Showing papers by "Macquarie University published in 1983"

The role of the fluid phase during regional metamorphism and deformation

Abstract: Evidence from rock microstructures, mass transfer and isotopic exchange indicates that substantial quantities of aqueous fluids are involved in low- and medium-grade regional metamorphism. Similar conclusions are drawn from many retrograde environments, whereas high-grade metamorphic fluids may be melt dominated. The mobile fluids play essential roles in metamorphic reactions, mass transport and deformation processes. These processes are linked by the mechanical consequences of meta- morphic fluid pressures (Pr) generally being greater than or equal to the minimum principal compressive stress. Under such conditions meta- morphic porosity comprises grain boundary tubules and bubbles together with continuously generated (and healed) microfractures. Deform- ation results in significant interconnected porosity and hence enhanced permeability. Lithologically and structurally controlled perme- ability variations may cause effective fluid channelling. Simple Rayleigh-Darcy modelling of a uniformly permeable, crustal slab shows that convective instability of metamorphic fluid is expected at the permeabilities suggested for the high Pf metamorphic conditions. Complex, large- scale convective cells operating in overpressured, but capped systems may provide a satisfactory explanation for the large fluid/rock ratios and extensive mass transport demonstrated for many low- and medium-grade metamorphic environ- ments. Such large-scale fluid circulation may have important consequences for heat transfer in and the thermal evolution of metamorphic

Factors determining desert dune type

Abstract: While most observers recognize four elemental types of desert dunes (longitudinal, transverse, barchan and star1–3) there is little agreement about which factors determine these types. The angular relationships between the resultant of sand shifting winds and both the crest and principal slipfaces of the elemental types have been discussed qualitatively for many decades. These relationships have been quantified but the wide range of dune types that combine the elemental forms, and the juxtaposition of different dune types, show that wind regime is not the only determinant; for example, sand availability has been considered important. We have now quantified the importance of both wind regime and sand availability as determinants of dune type. We show here that the four elemental types occur in areas uniquely defined by both the equivalent sand thickness of sediments held in the dunes and a measure of directional variability of sand-moving winds. Wind strength does not appear to be important, vegetation has an ambiguous role, and the particle size of dune sediments is unimportant.

Influence of conspecifics on choice of settlement sites by larvae of two pomacentrid fishes (Dascyllus aruanus and D. reticulatus) on coral reefs

Abstract: Field experiments investigating interactions between recruits and resident Dascyllus aruanus and D. reticulatus were carried out between 1978 and 1980 at Lizard Island, Great Barrier Reef, Australia. Standard Coral Units (SCUs) were constructed on a sandy substrate at a low tide depth of about 2 m. Each SCU was composed of living colonies of Pocillopora damicornis, measuring 60 cm in diameter by 40 cm in height. A grid of 12 SCUs was laid out such that adjacent SCUs were 20 m apart and at least 40 m from the nearest natural patch reef. Established SCUs were defaunated, and subsequently each was repopulated with a group of either D. aruanus or D. reticulatus. The fishes on each SCU were then censused over a 6 mo period spanning the recruitment season of these species. Over this period the net increase in numbers of D. aruanus was significantly greater on those SCUs predominantly inhabited by established D. aruanus than on SCUs where established D. reticulatus predominated. Conversely, the net increase in numbers of D. reticulatus was significantly greater on those SCUs predominantly inhabited by established D. reticulatus than on SCUs where established D. aruanus predominated. Although the results did not categorically rule out the possibility of differential survival after recruitment, they are most readily interpreted in terms of enhanced settlement of larvae on coral heads where conspecific fish predominate. Thus competition is not the only way in which resident reef fish may influence larval recruitment.

Stress Tolerance and Stress-Induced Injury in Crop Plants Measured by Chlorophyll Fluorescence In Vivo: Chilling, Freezing, Ice Cover, Heat, and High Light

Abstract: The proposition is examined that measurements of chlorophyll fluorescence in vivo can be used to monitor cellular injury caused by environmental stresses rapidly and nondestructively and to determine the relative stress tolerances of different species. Stress responses of leaf tissue were measured by FR, the maximal rate of the induced rise in chlorophyll fluorescence. The time taken for FR to decrease by 50% in leaves at 0°C was used as a measure of chilling tolerance. This value was 4.3 hours for chilling-sensitive cucumber. In contrast, FR decreased very slowly in cucumber leaves at 10°C or in chilling-tolerant cabbage leaves at 0°C. Long-term changes in FR of barley, wheat, and rye leaves kept at 0°C were different in frost-hardened and unhardened material and in the latter appeared to be correlated to plant frost tolerance. To simulate damage caused by a thick ice cover, wheat leaves were placed at 0°C under N2. Kharkov wheat, a variety tolerant of ice encapsulation, showed a slower decrease in FR than Gatcher, a spring wheat. Relative heat tolerance was also indicated by the decrease in FR in heated leaves while changes in vivo resulting from photoinhibition, ultraviolet radiation, and photobleaching can also be measured.

Tectonic Relationship between the Late Ordovician and Late Silurian palaeogeographies of southeastern Australia

Abstract: The Ordovician palaeogeography of southeastern Australia was an east‐facing mafic volcanic island arc separated from the Gondwanan continent by a marginal sea, probably floored by oceanic crust. By mid‐Silurian the palaeogeography had changed to an almost wholly ensialic configuration, with meridional horsts and grabens east of the Wagga Metamorphic Belt and widespread silicic magmatism. By extending a previously postulated match between the modern Andaman Basin and parts of southeastern Australia in the Late Ordovician, the transition from the Late Ordovician to Late Silurian palaeogeography can be explained. The entire Ordovician and Silurian interval can be understood in terms of a relatively simple and constant plate geometry involving southeastern Australia in regional dextral shear.

Introductory statistics with applications in general insurance

Abstract: This is a new edition of a very successful introduction to statistical methods for general insurance practitioners. No prior statistical knowledge is assumed, and the mathematical level required is approximately equivalent to school mathematics. Whilst the book is primarily introductory, the authors discuss some more advanced topics, including simulation, calculation of risk premiums, credibility theory, estimation of outstanding claim provisions and risk theory. All topics are illustrated by examples drawn from general insurance, and references for further reading are given. Solutions to most of the exercises are included. For the new edition the opportunity has been taken to make minor improvements and corrections throughout the text, to rewrite some sections to improve clarity, and to update the examples and references. A new section dealing with estimation has also been added.

The effects of a cyclonic storm on coral reef fish assemblages

Abstract: Visual censusing techniques were used to monitor the fish assemblages on eight shallow water coral patch reefs at Lizard Island (northern Great Barrier Reef) over a 27 month period. Larval settlement was distinctly seasonal with peaks occurring in December or January. Cyclones are most prevalent at this time of year. Three cyclones passed close to Lizard Island during the study period. Fish assemblages were censused before and immediately after one cyclone that struck at the time of peak larval settlement. The cyclone had little effect on adults but caused high juvenile mortality and re-distribution of sub-adult individuals. Because settlement strongly influences the diversity and density of adults, cyclones have marked effects on the fish assemblages as a whole. The high frequency of tropical storms in many coral reef areas and the depths to which their effects penetrate suggest that physical disturbances may be an important determinant of coral reef fish assemblage structure.

A second generation nonlinear factor analysis

Abstract: Nonlinear common factor models with polynomial regression functions, including interaction terms, are fitted by simultaneously estimating the factor loadings and common factor scores, using maximum-likelihood-ratio and ordinary-least-squares methods. A Monte Carlo study gives support to a conjecture about the form of the distribution of the likelihood-ratio criterion.

Plant species richness at the 0.1 hectare scale in Australian vegetation compared to other continents

Abstract: New data are reported, and literature data compiled, for species richness in 0.1 ha plots in Australian vegetation. We conclude that on present evidence the same vegetation types are rich, and the same types poor, at a 0.1 ha scale, in Australia as elsewhere. Tropical rainforest averages 140 species per 0.1 ha in permanently humid types. Temperate sclerophyll shrub-dominated types on low-nutrient soils are generally in the range 50–100 species, with open woodlands somewhat richer than scrublands. Warm semi-desert shrublands can have 50–80 species, counting ephemerals both of summer and of winter. Temperate closed forests generally have fewer than 50 species per 0.1 ha. For none of these types is there clear evidence that they are richer or poorer in species at a 0.1 ha scale than types in similar environments with similar growth-form mixes on other continents. We give data for grassy woodlands and sclerophyll scrublands in the monsoonal tropics; the fragments of data on such types available from other continents suggest there may be a wide range of species richness in sub-types of this very broad grouping. Generally, available data do not support the idea that floristic evolutionary history is a strong influence on the species richness of vegetation at the 0.1 ha scale, relative to the influence of the present-day climatic and soil environment.

Mesozoic origins and antecedents of Australia's Eastern Highlands

Abstract: Australia's Eastern Highlands are a conspicuous manifestation of a tectonic regime that has been previously shown to go back at least 65 Ma. This review of the Mesozoic stratigraphy of eastern Australia gives evidence of a very different regime before 95 Ma, related to the presence of a plate boundary close to the present east coast of the continent. During the prior regime, cratonic sedimentation in eastern Australia was dominated by labile sediment from an andesitic orogen coincident with the coast north of Brisbane during the Cretaceous, and further offshore in the Jurassic. Whereas the plate boundary north of Brisbane appears to have been simply convergent, that south to Bass Strait may have experienced prolonged oblique‐slip, manifested in the Jurassic by alkaline volcanism within the SE Highlands terrain. Following a Cenomanian (95–90 Ma) phase of transition, during which the eastern Australian plate boundary may have resembled that margining western North America at present, the plate boun...

Crustal growth in south‐eastern Australia—evidence from lower crustal eclogitic and granulitic xenoliths

Abstract: Mafic and ultramafic xenoliths in a basaltic cone at The Anakies in south-eastern Australia are geochemically equivalent to continental basaltic magmas and cumulates. The xenolith microstructures range from recognizably meta-igneous for intrusive rocks to granoblastic for garnet pyroxenites. Contact relationships between different rock types within some xenoliths suggest a complex petrogenesis of multiple intrusive, metamorphic and metasomatic events at the crust/mantle boundary during the evolution of south-eastern Australia. Unaltered spinel lher-zolite, typical of the uppermost eastern Australian mantle, is interleaved with or veined by the metamorphosed intrusive rocks of basaltic composition. Geothermobarometry calculations by a variety of methods show a concordance of equilibration temperatures ranging from 880°C to 980°C and pressures of 12 to 18 kbar (1200-1800 mPa). These physical conditions span the gabbro to granulite to eclogite transition boundaries. The water-vapour pressure during equilibration is estimated to be about 0.5% of the load pressure, using amphibole breakdown data. Large fluid inclusions of pure CO2 are abundant in the mineral phases in the xenoliths, and it is suggested that flux of CO2 from the mantle has been an important heat source and fluid medium during metamorphism of the mafic and ultramafic protoliths at the lower crust/upper mantle boundary. The calculated pressures and temperatures suggest that the south-eastern Australian crust has sustained a high geothermal gradient. In addition, the nature of the mineral assemblages and the contact relationships of granulitic rock with spinel lherzolite, characteristic of mantle material, suggest that the Moho is not a discrete feature in this region, but is represented by a transition zone approximately 20 km thick. These inferences are in agreement with geophysical data (including seismic, heat-flow and electrical resistivity data) determined for south-eastern Australia. Underplating at the crust/mantle boundary by continental basaltic magmas may be an important alternative or additional mechanism to the conventional andesite model for crustal accretion.

Adolescents' Expectations of Future Events – a Cross-Cultural Study of Australians, Americans, and Indians

Abstract: An important developmental task of adolescents is to consider future possibilities and begin to make choices and plans. In this investigation, samples of 15-year-olds of both sexes from small towns in India, the United States, and Australia were asked to list seven important events they expected in the future, to indicate the approximate time that would elapse before the occurrence of each, and whether each was pleasant or unpleasant. Raters categorized responses for content. The two American samples, twelve years apart, were very similar in their responses. All groups listed predominantly pleasant events. Australian girls showed longer time spans than American girls; and Indian boys, but not girls, produced longer time spans than most of the Australians or Americans… A number of significant differences in the content of responses appeared.

Effect of pressure on rare earth element partition coefficients in common magmas

Abstract: Geochemical modelling of magma generation and crystal fractionation processes at pressures corresponding to those of the lower crust1 and upper mantle2 is critically dependent on the trace element partition coefficients used in the calculations. The effects of temperature and melt composition on partition coefficients are reasonably well established3,4, but the possible effect of pressure has not been closely evaluated, apart from some work on nickel partitioning5. Rare earth elements (REE) are important in geochemical modelling, and the need for data on the pressure effect on REE partitioning has been pointed out3. We have done a series of experiments in which the role of pressure was isolated from that of temperature and melt composition (or melt structure), and we are able to demonstrate a systematic increase in La, Sm, Ho and Lu partition coefficients for sphene/silicate liquid and clinopyroxene/silicate liquid as pressure increases from 7.5 to 30 kbar.

Differential accumulation of the molecular forms of polygalacturonase in tomato mutants

Abstract: Endopolygalacturonase [poly (1–4-α-D galacturonide) glycanhydrolase, EC 3.2.1.15] activity was measured in samples of cv. Rutgers, Nr (never ripe) and F1 hybrids of rin (ripening inhibitor, + rin, ++), nor (nonripening, ++, + nor) and rin × nor (+ rin + nor) fruits taken at three day intervals during ripening. Day 1 of ripening was taken as the day on which the first persistent increase in ethylene production was recorded. The enzyme was first detected on day 3 in Rutgers, F1 rin and F1 nor, and on day 6 in Nr and F1 rin × nor. The Rutgers and F1 rin samples softened more rapidly than the other samples and they also contained more enzyme activity. Enzyme activity developed less rapidly in Nr than in any other samples, but the Nr and the nor hybrid, samples softened at comparable rates. In Rutgers and F1 rin, a high molecular weight form of the enzyme (PG1, Mr 100 000) predominated to day 6, and a lower molecular weight form (PG2, Mr 43 000 - 46 000) progressively increased after day 6. In all F1 nor, F1 rin × nor and Nr samples the enzyme was predominately or entirely as PG1. The interrelationship of PG1 and PG2 and their roles in ripening are discussed.

Body percept change in obese females after weight reduction therapy.

Abstract: Video-image representations of body size were measured on a television monitor that was modified to give a display continuum that ranged from 50% under- to 50% over-estimation of objective size. Sixty-eight females who were undergoing weight reduction counseling were measured before and after treatment. All Ss judged themselves to be significantly more obese than they actually were, with a tendency for errors to be greatest among the more obese Ss. After therapy, more realistic estimates of their physiques ensued. A drop-out rate of 23% was recorded: the drop-outs saw themselves as significantly more obese than those who graduated from the program.

Dynamic Recrystallization in a Naturally Deformed Albite

Abstract: Coarse-grained, deformed albite occurs in veins within a blueschist from the Cazadero region, California. In some grains, deformation and recrystallization are concentrated in narrow shear zones less than 50 μm wide. We have examined the substructural progression across these zones by transmission electron microscopy (TEM), in an attempt to determine the details of the dynamic recrystallization mechanism. The misorientation across subgrain and recrystallized grain boundaries has been determined by analysis of electron diffraction patterns.

Tense and time in English verb clusters of the primary pattern

Abstract: (2) / / she returned the tickets tomorrow, they would refund her money How, then, can regular temporal significance be imputed to the syntactical form of the English verb cluster? It is the object of this essay to suggest how — as far, at any rate, as concerns primary-pattern verb clusters A treatment of tense covering secondary-pattern verb clusters as well would require a vastly longer essay English verb clusters divide into those of the PRIMARY PATTERN and those of the SECONDARY PATTERN, the former being all and only those not incorporating a secondary auxiliary (Palmer 1974:30ff, 94ff) The secondary auxiliaries are will, would, shall, should, can, could, may, might, must, ought and two or three others The point of the segregation is that secondary-pattern verb clusters are systematically one word longer than primary-pattern ones — a syntactical fact which can hardly lack semantic significance

The Society for the Suppression of Vice and its Early Critics, 1802–1812

Abstract: The Society for the Suppression of Vice was founded in I802. It held its inaugural meeting at Gray's-Inn coffee house on 22 March of that year' after several months of preliminary negotiation.2 The particular forms of vice which the founders of the society selected for suppression they eventually listed as follows: profanation of the Lord's Day and profane swearing; publication of blasphemous, licentious and obscene books and prints; selling by false weights and measures; keeping of disorderly public houses, brothels and gaming houses; procuring; illegal lotteries; cruelty to animals.3 In their early years of activity members of the society had to face a considerable amount of hostility and ridicule. This much of the society's history is reasonably well known, partly as a result of research into 'the origins of Victorian morality',4 partly as a result of research into the urban and labour history of 'the age of the industrial revolution'.5 Yet existing accounts of the Vice Society's early activities remain vague, incomplete and sometimes contradictory, even on basic issues. Who, for example, founded the society? (Historians have commonly, though not unanimously, assumed the founders to be evangelicals acting under guidance, or at least inspiration, from William Wilberforce and the 'Clapham Sect'.)6 More generally, what were the motives of the founders? Why did they choose to define vice in the way that they