The Indotriradites dolianitii Morphon, a distinctive group of miospore species from the Lower Carboniferous of Gondwana

An emended diagnosis and generic reallocation are proposed for the trilete miospore Indotriradites dolianitii (Daemon, 1974) Loboziak et al., comb. nov. A new species, I. daemonii Loboziak et al., sp. nov., from Viséan strata of Western Gondwana, is erected. These two species, together with I. zosteriformis (Playford et Satterthwait) Playford, 1991 from the Viséan of Australia, belong to a cohesive morphological miospore category, here termed the Indotriradites dolianitii Morphon, which is evidently restricted to the Lower Carboniferous of Gondwana.

Radiizonates arcuatus, a distinctive new miospore species from the Lower Carboniferous of Western Gondwana

A new species of trilete zonate miospores, Radiizonates arcuatus, is established for Lower Carboniferous Western Gondwanan forms hitherto ascribed misguidedly to Radiizonates genuinus (Jushko) Loboziak and Alpern (1978), a Russian Lower Carboniferous species. The latter binomen is, moreover, not a valid combination and is more correctly designated as Vallatisporites genuinus (Jushko) Byvsheva, 1980. R. arcuatus is, from records to date, confined to westerly parts of Gondwana (Brazil, North Africa and Middle East), in which it is characteristic of Early Carboniferous strata, albeit with some slightly older and slightly younger occurrences.

Geochemical mass-balance and oxygen-isotope constrains on silcrete formation and its paleoclimatic implications in Southern Australia

Two geographically distinct silcrete associations are present in southern Australia, inland and eastern; these were sampled in central South Australia and central Victoria, respectively, At each site, both silicified and immediately adjacent unsilicified parent material were collected. Analytical data from these pairs were used to construct isocons, assuming Zr immobility, and to calculate the volume change and amount of silica introduced during silicification, These results, together with whole-rock oxygen isotope compositions, were used to determine the delta(18)O of th, introduced silica, The results show that the eastern silcretes in central Victoria are probably linked genetically to the associated basalts, weathering of which supplied the introduced silica, This conclusion is based on the close spatial connection between the two, as well as the substantial amount of introduced silica in the silcretes (greater than in the inland silcretes), resulting in volume increases in some eastern silcretes, Oxygen isotopic calculations for the silcretes indicate that the silica precipitated from groundwaters at temperatures slightly higher than present conditions. Silcrete formation apparently occurred during the Miocene and Pliocene (basalts in Victoria younger than Pliocene lack associated silcrete) and may reflect the much wetter climate in southeastern Australia at that time. The inland silcretes of central South Australia can be divided into pedogenic (the most common) and groundwater varieties. The pedogenic silcretes, which show typical soil features like columnar and nodular textures, contain moderate amounts of introduced silica that precipitated by evaporation from saline groundwaters, For the groundwater silcretes, which have massive textures and formed at or close to the water table, insufficient data are available to determine the mode of formation. The inland pedogenic silcretes have probably been farming from the Eocene-Miocene to the present, implying that conditions of seasonally high evaporation have occurred in central Australia during this time period. Thus silcrete formation depends on a complex interplay between climate and silica supply, and it is impossible to generalize that the presence of silcrete is indicative of a particular climate. Likewise, the elemental composition of silcretes, particularly Ti content, is not necessarily of climatic significance, Nevertheless, detailed geochemical and oxygen isotopic studies of a silcrete and its parent material can elucidate the mechanisms of silcrete formation, and if evaporation is indicated as a major factor in silcrete formation, then the climate at the time was likely to have been at least seasonally arid.

Urban and rural suicide differentials in migrants and the Australian-born, New South Wales, Australia 1985-1994

We estimated risk of suicide in adults in New South Wales (NSW) by sex, country of birth and rural/urban residence, after adjusting for age; we also examined youth suicide (age 15-24 years). The study population was the entire population of NSW, Australia, aged greater than or equal to 15 years during the period 1985-1994. Poisson regression was used to examine the relationship between predictor variables and the risk of suicide, with the focus on migrant status and area of residence. A significantly higher risk of suicide was found in male migrants from Northern Europe and Eastern Europe/former USSR, compared to Australian-born males; a significantly lower suicide risk occurred in males from Southern Europe, the Middle East and Asia. In female migrants, those from UK/Eire, Northern Europe, Eastern Europe/former USSR and New Zealand exhibited a significantly higher risk of suicide compared to Australian-born females. A significantly lower risk of suicide occurred in females from the Middle East. Male migrants overall were at significantly lower risk of suicide than the Australian-born, while female migrants overall had a significantly higher risk of suicide than Australian-born females. Among migrant males overall, the rural-urban suicide risk differential was significantly higher for those living in non-metropolitan areas (RR = 1.9; 95% CI: 1.7-2.1). Suicide risk was significantly higher in non-metropolitan male immigrants from the UK/Eire (RR = 1.4; 95% CI: 1.1-1.7), Southern Europe (RR = 1.7; 95% CI: 1.2-2.4), Northern/Western Europe (1.5; 95% CI: 1.2-1.9), the Middle East (RR = 3.8; 95% CI: 1.9-7.8), New :Zealand (RR = 1.4; 95% CI: 1.0-1.8) and 'other' (RR = 2.6; 95% CI: 1.9-3.5), when compared to their urban counterparts. There was no statistically significant difference in suicide risk between rural and urban Australian-born males. For female suicide, significantly lower risk was found in female immigrants living in non-metropolitan areas who were from Northern/Western Europe (RR = 0.7; 95% CI: 0.4-0.96), as well as the Australian-born (RR = 0.7; 95% CI: 0.6-0.8), when compared to their urban counterparts. The non-metropolitan/metropolitan relative risk for suicide in female migrants overall was not significantly different from one. Among male youth there was a significantly higher suicide risk in non-metropolitan areas, with a relative risk estimate of 1.4 for Australian-born youth (95% CI: 1.2-1.5) and 1.7 for migrant youth (95% CI: 1.2-2.4), when compared with metropolitan counterparts. We conclude that suicide among migrant males living in non-metropolitan areas accounts for most of the excess of male suicide in rural NSW, and the significantly lower risk of suicide for non-metropolitan Australian-born women does not apply to migrant women. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.

The last glacial cycle from the humid tropics of northeastern Australia: comparison of a terrestrial and a marine record

A detailed pollen record from the Ocean Drilling Program Site 820 core, located on the upper part of the continental slope off the coast of northeast Queensland, was constructed to compare with the existing pollen record from Lynch's Crater on the adjacent Atherton Tableland and allow the production of a regional picture of vegetation and environmental change through the last glacial cycle. Some broad similarities in patterns of vegetation change are revealed, despite the differences between sites and their pollen catchments, which can be related largely to global climate and sea-level changes. The original estimated time scale of the Lynch's Crater record is largely confirmed from comparison with the more thoroughly dated ODP record. Conversely, the Lynch's Crater pollen record has assisted in dating problematic parts of the ODP record. In contrast to Lynch's Crater, which reveals a sharp and sustained reduction in drier araucarian forest around 38,000 yrs BP, considered to have been the result of burning by Aboriginal people, the ODP record indicates, most likely, a stepwise reduction, dating from 140,000 yrs BP or beyond. The earliest reduction shows lack of a clear connection between Araucaria decline and increased burning and suggests that people may not have been involved at this stage. However, a further decline in araucarian forest, possibly around 45,000 yrs BP, which has a more substantial environmental impact and is not related to a time of major climate change, is likely, at least partially, the result of human burning. The suggestion, from the ODP core oxygen isotope record, of a regional sea-surface temperature increase of around 4 degrees C between about 400,000 and 250,000 yrs BP, may have had some influence on the overall decline in Araucaria and its replacement by sclerophyll vegetation. (C) 2000 Elsevier Science B.V. All rights reserved.