Evolutionary significance of latest Jurassic-earliest Cretaceous hydrocarbon seep assemblages from Central Spitsbergen, Svalbard.

Late Jurassic to earliest Cretaceous black shales of the middle to outer shelf Slottsmøya Member host 15 seep carbonate bodies containing a diverse (>30 species) assemblage of bivalves, gastropods, brachiopods and polychaete tubes. Bivalves are represented by up to 14 species, which are a mixture of globally distributed species and Boreal endemics. Among them Nucinella, two protobranch bivalves, the pectinid Camptonectes and a number of Buchia species dominate, with other taxa being only locally common. At least eight gastropod taxa have so far been recognized in the fossil seep fauna, most of which are also known from normal marine settings. Vent and seep-restricted gastropods are represented by possible hokkaidoconchids. Brachiopods are represented by a lingulid Lingularia similis? and at least five rynchonelliform brachiopods, which are also known from contemporary normal marine environments. Among the polychaetes, serpulid tubes occur together with organic tubes of unknown affinity, possibly vestimentiferans. In contrast to most of the low diversity Peregrinella-dominated seep assemblages from the Early Cretaceous period, the Svalbard seeps contain a high diversity fauna composed of a mixture of various molluscs, with subordinate brachiopod and polychaete taxa, most of which are also known from normal marine settings in the Arctic. Being composed predominantly of Boreal shallow water taxa with a few world-wide distributed species, the Svalbard seep fauna reflects palaeobiogeographic separation of the Boreal realm and recruitment of seep fauna from a local pool. The high diversity fauna together with the predominance of background fauna reflect a strong connection with the surrounding shallow marine environments. The most common chemosymbiotic genera, represented by a species of Nucinella and Solemya, are found in most of the localities, whereas a thyasirid and a lucinid are present in a single locality only. None of these genera is seep restricted and they are members of the surrounding Mesozoic reduced marine sediments. This inflow of chemosymbiotic fauna from contemporary shelf settings reflects the process of colonization of the seep environments by the shallow marine taxa.

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First Name: 
Krzysztof
Last Name: 
Hryniewicz
Telephone: 
004722851770
Affiliation: 
Natural History Museum, University of Oslo, 1172 Blindern, 0318 Oslo, Norway
First Name: 
Crispin T.S.
Last Name: 
Little
Affiliation: 
School of Earth and Environment, Woodhouse Lane, University of Leeds, Leeds LS2 9JT, United Kingdom
First Name: 
Hans Arne
Last Name: 
Nakrem
Affiliation: 
Natural History Museum, University of Oslo, 1172 Blindern, 0318 Oslo, Norway
First Name: 
Øyvind
Last Name: 
Hammer
Affiliation: 
Natural History Museum, University of Oslo, 1172 Blindern, 0318 Oslo, Norway
First Name: 
Michael R.
Last Name: 
Sandy
Affiliation: 
Departament of Geology, University of Dayton, Dayton OH 45469-2364, USA
First Name: 
Andrzej
Last Name: 
Kaim
Affiliation: 
Institute of Palaeobiology, Polish Academy of Sciences, ul. Twarda 51/55, 00-818 Warszawa, Poland
Choose keywords that are most applicable to your abstract. (Three maximum.): 
Evolutionary history (fossil and molecular data)
Abstract ID: 
CBE5-108