, dark and calcium carbonate depleted claystone or Rodríguez-Tovar and Uchman, 2004a,b, 2006, 2008; Rodríguez- marlstone. Commonly, the base of the boundary layer is defined by a Tovar et al., 2002, 2004, 2006). millimeter-thick rusty layer which contains the iridium and other In the Basque Basin (western Pyrenees) several outcrops of deep geochemical anomalies related with the extraterrestrial bolide marine (hemi)pelagic facies has been studied, revealing the well impact at the northern Yucatan peninsula (Schulte et al., 2010; developed, expanded and relatively complete K–Pg boundary Smit, 1999)whichdefine the formal position of the K/Pg boundary interval (see Apellaniz et al., 1997; Pujalte et al., 1998). These (Molina et al., 2006). Publications showing the presence of trace favourable features determined the numerous studies conducted in fossils at the K/Pg boundary interval are scarce (see Rodríguez-Tovar the uppermost Maastrichtian–lowermost Danian sediments of this and Uchman, 2008 for a review), especially those including a area, involving sequence stratigraphic, mineralogical, isotopic, detailed ichnological characterization (e.g., Ekdale and Bromley, geochemical, magnetostratigraphical and biostratigraphical analyses (see Alegret, 2007 for a recent review). In this exhaustive research, however, detailed ichnological analysis has been only recently initiated (Rodríguez-Tovar et al., 2010). In this paper we ⁎ Corresponding author. Tel.: +34 958 242724; fax: +34 958 248528. present the ichnological analysis of two of the best-preserved K/Pg E-mail addresses: [email protected] (F.J. Rodríguez-Tovar), [email protected] (A. Uchman), [email protected] (X. Orue-Etxebarria), boundary sections, Bidart, in SW France, and Sopelana, in N Spain [email protected] (E. Apellaniz), [email protected] (J.I. Baceta). (Figs. 1 and 2). Their ichnological features have been investigated in

Fig. 1. A) Paleogeographic map of the Pyrenean Basin, with location of Bidart, Sopelana and Zumaia sections. B) Schematic lithologic logs of the Bidart and Sopelana sections, including sequence stratigraphic distribution (bottom). Note: The Zumaia section is included for comparison. order to show some biogenic and sedimentary phenomena through 2. Location and setting the K/Pg boundary interval, and to deﬁne the similarities and differences between these two sections. The latter aspect is of special The late Cretaceous and Paleogene in the Pyrenees are represented interest, because in deep basins that presumably record homoge- by a wide variety of sedimentary rocks, including continental alluvial neous hemipelagic sediment supply, ichnological features may clastics, shallow marine carbonates and deep-water hemipelagites become a powerful tool to recognize subtle lateral changes in the and turbidites accumulated in a broad E–W elongated embayment sedimentation regime and the palaeoenvironmental conditions at opened into the Bay of Biscay and the North Atlantic (Baceta, 1996; the sea ﬂoor. Baceta et al., 2004; Plaziat, 1981; Pujalte et al., 1998). Basinal 44 F.J. Rodríguez-Tovar et al. / Sedimentary Geology 234 (2011) 42–55

Fig. 2. Lithological columns of the Sopelana B and Bidart sections with sample locations and range of trace fossils.

hemipelagites and turbidites were deposited in the central part of the The best known K/Pg boundary sections being of the Basque Basin embayment, the so-called Basque Basin (Pujalte et al., 1998), at are located in coastal cliffs between the north of Bilbao and the south depths ranging from 1000 to1500 m (Fig. 1). of Baiona. Up to twelve of these K/Pg sections can be identiﬁed, the The late Maastrichtian–earliest Ypresian was a phase or relative Zumaia section being the reference for all of them (see Apellaniz et al., tectonic quiescence, during which turbidite deposition was reduced 1997 for a synthesis). Bidart and Sopelana, the two K/Pg sections and the Basque Basin became dominated by regular alternations of selected for ichnological analysis, are 100 km apart (see Fig. 1 for hemipelagic limestones and marls, usually grouped in bedding correlation with the Zumaia section according the most signiﬁcant couplets and bundles as representative of precession and short- correlation levels a to e). The Bidart section is located in south- eccentricity climatic cycles (Dinarès-Turell et al., 2003, 2007). western France, in a long beach few kilometres to the north of the F.J. Rodríguez-Tovar et al. / Sedimentary Geology 234 (2011) 42–55 45

Bidart town (43º27′N and 1º35′E), within an upper Cretaceous– of white and reddish bioturbated limestones with thin (2–3 cm) Eocene succession that dips 15–35º to the north. The Sopelana section marlstone interbeds. is located north of Bilbao, in northern limb of the Cretaceous– The Bidart section can be considered, together with the classical Paleogene Byscay Sinclinorium (Fig. 1, 43º23′N and 2º59′W). The Zumaia section (Fig. 1), as one of the most complete land-based K/Pg upper Cretaceous–Paleocene basinal succession of the Sopelana boundary sections exposed in the eastern margin of the Atlantic section is affected by reverse and strike-slip faults, which cause Ocean (Apellaniz et al., 1997; Haslett, 1994; Seyve, 1990), as recently stratigraphic repetitions and the existence of three different K/Pg corroborated by magnetostratigraphic, calcareous nannofossils and boundary outcrops. Two of these sections have been analysed: planktic foraminifera analyses (Galbrun and Gardin, 2004; Gallala et Sopelana A (Sopelana Beach) and Sopelana B (above the cliff) al., 2009). These works reveal a continuous sedimentation across the sections, which in previous papers were labelled, respectively, as K/Pg boundary transition, without any biostratigraphically significant Sopelana III (Apellaniz, 1998) and Sopelana I (Orue-Etxebarria, 1983, hiatus. The planktic foraminifera biozonation (Gallala et al., 2009), 1984, 1985). is as follow: a) at the Upper Maastrichtian, the Abathomphalus mayaroensis Zone is differentiated, b) the Guembelitria cretacea Zone 3. Lithostratigraphy and biostratigraphy of the K/Pg boundary in that marks the base of the Lower Danian, around 15 cm thick in the the Basque Basin Bidart section, and subdivided into the Hedbergella holmdelensis and Parvularugoglobigerina longiapertura subzones, and c) the P. eugubina 3.1. Bidart and Sopelana sections Zone, around 100 cm thick in the Bidart section, that is subdivided into the P. sabina and Eoglobigerina simplicissima subzones. A profuse research has been conducted in the last decades in the The K/Pg boundary transition at the Sopelana section (A and B) has Bidart section (see Gallala et al., 2009 for a review). Recently, the K/Pg been comparatively less studied than that at Bidart. Descriptions of boundary transition at Bidart section was studied, focusing on the the Sopelana A section can be found in Lamolda et al. (1983) and trace fossil assemblage (Rodríguez-Tovar et al., 2010; Figs. 2 and 3). Orue-Etxebarria (1985). Especially interesting is the complex iridium The upper 4 m of the Maastrichtian contain grey and pinkish marls distribution, with two iridium spikes, the first coeval with the final and marly limestones. The rusty layer marking the K/Pg boundary is Cretaceous planktonic foraminiferal extinction, and the second in well preserved and about 2 mm thick. Above it, the first Danian coincidence with the nannoplankton crisis (Rocchia et al., 1988). deposits occur in an about 15 cm thick dark clay layer, overlain by Detailed analysis of the Sopelana section (A and B) corroborates nearly 23 cm thick reddish to greenish marls and marly limestones. similar facies composition as in the Bidart section, but different Above them, a 93 cm thick interval of partly parallel laminated thicknesses (Figs. 2 and 4). The upper 7 m of the Maastrichtian white to reddish limestones is present, followed by a 1–1.5 m thick consists of grey and pinkish marls of changing endurance. Above, the pebbly mudstone bed made up of roundish clasts of hemipelagic 4–5 cm thick dark clay K/Pg boundary layer from the base of the limestones embedded in a marl-lime matrix. This clastic deposit is Danian, containing the 2 mm thick rusty layer at the base, is followed interpreted as reflecting an episode of erosion and redeposition by by 22–25 cm of green-grey marls showing primary lamination in the submarine debris flows. The upper part of the studied section consists upper part. Overlapping it, a 90 cm thick interval of white and reddish

Fig. 3. Outcrop of the K/Pg boundary layer at Bidart. A) General view showing top of the Maastrichtian marlstones, the boundary layer and the Danian limestones and marlstones. Stars pointed by arrows indicate debris ﬂow calciruditic beds; note their convex up upper bedding planes. B) Detail of A. C) Boundary layer. D) Debris ﬂow calciruditic beds in the Danian (indicated by stars); compare to A. 46 F.J. Rodríguez-Tovar et al. / Sedimentary Geology 234 (2011) 42–55

Fig. 4. The Sopelana section and its trace fossils in the totally bioturbated Maastrichtian marlstones. A, B) The K–Pg boundary section; the boundary layer marked by the dashed line; a fault in A marked by solid line. C) Light-filled Chondrites isp. (Ch), vertical section, sample So-103. D) Dark-filled Chondrites isp., sub-horizontal parting surface, sample So-85e. E) Chondrites isp. (Ch), dark-filled Thalassinoides (Thd), light-filled Thalassinoides (Thi) and Planolites isp. (Pl), vertical section, sample So-105. F) Thalassinoides isp. (Th) and Chondrites isp. (Ch), horizontal parting surface, sample So-85c. G) Thalassinoides isp. (Th), Chondrites isp. (Ch), Planolites isp. (Pl) and Trichichnus isp. (Tr), vertical section, sample So-85 h. H) Zoophycos isp., sample So-91 polished along the spreite. I) ?Zoophycos isp. (?Zo) and ?Phycosiphon isp. (Phy), sub-horizontal section, sample So-91. limestones which includes a level with some evidence of soft- planktonic foraminifera (Lamolda et al., 1983). Thus, the lowermost sediment synsedimentary deformation, in the form of irregular part of the Paleogene corresponding to the Guembelitria cretacea Zone folding and fracturation with differentiation of isolated limestone was not identified (Lamolda et al., 1983; Mary et al., 1991). This zone clasts. Biostratigraphic analysis based on planktonic foraminifera and could be represented in the 2–3 cm just above the contact with the calcareous nannoplankton revealed that the first occurrence of the Maastrichtian, but the relative scarcity and poor preservation of Tertiary planktonic foraminifera Globigerina (E.) eugubina is a few planktonic foraminifera above the rusty layer avoid a conclusive centimetres (8–10 cm) above the extinction of Upper Cretaceous interpretation (Canudo, 1994). The incompleteness of the Sopelana A F.J. Rodríguez-Tovar et al. / Sedimentary Geology 234 (2011) 42–55 47 section was also revealed based on the graphic correlation analysis; the 2 cm separating the red layer from the FAD of P. eugubina imply the absence of the Zone P0 estimated in 50 000 yr in duration (MacLeod and Keller, 1991; MacLeod et al., 1997). The K/Pg boundary interval in the Sopelana B section situated 60 m from the former above the seacliffs, is more complete and significantly better preserved. According to Apellaniz et al. (1997) and Apellaniz (1998) the boundary layer marking the boundary is 7 cm thick and contains a planktic foraminifer assemblage characteristic of the Guembelitria cretacea Zone. The overlying marl-marlstones that are 28 cm thick are also well preserved. Their lower 22–23 cm corresponds to the Parvularugoglobigerina longiapertura Zone.

4. Trace fossil analysis

Only occasionally trace fossils or bioturbational structures have been mentioned in the K/Pg boundary section at Bidart (Gorostidi and Lamolda, 1995; Haslett, 1994; Smit and Ten Kate, 1982), while in the Sopelana section, Lamolda et al. (1983) refer to “a distinct burrowed surface” at the top of the purple marls corresponding to the latest Maastrichtian. Recently, Rodríguez-Tovar et al. (2010), present a preliminary ichnological analysis of the K/Pg boundary transition at the Bidart section, focusing on the effects of different tracemakers on the redistribution of calcareous nannofossils throughout the K/Pg boundary. The section shows a relatively abundant and conspicuous dark-coloured trace fossil assemblage with Chondrites, Planolites, Thalassinoides, Trichichnus and Zoophycos, and less abundant light- coloured ichnofossils including Planolites and Thalassinoides. Calcar- eous nannofossils are re-distributed in fillings of some ichnotaxa in the Bidart section, with danian calcareous nannofossil assemblages present in Maastrichtian samples, evidenced by abundant Paleogene calcareous nannofossils just below the K/Pg boundary (Rodríguez- Tovar et al., 2010). The sections were analyzed layer by layer. Selected samples were Fig. 5. Ichnofabrics and trace fossils of the pre-event Maastrichtian marlstones at Bidart. A) Thalassinoides isp. (Th) cross cut by Chondrites isp. (Ch), Planolites isp. (Pl), all in the collected continuously at the K/Pg boundary transition, and more totally bioturbated background; polished slab; sample Bd2. B) Zoophycos isp. (Zo) in the sparsely in the rest of the succession, and then cut and polished in the totally bioturbated background. Polished slab, sample Bd11. C) Trichichnus isp. (Tr)ona laboratory. The cut and polished surfaces were wetted in order to rough surface, sample Bd8. obtain better contrast for photographs. ?Phycosiphon isp. (Fig. 4I) is a patch of sub-horizontal small lobes 4.1. Synopsis of trace fossils with a marginal tunnel about 0.7 mm wide. The curvature and patchy occurrence suggests Phycosiphon incertum Fischer-Ooster, 1858, but The trace fossil assemblage identified in the K/Pg sections of Bidart fragmentary preservation only in one specimen preclude more certain and Sopelana is low diverse, with 5 common ichnogenera (Chondrites, determination. Phycosiphon is common in fine-grained marine Planolites, Thalassinoides, Trichichnus and Zoophycos), together with ? sediments and is produced by deposit feeders (Wetzel and Bromley, Phycosiphon only registered in the Sopelana section. 1994). Its geometry was lately studied by Naruse and Nifuku (2008). Chondrites isp. (Figs. 4C–D, F–G, 5A, 6A, D–G, 8B–C) is observed (1) Planolites isp. (Figs. 4E, G, 5A, 6D–E, H, 8B–D) occurs as horizontal on parting surfaces as branched burrow system composed of to oblique, straight to slightly winding, simple flattened cylinders, compressed straight or curved equidimensional cylindrical, unwalled 2.5–4 mm, mostly 3 mm wide, without lining. They are filled with elements (Figs. 4D, 6A, D), or in (2) cross section as patches of circular dark grey rarely light grey fine-grained material. Some fillings are to elliptical spots and short bars, some of them branched (Figs. 4C, E– penetrates with the small form of Chondrites. Planolites is a facies G); they are cross sections of a branched tubular burrow system. The crossing form. It has been discussed by Pemberton and Frey (1982) branches are under acute angle. The filling is darker (Fig. 4D–G), rarely and Keighley and Pickerill (1995) and interpreted as a pascichnion, lighter than the host rock (Fig. 4C). Larger forms (Fig. 4C–G), 1.2– probably produced by a number of different organisms. 2 mm in diameter, and smaller forms, 0.3–0.9 mm diameter (Fig. 4E), Thalassinoides isp. (Figs. 4C–G, 5A, 6A–B, E, G–H, 7A–B, F, 8B–C) can be distinguished. At least some of the larger forms belong to occurs as straight or slightly winding, horizontal to oblique flattened, Chondrites targionii (Brongniart, 1828) and at least some of the unlined cylinders, showing Y-shaped, rarely T-shaped branches and smaller forms belong to Chondrites intricatus (Brongniart, 1823) but rare, vertical to oblique shafts. The cylinders are swollen at the limited observations along the tunnels preclude accurate determina- branching points, which are mostly 55–110 mm apart. The cylinders tions. The smaller form can be found in the fillings of some are filled with homogenous, or rarely meniscate, mostly darker Thalassinoides or Planolites, and the larger forms in Thalassinoides. sediment. The menisci are composed of thicker (up to 7 mm) dark Chondrites von Sternberg, 1833 is a feeding system of unknown portions and narrower (up to 3 mm) light portions. Rarely, granulated trace makers (e.g., Osgood, 1970) which, according to Kotake (1991a), filling composed of light and dark chips of fine-grained sediment, less are surface ingestors, packing their faecal pellets inside burrows. that 1 mm in diameter, can be present. Some fillings are reworked According to Seilacher (1990) and Fu (1991), the tracemaker may be with the larger or smaller Chondrites (Figs. 4F, 5A). Prevailing smaller able to live at the aerobic–anoxic interface as a chemosymbiotic forms are 4–9 mm in diameter, with swellings up to 15 mm wide. organism. Some forms, especially in the Danian (Fig. 8C), are larger, 15–30 mm 48 F.J. Rodríguez-Tovar et al. / Sedimentary Geology 234 (2011) 42–55

Fig. 6. Ichnofabrics and trace fossils of the boundary layer at Bidart. A) Dark-filled Thalassinoides isp. (Th) cross cut by Chondrites isp. (Ch), Planolites isp. (Pl); rough surface of the totally bioturbated pinkish top Maastrichtian marlstones; field photograph. B) Dark-filled larger Thalassinoides isp. cross cut by a smaller one; rough surface at the top of pinkish Maastrichtian marlstones; sample Bd13A. C) Dark-filled Zoophycos isp., polished slab from the top of pinkish Maastrichtian marlstones; sample Bd13B. D) Dark-filled Chondrites isp. (Ch) and Planolites isp. (Pl). Rough surface at the top of pinkish Maastrichtian marlstones, sample Bd13C. E) Thalassinoides isp. (Th), Chondrites isp. (Ch) and Planolites isp. (Pl), all in the totally bioturbated background; polished slab; the boundary layer, sample Bd 17. F) Chondrites isp. (Ch)infilling of Thalassinoides isp. in the totally bioturbated background; in the middle part primary lamination (pl), bioturbated layer at the top; polished slab; the boundary layer, sample Bd 18. G) Thalassinoides isp. (Th) and Chondrites isp. (Ch) in the totally bioturbated background; polished slab; the boundary layer, sample Bd 19. H) Zoophycos isp. cross cut by ?Planolites isp. (Pl) and ?Thalassinoides isp. (Th); parting surface; top of the boundary layer, sample Bd 20. in diameter, with swellings up to 35 mm wide. At Bidart, smaller 1984). For further discussion of this ichnogenus and its ichnotaxo- forms commonly penetrate along fillings of older generation, larger nomic problems see Fürsich (1973), Ekdale (1992) and Schlirf (2000). Thalassinoides; and both are filled with dark sediment (Fig. 6B). The Trichichnus isp. (Figs. 4G, 5C) is a winding or straight, differently prevailing Y-shaped branches and swellings suggest assignation to oriented, rarely branched, 0.2–0.3 mm thick (rarely up to 0.7 mm), Thalassinoides suevicus Rieth, 1932. thread-like cylinder filled with ferruginous substance, with a Thalassinoides Ehrenberg, 1944 is a domichnial and fodinichnial yellowish halo around the cylinder. Trichichnus Frey, 1970 is a structure produced by crustaceans, mostly decapods (Frey et al., eurybathic marine trace fossil, which is common in fine-grained F.J. Rodríguez-Tovar et al. / Sedimentary Geology 234 (2011) 42–55 49

Fig. 7. Ichnological and sedimentological features of the lowest Danian sediments in the Sopelana B section. A) Bioturbational structures with Thalassinoides isp. (Th) in the K–Pg boundary layer, horizontal section, sample So-86. B) As in A but with ?Thalassinoides isp. (?Th). C, D) Laminated sediments of the K–Pg boundary layer, vertical sections, sample So-89. E) Debris ﬂow calcilutites above the boundary layer, vertical section, sample So-91. F) Partly bioturbated top of the bed represented by sample So-89, Thalassinoides (Th), horizontal section.

Fig. 8. Ichnofabrics and trace fossils of the Danian limestones and marlstones. A) Totally bioturbated marly limestones with Zoophycos isp. (Zo); vertical section, polished slab; sample 22. B, C) Thalassinoides isp. (Th), Chondrites isp. (Ch) and Planolites isp. (Pl) in totally bioturbated background; weathering surface. D) Zoophycos isp. cross cut by Planolites isp. (Pl), weathering surface. 50 F.J. Rodríguez-Tovar et al. / Sedimentary Geology 234 (2011) 42–55 sediments. Trichichnus is regarded as the domichnial burrows of Chondrites penetrates up to −25 cm at Bidart, −40 cm at Sopelana marine meiofaunal deposit feeders (Frey, 1970). Possibly, the B and −22 cm at Sopelana A. Thalassinoides was found up to −32 cm producer of Trichichnus was a chemosymbiont (Uchman, 1995), as at Bidart and −40 cm at Sopelana B, and −20 cm at Sopelana A. in the case of the Chondrites producer (Fu, 1991; Seilacher, 1990). Planolites is still present at −40 cm at Bidart, −30 cm at Sopelana B; McBride and Picard (1991) suggest that Trichichnus had a more dark-filled Planolites was not found at Sopelana A. opportunistic character than Chondrites because it occurs more deeply The values are minimal because the burrows can be filled from in very poorly oxygenated sediments. For taxonomic discussion see different levels above the boundary rusty layer, corresponding to Uchman (1999). 38 cm thick (15 cm thick dark clay layer + 23 cm thick reddish to Zoophycos isp. (Figs. 4H–I, 5B, 6C, 8A–D) occurs on parting surfaces greenish marls) at Bidart, and at least 22 cm thick at Sopelana A and at as horizontal or oblique lobes and tongues, up to 40 cm wide, filled least 25 cm thick at Sopelana B of green-grey marls. Data from the with spreite laminae encircled by a thin marginal tunnel. In cross Sopelana A section are not fully representative because of limited section it is seen as straight or curved stacked stripes, 1.5–4 mm thick, number of samples obtained by digging due to outcrop constraints. 7–28 mm apart, which can be massive or filled with spreite These data should be rather treated as complementary to the manifested on the surface as menisci-like structures. They are a part Sopelana B section. of a helical burrow system. Trichichnus is filled with pyritized sediment and ?Phycosiphon with Zoophycos s.l. is generally considered a structure produced by some light material. Therefore, depth of penetration of these ichnotaxa yet undiscovered deposit-feeder, which is referred to sipunculids cannot be measured in respect to the boundary layer. However, it is (Wetzel and Werner, 1981), polychaete annelids, arthropods (Ekdale known that Phycosiphon belongs to shallow and moderate deep tiers and Lewis, 1991), or echiuran worms (Kotake, 1992). Kotake (1989, and Trichichnus is a deep-tier burrow (e.g., Uchman, 1999). 1991b) reported that Zoophycos is produced by surface ingestors of organic detritus. However, the precise ethological interpretation of 4.2.4. Trace fossil distribution through the K/Pg boundary interval Zoophycos remains still controversial. Bromley and Hanken (2003) The boundary layer at Bidart contains the rusty layer at the base, suggested that the upper helical part of a large Pliocene Zoophycos just above 1–2 cm thick, grey, thin, totally bioturbated marly from Rhodes, Greece, is a deposit-feeding structure, and lateral lobes mudstone (Fig. 9). The rusty layer is only partly bioturbated. Above, developing from its lower part are sulphide wells for chemosymbiotic the boundary layer is totally bioturbated, except for two laminated bacteria. The same interpretation refers to a similar but smaller intervals, which are crossed only by some trace fossils (Fig. 6F). At Zoophycos from the Miocene of Austria, which displays very steep Sopelana (Fig. 4A–B), the boundary layer is disturbed by tectonic lobes in its lowermost part (Pervesler and Uchman, 2004). sliding, therefore its primary internal structure is partly obliterated. In the Sopelana A section, the boundary layer is totally bioturbated, with 4.2. Ichnological features two rusty laminae in the lower part (Fig. 9). In the Sopelana B section, the boundary layer is totally bioturbated (Fig. 7A–B) except for its 4.2.1. Abundance of trace fossils, and size of Thalassinoides uppermost laminated few centimetres (Fig. 7C–D). The trace fossils The trace fossil abundance (number of specimens and visual content of the boundary layer is almost the same as the dark-filled density estimations), and size of Thalassinoides, varies significantly trace fossil assemblage. between the Bidart and Sopelana sections (Sopelana A and B sections In the lowest 2 m of Danian above the boundary layer at Bidart, considered together). Thalassinoides is distinctly more abundant and trace fossils are poorly recorded (Fig. 9); partly by diagenetic larger at Bidart (mean diameter of 35 specimens=10.1 mm, maximal obliteration in the lower part and by the presence of the debris flow width 30 mm) than at Sopelana (mean diameter of 28 speci- calcirudite beds (Fig. 3D) in the upper part. The top of the first mens=6.4 mm, maximal width 14 mm). The larger Chondrites is calcirudite layer is bioturbated and contains ?Thalassinoides. The beds around two times more abundant in the K/Pg boundary at Bidart than of the first metres are at least partly bioturbated, but no discrete trace at Sopelana. Reverse tendency is clear for the smaller Chondrites and fossils was recognized. Above, well preserved Chondrites, Planolites, very distinctly (by more or less four times) for Trichichnus. Zoophycos Thalassinoides and Zoophycos, are well visible on bioturbated is comparatively more abundant at Bidart than at Sopelana. ? background (Fig. 8A–D). Phycosiphon has been only recognized at Sopelana. At Sopelana, the first metre of sediments above the boundary layer is totally bioturbated (Fig. 9) except for the debris flow deposits 4.2.2. Feeding behaviour (Fig. 7E–F). In the bioturbated parts, trace fossils are poorly visible, The trace fossil assemblage reveals different feeding behaviour. probably due to poor colour contrast and diagenetic obliteration. They belong to domichnia/fodinichnia (Thalassinoides), chemichnia (Chondrites, Trichichnus), pascichnia (Planolites) and fodinichnia 5. Discussion (Zoophycos,?Phycosiphon). All of them indicate that the tracemakers obtained food from sediment. 5.1. Trace fossil assemblage, abundance of trace fossils, size of Thalassinoides and depositional environment 4.2.3. Depth of penetration The dark filling of some trace fossils located in the uppermost The trace fossil assemblage is low diverse. All the ichnotaxa Maastrichtian sediments clearly derives from the dark sediments of identified are rather common in fine-grained, low-energy open- the K/Pg boundary layer (black-filled trace fossil ranges in Fig. 9). marine sediments of the Mesozoic and Cenozoic. Their low diversity Detailed microfacies analysis at Sopelana, especially in section B, and the presence of Zoophycos suggest the Zoophycos ichnofacies, reveals the presence of numerous dark-filled trace fossils coming which typically occurs down the offshore but beyond the areas of down from the dark-boundary layer into the light upper Maastrich- turbiditic sedimentation (e.g., Frey and Seilacher, 1980). The total tian sediments. Dark-filled Chondrites and Zoophycos are present from bioturbation of the fine-grained calcareous sediments that character- several centimetres above to below the K/Pg boundary. Zoophycos and ized the two K/Pg boundary sections studied, and the general lack of Chondrites are the deeper trace fossils. In the Bidart section, large storm or turbiditic beds agrees with this general interpretation. Thus, dark-coloured Zoophycos isp. is the deepest trace, in some cases ichnological data point to upper bathyal zone, with no significant penetrating up to −45 cm (45 cm below the K/Pg boundary layer) in differences between the depositional settings corresponding to both the marlstones underlying the K/Pg boundary surface. In the Sopelana sections. This interpretation accords partly with previous data based B section it occurs at depths of −22 cm below the boundary. on microfossil assemblages. The dominance of calcareous taxa in the F.J. Rodríguez-Tovar et al. / Sedimentary Geology 234 (2011) 42–55 51

Fig. 9. The K/Pg boundary sections at Bidart and Sopelana showing the boundary layer and trace fossil ranges.

Upper Maastrichtian and lower Danian benthic foraminiferal assem- and thus a dominance of smaller forms (small Chondrites, and blages from the Bidart section are interpreted as indicating upper– Trichichnus). This is in accordance to the decrease of both macro- middle bathyal depths between 500 and 700 m (Alegret et al., 2004). benthic biomass (Rowe, 1983) and number of macrofaunal organisms Kuhnt and Kaminski (1993) assigned middle bathyal water depth to with increasing depth, especially rapid in the first 2 km (Rowe, 1983; the Maastrichtian–Paleocene of the Zumaia section, comparable with Rowe et al., 1982), and the decrease of biomass with distance to the the Sopelana section, based on agglutinated foraminiferal assem- shore (if not disturbed by upwellings and other currents) (Gage and blages, with absolute values at about 1.000 m depth suggested by Tyler, 1991, and references therein). Also the size of the animals Herm (1965). decreases generally with increasing depth (e.g., Gage and Tyler, 1991; According to sequence stratigraphic analyses (Fig. 1), the K/Pg Thiel, 1975). Thus, the variability within the Zoophycos ichnofacies can boundary transition is included in a transgressive system tract (TST) be a proxy of food availability related in simple cases to the distance belonging to a 3rd order depositional sequence (Apellaniz et al., 1997; from the shore and water depth. Smaller size of ichnotaxa and Baceta, 1996; Pujalte et al., 1998). The top of this sequence is related to decrease in abundance of larger trace fossils can point to more distant an erosive event, resulting from a sea-level drop, reflected by breccias and deeper settings. well developed at the Bidart section. This interpretation accords with that from Peybernés et al. (1996), interpreting that the breccias were 5.2. Feeding behaviour, nutrients availability and oxygenation of deposited under conditions of low sea level, and the underlying sediments limestones under high sea-level conditions. Other possibility is that they could be interpreted as a slump triggered by local tectonics The presence of chemichnia and trace fossils which tracemakers during the early Danian (Alegret et al., 2004). For Seyve (1984), the sequestered sediments from the sea floor in deep burrows (Zoophy- Bidart section can be interpreted as located close to a palaeoslope. cos) suggest at least periodical food deficiency pressing animals to Alegret et al. (2004) interpreted that the dominance of calcareous more sophisticated searching for food. benthic foraminifera through the Bidart section may be indicative of a Variations between oligotrophic and mesotrophic conditions have small supply of terrigenous sediment at Bidart as compared to the been alluded to interpret marked quantitative changes in benthic coeval Sopelana section (Kuhnt and Kaminski, 1993), where agglu- community structure through the K/Pg boundary transition in both tinated foraminifera are dominant. sections (Alegret et al., 2004; Kuhnt and Kaminski, 1993). In the The higher abundance of Thalassinoides and its larger size, higher Sopelana sections, major change in the quantitative composition of abundance of Zoophycos and larger Chondrites, lower abundance of deep-sea agglutinated foraminiferal community structure is related, Trichichnus and small Chondrites at Bidart than at Sopelana can be probably, to a dramatic drop of productivity in surface waters, nearly related to palaeogeographic position and the distance of the basin instantaneously with the terminal Cretaceous event, that determined margin. The Sopelana section occupied a more basinal position than the collapse of the food web for benthic communities (Kuhnt and the Bidart section during the Maastrichtian and Paleocene. This can Kaminski, 1993). At the lower part of the boundary clay, just after the result in a slightly greater depth, as confirmed by the foraminiferal K/Pg boundary, they record the predominance of low-oxygen tolerant data, and lesser food supply at Sopelana than at Bidart. Environmental and infaunal agglutinated foraminiferal assemblages, in relation to stress related to decrease in food can result in decrease in abundance oligotrophic surface conditions. Coarsely agglutinated forms are of larger trace fossils (Thalassinoides, larger Chondrites, and Zoophycos) common, indicating the increase in detrital supply to the deep sea, 52 F.J. Rodríguez-Tovar et al. / Sedimentary Geology 234 (2011) 42–55 which Kuhnt and Kaminski (1993) interpret in terms of a short-lived Maastrichtian sediments at the Bidart section could be related with regressive event. Although not present in Sopelana, cm-thick a higher rate of sedimentation; a 40 mm/kyr sedimentation rate for siliciclastic or mixed carbonate-siliciclastic turbidites occur overlying the Maastrichtian is calculated for the Bidart section (Nelson et al., or within the K/Pg clay in several basinal sections in the area between 1991) against 25 mm/ky for the Sopelana section (Mary et al., 1991). Sopelana and Bidart (e.g., Zumaia, Urrutxua, Herrera or Monte Urko; Baceta, 1996; Apellaniz, 1998). Thus, the relative abundance of 5.4. The Cretaceous–Paleogene (K–Pg) event incidence coarsely agglutinated foraminifers could be explained rather by the presence of discrete levels rich in resedimented sand detrital grains. The trace fossil assemblage can be considered with respect to the In the Bidart section, benthic assemblage shows a similar pattern K–Pg event. The content of pre-event latest Maastrichtian ichnoas- (Alegret et al., 2004). Upper Maastrichtian benthic foraminiferal semblage, characterized by light-filled trace fossils is nearly the same assemblages are diverse and heterogeneous, with infaunal and as the lowest Danian ichnoassemblage characterized by dark filling epifaunal forms, revealing mesotrophic conditions. At the K/Pg deriving from the boundary layer (Figs. 4D–I, 6A–D). Light-filled boundary, a drastic decrease in diversity and heterogeneity is Zoophycos has not been observed in the uppermost 7 m of Maas- recorded, which is coeval with a major diminution in the percentage trichtian at Sopelana, but it is present below. Trichichnus was not of infaunal taxa. This drastic change is related to a significant decrease detected at above the boundary layer at Bidart and at Sopelana. Thus, in the food supply from surface waters to the sea floor, oligotrophic according to trace fossil assemblages, the K/Pg boundary event reveals conditions, due to the collapse of the food web accompanying the a minor incidence on macrobenthic environment. Previous trace fossil mass extinction of primary producers (during very limited food analyses in other K/Pg boundary sections have revealed that changes supply to the sea floor, food particles were consumed at the sediment in environmental parameters at the seafloor during the deposition of surface by epifaunal species, whereas the percentage of infaunal the K/Pg boundary sediments did not significantly affect colonization species decreased due to the lack of organic matter in the underlying by macrobenthic tracemakers, showing a relatively rapid colonization, sediment). In the early Danian, the low diversity of the assemblages, specially by organisms with a high independence with respect to together with the low percentage of infaunal forms, suggests that substrate features (i.e., Chondrites and Zoophycos tracemakers; primary productivity had not completely recovered for more than Rodríguez-Tovar and Uchman, 2004a, 2006, 2008; Rodríguez-Tovar, 200 kyr after the K/Pg boundary event. However, even if benthic 2005; Rodríguez-Tovar and Martín-Peinado, 2009). This compara- foraminifera indicate oligotrophic conditions just after the K/Pg tively minor incidence in sections the here studied, accords with that boundary, blooms of dinoflagellates have been documented in the interpreted for the benthic environment based on microfossils dark clay layer (Peybernés et al., 1996), which would have provided data. Benthic foraminifera assemblage reveals similar response large amounts of food that reached the sea floor. For Alegret et al. through the K/Pg boundary transition in the Sopelana (Kuhnt and (2004), primary productivity during the early Danian was dominated Kaminski, 1993) and Bidart (Alegret et al., 2004) sections. As is by blooms of non-calcareous primary producers; such a change in generally recognized at the K/Pg boundary, benthic foraminifers did phytoplankton composition induced a stressful environment for the not experienced significant extinction (only three species disappears benthic fauna. These authors indicated that it was not only the drastic in Bidart; Alegret et al., 2004) in any of both sections, comparing with decrease in primary productivity, but also the changes in phytoplank- the well known mass extinction of planktic organisms which is ton type (from calcareous to organic-walled phytoplankton) just after interpreted as revealing a weak benthopelagic coupling at that time the K/Pg boundary that caused the low diversity, high-dominance (Alegret et al., 2004 and references therein). However, marked benthic foraminiferal assemblages from the lower part of the dark clay quantitative changes in their community structure (percentage of layer (Alegret et al., 2004). It seems, however, that the changes did not particular morphogroups, diversity, etc.), are evident and mainly influenced tracemakers. related to changes in productivity at the K/Pg boundary (see above; Total bioturbation of sediments (except for some interval of the Kuhnt and Kaminski, 1993; Alegret et al., 2004). In the Sopelana boundary layer and the debris flow sediments in the Danian) suggest section, benthic foraminiferal populations show a slow recovery that generally good oxygenation below sediment–water interface. Data took at least 50 ky following the K/Pg boundary event (Kuhnt and from benthic microfossils do not reveal a significant incidence of low Kaminski, 1993). oxygenation in microbenthic environment (Alegret et al., 2004; Kuhnt The planktic foraminiferal extinction pattern in the Bidart section and Kaminski, 1993); only, as previously indicated, just after the K/Pg suggest a sudden catastrophic extinction at the K/Pg boundary, at the boundary at the Sopelana section, low-oxygen tolerant and infaunal base of the 2 mm thick rusty layer, affecting, at least 53 species out of agglutinated foraminiferal assemblages are dominant, but mainly the 72 species registered at the uppermost Maastrichtian (Gallala related to oligotrophic conditions (Kuhnt and Kaminski, 1993). et al., 2009).

5.3. Depth of penetration and rate of sedimentation 5.5. Bioturbational redistribution of sediment components through the K/Pg boundary event The penetration depth of the dark-filled trace fossils can be treated as frozen tiering pattern of burrows (Bromley, 1996). At Bidart the One especially important aspect to be taken into consideration is the deepest trace fossil is Zoophycos, similarly to the Caravaca section in possible bioturbational disturbance of the K/Pg boundary, a fact which the Betic Cordillera (Rodríguez-Tovar and Uchman, 2006). Zoophycos is usually underestimated. Detailed ichnological analysis in the tracemaker probably preferred the partly stiff or partly firm substrate Caravaca section (SE Spain), revealed that trace fossils range contin- of the Maastrichtian marls, which were dewatered during the slowly uously from the lowermost Danian to the uppermost Maastrichtian accumulating Danian dark-boundary layer. The increased cohesion sediments, with the rusty layer being cross cut by Zoophycos and may have prevented the Chondrites tracemaker to get deeper Chondrites, and also penetrated laterally by Chondrites (Rodríguez- penetration. Commonly, Chondrites, is the deepest tier burrow in the Tovar and Uchman, 2008). Thus, the authors claimed on the possible Cretaceous marls (Ekdale and Bromley, 1991). Such a situation is met redistribution of the components related to the K/Pg boundary impact at Sopelana, however Thalassinoides penetrates almost to the same due to the tracemakers activity. Recently, the effects of different depth. Zoophycos is distinctly rarer here than at Bidart, what suggests tracemakers on the redistribution of calcareous nannofossils through- it was approaching to its environmental limit. In such a situation, the out the K/Pg boundary at the Bidart section have been revealed Zoophycos tracemaker could penetrate to smaller depth than in its (Rodríguez-Tovar et al., 2010). Bloom of the Paleogene calcareous optimal environment. A comparatively higher cohesion for the nannofossil appearances just below the K/Pg boundary are related to F.J. Rodríguez-Tovar et al. / Sedimentary Geology 234 (2011) 42–55 53 infiltration into dark trace fossil infillings proceeding from the earliest distal position of Sopelana relative to Bidart, with a slightly higher Paleogene. In the Sopelana sections a complex iridium distribution is depth and smaller food supply. recognized, with two iridium spikes registered in the dark-boundary Feeding strategies showing the presence of chemichnia and trace layer (the first coeval with the final Cretaceous planktonic foraminiferal fossils which tracemakers sequestered sediments from the sea floor in extinction, and the second in coincidence with the nannoplankton deep burrows (Zoophycos) denotes some intervals of periodical food crisis; plate B in Rocchia et al., 1988). As previously indicated, distri- deficiency pressing animals to more sophisticated searching for food. bution of dark-trace fossil in the Sopelana sections (Fig. 9) reveals that A generalized total bioturbation of sediments point to good the boundary layer is totally bioturbated, with a continuous record of oxygenation below sediment–water interface. Chondrites from the entire dark-boundary layer, except for its The similarity between the pre-event (light-filled trace fossils) and uppermost laminated few centimetres, to the uppermost Maastrichtian the post-event (dark-filled trace fossils) trace fossil assemblage sediments. Moreover, Planolites and Thalassinoides range from the reveals a minor incidence of the K/Pg boundary event on the macro- lower part of the dark-boundary layer to the uppermost Maastrichtian benthic environment. The near continuous record of dark-filled trace sediments, except for Zoophycos registered only in the dark-boundary fossils through the K/Pg boundary interval, from the upper part of the layer. Thus the interval of the dark-boundary layer recording the two dark-boundary layer, especially in the Sopelana section, to the iridium spikes is affected by an important significant bioturbation. uppermost Maastrichtian sediments prevent on a possible redistri- Therefore, a redistribution by tracemakers activity affecting iridium bution of the biotic and abiotic components. concentration in the dark-boundary layer is possible in the Sopelana sections, but a more detailed analysis, out of the focus of this research, is necessary for confirmation, even more taking into account that Acknowledgements recently, the relatively mobile behaviour of iridium within the sediments in depth has been demonstrated (Martín-Peinado and The field research was partially supported by the Basque Country Rodríguez-Tovar, 2010; Miller et al., 2010; Racki et al., in press). University and by the Zaragoza University. Additional support for A.U. was given by the Jagiellonian University (DS funds). This research was 5.6. Continuity at the K/Pg boundary transition supported by projects CGL2008-03007/CLI, CGL2008-00009/BTE, and RNM-3715, and the research group RNM-178. As previously commented, the Bidart section can be considered as one of the most complete K/Pg boundary sections exposed in the eastern margin of the Atlantic Ocean (Apellaniz et al., 1997; Haslett, References 1994; Seyve, 1990). Recent magnetostratigraphic, calcareous nanno- Alegret, L., 2007. Recovery of the deep-sea floor after the Cretaceous–Paleogene fossil and planktic foraminifera analyses reveal a continuous sedi- boundary event: the benthic foraminiferal record in the Basque–Cantabrian basin mentation across the K/Pg boundary transition, without any and in South-eastern Spain. Palaeogeography, Palaeoclimatology, Palaeoecology biostratigraphically significant hiatus (Galbrun and Gardin, 2004; 255, 181–194. Alegret, L., Kaminski, M.A., Molina, E., 2004. Paleoenvironmental recovery after the Gallala et al., 2009). However at the Sopelana section, the lowermost Cretaceous/Paleogene boundary crisis: evidence from the marine Bidart section part of the Paleogene (Guembelitria cretacea Zone) was not identified (SW France). Palaios 19, 574–586. (Lamolda et al., 1983; Mary et al., 1991), and graphic correlation Apellaniz, E., 1998. Los foraminíferos planctónicos en el tránsito Cretácico-Terciario. Ph.D. Thesis, Universidad del País Vasco, España. analysis indicated the incompleteness of the Sopelana section with Apellaniz, E., Baceta, J.I., Bernaola-Bilbao, G., Nuñez-Betelu, K., Orue-Etxebarria, X., the absence of the Zone P0 estimated in 50,000 yr in duration Payros, A., Pujalte, V., Robin, E., Rocchia, R., 1997. Analysis of uppermost (MacLeod and Keller, 1991; MacLeod et al., 1997). The distribution of Cretaceous-lowermost Tertiary hemipelagic successions in the Basque Country (western Pyrenees): evidence for a sudden extinction of more than half planktic trace fossils in the Sopelana section does not reveal any evident foraminifer species at the K/T boundary. Bulletin de la Societé Géologique de France disruption of ichnological features, but a continuous and similar 168, 783–793. record from the dark-boundary layer to the upper Maastrichtian Baceta, J.I., 1996. El Maastrichtiense superior, Paleoceno e Ilerdiense inferior de la sediments. Macrobenthic colonization of the dark-boundary layer Región Vasco-Cantábrica: secuencias, cronoestratigrafía y paleoceanografía. Ph.D. Thesis, Universidad de Zaragoza, España. could be conducted 50,000 yr after the K/Pg boundary, according to Baceta, J.I., Pujalte, V., Serra-Kiel, J., Robador, A., Orue-Etxebarria, X., 2004. La Cordillera the estimation of the duration of the absent Zone P0 (MacLeod and Pirenaica: Maastrichtiense superior, Paleoceno e Ilerdiense inferior. In: Vera, J.A. – Keller, 1991; MacLeod et al., 1997). However, during this time (Ed.), Geología de España: SGE-IGME, pp. 308 313. Bromley, R.G., 1996. Trace Fossils. Biology, Taphonomy and Applications, Second changes in substrate features (i.e., substrate consistency) around the Edition. Chapman & Hall, London. K/Pg boundary must be envisaged, determining variations in the Bromley, R.G., Hanken, N.-M., 2003. Structure and function of large, lobed Zoophycos, ichnological features which were no registered. Thus, the absence of Pliocene of Rhodes, Greece. Palaeogeography, Palaeoclimatology, Palaeoecology 192, 79–100. sediments corresponding to an estimated duration of 50,000 yr is not Brongniart, A.T., 1823. Observations sur les Fucoïdes. Société d'Historie Naturelle de confirmed by ichnological analysis. Paris, Mémoire 1, 301–320. Brongniart, A.T. 1828. Histoire des végétaux fossiles ou recherches botaniques et géologiques sur les végétaux renfermés dans les diverses couches du globe, 1. G. 6. Concluding remarks Dufour and E. d'Ocagne, Paris. Canudo, J.J., 1994. Bioestratigrafía y evolución de los foraminíferos planctónicos en Ichnological analysis at the K/Pg boundary transition in the Bidart el tránsito Cretácico-Terciario en España. In: Molina, E. (Ed.), Evolución y registro fossil: Cuadernos Interdisciplinares de la Universidad de Zaragoza, vol. 5, (SE France) and Sopelana (N Spain) sections reveals a low diverse pp. 141–165. trace fossil assemblage, with five common ichnogenera (Chondrites, Dinarès-Turell, J., Baceta, J.I., Pujalte, V., Orue-Etxebarria, X., Bernaola, G., Lorito, S., Planolites, Thalassinoides, Trichichnus and Zoophycos), together with ? 2003. Untangling the Paleocene climatic rhythm: and astronomical calibrated Early Phycosiphon registered only in the Sopelana section. This assemblage Paleocene magnetostratigraphy and biostratigraphy at Zumaia (Basque basin, northern Spain). Earth and Planetary Science Letters 216, 483–500. suggests the Zoophycos ichnofacies, which typically occurs down the Dinarès-Turell, J., Baceta, J.I., Bernaola, G., Orue-Etxebarria, X., Pujalte, V., 2007. Closing offshore but beyond the areas of turbiditic sedimentation. the Mid-Palaeocene gap: toward a complete astronomically tuned Palaeocene Epoch and Selandian and Thanetian GSSPs at Zumaia (Basque Basin, W Pyrenees). Minor differences in the earliest Danian ichnoassemblage (dark- – fi Earth and Planetary Science Letters 262, 450 467. lled trace fossils) between sections are related to palaeogeographic Ehrenberg, K., 1944. Ergänzende Bemerkungen zu den seinerzeit aus dem Miozän von position within the upper bathyal zone and to the distance to the Burgschleinitz beschrieben Gangkernen und Bauten dekapoder Krebse. Paläonto- basin margin. The higher abundance of large Thalassinoides, Zoophycos logische Zeitschrift 23, 345–359. Ekdale, A.A., 1992. Muckraking and mudslinging: the joys of deposit-feeding. In: and larger Chondrites, and lower abundance of Trichichnus and small Maples, C.G., West, R.R. (Eds.), Trace Fossils: The Paleontological Society Short Chondrites, at Bidart than at Sopelana, is in agreement with a more Courses in Paleontology, Vol. 5, pp. 145–171. 54 F.J. Rodríguez-Tovar et al. / Sedimentary Geology 234 (2011) 42–55

Ekdale, A.A., Bromley, R.G., 1984. Sedimentology and ichnology of the Cretaceous– Orue-Etxebarria, X., 1984. Los foraminíferos planctónicos del Paleógeno del Sinclinorio Tertiary boundary in Denmark: implications for the causes of the terminal de Bizkaia (Corte de Sopelana–Punta de la Galea). Kobie 14, 351–429. Cretaceous extinction. Journal of Sedimentary Petrology 54, 681–703. Orue-Etxebarria, X., 1985. Descripción de Globigerina hillebralldti n. sp. en ellimite Ekdale, A.A., Bromley, R.G., 1991. Analysis of composite ichnofabrics: an example in Cretácico/Terciario de 1a sección de Sopelana (Pais Vasco). Evolución de los uppermost Cretaceous chalk of Denmark. Palaios 6, 232–249. primeros foraminíferos planctónicos al comienzo del Terciario. Newsletters on Ekdale, A.A., Lewis, D.W., 1991. The New Zealand Zoophycos revisited. Ichnos 1, Stratrigraphy 15, 71–80. 183–194. Osgood, R.G., 1970. Trace fossils of the Cincinnati Area. Palaeontographica Americana 6, Ekdale, A.A., Stinnesbeck, W., 1998. Trace fossils in Cretaceous–Tertiary (KT) boundary 193–235. beds in northeastern Mexico: implications for sedimentation during the KT Pemberton, G.S., Frey, R.W., 1982. Trace fossil nomenclature and the Planolites– boundary event. Palaios 13, 593–602. Palaeophycus dilemma. Journal of Paleontology 56, 843–881. Fischer-Ooster, C., 1858. Die fossilen Fucoiden der Schweizer-Alpen, nebst Erörterun- Pervesler, P., Uchman, A., 2004. Ichnofossils from the type area of the Grund Formation gen über deren geologisches Alter. Huber, Bern. (Miocene, Lower Badenian) in northern Lower Austria (Molasse Basin). Geologica Frey, R.W., 1970. Trace fossils of Fort Hays Limestone Member of Niobrara Chalk (Upper Carpathica 55, 103–110. Cretaceous), West-Central Kansas. The University Kansas Paleontological Con- Peybernés, B., Fondecave-Wallez, M.J., Eichène, P., Bost, J., Sibe, B., Marais, M., Quilès, G., tributions 53, 1–41. 1996. La Limite Crétacé–Paléocène: Phénomènes Biologiques, Evénements Géolo- Frey, R.W., Seilacher, A., 1980. Uniformity in marine invertebrate ichnology. Lethaia 23, giques d'après les Sites de la Côte Basque. Centre Régional de Documentation 183–207. Pédagogique d'Aquitaine, Bordeaux. Frey, R.W., Curran, A.H., Pemberton, G.S., 1984. Tracemaking activities of crabs and their Plaziat, J.C., 1981. Late Cretaceous to late Eocene paleogeographic evolution of environmental significance: the ichnogenus Psilonichnus. Journal of Paleontology southwest Europe. Palaeogeography, Palaeoclimatology, Palaeoecology 36, 58, 511–528. 263–320. Fu, S., 1991. Funktion, Verhalten und Einteilung fucoider und lophoctenoider Pujalte, A., Baceta, J.I., Orue-Etxebarria, X., Payros, A., 1998. The Paleocene of the Basque Lebensspuren. Courier Forschungsinstitut Senckenberg 135, 1–79. Country, W Pyrenees, Spain: facies and sequence development in a deep-water Fürsich, F.T., 1973. A revision of the trace fossils Spongeliomorpha, Ophiomorpha and starved basin. In: de Graciansky, P.C., Hardenbol, J., Jacquin, T., Vail, P.R. (Eds.), Thalassinoides. Neues Jahrbuch für Geologie und Paläontologie Monatschefte 12, Mesozoic and Cenozoic Sequence Stratigraphy of European Basins: SEPM, Concepts 719–735. in Sedimentology and Paleontology, vol. 60, pp. 311–325. Gage, J.D., Tyler, P.A., 1991. Deep-Sea Biology: A Natural History of Organisms at the Racki, G., Machalski, M., Koeberl, C., Harasimiuk, M., in press. The weathering-modified Deep-Sea Floor. Cambridge Univ. Press, Cambridge. record of a new Cretaceous-Palaeogene site at Lechówka near Chelm, SE Poland, Galbrun, B., Gardin, S., 2004. New chronostratigraphy of the Cretaceous–Paleogene and its palaeobiologic implications. Acta Paleontologica Polonica 55, (in press), boundary interval at Bidart (France). Earth and Planetary Science Letters 224, 19–32. doi:10.4202/app.2010.0062. Gallala, N., Zaghbib-Turki, D., Arenillas, I., Arz, J.A., Molina, E., 2009. Catastrophic mass Rieth, A., 1932. Neue Funde spongeliomorpher Fucoiden aus dem Jura Schwabens. extinction and assemblage evolution in planktic foraminifera across the Creta- Geologische und Paläontogische Abhandlungen, N.F. 19, 257–294. ceous/Paleogene (K/Pg) boundary at Bidart (SW France). Marine Micropaleontol- Rocchia, R., Boclet, D., Bonté, P., Buffetaut, E., Orue-Etxebarria, X., Jaeger, J.-J., Jéhanno, ogy 72, 196–209. C., 1988. Structure de l'anomalie en iridium à la limite Crétacé-Tertiarie du site de Gorostidi, A., Lamolda, M.A., 1995. La nanoflora calcárea y el tránsito KT de la sección de Sopelana (Pays Basque Espagnol). Comptes Rendus de lÁcadémie des Sciences de Bidart (SW de Francia). Revista Española de Paleontología extra, pp. 153–168. Paris 307, 1217–1223. Haslett, S.K., 1994. Planktonic foraminiferal biostratigraphy and paleoceanography of Rodríguez-Tovar, F.J., 2005. Fe-oxide spherules infilling Thalassinoides burrows at the the Cretaceous–Tertiary boundary section at Bidart, South-west France. Cretaceous Cretaceous–Paleogene (K–P) boundary: evidence of a near-contemporaneous Research 15, 179–192. macrobenthic colonization during the K–P event. Geology 33, 585–588. Herm, D., 1965. Mikropalaeontologische-stratigraphische Untersuchungen in Kreide- Rodríguez-Tovar, F.J., Martín-Peinado, F.J., 2009. The environmental disaster of flysch zwischen Deva und Zumaya (Prov. Guipúzcua, Nordspanien). Zeitschrift der Aznalcóllar (southern Spain) as an approach to the Cretaceous–Palaeogene mass Deutschen Geologischen Gesellschaft 15, 277–348. extinction event. Geobiology 7, 533–543. Keighley, D.G., Pickerill, R.K., 1995. The ichnotaxa Palaeophycus and Planolites: historical Rodríguez-Tovar, F.J., Uchman, A., 2004a. Trace fossils after the K–T boundary event perspectives and recommendations. Ichnos 3, 301–309. from the Agost section, SE Spain. Geological Magazine 141, 429–440. Kotake, N., 1989. Paleoecology of the Zoophycos producers. Lethaia 22, 327–341. Rodríguez-Tovar, F.J., Uchman, A., 2004b. Ichnotaxonomic analysis of the Cretaceous/ Kotake, N., 1991a. Packing process for filling material in Chondrites. Ichnos 1, 277–285. Palaeogene boundary interval in the Agost section, south-east Spain. Cretaceous Kotake, N., 1991b. Non-selective surface deposit feeding by the Zoophycos producers. Research 25, 635–647. Lethaia 24, 379–385. Rodríguez-Tovar, F.J., Uchman, A., 2006. Ichnological analysis of the Cretaceous– Kotake, N., 1992. Deep-sea echiurans: possible producers of Zoophycos. Lethaia 25, Palaeogene boundary interval at the Caravaca section, SE Spain. Palaeogeography, 311–316. Palaeoclimatology, Palaeoecology 242, 313–325. Kuhnt, W., Kaminski, M.A., 1993. Changes in the community structure of deep water Rodríguez-Tovar, F.J., Uchman, A., 2008. Bioturbational disturbance of the Cretaceous– agglutinated foraminifers across the K/T boundary in the Basque Basin (Northern Palaeogene (K–Pg) boundary layer: implications for the interpretation of the K–Pg Spain). Revista Española de Micropaleontología 25, 57–92. boundary impact event. Geobios 41, 661–667. Lamolda, M.A., Orue-Etxebarria, X., Proto-Decima, F., 1983. The Cretaceous–Tertiary Rodríguez-Tovar, F.J., Martínez-Ruiz, F., Bernasconi, S.M., 2002. Carbon isotope boundary in Sopelana (Biscay, Basque country). Zitteliana 10, 663–670. composition of bioturbation infills as indication of the macrobenthic-colonisation MacLeod, N.M., Keller, G., 1991. How complete are Cretaceous/Tertiary boundary timing across the Cretaceous–Tertiary boundary (Agost section, SE Spain). sections? A chronostratigraphic estimate based on graphic correlation. Geological Geochimica et Cosmochimica Acta 66, A644. Society of America Bulletin 103, 1439–1457. Rodríguez-Tovar, F.J., Martínez-Ruiz, F., Bernasconi, S.M., 2004. Carbon isotope evidence MacLeod, N., Rawson, P.F., Forey, P.L., Banner, F.T., Boudagher-Fadel, M.K., Bown, P.R., for the timing of the Cretaceous–Palaeogene macrobenthic colonisation at the Burnett, J.A., Chambers, P., Culver, S., Evans, S.E., Jeffery, C., Kaminski, M.A., Lord, A. Agost section (southeast Spain). Palaeogeography, Palaeoclimatology, Palaeoecol- R., Milner, A.C., Milner, A.R., Morris, N., Owen, E., Rosen, B.R., Smith, A.B., Taylor, P.D., ogy 203, 65–72. Urquhart, E., Young, J.R., 1997. The Cretaceous–Tertiary biotic transition. Journal of Rodríguez-Tovar, F.J., Martínez-Ruiz, F., Bernasconi, S.M., 2006. Use of high-resolution the Geological Society of London 154, 265–292. ichnological and stable isotope data for assessing completeness of a K–P boundary Martín-Peinado, F.J., Rodríguez-Tovar, F.J., 2010. Mobility of iridium in terrestrial section, Agost, Spain. Palaeogeography, Palaeoclimatology, Palaeoecology 237, environments: implications for the interpretation of impact-related mass-extinc- 137–146. tions. Geochimica et Cosmochimica Acta 74, 4531–4542. Rodríguez-Tovar, F.J., Uchman, A., Molina, E., Monechi, S., 2010. Bioturbational re- Mary, C., Moreau, M.G., Orue-Etxebarria, X., Apellaniz, E., Courtillot, V., 1991. distribution of Danian calcareous nannofossils in the uppermost Maastrichtian Biostratigraphy and magnetostratigraphy of the Cretaceous/Tertiary Sopelana across the K–Pg boundary at Bidart, SW France. Geobios 43, 569–579. section (Basque country). Earth and Planetary Science Letters 106, 133–150. Rowe, 1983. Biomass and production of deep-sea biomass. In: Rowe, G.T. (Ed.), Deep- McBride, E.F., Picard, D.M., 1991. Facies implications of Trichichnus and Chondrites in sea Biology. Wiley-Interscience, New York, pp. 97–121. turbidites and hemipelagites, Marnoso-arenacea Formation (Miocene), Northern Rowe, G.T., Polloni, P.T., Haedrich, R.L., 1982. The deep-sea macrobenthos on the Apennines, Italy. Palaios 6, 281–290. Continental margin of the northwest Atlantic Ocean. Deep-Sea Research 29A, 257–278. Miller, K.G., Sherrell, R.M., Browning, J.V., Paul Field, M., Gallagher, W., Olsson, R.K., Schlirf, M., 2000. Upper Jurassic trace fossils from the Boulonnais (northern France). Sugarman, P.J., Tourto, S., Wahyudi, H., 2010. Relationship between mass extinction Geologica et Palaeontologica 34, 145–213. and iridium across the Cretaceous–Paleogene boundary in New Jersey. Geology 38, Schulte, P., Alegret, L., Arenillas, I., Arz, J.A., Barton, P.J., Bown, P.R., Bralower, T.J., 867–870. Christeson,G.L.,Claeys,P.,Cockell,C.S.,Collins,G.S.,Deutsch,A.,Goldin,T.J.,Goto, Molina, E., Alegret, L., Arenillas, I., Arz, J.A., Gallala, N., Hardenbol, J., Von Salis, K., Steurbaut, K., Grajales-Nishimura, J.M., Grieve, R.A.F., Gulick, S.P.S., Johnson, K.R., Kiessling, E., Vandenbeghe, N., Zaghbib-Turki, D., 2006. The global boundary stratotype section W., Koeberl, C., Kring, D.A., MacLeod, K.G., Matsui, T., Melosh, J., Montanari, A., and point for the base of the Danian Stage (Paleocene, Paleogene, "Tertiary", Cenozoic) Morgan,J.V.,Neal,C.R.,Nichols,D.J.,Norris,R.D.,Pierazzo,E.,Ravizza,G., at El Kef, Tunisia: original definition and revision. Episodes 29, 263–273. Rebolledo-Vieyra, M., Reimold, W.U., Robin, E., Salge, T., Speijer, R.P., Sweet, A.R., Naruse, H., Nifuku, K., 2008. Three-dimensional morphology of the ichnofossils Phycosiphon Urrutia-Fucugauchi,J.,Vajda,V.,Whalen,M.T.,Willumsen,P.S.,2010.The incertum and its implication for paleoslope inclination. Palaios 23, 270–279. Chicxulub asteroid impact and mass extinction at the Cretaceous–Paleogene Nelson, B.K., MaCleod, G.K., Ward, P.D., 1991. Rapid change in strontium isotopic Boundary. Science 327, 1214–1218. composition of sea water before the Cretaceous/Tertiary boundary. Nature 351, Seilacher, A., 1990. Aberration in bivalve evolution related to photo- and chemosym- 644–647. biosis. Historical Biology 3, 289–311. Orue-Etxebarria, X., 1983. Los Foraminíferos planctónicos del Paleógeno del Sinclinorio Seyve, C., 1984. Le passage Crétacé–Tertiaire à Pont Labau. Bulletin des Centres de de Bizkaia (Corte de Sopelana—Punta de la Galea). Kobie 13, 175–249. Recherches Exploration-Production Elf-Aquitaine 8, 385–423. F.J. Rodríguez-Tovar et al. / Sedimentary Geology 234 (2011) 42–55 55

Seyve, C., 1990. Nannofossil biostratigraphy of the Cretaceous–Tertiary boundary in the Uchman, A., 1995. Taxonomy and palaeoecology of flysch trace fossils: the Marnoso- French Barque Country. Bulletin Centre Recherches Exploration-Production Elf arenacea formation and associated facies (Miocene, Northern Apennines, Italy). -Aquitaine 14, 553–572. Beringeria 15, 3–115. Smit, J., 1999. The global stratigraphy of the Cretaceous–Tertiary boundary impact Uchman, A., 1999. Ichnology of the Rhenodanubian flysch (Lower Cretaceous-Eocene) ejecta. Annual review of Earth and Planetary Sciences 27, 75–113. in Austria and Germany. Beringeria 25, 65–171. Smit, J., Ten Kate, W.G.H.Z., 1982. Trace-element patterns at the Cretaceous–Tertiary Wetzel, A., Bromley, R., 1994. Phycosiphon incertum revisited: Anconichnus horizontalis boundary: consequences of a large impact. Cretaceous Research 3, 307–332. is its junior subjective synonym. Journal of Paleontology 68, 1396–1402. Sternberg, G.K., 1833. Versuch einer geognostisch-botanischen Darstellung der Flora Wetzel, A., Werner, F., 1981. Morphology and ecological significance of Zoophycos in der Vorwelt. IV Heft. C. E. Brenck, Brenck, Regensburg. deep-sea sediments off NW Africa. Palaeogeography, Palaeoclimatology, Palaeoe- Thiel, H., 1975. The size structure of the deep-sea benthos. Internationale Revue der cology 32, 185–212. Gesamten Hydrobiologie 60, 575–606.