Marine invertebrate fossils from the Permian–Triassic boundary beds of two core sections in the northern Perth Basin, Western Australia

Abstract

<p>Marine macroinvertebrate fossils from two petroleum exploration cores, Apium-1 and Redback-2, are described, and found to contain two separate assemblages. The assemblage from the Apium-1 core was recovered from an ca 5-m-thick interval (2756.35–2751.28 m) in the basal Hovea Member (‘inertinitic interval’) of the Kockatea Shale and includes the following forms: ?<i>Spinomarginifera</i> sp., <i>Cimmeriella</i> sp., ?<i>Etherilosia</i> sp., <i>Elivina</i> sp., <i>Cleiothyridina</i> sp., and Paeckelmanelloidea gen. et. sp. indet. (all brachiopods). The age of this assemblage is interpreted as Changhsingian, as constrained by its association with the palynofloral <i>Dulhuntyispora parvithola</i> Zone. The assemblage from the Redback-2 core was recovered from the ‘sapropelic interval’ of the Hovea Member of the Kockatea Shale between 3806 m and 3786 m and comprises the following forms: Lingulidae gen. et sp. indet. (brachiopod), <i>Claraia perthensis</i> Dickins & McTavish, <i>Crittendenia</i> cf. <i>australasiatica</i> (Krumbeck), ?<i>Paralledon,/i> sp. (bivalves), ?<i>Otoceras</i> sp. (ammonoid), <i>Microconchus utahensis</i> Zaton, Taylor & Vinn (microconchid) and <i>Magniestheria mangaliensis</i> (Jones) (spinicaudatan). Among these, the first local appearances of the lingulid species, ?<i>Otoceras</i> sp. and <i>M. mangaliensis</i> are associated with the palynofloral <i>Protohaploxypinus microcorpus</i> Zone and are interpreted as latest Changhsingian in age. Other occurrences of the Redback-2 fossil assemblage overlap with the palynofloral <i>Kraeuselisporites saeptatus</i> Zone and are considered to be of earliest Triassic (Griesbachian) age. </p>