Bivalves from the latest Jurassic-earliest Cretaceous hydrocarbon seep carbonates from central Spitsbergen, Svalbard

Abstract

The bivalve fauna from the latest Jurassic-earliest Cretaceous hydrocarbon seep deposits from central Spitsbergen, Svalbard comprises at least 17 species, four of which belong to chemosymbiotic taxa often found at seeps. These are the solemyid Solemya (Petrasma) cf. woodwardiana; Nucinella svalbardensis sp. nov., which belongs to a group of large Nucinella species known from seeps and deep water environments; the lucinid bivalve, Tehamatea rasmusseni sp. nov., included in a genus widely distributed in other Jurassic-Cretaceous seeps; and Cretaxinus hurumi gen. et sp. nov., which is the oldest known thyasirid and is discussed in relation to other large seep-restricted genera in this family. The remaining species in the fauna belong to 'background' genera known from coeval normal marine sediments, mostly from the Boreal area. These include the nuculid Dacromya chetaensis, two new malletiids (Mesosaccella rogovi sp. nov. and M. toddi sp. nov.), the oxytomiid Oxytoma octavia, at least three Buchia species, at least two pectinids, including Camptonectes (Costicamptonectes) aff. milnelandensis and Camptonectes (Camptochlamys) clatrathus, the limid Pseudolimea arctica, the arcticid Pseudotrapezium aff. groenlandicum, and the pholadomyid Goniomya literata. The large number of 'background' species in the bivalve fauna is probably a reflection of the shallow-water setting of the Svalbard seeps. This might also explain the lack of the seep-restricted modiomorphid bivalve Caspiconcha from the fauna. With solemyids, Nucinella, lucinids and thyasirids, the latest Jurassic-earliest Cretaceous bivalve seep fauna of Svalbard contains typical representatives of the Mesozoic bivalve seep faunas, both long established and young evolutionary colonists.

Integrating subsurface and outcrop data of the Middle Jurassic to Lower Cretaceous Agardhfjellet Formation in central Spitsbergen

“…Hydrocarbon seep deposits of the uppermost Agardhfjellet Formation have revealed over 17 species of bivalves and a number of other invertebrates (Hryniewicz et al, 2014). The invertebrate remains recovered from the shales and siltstones in the outcrop are fragmented due to frost wedging, and macrofossils can be difficult to recover.…”

Early Jurassic protobranch bivalves from Chubut, Argentina

“…Wasmer and Hautmann (in Wasmer et al, 2012) pointed out that Triassic species referred to Palaeoneilo lack overlap of teeth rows, and also lack a posterior shell constriction, as is characteristic of Paleozoic species. Other authors prefer to refer Mesozoic species to Mesosaccella without further discussion, though admitting that this last genus has become a “bucket taxon” (see for instance Duff, 1978; Hryniewicz et al, 2014).…”

Brachiopods from Late Jurassic—Early Cretaceous hydrocarbon seep deposits, central Spitsbergen, Svalbard

“…In addition to brachiopods from the Sassenfjorden area the hydrocarbon seeps contain a high diversity of bivalves (17 species, Hryniewicz et al 2014), gastropods (~10 species; unpublished data) and serpulids (four species; Vinn et al in press). This makes the Spitsbergen seep faunas very different from many of the Palaeozoic-Mesozoic seep deposits that contain shell beds or lenses dominated by monospecific accumulations of brachiopods (e.g.…”