Experimental and computational study of trace element distribution between orthopyroxene and anhydrous silicate melts: substitution mechanisms and the effect of iron

Although orthopyroxene (Opx) is present during a wide range of magmatic differentiation processes in the terrestrial and lunar mantle, its effect on melt trace element contents is not well quantified. We present results of a combined experimental and computational study of trace element partitioning between Opx and anhydrous silicate melts. Experiments were performed in air at atmospheric pressure and temperatures ranging from 1,326 to 1,420°C in the system CaO-MgO-A

Quantifying garnet-melt trace element partitioning using lattice-strain theory: New crystal-chemical and thermodynamic constraints

Many geochemical models of major igneous differentiation events on the Earth, the Moon, and Mars invoke the presence of garnet or its high-pressure majoritic equivalent as a residual phase, based on its ability to fractionate critical trace element pairs (Lu/Hf, U/Th, heavy REE/light REE). As a result, quantitative descriptions of mid-ocean ridge and hot spot magmatism, and lunar, martian, and terrestrial magma oceans require knowledge of garnet-melt partition coefficients over a wide range of conditions. In this contribution, we present new crystal-chemical and thermodynamic constraints on the partitioning of rare earth elements (REE), Y and Sc between garnet and anhydrous silicate melt as a function of pressure (P), temperature (T), and composition (X). Our approach is based on the interpretation of experimentally determined values of partition coefficients D using lattice-strain theory. In this and a companion paper (Draper and van Westrenen this issue) we derive new predictive equations for the ideal ionic radius of the dodecahedral garnet X-site,

Expression analysis of imbalanced genes in prostate carcinoma using tissue microarrays

To identify candidate genes relevant for prostate tumour prognosis and progression, we performed an exhaustive gene search in seven previously described genomic-profiling studies of 161 prostate tumours, and four expression profiling studies of 61 tumours. From the resulting list of candidate genes, six were selected for protein-expression analysis based on the availability of antibodies applicable to paraffinised tissue: fatty acid synthase (FASN), MYC, β-adrenergic receptor kinase 1 (BARK1, GRK2) the catalytic subunits of protein phosphatases PP1α (PPP1CA) and PP2A (PPP2CB) and metastasis suppressor NM23-H1. These candidates were analysed by immunohistochemistry (IHC) on a tissue microarray containing 651 cores of primary prostate cancer samples and benign prostatic hyperplasias (BPH) from 175 patients. In univariate analysis, expression of PP1α (P=0.001) was found to strongly correlate with Gleason score. MYC immunostaining negatively correlated with both pT-stage and Gleason score (P<0.001 each) in univariate as well as in multivariate analysis. Furthermore, a subgroup of patients with high Gleason scores was characterised by a complete loss of BARK1 protein (P=0.023). In conclusion, our study revealed novel molecular markers of potential diagnostic and therapeutic relevance for prostate carcinoma

Dumortierite from the Gfohl unit, Lower Austria: chemistry, structure, and infra-red spectroscopy

International audienceFor dumortierite from Gfohl Lower Austria, crystal structure refinement in combination with chemical analyses gives the optimized formula (Al(0.78)square(0.12)Mg(0.09)Ti(0.01)) (Al(5.70)square(0.20)Ti(0.06)Fe(0.04)) (Si2.85Al0.15) B O-16 [O-1.17(OH)(0.8) F-0.02], with a = 4.6900(3), b = 11.7875(6), c = 20.1823(11) angstrom. For dumortierite from Wei ss enkirchen in der Wachau, Lower Austria, crystal structure refinement in combination with the chemical analyses gives the optimized formula (Al(0.74)square(0.13)Mg(0.12)Ti(0.01)) (Al(5.70)square(0.20)Ti(0.08)Fe(0.02)) (Si2.83Al0.17) B O-16 [O-1.14(OH)(0.85)F-0.01], with a = 4.6948(2), b = 11.8037(5), c = 20.2106(8) angstrom. Complete chemical characterizations, including light elements (B, H, Li, Be), were combined for the first time with high-quality structure refinements with R-values in the range 0.018-0.019, allowing assignment of site-occupancies with confidence. The optimizations demonstrate that all Mg occupies the M1 sites. Mg substitution at M1 plays a prevailing role in the high number of absorption bands. Contrary to M2, M3 and M4, the M1 site has substantial vacancies. Whereas the average M-O distances of the M2 and M3 sites are similar in each sample, the M-O distances of the M4 sites in both samples are distinctly lower than M2 and M3. This is a clear indication that, unlike the M2 and M3 sites, the M4 sites contain almost no vacancies and no significant substitutions of Fe or Ti. Significant amounts of tetrahedrally-coordinated Al were only found at the T1 sites (0.15 apfu) but not at the 72 sites. The MgO content, similar to 0.7-0.8 wt%, is relatively high for "normal" dumortierite, but similar to dumortierites from the Saxonian Erzgebirge, Germany. Both dumortierite samples from the Gfohl unit contain relatively high OH contents (0.81-0.85 pfu), and measureable amounts of both F and BeO, with 0.05-0.06 wt% and 0.01-0.02 wt%, respectively. The compositions of these dumortierite crystals from different localities are very similar and may therefore reflect similar PT conditions and fluids during crystallization in these pegmatites of the same geological unit (Gfohl unit). FTIR spectroscopy reveals spectra in the 4000-3000 cm(-1) domain that are markedly different from those of dumortierite samples of different origin. The lack of a band at 3675 cm-1 in the sample from Gfohl and the importance of the 3696 cm-1 band in both investigated dumortierite samples suggest a possible ordering of Mg and 0 at the M1 site, in accord with the conclusions from the structure study