Southern Fiordland Research Articles

Lithostratigraphy of Paleozoic metasediments in southern Fiordland, New Zealand

ABSTRACT The lithostratigraphy of Early Paleozoic metasediments from southern Fiordland is described, with three groups and 14 formations formally defined. In southwest Fiordland, the Fanny Bay Group is a quartz-rich succession of metamorphosed sandstone, mudstone, and quartzite; the Cameron Group is a lithologically variable succession of metavolcanic, psammitic, pelitic and calc-silicate rocks; the Edgecumbe Group is a volcaniclastic succession of metaconglomerate, metasandstone, and metabasalt. South-central Fiordland schists and gneisses are subdivided into either amphibolitic, pelitic, or psammitic lithological associations. Based on fossils, detrital zircon ages, intrusive relationships, and correlation with rocks in northwest Nelson, Fanny Bay Group is most likely latest Cambrian to Late Ordovician whereas Cameron and Edgecumbe groups, together with the south-central Fiordland metamorphic rocks, are likely to be middle to late Cambrian. Fanny Bay lithostratigraphy most closely matches that of the Buller Terrane of northwest Nelson, whereas the Edgecumbe Group most closely matches the northwest Nelson Cambrian lithostratigraphy of the Takaka Terrane. Cameron Group and south-central Fiordland metasediments are similar to each other but their relationship to northwest Nelson rocks is unclear. The Old Quarry Fault separates the Fanny Bay Group from the Edgecumbe and Cameron groups, and is probably a southern continuation of northwest Nelson’s Anatoki Fault.

Reconstructing atmospheric circulation over southern New Zealand: Establishment of modern westerly airflow 5500 years ago and implications for Southern Hemisphere Holocene climate change

Late-twentieth century changes in the intensity and migration of Southern Hemisphere westerly winds have been implicated in spatially complex variability in atmospheric and ocean circulation, and ice-sheet dynamics, across the mid- to high-latitudes. A major uncertainty, however, is whether present day hemispheric-wide symmetrical airflow is representative of past behaviour. Here we report a multi-proxy study from Stewart Island and southern Fiordland, New Zealand (46–47°S) reconstructing Holocene changes at the northern limit of westerly airflow. Increased minerogenic input and a pronounced shift in cool-loving vegetation around 5500 years ago is consistent with the establishment of westerly airflow at this latitude in the southwest Pacific. In marked contrast, stronger winds are reported further south over the subantarctic Auckland (50°S) and Campbell (52°S) Islands from 8000 years ago. Intriguingly, reconstructions from the east Pacific suggest a weakening of core westerly airflow after 8500 years ago, but an expansion along the northern limits sometime after 5500 years ago. Our results suggest similar atmospheric circulation changes have been experienced in the Pacific since 5500 years ago, but indicate an expanded network of sites is needed to comprehensively test the driver(s) and impact(s) of Holocene mid-latitude westerly winds across the Southern Hemisphere.

Anatomy of the 2009 Fiordland earthquake ( Mw 7.8), South Island, New Zealand

We have analyzed the July 15, 2009, Fiordland earthquake ( M w 7.8), which occurred in the southwestern part of the South Island of New Zealand. This thrust-related earthquake in the southern Fiordland subduction zone is the largest New Zealand earthquake in the past 80 years. We have constrained a rupture model for this earthquake using coseismic offsets derived from the continuous geodetic network (Global Positioning System) of the New Zealand Institute of Geological and Nuclear Sciences (GNS Science). Our analysis concludes that this earthquake significantly increased the Coulomb stress on the overriding plate, particularly on the offshore portion of the Alpine fault.

Autochthonous inheritance of zircon through Cretaceous partial melting of Carboniferous plutons: the Arthur River Complex, Fiordland, New Zealand

TIMS and SHRIMP U–Pb analyses of zircons from Milford Orthogneiss metadiorite (P = 1–1.4 GPa; T ≥ 750°C) of the Arthur River Complex of northern Fiordland reveal a bimodal age pattern. Zircons are predominantly either Paleozoic (357.0 ± 4.2 Ma) and prismatic with oscillatory zoning, or Cretaceous (133.9 ± 1.8 Ma) and ovoid with sector or patchy zoning. The younger age component is not observed overgrowing older grains. Most grains of both ages are overgrown by younger Cretaceous (~120 Ma) metamorphic zircon with very low U and Th/U (0.01). We interpret the bimodal ages as indicating initial igneous emplacement and crystallisation of a dioritic protolith pluton at ~357 Ma, followed by Early Cretaceous granulite-facies metamorphism at ~134 Ma, during which a significant fraction (~60%) of the zircon grains dissolved, and subsequently reprecipitated, effectively in situ, in partial melt pockets. The remaining ~40% of original Paleozoic grains were apparently not in contact with the partial melt, remained intact, and show only slight degrees of Pb loss. Sector zoning of the Cretaceous grains discounts their origin by solid state recrystallisation of Paleozoic grains. The alternative explanation—that the Paleozoic component represents a 40% inherited component in an Early Cretaceous transgressive dioritic magma—is considered less likely given the relatively high solubility of zircon in magma of this composition, the absence of 134 Ma overgrowths, the single discrete age of the older component, equivalent time-integrated 177Hf/176Hf compositions of both age groups, and the absence of the Cambrian-Proterozoic detrital zircon that dominates regional Cambro-Ordovician metasedimentary populations. Similar bimodal Carboniferous-Early Cretaceous age distributions are characteristic of the wider Arthur River Complex; 8 of 12 previously dated dioritic samples have a Paleozoic component averaging 51%. Furthermore, the age and chemical suite affinity of these and several more felsic rocks can be matched with those of the relatively unmetamorphosed Carboniferous plutonic terrane along the strike of the Mesozoic margin in southern Fiordland, also supporting the in situ derivation of the Carboniferous “inherited” component.

Plutonic rocks of Western Fiordland, New Zealand: Field relations, geochemistry, correlation, and nomenclature

This paper provides a comprehensive description of the plutonic rocks of western Fiordland between Breaksea and Sutherland Sounds. The area is dominated by the Early Cretaceous Western Fiordland Orthogneiss (WFO), but also includes smaller bodies of Paleozoic and Cretaceous granitoid. Plutonic rocks of western Fiordland intrude metasediments of the Western Province, many of whose age and terrane affinities remain undefined. Paleozoic granitoids in western Fiordland include the Pandora Orthogneiss (c. 500 Ma) and widespread related sills within Paleozoic metasedimentary rocks; the All Round Pluton (c. 340 Ma); the Deas Cove Granite (c. 372 Ma); and possibly the Straight River Granite. The Pandora Orthogneiss is one of the oldest plutons yet found in the Median Batholith. Correlatives include the Jaquiery Granite Gneiss in central Fiordland and orthogneiss in Doubtful Sound. Plutonism of Ross/Delamarian age is therefore widespread in those parts of Fiordland where Cambrian or older Western Province metasedimentary rocks form basement. The All Round Pluton and Deas Cove Granite are correlatives of the S‐type Ridge and A/I‐type Foulwind Suites, respectively. The c. 125–116 Ma WFO includes at least seven major dioritic and monzodioritic plutons in western Fiordland, one in central Fiordland, and one in central Stewart Island. Plutons which compose the WFO are distinguished by differences in their age, petrography, structural and metamorphic histories, and geochemistry. The WFO in northern Fiordland and the correlative Walkers Pluton on Stewart Island were emplaced in the mid crust (4–9 kbar) at depths comparable with some Separation Point Suite plutons of similar age. WFO plutons in southern Fiordland were emplaced at greater depths (10–18 kbar). WFO plutons have been variably recrystallised to eclogite; omphacite‐, garnet‐, two‐pyroxene‐, and hornblende‐granulite; and hornblende‐amphibolite facies assemblages, reflecting different PTX conditions during metamorphism of each body. Some parts of the WFO remain undeformed and unmetamorphosed. Evidence of up to c. 6 kbar loading after emplacement is limited to WFO plutons in northern Fiordland and adjacent country rocks. Extensional ductile shear zones previously shown to locally separate the WFO from adjacent rocks are discontinuous later features, commonly localised along earlier intrusive contacts between WFO plutons and metasedimentary country rocks. They do not form a regionally extensive detachment between the upper and lower plates of a metamorphic core complex. The WFO has previously been included in the Separation Point Suite since both units share a high Sr/Y (HiSY) chemistry and were emplaced at broadly the same time. However, the WFO and Separation Point Suite have distinct chemistries. Separation Point Suite rocks generally contain greater Sr, Na, and Al, and have lower Sr/Rb ratios, rare earth element and Y contents, than WFO rocks with comparable amounts of SiO2. Many aspects of the WFO chemistry (aside from its HiSY character) are similar to that of the older Darran Suite rather than the Separation Point Suite. This may reflect a greater amount of partial melting during generation of the SiO2‐poor WFO than the SiO2‐rich Separation Point Suite. Alternatively it may indicate derivation of the WFO and Separation Point Suite from different sources, albeit at depths greater than those where residual plagioclase is stable. Relatively large variations in the major element chemistry of the Separation Point Suite reflect fractionation and/or accumulation of plagioclase, whereas the more limited variability in the major element chemistry of the WFO reflects minor fractionation and/or accumulation of hornblende and/or clinopyroxene.

Large Subduction Thrust Earthquake Shakes Southern New Zealand

At 9:22 P.M. local time on 15 July 2009, the largest earthquake in New Zealand in the past 80 years occurred in the southern Fiordland subduction zone of the country's South Island. The Mw 7.6 earthquake ruptured the interface between the subducting Australian plate and the overlying Pacific plate, with the deeper end of the rupture underlying the coast of Fiordland, a sparsely populated region in the southwestern corner of the South Island. The proximity of the rupture to land, together with the recent deployment of seismographs and continuous Global Positioning System (GPS) receivers in Fiordland as part of the GeoNet project run by GNS Science (http://www.geonet.org.nz), ensures an abundance of recordings close to the rupture. As a result, this event promises to be one of the better recorded subduction thrust earthquakes to date.

Plutonic rocks of the Median Batholith in southwest Fiordland, New Zealand: Field relations, geochemistry, and correlation

This paper provides a first description of all major plutonic rock units between Resolution Island and Lake Poteriteri in southwest Fiordland. Plutonic rocks, of which c. 95% are granitoids, comprise c. 60% of the basement in southwest Fiordland. Approximately 50% of the plutonic rocks were emplaced between c. 355 and 348 Ma, 5% at c. 164 Ma, 25%between c. 140 and 125 Ma, and 20% between c. 125 and 110 Ma. These episodes of plutonism occurred in response to terrane amalgamation, continental thickening, and subduction along the convergent margin of Gondwana. Correlatives of Devonian plutonic rocks which occur in Nelson are absent from the area described here. A wide variety of plutonic rocks were emplaced at c. 355–348 Ma. These include relatively small plutons of K‐ and Rb‐rich gabbro‐diorite and members of at least three distinct suites of granitoids. Plutons of two‐mica ± garnet granodiorite, granite, and minor tonalite share affinities with the S‐type Ridge Suite and are the most widespread c. 355–348 Ma old granitoids in southern Fiordland. Plutons rich in Ca, Fe and Zr, depleted in K and Na, and containing quartz diorite, tonalite, and minor granodiorite with the unusual assemblage red‐brown biotite, garnet ± hornblende ± clinopyroxene also occur widely in southern Fiordland. These plutons are similar to peraluminous A‐type granitoids, indicating A as well as I and S‐type plutonism occurred in the Western Province at this time. The Newton River and Mt Evans Plutons have no correlatives amongst c. 355–348 Ma granitoids in southern Fiordland, but their chemistry is similar to that of the older Karamea Suite. Three regional‐scale metasedimentary units—locally fos‐siliferous Fanny Bay Group Buller Terrane rocks in southern Fiordland, Edgecumbe and Cameron Group Takaka Terrane rocks in south‐central Fiordland, and undifferentiated Deep Cove Gneiss high‐grade metasedimentary rocks of western Fiordland—are all stitched by c. 355–348 Ma old plutons, indicating they have been in close proximity since at least c. 355–348 Ma. In south‐central Fiordland, c. 355–348 Ma old plutons cut across fabrics defined by upper amphibolite facies mineral assemblages, indicating low pressure/high temperature metamorphism in this area before this time. The c. 164 Ma old leucocratic Lake Mike Granite is a unique pluton in southwest Fiordland with no obvious correlatives. Plutons emplaced between c. 140 and 125 Ma are similar to the Rahu Suite, although isotopic data are required to confirm this correlation. Rahu Suite plutonism may therefore have begun by c. 140 Ma, rather than c. 120 Ma as previously suggested. Plutons emplaced between c. 125 and 110 Ma have high Sr/Y ratios comparable with the Separation Point Suite. They occur in both an outboard location around Lake Poteriteri and an inboard location around the western end of Dusky Sound. The c. 115 Ma two‐mica garnet granites of the Anchor Island Intrusives #2 probably formed by partial melting of adjacent ortho‐ and paragneisses, indicating that upper amphibolite facies metamorphism in western Dusky Sound occurred during the Early Cretaceous. The Dusky Fault does not pass directly out to the coast through outer Dusky Sound as previously mapped. Instead it merges with the major northeast‐striking Lake Fraser Fault at Cascade Cove, which crosses the outer coast near West Cape. The Last Cove Fault is a minor structure which cannot be traced beyond Last Cove rather than a major fault of regional extent as has been previously suggested.

Miocene‐Recent deformation, surface elevation, and volcanic intrusion of the overriding plate during subduction initiation, offshore southern Fiordland, Puysegur margin, southwest New Zealand

We analyse results of dredge sampling, a high‐resolution seismic reflection survey, and unpublished petroleum industry data from part of the overriding continental plate of the Fiordland subduction zone. Plate tectonic calculations show that convergence rates have progressively increased since Miocene time, when subduction‐related processes started. An initial deformation phase was characterised by reverse throw on pre‐existing structures during the interval 16–8 Ma. This is interpreted to be when a throughgoing subduction interface developed, as fracture zone linkage and spreading ridge extinction occurred south of New Zealand. A Pliocene‐Quaternary deformation phase characterised by renewed folding and reverse faulting on structures subparallel to the plate boundary may be due to a regional change in plate motion or the inherited geometry of the Eocene continent/ocean transition that is obliquely colliding with the plate boundary, or both. Initial uplift of the region south of Fiordland to sea level was followed by c. 1800 m of subsidence at the Snares Depression. This subsidence may have been an isostatic response to tectonic erosion of a crustal root, or due to negative slab buoyancy associated with greater total convergence, or both. Persistence of Fiordland topographic elevations above sea level, and continued rock uplift of Fiordland, is likely to be related to greater initial crustal thickness of the overriding Pacific plate in the north, and the present southward transition from continental collision to intra‐oceanic subduction. The locations of the first three subduction‐related volcanoes have a relationship to pre‐existing faults and raise the possibility that volcanism and deformation may be intimately associated during subduction initiation.

Age structure, dispersion and diet of a population of stoats (Mustela erminea) in southern Fiordland during the decline phase of the beech mast cycle

The dispersion, age structure and diet of stoats (Mustela erminea) in beech forest in the Borland and Grebe Valleys, Fiordland National Park, were examined during December and January 2000/01, 20 months after a heavy seed‐fall in 1999. Thirty trap stations were set along a 38‐km transect through almost continuous beech forest, at least 1 km apart. Mice were very scarce (<1 capture per 100 trap nights, C/100TN) along two standard index lines placed at either end of the transect, compared with November 1999 (>60/100TN), but mice were detected (from footprints in stoat tunnels) along an 8 km central section of the transect (stations 14–22). Live trapping with one trap per station (total 317.5 trap nights) in December 2000 caught 2 female and 23 male stoats, of which 10 (including both females) were radio collared. The minimum range lengths of the two females along the transect represented by the trap line were 2.2 and 6.0 km; those of eight radio‐tracked males averaged 2.9 ±1.7 km. Stations 14–22 tended to be visited more often, by more marked individual stoats, than the other 21 stations. Fenn trapping at the same 30 sites, but with multiple traps per station (1333.5 trap nights), in late January 2001 collected carcasses of 35 males and 28 females (including 12 of the marked live‐trapped ones). Another two marked males were recovered dead. The stoat population showed no sign of chronic nutritional stress (average fat reserve index = 2.8 on a scale of 1–4 where 4 = highest fat content); and only one of 63 guts analysed was empty. Nevertheless, all 76 stoats handled were adults with 1–3 cementum annuli in their teeth, showing that reproduction had failed that season. Prey categories recorded in descending frequency of occurrence were birds, carabid beetle (ground beetle), weta, possum, rat, and mouse. The frequencies of occurrence of mice and birds in the diet of these stoats (10% and 48%, respectively) were quite different from those in stoats collected in Pig Creek, a tributary of the Borland River (87%, 5%), 12 months previously when mice were still abundant. Five of the six stoat guts containing mice were collected within 1 km of stations 14–22.

Capture probability and heterogeneity of trap response in stoats (Mustela erminea)

The technique most widely used to control the stoat, an introduced predator in New Zealand, is to set Fenn (kill) traps, usually in lines or (less often) in grids. There has been no analysis of trap response in stoats, nor of the extent of potential variation in probability of capture. We report the results of an analysis of mark–recapture data recorded from stoats observed during a period of high stoat and mouse density in January 1980 in the Eglinton and Hollyford Valleys (northern Fiordland), using livetraps set in lines at one per 400 m over 14 km in each valley. Over 8 days of trapping (1–11 January), 89 stoats were tagged. The daily probability of first capture for all ages, both sexes, was 0.14 (with 95% confidence intervals 0.07–0.25) and of recapture 0.10 (0.07–0.14).We also analysed a new set of mark–recapture data collected during a period of very low mouse density in the Grebe Valley (southern Fiordland) in December 2000, using 19 live-traps set in a line at one per kilometre over 20 km. In this study 21 adult stoats and no young of year were tagged. The daily probability of first capture for adult males was 0.12 (0.04–0.31), and of recapturing them, 0.15 (0.10–0.23). A month later, in late January 2001, 68 Fenn traps set at four per kilometre caught 48 previously unmarked stoats, plus 12 of the 21 marked stoats released alive.Heterogeneity in probability of recapture was investigated by taking a longer subset of the 1980 data (1–17 January) and grouping individuals by sex and age. In the best closed-captures models, ranked using AICc, first-capture probability was similar for all stoats (0.17 (0.12–0.24)), and evidence of variation in the probability of recapture between age and sex classes was present but weak. The confidence limits around the recapture probabilities for adult males and females overlapped completely. Recapture probabilities for young-of-the-year males remained about the same (0.14 (0.11–0.19)), while the recapture probability of young-of-the-year females halved after first capture (0.07 (0.04–0.11)).Pledger's finite-mixture models demonstrating individual heterogeneity in trappability produced lower AICc values than the closed-captures models partitioning variation in recapture probability by age and sex alone. The observed heterogeneity in trap response is therefore not due only to variable individual response to traps, but is also to opportunity, as might be expected in data collected from a line of traps where the edge effect on trap-encounter rate is high. However, the extent to which trap-encounter rate helps to explain the observed heterogeneity is unknown. Indeed, there may be other sources of individual heterogeneity that are not related to age/sex or to trap-encounter rate, and this is a potential problem for wildlife managers using conventional trap lines to remove stoats to protect native species.

Frontal accretion and thrust wedge evolution under very oblique plate convergence: Fiordland Basin, New Zealand

ABSTRACTA thrust wedge with unusual geometry has developed under very oblique (50–60°) convergence between the Pacific and Australian Plates, along the 240‐km length of the Fiordland margin, New Zealand. The narrow (25 km‐wide) wedge comprises three overlapping components, lying west of the offshore section of the Alpine Fault, and straddles a change of &gt; 30° in the regional strike of the plate boundary. Swath bathymetry, marine seismic reflection profiles, and dated samples together reveal the stratigraphy, structure, and evolution of the wedge and the underthrusting, continental, Caswell High (Australian Plate). Lateral variations in the composition and structure of the accretionary wedge, and the depth of the décollement thrust, result partly from variations in crustal structure and basement relief of the underthrust plate, and from associated variations in the thickness of turbidites available for frontal accretion. In the southern Fiordland Basin the underthrust plate is undergoing flexural uplift and extension, and a thick turbidite section is available for accretion. Along‐strike, a structurally elevated portion of the underthrust plate is very obliquely colliding with the central part of the accretionary wedge, the turbidite section available for accretion is condensed, and structural inversion occurs in the underthrust plate. Growth of the thrust wedge is inferred to have commenced in the Pliocene prior to 3 ± 1 Ma, but much of the wedge developed in the Quaternary. The spatial distribution of thrusting has varied through time, with most late Quaternary shortening occurring on structures within 10 km of the right‐stepping deformation front. Estimates of the magnitude and rates of deformation indicate that the wedge accommodates a significant component of the oblique convergence between the Pacific and Australian Plates. Shortening of up to 7.3 ± 1.4 km and 9.1 ± 1.8 km within the southern and central parts of the wedge, respectively, represent about 5–15% of the total 70–140 km of shortening predicted across the plate boundary since 6.4 Ma, and about 10–30% since 3 Ma. Late Quaternary shortening rates of the order of 1–5 mm yr−1, estimated across both the northern and southern parts of the wedge, represent about 10–50 and 5–21% of the total NUVEL‐1 A shortening across the plate boundary at these respective latitudes, implying that most shortening is occurring onshore. Furthermore, possible oblique‐slip thrusting within the wedge may be accommodating boundary‐parallel displacement of 0–6 mm yr−1, representing 0–17% of the total predicted within the plate boundary.

Comparison of altitudinal sequences of vegetation on granite and metasedimentary rocks in the Preservation Ecological District, southern Fiordland, New Zealand

Abstract Vegetation and soils were sampled along paired altitudinal sequences on granite and adjoining metasedimentary rocks from sea level to treeline at approximately 900 m elevation at Dusky Sound, Fiordland. Soils derived from granite are less fertile, and are inferred to provide less rooting volume than those on metasediment. Nothofagus menziesii alone dominates the continuous tall forest on metasediment; in the forest on granite, four or more species form the canopy. On granite, treeline is depressed by 150 m, and shrubland and grassland alternate on mineral soil and peat respectively, at altitudes supporting N. menziesii forest 11 – 15 m tall on metasediment. Total species richness and density of woody stems are greater on granite, but mean tree basal area is consistently less than that on metasediment. The dominance/diversity models tested indicate that community structure changes with altitude in different ways on the two substrates, a pattern that is difficult to explain until we know more about the influence of the environment on dominance/diversity relations.

Marine terraces of the Waitutu district and their relation to the late Cenozoic tectonics of the southern Fiordland region, New Zealand

Abstract At least 13 marine terraces or their remnants, with maximum shoreline altitudes of c. 3 m, 60, 90, 140, 230, 320, 370, 460, 580, 660, 780, 870 and 1040 m, are preserved in the Waitutu district of southeast Fiordland. Alluvial terraces related to glaciation of the immediate hinterland cross the marine terraces and allow the terraces to be confidently matched to the glacial/interglacial sequence. Three well-preserved marine terraces of the Last Interglacial separate fluvioglacial terraces of the Last and Penultimate Glaciations. An uplift rate of 1.1 mm/yr, derived from the altitude of the fourth youngest terrace inferred to represent oxygen isotope stage 5e, is used to estimate the ages of the older marine terraces by linear extrapolation, up to > 900,000 years. The Waitutu marine terraces traced into southwestern Fiordland decrease markedly in height, to levels corresponding to an uplift rate of 0.6 mm/yr. The higher peaks of Fiordland conform to a summit-level surface which is interpreted to be,...

Ecological studies of a marine terrace sequence in the Waitutu Ecological District of southern New Zealand. Part 4: Insecta: Lepidoptera and Coleoptera

Abstract The very small portion of the fauna sampled shows no indication of an ancient element. In fact most species encountered are rather widespread, except, for example, the impressive stag bettIe Dorcus philpotti, which elsewhere is known only from southern Fiordland to the west ofHump Ridge. The low number of species in the bog areas is also notable since in the eastern South Island this habitat has a rich moth fauna. The faucity of understorey plant species palatable to deer is likely to have depleted the variety and viability of moths in forest habitats.

Inferred uplift rates from raised marine surfaces, southern Fiordland, New Zealand

Abstract Well-preserved remnants of a flight of raised marine benches can be recognised at altitudes of up to 1000 m above sea level in the extreme southwest of Fiordland. Radiocarbon-dated wood samples indicate an uplift rate of about 1.5 mm/year for the youngest raised surface, and a long-term rate of 3.2 mm/year is calculated on the basis of correlation of the sequence with similar raised marine features in Taranaki and New Guinea. The uplift rate does not appear to have been constant through time but has fluctuated between 5.4 and 1.5 mm/year. There is no convincing evidence of seaward tilting, instead it appears that much of southern Fiordland is rising rather uniformly.

An Oligocene submarine rockfall/avalanche breccia, Fiordland, New Zealand

Abstract Fan and canyon sediments of the Bal-leny Group (Cretaceous-Oligocene) of southern Fiordland, New Zealand, were deposited in small, fault-controlled, extensional basins and contain numerous examples of coarse mass-flow deposits. At Green Islets Peninsula, a 180 m thick breccia is well exposed in coastal outcrops. The massive, poorly sorted breccia is composed of pebble- to boulder-sized, angular blocks of the local basement and overlies, and locally interdigitates with, pelagic carbonate of the Chalky Island Formation. The breccia apparently formed as a rock avalanche^) which cascaded off a basement high into a basin margin setting. The total volume of the breccia is c. 108 m3, and the most distal portion exposed appears to have travelled about 1000 m. Field relations do not unequivocally indicate whether the main breccia unit represents a single event consisting of an amalgam of several surges which forcibly interdigitated with the marl, or multiple events representing basin margin, debris-cone l...

Naturalised plants in south-west South Island, New Zealand

Abstract Of 140 species of naturalised plants found at 58 sites between Haast and southern Fiordland 24 were deliberately planted and persist at their original sites, 51 are accidental introductions restricted to hut, settlement, and road sites, and 6S occur only at unmodified sites, especially coasts, lake edges, and valley floor grasslands. Those which most threaten native vegetation are gorse (Ulex europaeus), broom (Cytisus scoparius), crack willow (Salix fragilis), Canadian pondweed (Elodea canadensis), and marram grass (Ammophila arenaria). Control of naturalised plants particularly within Fiordland National Park is discussed.

Triterpene methyl ethers inChionochloa(Gramineae): Distribution in western South Island, New Zealand

Abstract Earlier investigations of infraspecific triterpene methyl ether chemodemes of Chionochloa in western South Island left some uncertainty about geographic limits. Further sampling shows that the ,β-amyrin methyl ether chemodeme of C. rigida extends from southern Fiordland to Alex Knob in Westland; in C. pallens the miliacin chemodeme extends from the head of Lake Wakatipu to the Paparoa Range, and the Fiordland cycloartenol methyl ether chemodeme is recognised about as far north as Milford Sound. The range of the cycloartenol methyl ether chemodeme of C. rubra is extended to include the Paparoa Range, and into Canterbury under the Main Divide. Constancy in triterpene methyl ether synthesis is confirmed for C. pungens on Stewart I., and for C. rubra from the Volcanic Plateau. Chionochloa elata is recognised as a species, and although it synthesises miliacin is not absolutely constant in this. Natural hybrids show independent gene action controlling triterpene methyl ether synthesis.

Notes on the Geology and Archaeology of the Martins Bay District

Abstract The Martins Bay district, 12 miles north-east of Milford Sound, includes part of the southern end of the Alpine Fault. North-west of the fault thermally metamorphosed greywacke and argillite is correlated with the Waiuta Group and thought to be Precambrian in age. From Milford Sound north for 6 miles a wedge of marble and carbonaceous argillite (Kaipo Formation) with thick bands of pyritised granite lies between the fault and the Waiuta Group, and is thought to be the faulted north-eastern extension of the Ordovician rocks of southern Fiordland, Fiordland gneiss lies to the south-east of the fault. A coastal strip of Tertiary rocks without diagnostic fossils is correlated with rocks of the Paringa district. The Penguin Rock Breccia, thought to have been produced by volcanic eruptions, is the oldest. The Otitia Formation rests unconformably on the Waiuta Formation and on the Penguin Rock Breccia, consists largely of limestone, and is considered to be Oligocene. The Tititira Formation is faulted ag...