LATE CRETACEOUS-EARLY TERTIARY ECHINOIDS 



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Chalk with flint 



Dolomitic Limestones 

 and marls 



Marls and sandy marls 

 with thin limestones 



Calcareous sandstones 



Thin limestones 

 and sandy marls 



Sandy limestones 



Thin limestones and 

 sandy marls 



Massive limestones 



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Fig. 5 Stratigraphic section through the Maastrichtian at Olazagutia Pass, 



Navarra, showing the distribution of echinoids. 



top is followed by dolomitized limestones and more massive 

 dolomites. The entire succession apparently represents a shallowing 

 upward cycle, presumably correctable with the upper part of the 

 Cabo de Lata Formation in Santander. 



This locality was first studied by Ruiz de Gaona (1943) who 

 recorded a single echinoid (Salenia) from it. A detailed stratigraphic 

 section was published by Amiot (in Ciry et ai. 1967) and its 

 microfauna studied by Ramirez del Pozo ( 1971 ). Ramirez del Pozo 

 recorded the following from this section: Orbitoides media. 

 Siderolites calcitrapoides, Lepidorbitoides socialis, Globotruncana 

 contiisa, Marssonella cf. trochus, Nummofallotia cretacea, 

 Omphalocyclus macroporus and Racemigumbelina fructicosa. 

 amongst others, suggestive of a Late Maastrichtian age. A small 

 number of echinoids have previously been reported from this section 

 byRadig(1973). 



Erice. A former limestone quarry on the northern side of the 

 motorway A15 in the vicinity of Erice, exposes Cretaceous and 

 Danian sediments. The succession commences with a series of 

 alternating marly limestones and marls containing ammonites and 

 large Echinocorys, considered to be Late Campanian in age. There is 

 then a sharp break, probably representing a faulted contact, after 

 which come a succession of deep-water, light-coloured limestones, 

 in part conglomeratic, and locally showing slump fabrics. These are 

 thick to medium-bedded at the base, but more thinly bedded up- 

 wards. The lower beds yield a fauna that includes Coraster vilanovae. 



Cyclaster gindrei and Echinocorys sciitata forma pyrcnaica, that in 

 this area characterizes the upper part of the Danian. 



Sarasate. Alternating grey to blue (sometimes slumped) marly 

 limestones and dark shales crop out immediately to the north of 

 motorway A 15 at the foot of Sarasate hill, south-west of the town of 

 Irurtzun. Their macrofauna is limited to inoceramids, echinoids, less 

 common brachiopods and rare ammonites, all of them attributed to 

 the Maastrichtian. They were deposited in a shelf basin or shelf 

 margin setting. Echinoids from here include Stegasteraltits Seunes, 

 S. bouillei Cotteau and Echinocorys scutata forma ovata Leske. 



Higher up the hill (Astieso) there is a small outcrop of Danian 

 limestone by the side of a forestry track which yields Coraster and 

 Cyclaster aturicus Seunes. 



Larumbe. On the eastern side of the village of Larumbe 

 Maastrichtian black shales crop out. These have yielded fragments 

 of Stegaster and an unidentified large spatangoid. As at Sarasate, 

 these beds are interpreted as outer shelf or shelf basin deposits. They 

 are more or less conformably overlain by white limestones of Danian 

 age. Near the base there are two to three 'pebbly conglomeratic' 

 levels, followed by thick to medium-bedded strata with thin more 

 marly joints. These then pass upwards into a more regularly alternat- 

 ing series of limestones and marls. Jeronia occurs in the conglomeratic 

 beds along with Echinocorys, while Coraster is most common 

 towards the top of the section. 



The uppermost beds here contain numerous planktonic 

 foraminifera. These appear very close to Planorotalites pseudo- 

 menardii (Bolli) and Acarinina mckannai (White), which indicate 

 Zone P4 (early Late Palaeocene). The new arcestid was found in the 

 upper marly alternations together with Coraster. 



Casas de Oraien. This locality is placed in the middle of a wooded 

 area some 200 m north-west of the farm buildings forming the 

 hamlet of Oraien, which lies close to the village of Larumbe. The 

 outcrop exposes medium-bedded, gritty calcareous sandstones in 

 which echinoids, fragments of crinoid stems and oysters are the most 

 common macrofaunal elements. The microfauna includes disco- 

 cyclinid foraminifera indicative of a Thanetian age. The heterogene- 

 ous nature and size of the clasts, the shallow-water nature of the 

 fossils contained and the fact that most echinoids are found chaoti- 

 cally in 'nests' , suggest that these beds represent debris flow deposits 

 where neritic material has been transported into a deeper part of the 

 basin. 



Aristregui. The road-cutting 500 m north of the village of Aristregui 

 exposes a calcareous unit delimited by sharp contacts with predomi- 

 nantly marly levels both under and over it. A basal medium-bedded 

 calcareous unit is followed by an alternation of marly limestones and 

 marls, sometimes sandy, in which several intraformational 

 conglomeratic levels occur. These beds have been dated on the basis 

 of their microfauna as late Danian to early Thanetian (ZB 3-6) 

 (Plaziat et ai, 1975). Plaziat et al. recorded the presence of the 

 echinoids Coraster benehamicus, C. cf. sphaericus, Echinocorys 

 douvillei and Jeronia pyrenaica from near the base. 



FAUNAL CHANGES ACROSS THE 

 CRETACEOUS - TERTIARY BOUNDARY 



The Late Cretaceous echinoid faunas from the Santander, Basque 

 and Navarra regions of Spain are clearly very different, and were 

 living in very different environments. Does this have any influence 

 on the intensity of extinction suffered at the K-T boundary event? 



