Belemnite biostratigraphy of the New Zealand Late Jurassic Mangaoran (Early Puaroan) Substage and the Puaroan Stage revisited

Abstract

Challinor, currently used to define the base of the Puaroan Stage, is a composite taxon some members of which are here re-identified as H. arkelli and H. mangaoraensis. The remainder are re-described as Hibolithes sp A. Its morphology and stratigraphic range are poorly known and the species is unsuitable as a stage boundary marker. Hibolithes arkelli regularly appears near the base of the Puaroan Stage as presently defined and a formal re-definition based on that taxon is proposed. Although this alters the faunal basis of the stage, the position of its base remains unchanged.

Stratigraphy of Tithonian (Ohauan‐Puaroan ) marine beds near Port Waikato, New Zealand, and a redescription ofBelemnopsis aucklandica(Hochstetter)

“…The base of the Puaroan Stage and of the Mangaoran Substage is now recognised by the first appearance of Hibolithes arkelli Stevens (Challinor 1999), although the original position of the base of the stage remains unaltered. The indicator fossil of the Late Puaroan (Mangaoran) Substage {Belemnopsis aucklandica) remains unchanged, although the reinterpretation of a single belemnite specimen has altered the extent of the Waikatoan type section (see below).…”

“…Fossils of restricted Puaroan age are known from above those of Ohauan age on Okahu Stream (Challinor 1974) and a few more belemnites have since become available. More importantly, studies of the ammonites (Stevens 1997) and belemnites (Challinor 1996(Challinor , 1999 have been published. These allow a more confident assessment of the fossil succession, age determinations, and lithological correlations.…”

“…Hibolithes is the only fossil found in any numbers within the Early Puaroan at Port Waikato, and Belemnopsis aucklandica is abundant in the early part of the Late Puaroan. Early Puaroan Hibolithes have been restudied (Challinor 1999), and this study re-examines Belemnopsis aucklandica in an attempt to minimise the possibility of misidentification with some Hibolithes. The writer's fossil collections, on which this and other published studies are partly based, will shortly be deposited in the Department of Geology, University of Auckland.…”

“…2). Strata of Early Puaroan age (Challinor 1977(Challinor , 1999 are centred on Daff Road (Fig. 2), and a Late Puaroan sequence (Challinor 1977) extends westwards along Daff Road (Fig.…”

“…The H. arkelli zone is now known to extend through c. 900 m of beds on the western limb of Kawaroa Anticline near Puti Point (Challinor 1999). Aulacosphinctoides brownei extends through most of the Mangaoran Substage (topmost Kinohaku Siltstone east of Kawhia Harbour, Challinor 1999; up to middle Puti Siltstone, Stevens 1997).…”