Monitoring fluid chemistry in iron oxide–copper–gold‐related metasomatic processes,eastern Mt Isa Block,Australia

Most researchers in the Proterozoic eastern Mt Isa Block, NW Queensland, Australia, favour magmatic fluid and salt sources for sodic‐(calcic) alteration and iron oxide–copper–gold mineralization. Here we compare spatial, mineralogic and stable isotope data from regional alteration assemblages with magmatic and magmatic‐hydrothermal interface rocks in order to track chemical and isotopic variations in fluid composition away from inferred fluid sources. Tightly clustered δ¹⁸O values for magnetite, quartz, feldspar and actinolite for igneous‐hosted samples reflect high temperature equilibration in the magmatic‐hydrothermal environment. In contrast, these minerals record predominantly higher δ¹⁸O values in regional alteration and Cu–Au mineralization. This dichotomy reflects partial equilibration with isotopically heavier wallrocks and slightly lower temperatures. Increases in Si concentrations of metasomatic amphiboles relative to igneous amphiboles in part reflect cooling of metasomatic fluids away from igneous rocks. Variations in X_Mg for metasomatic amphiboles indicate local wallrock controls on amphibole chemistry, while variations in X_Cl/X_OH ratios for amphiboles (at constant X_Mg) indicate variable aH₂O/aHCl ratios for metasomatic fluids. Biotite geochemistry also reflects cooling and both increases and decreases in aH₂O/aHCl for fluids away from plutonic rocks. Decreased aH₂O/aHCl ratios for metasomatic fluids reflect in part scavenging of chlorine out of meta‐evaporite sequences, although this process requires already saline fluids. Local increases in aH₂O/aHCl ratios, as well as local decreases in δ¹⁸O values for some minerals (most notably haematite and epithermal‐textured quartz), may indicate ingress of low salinity, low δ¹⁸O fluids of possible meteoric origin late in the hydrothermal history of the region. Taken together, our observations are most consistent with predominantly magmatic sources for metasomatic fluids in the eastern Mt Isa Block, but record chemical and isotopic variations along fluid flow paths that may be important in explaining some of the diversity in alteration and mineralization styles in the district.     

THE ENDURING POWER OF RACISM: A RECONSIDERATION OF WINTHROP JORDAN'S WHITE OVER BLACK

As a history of the origins and development of American racism, White over Black received great acclaim upon its publication in 1968. Deeply researched and covering some 650 pages, it eschewed professional jargon and offered a deft prose style and close attention to matters of sexuality in revealing the origins and lasting influence of racist attitudes arising from Englishmen's impressions of blacks before they became, preeminently, slaves in North America. Jordan's careful weighing of evidence and causation made readers appreciate what he believed his evidence repeatedly demonstrated about white Americans’ attitudes toward African‐Americans: “the power of irrationality in men.” Despite the initial acclaim and scholarly achievement, White over Black soon lost pace with the curve of politics and academic fashion. By the mid‐1970s, the post‐World War II liberal consensus on racial issues had disintegrated, and professional historians were writing principally for other professional historians. Within a decade after its publication, White over Black was relegated to the wasteland of the “suggested supplemental reading list.” However, the book's grasp of the fundamental historical issues requiring explanation has received recent affirmation from influential scholarly and political quarters. A dispassionate review of the literature leading up to and following White over Black's publication indicates that Jordan's emphasis on the causal contribution of racist attitudes to the rise of African slavery in British North America was on target. Moreover, Jordan's appreciation that academic historians should write for nonprofessionals is now widely held inside the academy. The historical accuracy and cogency of expression of Jordan's perspective on race and slavery make White over Black worth reexamining.     

Granite‐related overpressure and volatile release in the mid crust: fluidized breccias from the Cloncurry District,Australia

The source and transport regions of fluidized (transported) breccias outcrop in the Cloncurry Fe‐oxide–Cu–Au district. Discordant dykes and pipes with rounded clasts of metasedimentary calc–silicate rocks and minor felsic and mafic intrusions extend several kilometres upwards and outwards from the contact aureole of the 1530 Ma Williams Batholith into overlying schists and amphibolites. We used analytical equations for particle transport to estimate clast velocities (≥20 m sec^?1), approaching volcanic ejecta rates. An abrupt release of overpressured magmatic‐hydrothermal fluid is suggested by the localization of the base of the breccias in intensely veined contact aureoles (at around 10 km, constrained by mineral equilibria), incorporation of juvenile magmatic clasts, the scale and discordancy of the bodies, and the wide range of pressure variation (up to 150 MPa) inferred from CO₂ fluid inclusion densities and related decrepitation textures. The abundance of clasts derived from depth, rather than from the adjacent wallrocks, suggests that the pressure in the pipes was sufficient to restrict the inwards spalling of fragments from breccia walls; that is, the breccias were explosive rather than implosive, and some may have vented to the surface. At these depths, such extreme behaviour may have been achieved by release of dissolved fluids from crystallizing magma, in combination with a strongly fractured and fluid‐laden carapace, sitting under a strong, low permeability barrier. The relationship of these breccias to the Ernest Henry iron‐oxide–Cu–Au deposit suggests they may have been sources of fluids or mechanical energy for ore genesis, or alternately provided permeable pathways for later ore fluids.     

INDUSTRIAL DIVERSIFICATION IN THE CANADIAN URBAN SYSTEM

On the basis of a statistical analysis of their employment profiles, Canadian cities are grouped into four economic categories: manufacturing, mixed, nodal, and a heterogeneous group containing political, military, and mining towns. Indexes of industrial diversification are calculated for all cities for 1951, 1961, and 1971 using comparable data for the three years. It is shown that industrial diversification is significantly related to the economic typology and also to city size; but city size is not related to economic type. Through time, most cities become more diversified as they grow larger, lending support to the theory of import substitution.
Si on se réfère à une analyse statistique de leurs profils d'emploi, on peut regrouper les villes canadiennes en quatre catégories économiques: industrielles, mélangées, nodales, et un groupe hétérogène composé de villes à vocation politique, militaire, et minière. On calcule les indices de diversification industrielle de toutes les villes pour 1951, 1961, et 1971 en utilisant des données comparables pour chaque année. Ils montrent que la diversification industrielle est liée d'une manière significative à la fois au type d'économie et à la taille des villes, mais que celle-ci n'est pas fonction du type d'économie. Au fil du temps, la plupart des villes diversifient leurs activités au fur et à mesure de leur croissance, ce qui vient à l'appui de la théorie du remplacement des importations.     

吴伟的个性特征及其艺术成就

本文梳理了吴伟的生平及其艺术成就,强调了其才华出众、放纵不羁的个性。进而探讨其作为宫廷画家倍受成化、弘治帝宠遇的原因,特别指出围绕吴伟一生的好运及其个人的魅力与浙派兴衰的息息相关。最后提示吴伟粗放纵肆的画风与古代文献记载是相符合的。     

LOCAL CHANGES IN LINGUISTIC BALANCE IN THE BILINGUAL ZONE: FRANCOPHONES DE L'ONTARIO ET ANGLOPHONES DU QUÉBEC

The issue of minority populations and linguistic change for anglophone and francophone groups in Quebec and Ontario is very important, affecting relationships between the groups and individual perceptions of social power. This paper begins an analysis of linguistic change in the transition or contact zone of bilingualism along the Quebec-Ontario border in the period 1961-86. Written in both languages, it describes changes in absolute numbers and percentage share of the total population of the minority group, anglophones in Quebec and francophones in Ontario. It defines regions of change, and, combining the two measures in a series of graphs, shows levels of change at the local level.
La géographie des populations anglophone et francophone àľintérieur de la zone de transition que constituent ľEst ontarien et le Sud du Québec a sensiblement changé au cours des derniers trente ans. Cet article, rédigé dans les deux langues, décrit ces changements àľéchelle locale sur la base de la comparaison des donnees sur la langue maternelle des recensements del 961 et de 1986. Ľétude identifie les municipalités où les changements dans les nombres au sein des populations minoritaires ont été les plus significatifs ainsi que celles ù ces changements ont le plus affecté le rapport minorité-majorité. Elle met en lumière certains profils de changement et décrit les caractères ethno-linguistiques et géographiques des localités qui en sont représentatives. Elle permet, enfin, de comparer ľévolution des populations franco-ontarienne et anglo-québécoise & ľéchelle locale.     

THE IMPLICATIONS OF ROBERT BRANDOM'S INFERENTIALISM FOR INTELLECTUAL HISTORY

Quentin Skinner's appropriation of speech act theory for intellectual history has been extremely influential. Even as the model continues to be important for historians, however, philosophers now regard the original speech act theory paradigm as dated. Are there more recent initiatives that might reignite theoretical work in this area? This article argues that the inferentialism of Robert Brandom is one of the most interesting contemporary philosophical projects with historical implications. It shows how Brandom's work emerged out of the broad shift in the philosophy of language from semantics to pragmatics that also informed speech act theory. The article then goes on to unpack the rich implications of Brandom's inferentialism for the theory and practice of intellectual history. It contends that inferentialism clarifies, legitimizes, and informs intellectual historical practice, and it concludes with a consideration of the challenges faced by inferentialist intellectual history, together with an argument for the broader implications of Brandom's work.