Silicified Eocene molluscs from the Lower Murchison district, Southern Carnarvon Basin, Western Australia

Abstract

-Silicified Middle to Late Eocene shallow water sandstones outcropping in the Lower Murchison District near Kalbarri township contain a silicified fossil fauna including foraminifera, sponges, bryozoans, solitary corals, brachiopods, echinoids and molluscs. The known molluscan fauna consists of 51 species, comprising 2 cephalopods, 14 bivalves, 1 scaphopod and 34 gastropods. Of these taxa three are newly described, Cerithium lvilya, Zeacolpus bartol1i, and Lyria lamellatoplicata. 25 of these molluscs are identical to or closely comparable with taxa from the southern Australian Eocene. The occurrence of this fauna extends the Southeast Australian Province during the Eocene from southwest Western Australia along the west coast north to at least 27°present day south latitude; consequently the province is here renamed the Southern Australian Province.

Eocene molluscs from the Merlinleigh Sandstone, Carnarvon Basin, Western Australia

“…This paper continues studies by the authors (Darragh and Kendrick 1980, 2000, 2008 on the Eocene molluscan faunas of southern and western Australia, herein with regard to the most northerly of these, from the Merlinleigh Sandstone, eastern Carnarvon Basin (Playford et al 1975 and references;Cockbain 1981). The formation is a thin (up to 15 m), transgressive, poorly cemented, silicifi ed quartz sandstone with subordinate siltstone and conglomerate, exposed discontinuously between the Gascoyne and Lyndon Rivers, near the northern margin of the Yilgarn Block (Johnstone et al 1973), with the most productive outcrops located in and adjacent to the Kennedy Range.…”

Further Mollusca from the late Eocene Pallinup Formation, Eucla Basin, Western Australia

“…Of the other genera, 64 (49%) are known from other Eocene formations in eastern Australia and 33 (25.5%) are known from younger formations in eastern Australia. Overall about 74% of the genera are found in the Southern Australian Province (Darragh and Kendrick 2008), so it is concluded that the Eucla Basin during the late Eocene was within that province which at that time extended from the southern Carnarvon Basin to the Gippsland Basin.…”

“…The other taxa are represented by only one to four specimens. Seven species (23% of the bivalve fauna) are closely related or identical to species occurring in the unnamed sandstone at Kalbarri (Darragh and Kendrick, 2008), whereas only one species, Spondylus cf. S. gaderopoides McCoy, 1876, occurs in the Merlinleigh Sandstone (Darragh and Kendrick, 2010).…”

“…Late Eocene molluscan faunas in Western Australia have been described from an unnamed sandstone near Kalbarri (Darragh and Kendrick 2008) and from the Merlinleigh Sandstone (Darragh and Kendrick 2010), both in the Carnarvon Basin, as well from the Pallinup Formation, Eucla Basin (formerly Bremer Basin) on the southern coast Kendrick 1980, 2000). In the latter case only the bivalves and 23 of the gastropods were described.…”

The family Carditidae (Bivalvia) in the early Danian of Patagonia (Argentina)

“…Rotundicardia latissima (Tate, 1886) (Darragh and Kendrick, 2008, fig. 1.5, Lower Browns Creek, Upper Browns Creek, Blanche Point formations and Southern Carnavon Basin, middle-late Eocene, Australia) can be distinguished from R. mariobrosorum because the South American species has a more subquadrate shape and radial ribs with more prominent nodes.…”