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Abstract A freshwater diatomite deposit near Dunedin, South Island, New Zealand provides an exceptional archive of mid-latitude, seasonal climate variation during latest Oligocene-early Early Miocene time. The diatomite accumulated in a small ~ 1.5 km diameter maar-floored lake that formed during basaltic volcanism. Except for exposures of basanite dated at 23.2 Ma by 40 Ar/ 39 Ar, and remnants of a Paleogene sandstone and conglomerate cover, the diatomite body is surrounded by Otago Schist. Geophysical profiles indicate that the total diatomaceous sediment thickness may exceed 100 m. Two depositional facies are described from 15.5 m of weakly-consolidated fresh diatomite accessible in two pits. A thinly laminated facies, comprising 60% of the section, consists of dark brown and white couplets of average thickness 0.5 mm. Both brown and white laminae are composed essentially of frustules of a single pennate diatom, along with 1–2% of siliceous sponge spicules. Dark laminae also contain abundant 5–7.5 µm diameter siliceous chrysophycean stomatocysts and organic matter. Decalcified complete skeletons of Galaxias , a southern hemisphere group of freshwater or diadromous fish, are found throughout. Diverse well-preserved leaves, some with attached scale insects, are dominated by Lauraceae. Rare flowers are also present. Trace fossils preserved in the laminated comprise 1–1.5 mm wide pale diatomaceous strings of probable faecal origin, and isolated 20–40 mm diameter sand lenses interpreted as faecal remains of swimming waterfowl. The second diatomite facies group comprises dark brown speckled beds, interpreted as sediment gravity flows. Up to 14 cm thick and interspersed throughout the study section, they incorporate abundant laminated diatomite flecks and leaves, and minor woody plant matter and terrigenous silt. Almost all are capped by 1–8 mm of white diatomite that is interpreted as post-flow fall-out of resuspended diatom frustules. Associated breccia and swirly beds up to 8 cm thick are composed of variably contorted clasts of laminated diatomite in a speckled matrix. Nodules, spheroids, and films of authigenic framboidal pyrite are commonly associated with plant and fish remains. As in modern lakes, white laminae likely formed from diatom blooms when light flux, temperature, or nutrients were optimal during spring–early summer; dark laminae accumulating during autumn–winter months. Laterally continuous pinstripe lamination, absence of bioturbation, and excellent fish and plant preservation indicate that the profundal lake and floor were anoxic. Periodic variations in couplet thickness of ~ 3–10 years compare with Quaternary records of El Nino–Southern Oscillation variability and indicate that the early Early Miocene low altitude New Zealand climate was seasonal and strongly ocean-influenced, as it is today.

ABSTRACTSusan Bulmer's PhD thesis, “Prehistoric culture change in the Port Moresby region”, was a very important, and still often cited, contribution to Papuan South Coast prehistory in the 1970s. Fieldwork for the thesis included the excavation of important sites at Taurama Beach and on Nebira Hill. This paper outlines recent archaeological and bioarchaeological research on stone artefacts, pottery and skeletal materials from these sites and discusses the implications of this research for early ideas about late prehistoric culture change in the Port Moresby region. The results of the recent studies suggest a complex of cultural (Austronesian and Papuan) and environmental influences, as well as population movements into the region over the past 1200 years, leading to the state of affairs at the close of prehistory. This picture is similar to that painted by Bulmer and others during the pioneering period of Papuan South Coast archaeology over 40 years ago.

Occurrences of densely packed benthic organisms in extant reefs are of two types: 1) live-live interactions, where two living organisms interact, and 2) live-dead associations, where only one is alive and uses the other as a substrate. The latter are common in reef deposits due to biostratinomic feedback, i.e. dense skeletal accumulations provide hard substrates for clonal recruitment, thus facilitating greater frequency of live-dead encounters than in lower biomass level-bottom communities dominated by solitary organisms. Differentiating between these two types in ancient reefs is difficult, often impossible.

Abstract Leaching processes are believed to be responsible for the unusually low-ash content (sometimes less than 1%) of the thick (up to 35 m) Cretaceous coals located in the Greymouth coalfield, South Island, New Zealand. Although leaching of inorganics in peat is a generally accepted process, little is known about leaching after burial. The “Main” and “E” seams in the Greymouth coalfield show good correlation between low ash and bed thickness. The ash content, however, is often less than 1%, which is lower than most known modern analogues (i.e. peat). There are several lines of evidence that suggest that mineral matter may have been removed from the coal not only in the peat stage but also after burial. For example, etching features found in quartz grains and clay aggregates indicate that some leaching processes have taken place. In addition, liptinitic material (e.g., bitumen) in the cleat networks supports the conclusion that there has been some movement of solutions through the coal after burial. These solutions may have helped to remove some of the inorganics originally within the Greymouth coals.

Introduction Tephrochronology in its original sense is the use of tephra layers as time-stratigraphic marker beds to establish numerical or relative ages (Lowe and Hunt, 2001). Tephra layers have been described and studied in New Zealand for more than 160 years (the German naturalist and surgeon Ernst Dieffenbach described ‘recognizable’ tephra sections in his 1843 book Travels in New Zealand), and the first isopach map, showing fallout from the deadly plinian basaltic eruption of Mt Tarawera on 10 June 1886, was published in 1888 (Lowe, 1990; Lowe et al., 2002). More recently, a wide range of tephra-related paleoenvironmental research has been undertaken (e.g., Lowe and Newnham, 1999; Newnham and Lowe, 1999; Newnham et al., 1999, 2004; Shane, 2000), including new advances in the role of tephra in linking and dating sites containing evidence for abrupt climatic change (e.g., Newnham and Lowe, 2000; Newnham et al., 2003). Here we focus on the use of tephrochronology in dating the arrival and impacts of the first humans in New Zealand, a difficult problem for which this technique has proven to be of critical importance.

A shoreline and archaeological excavations at Cook's Cove, eastern North Island, New Zealand were examined for stratigraphy and plant microfossils and results compared with previous interpretations of this site. Buried soils, distal tephras and pollen revealed evidence of pre- and post-settlement forest disturbance. Microfossil starch and calcium oxalate crystals of introduced sweet potato (Ipomoea batatas) and taro (Colocasia esculenta) were identified throughout the deposits, indicating intensive local cultivation and processing of these crops. Results are consistent with revised New Zealand geochronological models and, bearing in mind loss of evidence by erosion, differ in several respects to those of previous studies, as follows. The sea-rafted Taupo Pumice (AD 200) and Loisel's Pumice (from multiple off-shore sources) were not as widespread. Although microscopic charcoal was present to the full depth of all profiles, we did not observe macroscopic pieces below the Loisel's Pumice. The only material w...

Abstract A diverse assemblage of fossil leaves showing cellular detail is reported from the Late Oligocene–Early Miocene Gore Lignite Measures, southern New Zealand. The leaf-remains include at least five conifers, such as the genera Agathis , Dacrycarpus , Phyllocladus and Dacrydium , as well as a number of angiosperms including Gymnostoma , Nothofagus Subgenus Brassospora , Phormium , Proteaceae, Sapindaceae and Ericaceae. A parallel palynological study has identified a number of the same elements. The leaf layers represent litter horizons laid down in pools on the surface of a subtropical ombrotrophic forest mire that formed on an extensive low-lying coastal plain. Highly acidic water ponded in tree-fall depressions prevented microbial decay of the foliage. Taxa represented by both leaves and pollen are considered to have been components of the autochthonous swamp forest. Some other pollen grains are thought to represent local elements, based on the pollination biology of their nearest living relatives. Other taxa whose extant representatives are wind-pollinated may have grown further away.

Abstract Tephra deposits are used by many disciplines of the natural sciences, not only for gaining important insight into volcanism, but also for chronological purposes, especially the dating of sedimentary sequences throughout geological time. Use of these deposits as isochronous tie points relies on the ability to accurately correlate tephra from one site to another including more diffuse, distal sites, as well as to possibly identify the source eruption. However, the ability to uniquely identify tephra deposits, and thus correlate them with certainty, is not without its complications. Here we present a case study from North Island, New Zealand, to highlight the complications and intricacies of achieving robust tephra deposit correlations. We highlight three key issues including: 1) the large uncertainties associated with direct dating techniques for older (≥1 Ma) tephra horizons; 2) the lack of/or minimalist amount of published and accessible geochemical data; and 3) the lack of data pertaining to the source regions themselves. We report new age and geochemical data for tephra deposits from a region that has been the depositional site of many eruptions since at least 12 Ma. Of the tephra horizons sampled in this region, six contained sufficient zircons for fission-track dating. Ages of the horizons range from 1.4 to 5.7 Ma, in good agreement with previously assigned age constraints based on biostratigraphic and/or paleomagnetic markers. However, the precision of these ages (2σ uncertainties of ±0.4–1.6 Ma) is insufficient to correlate the tephra horizons to either their specific source (eruption event) or alternative tephra deposits using geochronology alone. Therefore, in addition to the new (and existing) age data, we present the results of major and trace element analysis of glass shards from 18 tephra horizons. For most horizons the geochemical signatures of the glass shards are internally homogeneous for both major and trace elements, suggesting a single source eruption. In a few cases, however, the tephra horizons exhibit heterogeneous geochemical signatures, which, when coupled with the deposit morphology, suggest evidence for reworking, post-depositional devitrification, and a more complex source history. We discuss correlation of the tephra horizons to onshore and offshore counterparts and also to source. Our results emphasise the importance of combining geochronological constraints with geochemical fingerprinting and additional parameters including stratigraphy to provide the most accurate correlations. As a result, we encourage the use of electronic storage files in publications to give access to full geochemical (including secondary standard data) and chronological datasets. This will not only allow complete characterisation of the tephra, but also facilitate rigorous statistical assessment to produce accurate correlation to other deposits in future studies.

UDC 551.44:556.33:543.38(445.61) Kevin S. Simon: Organic matter flux in the epikarst of the Dorvan karst, France Availability of organic matter plays an important role in karst ecosystems. Somewhat surprisingly, study of the composition and distribution of organic matter in karst aquifers is rare. The most comprehensive study or organic matter flux to date is a two year continuous monitoring of detritus and animal flux in epikarst drip waters and an epikarst-fed cave stream in the Dor van karst, France. Analysis of those data reveals high temporal variation in detritus and animal flux in both habitats, but little evidence of seasonality in flux. water flux explained 30-69% of the variation in animal flux in both habitats and detritus flux in the epikarst seepage water. Detritus flux in the cave stream was better explained by peak monthly discharge. Lack of coherence between organic matter flux in epikarst seepage and the epikarst stream suggests organic matter transport is governed by differing factors in the two habitats. Overall, much of the particulate organic matter flux in the epikarst occurs as living animals suggesting a dominant role of ecological processes in organic matter transport.