Mineral chemistry of igneous melanite garnets from analcite-bearing volcanic rocks, Alberta, Canada

The mineral chemistry of melanite garnets from the Crowsnest volcanic rocks of SW Alberta, Canada, has been investigated by using electron microprobe scans, quantitative analyses and multivariate statistical analysis. The garnets occur with aegirine-augite, sanidine, analcite and rare plagioclase as phenocrysts in trachyte and phonolite flows, agglomerates and tuffs. Wavelength dispersive microprobe scans reveal complex zonation patterns, both normal and oscillatory. The results of fifty quantitative analyses were subjected to R-mode factor analysis to delineate the chemical exchanges producing the zonation. The chemical zonation of the garnets may be attributed to four independent binary exchanges; Al-Fe3+, Si-Ti, Ca-Mn and Mg-Fe2+. The stoichiometry of these garnets, based on microprobe and wet chemical Fe analyses, combined with the strongly antithetic behavior of Si and Ti lead us to infer that the Ti in these garnets is dominantly tetravalent. It is clear from this study that quantitative modelling of the processes of crystal growth and zonation of melanite garnets in alkaline, undersaturated igneous rocks should be aimed at simulating the four chemical exchanges listed above

Heterozygous missense mutations in steroidogenic factor 1 (SF1/Ad4BP, NR5A1) are associated with 46,XY disorders of sex development with normal adrenal function

Context: Steroidogenic factor 1 ( SF1/AdBP4/FTZF1, NR5A1) is a nuclear receptor transcription factor that plays a key role in regulating adrenal and gonadal development, steroidogenesis, and reproduction. Targeted deletion of Nr5a1 ( Sf1) in the mouse results in adrenal and gonadal agenesis, XY sex-reversal, and persistent Mullerian structures in males. Consistent with the murine phenotype, human mutations in SF1 were described initially in two 46, XY individuals with female external genitalia, Mullerian structures ( uterus), and primary adrenal failure.Objective: Given recent case reports of haploinsufficiency of SF1 affecting testicular function in humans, we aimed to identify SF1 mutations in a cohort of individuals with a phenotypic spectrum of 46, XY gonadal dysgenesis/impaired androgenization ( now termed 46, XY disorders of sex development) with normal adrenal function.Methods and Patients: The study included mutational analysis of NR5A1 in 30 individuals with 46, XY disorders of sex development, followed by functional studies of SF1 activity.Results: Heterozygous missense mutations in NR5A1 were found in four individuals ( four of 30, 13%) with this phenotype. These mutations ( V15M, M78I, G91S, L437Q) were shown to impair transcriptional activation through abnormal DNA binding ( V15M, M78I, G91S), altered subnuclear localization ( V15M, M78I), or disruption of the putative ligand-binding pocket ( L437Q). Two mutations appeared to be de novo or germline changes. The other two mutations appeared to be inherited in a sex-limited dominant manner because the mother is heterozygous for the change.Conclusions: These studies demonstrate that SF1 mutations are more frequent than previously suspected causes of impaired fetal and postnatal testicular function in 46, XY individuals

Introduction: new research in monetary history - A map

This handbook aims to provide a comprehensive (though obviously not exhaustive) picture of state-of-the-art international scholarship on the history of money and currency. The chapters of this handbook cover a wide selection of research topics. They span chronologically from antiquity to nowadays and are geographically stretched from Latin America to Asia, although most of them focus on Western Europe and the USA, as a large part of the existing research does. The authors of these chapters constitute, we hope, a balanced sample of various generations of scholars who contributed to what Barry Eichengreen defined as "the new monetary and financial history" – an approach that combines the analysis of monetary aggregates and policies with the structure and dynamics of the banking sector and financial markets. We have structured this handbook in ten broad thematic parts: the historical origins of money; money, coinage, and the state; trade, money markets, and international currencies; money and metals; monetary experiments; Asian monetary systems; exchange rate regimes; monetary integration; central banking and monetary policy; and aggregate price shocks. In this introduction, we offer for each part some historical context, a few key insights from the literature, and a brief analytical summary of each chapter. Our aim is to draw a map that hopefully will help readers to organize their journey through this very wide and diverse research area

Activity variations attending tungsten skarn formation, Pine Creek, California

An integrated geochemical analysis of the well-exposed Pine Creek, California tungsten skarn deposit has been undertaken to evaluate changes in chemical gradients across various lithologies. Thermodynamic calculations using available experimental and thermodynamic data allow limits to be assigned to the activities of important chemical components in the metasomatic environment. Quantifiable changes in “non-volatile” component activites (CaO, MgO, Al 2 O 3 , Fe 2 O 3 , WO 3 ) and in fugacities (O 2 , F 2 ) have been traced across the system. The activities of Al 2 O 3 , Fe 2 O 3 and WO 3 generally increase from the marble (<10 2 , <10 −6 , <10 −5 respectively), through the outer skarn zone and into the massive garnet skarn (10 −1.7±0.3 , 10 −3.4±0.4 , 10 −4.8±0.1 ) While CaO and MgO activities decrease for the same traverse from 10 −5 and 10 −2.1±1 respectively, to <10 −5.7 and <10 −3 . Calculated oxygen fugacities are 10 −23.5+1.0 at T =800 K (527° C), about one log unit below QFM, and more reducing than that required by Mt-Py-Po. The high variance of the garnet-pyroxene-quartz assemblages adds sufficient uncertainty to the calculated activities for individual specimens that only the large-scale trends survive the small-scale scatter. None of the chemical variables emerge as major independent or controlling factors for the mineralogy or phase compositions. Changes in the activity of one component may be offset by compensatory changes in another resulting in an environment that, while different from Pine Creek, could still host scheelite mineralization. Mass balance calculations indicate that the exposed endoskarn cannot have supplied the necessary chemical components to convert the country rock to skarn.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47341/1/410_2004_Article_BF00381557.pd

Architecture of the Oman-UAE ophiolite : evidence for a multi-phase magmatic history

The Oman–United Arab Emirates ophiolite is the world’s largest ophiolite. It is divided into 12 separate faultbounded blocks, of which the northern three lie wholly or partly in the United Arab Emirates. Extensive mapping has shown that the United Arab Emirates blocks contain mantle and crustal sections which correspond to the classic ‘Penrose conference’ ophiolite definition but which are cut by a voluminous later magmatic sequence including ultramafic, mafic and felsic components. Samples from the later magmatic sequence are dated at 96.4±0.3, 95.74±0.3 and 95.2±0.3 Ma; the early crustal section, which has not been dated directly, is thus constrained to be older than c. 96.4 Ma. Petrological evidence shows that the early crustal section formed at a spreading ridge, but the later magmatic sequence was formed from hydrous magmas that produced different mineral crystallisation sequences to normal midocean ridge basalt (MORB). Mineral and whole-rock geochemical analyses show that the early crustal rocks are chemically similar to MORB, but the later magmatic sequence has chemical features typically found in suprasubduction zone (SSZ) settings. The ophiolite in the United Arab Emirates thus preserves clear evidence for two stages of magmatism, an early episode formed at a spreading centre and a later episode associated with the onset of subduction. Similar two-stage magmatism has been recognised in the Oman sector, but the United Arab Emirates contains the most voluminous SSZ magmatism yet described from this ophiolite