Paleogene marine bivalves of the deep-water Keasey Formation in Oregon, Part III: The heteroconchs

Abstract

People and institutions providing invaluable assistance with the Keasey bivalve project are acknowledged at the end of the anomalodesmatan chapter (Hickman 2014). This monographic treatment of the bivalve fauna is dedicated to the late Harold Vokes in grateful recognition of the material that he collected and for encouraging me many years ago to undertake completion of a project in which he had already invested considerable effort. Paul Valentich-Scott has generously shared his enthusiasm and encyclopedic knowledge of the living bivalve fauna of the Northeastern Pacific as well as providing access to important collections in the Santa Barbara Museum of Natural History.

Evolutionarily ancient deep‐water seep communities in the Eocene Tethys: examples from Buje (Croatia)

“…aff conradii from Greenland (Rosenkrantz 1970), late Eocene and early Oligocene Co . bathyaulax Hickman, 2015, from Oregon, USA, and late Eocene Co . kiritachiensis Hryniewicz et al ., 2017, from Japan are herein included in Channelaxinus with some doubt because they have shell shape similar to species of this genus, but the presence or absence of a long and narrow submarginal sulcus cannot be ascertained based on the available data (Hryniewicz et al .…”

“…Furthermore, removing the above mentioned species from Conchocele restricts Conchocele to large thyasirids with long and well impressed anterior adductor muscle scars, relatively long posterior shell folds and shallow posterior sinuses, from Eocene and younger deposits from the Pacific margins and the Caribbean region, with the oldest Conchocele species being Co . taylori Hickman, 2015, of late Eocene to early Oligocene age.…”

A methane seep from the deep-marine, late Eocene Keasey Formation, Rock Creek, Columbia County, Oregon

“…1). The upper member of the Keasey Formation, exposed in the vicinity of Vernonia and to the south approximately along state highway 47, consists of 50 m of well-bedded, alternating light and dark gray tuffaceous siltstone and mudstone, and is characterized by numerous well-cemented calcareous horizons and concretionary siltstones, and the Vernonia-Timber fossil seep site (Nesbitt et al 1994, Hickman 2015).…”

“…The purpose of this paper is to describe seep carbonate deposits and fossils within a thick siliciclastic sequence exposed along the banks of Rock Creek, near Vernonia in Columbia County, Oregon (Fig. 1) within the middle member of the Keasey Formation (Campbell and Bottjer 1993, Nesbitt et al 2006, Hickman 2015. This provides a substantial descriptive approach characterizing not only the seep deposits themselves, but furnishing a detailed account of the lithostratigraphy and associated molluscan faunas throughout a 35 m stratigraphic interval.…”

“…carbonate conduit 75 m to the west, and a more diffusive carbonate signature consisting of blebby nodules 55 m west of the latter. The macro-invertebrate assemblages and benthic foraminifera from adjacent non-seep sedimentary rocks are characteristic of the Refugian Stage, latest Eocene (Priabonian) or straddling the Eocene-Oligocene boundary (McDougall 1979, Nesbitt et al 2006, Martin et al 2007, Hickman 2003a, 2015.…”