Southwest Auckland Research Articles

Synonymy and stratigraphic ranges of Belemnopsisin the Heterian and Ohauan Stages (Callovian‐Tithonian), southwest Auckland, New Zealand

Belemnopsis stevensi, Belemnopsis maccrawi, and Belemnopsis sp. A (Challinor 1979a) are synonymous; B. stevensi has priority. New belemnite material from Kawhia Harbour and Port Waikato, together with graphical study methods, indicates that many small fragmentary specimens associated with B. stevensi in the lower part of its stratigraphic range are probably the same taxon. B. stevensi has been found only in the Middle and Upper Heterian Stage (Lower Kimmeridgian) at Kawhia and only in the Lower Ohauan Stage (Upper Kimmeridgian) at Port Waikato. This apparently disjunct distribution is attributed to poor exposure in the relevant sections. Belemnopsis kiwiensis n.sp., Belemnopsis cf. sp. B, Belemnopsis sp. B, Belemnopsis sp. D, and Belemnopsis spp. are associated with B. stevensi near the lowest known point in its stratigraphic range. The distribution of stratigraphically useful belemnites within the Heterian and Ohauan Stages is: Conodicoelites spp. (Lower Heterian; correlated with Lower Callovian); Belemnopsis annae (Lower and Middle Heterian; Lower Callovian/Lower Kimmeridgian); Belemnopsis stevensi (Middle Heterian/Lower Ohauan; Kimmeridgian); Belemnopsis keari (Upper Heterian; Kimmeridgian); Belemnopsis trechmanni (Upper Ohauan; Upper Kimmeridgian/Middle Tithonian). The apparently extreme range of Belemnopsis annae remains unexplained. Klondyke Sandstone (new) is recognised as the basal member of Moewaka Formation (Port Waikato area).

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

Some 1500 m of marine Ohauan and Puaroan strata in the Port Waikato region of New Zealand are restudied in an attempt to resolve lithostratigraphic and biostratigraphic anomalies in published works. New correlations are proposed for some units of the Apotu Group. A lower 650 m siltstone, previously correlated entirely with Kinohaku Siltstone, is here regarded as including the interval Kinohaku Siltstone to Lower Puti Siltstone (new member). The Waiharakeke Conglomerate is not represented in the area by coarse sediments. A thin sandstone unit overlying the Lower Puti Siltstone and previously correlated with Waiharakeke Conglomerate is here correlated with the Ruakiwi Sandstone. The overlying 400 m siltstone, regarded previously as the entire Puti Siltstone, is here recognised as a new member, the Upper Puti Siltstone. The Coleman Conglomerate is much thicker in the region than mapped, and located higher in the sequence. Biostratigraphy is a key element in correlating the sequence with named units to the south. The sequence is mostly siltstone, but sandstone units provide some lithostratigraphic control. Belemnites are almost the only fossils found in the Late Ohauan and Early Puaroan part of the sequence and are important in the Late Puaroan. Formal belemnite zones, based in part on their stratigraphic distributions in other parts of southwest Auckland, are erected. Occasional ammonites provide tie points that correlate the succession with the standard stratigraphic column for the Tethyan realm. Belemnopsis aucklandica (Hochstetter) is redescribed and considered to be of full specific status as is its former subspecies, Belemnopsis trechmanni Stevens. Many pre‐adult Belemnopsis aucklandica differ in form from adults; some have been previously identified in the field as Hibolithes. Some earlier identifications of belemnites from the Late Puaroan of Port Waikato are incorrect; most are now included in Belemnopsis aucklandica.

Bajocian (middle Jurassic) Ammonitina of New Zealand

A relatively rich, previously unknown fauna of Ammonitina is described from the Bajocian of southwest Auckland. The great majority are Sphaeroceratidae. The Chondroceras fauna has yielded C. orbignyanum and C. (Defonticeras) cf. oblatum, clearly indicating the Humphriesianum Chron. Also associated is the bivalve index Retroceramus inconditus. The superjacent fauna of Waikatoceratinae (n. subfam.) is almost exclusively endemic to New Zealand, with Waikatoceras crassum, W. hudsoni, Opuatia circularis, O. inflata, and O. challinori n. genn. et spp. Accessory taxa include Chondroceras cf. orbignyanum, and Toxamblyites aff. densicostatus, previously known only from the upper Lower Bajocian of Europe and North Africa. However, stratigraphic evidence together with the bivalve index Retroceramus marwicki clearly date the Waikatoceratinae fauna as mostly post‐Humphriesianum Chron (i.e., early Late Bajocian). The presence of Toxamblyites in this fauna suggests that its range was one chron longer in the Southwest Pacific than in Eurafrica—unless the fragmented specimens were reworked, which is considered unlikely. Relatively rare and often immature phylloceratids and lissoceratids are also associated. Other single finds of Middle Jurassic Ammonitina from other New Zealand regions are also discussed. Other stratigraphically important taxa include the bivalve Meleagrinella n. sp. and the belemnite Hibolithes catlinensis. The boundary between the Middle and Upper Temaikan regional substages can be defined by the first occurrence of either Retroceramus marwicki or of Waikatoceratinae; both boundaries lie in the Humphriesianum Chron. The bivalve index is widespread, permitting inter‐regional correlation, whereas the ammonite index allows reasonably precise dating.

Mesozoic stratigraphy of the Marokopa area, southwest Auckland, New Zealand

The Late Triassic and Jurassic rocks of the Marokopa area, southwest Auckland, form part of the western limb of the Kawhia Syncline. Within the area mapped, the Late Triassic ‐ Early Jurassic Newcastle Group consists of 3100 m of generally fine to very fine sandstone and siltstone with common tuff beds, and occasional coarser sandstones and shellbeds. Faunas are marine, generally sparse to moderate, and dominated by bivalves and brachiopods. The Arawi Shellbed, Ngutunui Formation, Tewharau Formation, Ururoa Shellbed, and Ururoa Formation are recognised. The Middle Jurassic Rengarenga Group marks a change to shallow water, marginal marine, and nonmarine conditions. Lithologies are generally coarse to medium sandstone with abundant fine plant fragments, with occasional pebble‐granule conglomerates, tuffs, and shellbeds. Thin coal and plant beds mark the southern limit of nonmarine conditions in the Rengarenga Group. Fully marine conditions return with the Late Jurassic Kirikiri Group. Oraka Sandstone and Ohineruru Formation consist mainly of slightly calcareous, concretionary fine sandstone and sandy siltstone, with a rich molluscan fauna dominated by bivalves. These formations are separated by the 1 m thick Captain King's Shellbed, with a glauconitic sandstone matrix and a distinctive molluscan and brachiopod fauna. The uppermost part of the sequence in the mapped area is the interfingering Kiwi Sandstone and Waikutakuta Formation. Strata generally dip regularly to the east‐northeast at between 20 and 45°. Minor folding may be present in the Kairimu valley. The north‐south trending Whareorino Fault is part of the Taharoa Fault Zone. A NE‐ENE trend is shown by two faults in the Marokopa valley and two in the eastern part of the area. A fault in the Paraohanga valley shows a northwest trend.

Atractitesguards from the Early Jurassic of New Zealand

Three specimens of Atractites aratauraensis n. sp. are described from the basal or Early Jurassic of southwest Auckland. They represent the first member of the family Xiphoteuthididae Naef, 1922, and the first complete aulacocerid guards known from New Zealand. All previously described New Zealand Aulacocerida are members of the family Aulacoceratidae Mojsisovics, 1882.

The first find of Eurycephalitinae (Jurassic Ammonitina) in New Zealand and its biogeographic implications

Uppermost temaikan strata from southwest Auckland Province, North Island, New Zealand, have recently yielded a small fauna of Middle Jurassic ammonites previously believed to be endemic to the eastern Pacific borderlands, although a single fragment of the new species described below was previously reported in a large Tethyan assemblage from Papua, New Guinea, by Westermann and Callomon (1988). The New Zealand assemblage consists of the dimorphic pair Xenocephalites (♂) and Lilloettia (♀) with close morphologic ties to species from the latest Bathonian Steinmanni Standard Zone of the Andean Province (Riccardi et al., 1989). This new find permits direct time-correlation of the uppermost part of the Temaikan Stage (Marwick, 1951, 1953) with the East-Pacific latest Bathonian Steinmanni Zone and with the East-Tethyan Late Bathonian Macrocephalites apertus Association. The upper Temaikan Stage of south Otago Province, southeastern South Island, New Zealand, has also yielded rare representatives of the Tethyan Macrocephalitinae, so that the New Zealand area in the late Middle Jurassic was in the overlap area of Tethyan and East-Pacific Subrealms.

Late Pliocene distal silicic ignimbrites, Port Waikato, New Zealand: Implications for volcanism, tectonics, and sea-level changes in South Auckland

Abstract At least five distal silicic ignimbrites occur in coastal alluvial plain pumiceous sandstone, mudstone, and peat of the basal Kaihu Group at Oruarangi, 5 km south of Port Waikato on the southwest Auckland coastline. The ignimbrites are 0.1-3.0 m thick, include rip-up paleosol clasts, carbonised logs, and gas-escape pipes, and are intimately associated with synignimbrite sedimentary wash deposits. The ignimbrite-bearing succession rests on Jurassic Huriwai Group and is unconformably overlain by thick dune-sand deposits of the mainly Pleistocene Awhitu Formation. Palynomorphs supported by magnetic polarity data suggest a latest Pliocene age for the succession, from late Mangapanian(?) to Hautawan (c. 2.5-1.8 m.y. B.P.). Correlative units include the Ohuka Carbonaceous Sandstone Member of the Kaawa Formation at the nearby Kaawa-Ohuka section, and the widespread Puketoka Formation of inland South Auckland. The eruptive source(s) for the ignimbrites may have included sites in southern Coromandel Penin...

Biostratigraphic evidence for the Manganui Fault, near Awakino, southwest Auckland

Abstract New biostratigraphic evidence confirms the existence of a major fault, the Manganui Fault, within Triassic-Jurassic Murihiku Supergroup rocks in the Manganui Valley, between Awakino and Paparahia (southwest Auckland Province, North Island). The Manganui Fault is interpreted as a steeply dipping fault with a minimum apparent vertical throw of c. 5500 m. There is some indirect evidence to suggest possible strike-slip activity. Timing of the last major fault movement is inferred to be pre-Oligocene. The Manganui Fault is significant because of its age, magnitude and regional context. It is considered to be a segment of a much more continuous feature, the Taharoa Fault, along which there are significant mid-Cenozoic andesitic volcanics. Several magnetic anomalies along the line of the Manganui Fault may represent buried volcanics of comparable composition and relationship.

Textural procedures for the environmental discrimination of late Neogene coastal sand deposits, southwest Auckland, New Zealand

The coastal region of much of the northwestern North Island, New Zealand consists of late Neogene, poorly consolidated, coastal sand and tephra deposits of the Kaihu Group. Determination of the environments of formation of these deposits using standard grain size analytical approaches has met with limited success, both in this and previous studies. However, here we demonstrate that samples from known beach, dune and tephra facies can be differentiated in at least 90% of cases using stepwise and canonical discriminant analyses of the textural data. Classification models derived from the canonical analyses are used to distinguish the depositional facies of homogenised, subsurface drillhole samples collected at Taharoa, the site of a large, currently mined ironsand deposit in southwest Auckland. A SEM, process-based, interpretation of the quartz grain surface features in the sand deposits shows general agreement with the environments determined from the discriminant function analyses despite a considerable degree of post-depositional alteration.

New Zealand Warepan (Upper Triassic) sequences: Murihiku Supergroup of the North Island

Abstract The stratigraphy and structure of Monotis-bearing strata (Warepan Stage of the Upper Triassic — ca. Mid-Upper Norian) of the Kawhia Regional Syncline, southwest Auckland, are described. Sequences on the western limb of the syncline are documented from southwest Kawhia, coastal and inland Kiritehere and the Awakino district, and on the eastern limb from near Whatawhata and Aria. All except those in Piripiri Stream, Awakino, and near Te Arawi, Kawhia, have been disrupted by penecontemporaneous submarine slumping and that at Te Arawi is seriously disturbed by intrusion of the Mid-Tertiary Orangiwhao Andesite. Slumping in the Kiritehere coastal sequence is shown to have occurred in Lower Oapirian, not Warepan times and the involvement of beds with M. (Maorimonotis) calvata Marwick in the slumping at Whatawhata suggests that movement here could also have been Otapirian. Slumping of the beds exposed in Turipoto Stream, Awakino, and in the Mokau River near Aria took place, however, during Warepan times. The Monotis-bearing sequence near Aria is part of a 300-m-thick series of sparsely fossiliferous Oretian to Heterian (about Karnian/Norian to Kimmeridgian) chipwackes, interbedded argillites and graded fine sandstones etc. characteristic of the redeposited Morrinsville Facies, rather than the Oparau Facies as would be expected from its position on the eastern limb of the Kawhia Regional Syncline west of the Waipa Fault.

Recognition and distribution of HeterianBelemnopsisin south-west Auckland

Belemnopsis annae, Belemnopsis maccrawi, and Belemnopsis keari are characteristic taxa of the Heterian stratotype at Kawhia Harbour, New Zealand. When morphological criteria are used, their recognition elsewhere can be difficult. Contrasts in body form are slight, and when collections consist of fragmentary specimens or of juveniles there is a strong possibility of misidentification. Statistical procedures based on apical line positions and on cross sectional shape provide a simple method of recognition. Supporting stratigraphic evidence is available. The succession of taxa present in the Heterian stratotype can be recognised in the Port Waikato region, and two of them are shown to be widely distributed in south–west Auckland.

New lower or middle Jurassic Belemnite from South-West Auckland, New Zealand

Abstract Belemnopsis deborahae Challinor n.sp., a short, robust, almost sub-conical Belemnopsis, is described from strata of upper Ururoan-lower Ternaikan age In the Port Waikato district. In some features Belemnopsis deborahae resembles Conodicoelites, but present evidence favours placing it in Belemnopsis.

Proposal to redefine the puaroan stage of the New Zealand jurassic system

Abstract Buchia plicata occurs in the uppermost levels of the Puaroan stage, but was used by Marwick to define the base of the Puaroan. Modern research has thrown doubt on the basal Puaroan occurrences of B. plicata and indicated a need for redefinition of the Puaroan stage. Benthic fossils are sparsely distributed adjacent to the Ohauan-Puaroan boundary and the remains of non benthic forms, in particular belemnites, offer the greatest promise of providing a faunal basis for the boundary. Fossil1 collections from topmost Ohauan and basal Puaroan strata indicate that a homotaxial faunal succession of belemnite guards is present in several sections in south-west Auckland. The belemnite Hibolithes arkelli grantmackiei Challinor appears consistently near the base of most sections and is an appropriate fossil with which to define the base of the Puaroan Stage. Faunal correlation between Puaroan sections at Kawhia Harbour and Port Waikato can now be made with reasonable confidence and stratigraphic continuity b...

Lower Pleistocene Palynomorphs from the Ohuka Carbonaceous Sandstone, South-West Auckland, New Zealand

Abstract Basal Hautawan pollen samples from the Ohuka Carbonaceous Sandstone contain pollen referable to Acacia and ?Eucalyplus, which indicates that floral change near the Pliocene-Pleistocene boundary may have been caused more by a decrease in effective precipitation than by decreasing temperatures. This desiccation may have been wind induced.

The Ngatutura Volcanics, Southwest Auckland

Abstract Basaltic volcanism occurred in three centres at Ohuka, southwest Auckland, in response to late Pliocene-early Pleistocene fault movements. Eruption took place at, or close to, sea level, and volcanoclastic deposits at each centre include agglomerates, sub-aqueous breccias of terrestrial origin, and laharic breccias. Associated flow and dyke rocks are well-jointed, fine-grained alkali olivine basalts which display little variation in their petrographic, mineralogical, and che:nical characters.

New upper jurassic belemnite from Southwest Auckland, New Zealand

Abstract Hibolithes arkelli grantmackiei Challinor n. subsp. has been collected from Upper Ohauan-Lower Puaroan strata in the Ahuroa Valley, Waingaro, and Kawhia regions of South-west Auckland. It is a belemnite whose guard is characterised by moderate hastation, a compressed cross section, and a weakly developed ventral groove. H. arkelli grantmackiei is similar in some respects to H. minor and in many respects to H. arkelli arkelli. Its vertical range is limited and it appears to be confined to the topmost Kinohaku Siltstone and the lower Waiharakeke Conglomerate.

Upper Quaternary warping and uplift rates in the Bay of Plenty and west coast, North Island, New Zealand

Abstract Coastal terraces around the Bay of Plenty are examined from Waihi to East Cape. The tephra stratigraphy described by other authors is extended; in particular a pumiceous tephra formation immediately underlying Hamilton Ash Formation is named the Little Waihi Formation. Two terraces can be traced confidently around the Bay; the younger (BOP2) is capped by Rotoehu Ash and younger tephras and the older (BOP3) is capped by Little Waihi or Hamilton ashes and younger tephras. Wave-cut surfaces beneath the mantling deposits vary in height around the Bay, indicating warping. Near Maketu, both BOP2 and BOP3 cut surfaces are within 2 m of sea level; near East Cape they are about 50 m and 100 m, respectively. West coast terraces are traced from Kaipara and south-west Auckland into north Taranaki and thence to Wanganui. The following formations are correlated: (a) Waioneke—Waiau B—Rapanui; (b) Shelly Beach—Waiau A—Ngarino; (c) Parawai— Brunswiak; and (d) Nihinihi and upper Kaihu Formations—Kaiatea Group of T...

Tertiary penguins from the North Island of New Zealand

Abstract Two new records of Oligocene penguin remains from southwest Auckland are added to the previously known occurrence (Marples and Fleming, 1963). All three are considered unidentifiable as to genus or species, but measurements of femora show that three separate species are represented, and from these and other bones it is probable that more than one genus is involved; comparative osteology also indicates that they are unlikely to have been conspecific with any of the described forms known from South Island localities, despite a similarity of facies. One specimen, the Glen Murray Penguin of Whaingaroan age, is one of the largest forms known, and it is of note that South Island forms of comparable size are of upper Eocene age, when conditions are believed to have been warmer than in the Oligocene.

A reappraisal of the Ngatutura volcanics and the Plio-Pleistocene boundary in South-west Auckland

Abstract Alkali-olivine basaltic vulcanism in the Ngatutura-Ohuka area has been considered to occupy a position close to or at the Plio-Pleistocene boundary, dated at 2 · 5 m.y. by correlation with dated centres further south. Re-examination of the stratigraphic position of the volcanic centre at Ngatutura Point shows that both minor late Pliocene and major early Pleistocene phases of activity occurred, none of which was necessarily contemporaneous with the southern centres. Breccias, erupted in the early Pleistocene, contain a cool Nukumaruan microflora. Associated basalts possess ages concentrated in the range 1 · 4—1 · 8 m.y. and have a reversed magnetic polarity. It is concluded that the major eruption commenced during the Matuyama Reversed Epoch between the Olduvai and Reunion events.

Plant Microfossils from the Hawks Crag Breccia, south-west Nelson, New Zealand

Abstract Thirty miospore species from a sandstone sample of the Hawks Crag Breccia at Fox River are listed and some are described. Twenty-four species are recorded from this formation for the first time; of these, three are new. The assemblage is compared with Upper Jurassic and Lower Cretaceous microfloras from Australia and New Zealand and with other microfloras from the Hawks Crag Breccia and Ohika Beds. Microfloral composition of Tithonian assemblages from the Puaroan B and overlying Huriwai Formation of south-west Auckland is summarised. The Hawks Crag assemblage is concluded to be either Albian or Heterian-Ohauan in age (Lower to Middle Kimmeridgian). The apparent conflict of the Jurassic age-determination and the mid-Cretaceous age, indicated by radiometric methods in underlying crystalline rocks, is discussed. If the Jurassic age is correct, phytogeographic considerations suggest that certain floral elements present in New Zealand in the late Jurassic migrated slowly to the Australian continent, w...