Platinum-Group Element Geochemistry of the Escondida Igneous Suites, Northern Chile: Implications for Ore Formation

Platinum-group element (PGE) geochemistry may be used to constrain the timing of sulfide saturation in magmas, which influences the Cu and Au fertility of evolving magmatic systems. We report new geochronological and geochemical data, with emphasis on PGE geochemistry, for a suite of regional porphyritic hornblende–diorite intrusions and ore-bearing porphyries from the super-giant Escondida and smaller Zaldivar Cu deposits of Northern Chile. The regional dioritic intrusions have zircon U–Pb ages between 39·6 to 37·1 Ma, which overlap with the ages of the ore-bearing Escondida and Zaldivar porphyries (38·1 to 35·0 Ma). Whole-rock major and trace element, and Sr–Nd–Pb and zircon O–Hf isotope geochemistry indicate that the regional diorites and ore-bearing porphyries are co-magmatic and originated from the same mantle-derived magma by fractional crystallization, with minor contamination by Paleozoic crust (∼10%). The low concentrations of PGE in the regional diorites show that they reached sulfide saturation before the MgO content of the melt fell to 4·7 wt %, the MgO content of the most primitive sample analysed. The fraction of sulfide melt which separated from the melts that formed the regional diorites is estimated to be ∼0·12 wt %; this resulted in the partitioning of highly chalcophile elements (Au and PGE) into a sulfide phase that was retained in cumulus rocks at depth. However, the fraction of sulfide melt was too low to have a significant effect on the Cu content of the fractionating melt. As a consequence, when the evolving melt eventually reached volatile saturation, it contained enough Cu (40 ± 10 ppm) to form a super-giant Cu deposit. In contrast, Au was largely stripped from the melt by sulfide precipitation, with the result that the mineralization at Escondida is Cu dominant, with only minor Au. The Zaldivar deposit, on the other hand, contains even less Au, which is attributed to a longer fractionation interval between sulfide and volatile saturation. This study provides evidence to support previously proposed models which suggest that the timing of sulfide saturation, the amount of sulfide melt produced, the water content and oxidation state of the melt, and the magma volume are critical factors in determining the potential to form a porphyry Cu deposit. Plots of Pd/MgO against Y can be used as empirical indicators of magma fertility for porphyry mineralization, and to discriminate between Cu–Au and Cu-dominated systems, but cannot predict the size of the deposit. The super-giant status of the Escondida deposit is attributed to it being underlain by a large batholith with a calculated minimum mass of 1012 tonnes (∼400 km3).This work was supported by the Australian Research Council [DP170103140]

Determination of Abundances of Fifty-Two Elements in Natural Waters by ICP-MS with Freeze-Drying Pre-concentration

To precisely determine the abundances of fifty-two elements found within natural water samples, with mass fractions down to fg g(-1) level, we have developed a method which combines freeze-drying pre-concentration (FDC) and isotope dilution internal standardisation (ID-IS). By sublimation of H2O, the sample solution was reduced to 0.3 mol l(-1) to avoid hydrolysis. Matrix-affected signal suppression was not significant for the solutions with NaCl concentrations lower than 0.2 and 0.1 cg g(-1) for quadrupole ICP-MS and sector field ICP-MS, respectively. The recovery yields of elements after FDC were 97-105%. The detection limits for the sample solutions prepared by FDC were <= 10 pg g(-1), except for Na, K and Ca. Blanks prepared using FDC were at pg-levels, except for eleven elements (Na, Mg, Al, P, Ca, Mn, Fe, Co, Ni, Cu and Zn). The abundances of fifty-two elements in bottled drinking water were determined from five different geological sources with mass fractions ranging from the fg g(-1) to mu g g(-1) level with high accuracy

Effects of facial mask treatment are attributed to accelerated maxillary growth and inhibited counter-clockwise total rotation of the mandibular corpus: A structural superimposition study

福岡歯科大学2016年

Application of a Simplified Method of Chloroplast Enrichment to Small Amounts of Tissue for Chloroplast Genome Sequencing

Premise of the study: High-throughput sequencing of genomic DNA can recover complete chloroplast genome sequences, but the sequence data are usually dominated by sequences from nuclear/mitochondrial genomes. To overcome this deficiency, a simple enrichment method for chloroplast DNA from small amounts of plant tissue was tested for eight plant species including a gymnosperm and various angiosperms. Methods: Chloroplasts were enriched using a high-salt isolation buffer without any step gradient procedures, and enriched chloroplast DNA was sequenced by multiplexed high-throughput sequencing. Results: Using this simple method, significant enrichment of chloroplast DNA-derived reads was attained, allowing deep sequencing of chloroplast genomes. As an example, the chloroplast genome of the conifer Callitris sulcata was assembled, from which polymorphic microsatellite loci were isolated successfully. Discussion: This chloroplast enrichment method from small amounts of plant tissue will be particularly useful for studies that use sequencers with relatively small throughput and that cannot use large amounts of tissue (e.g., for endangered species)

On the origin and evolution of the asteroid Ryugu: A comprehensive geochemical perspective

Presented here are the observations and interpretations from a comprehensive analysis of 16 representative particles returned from the C-type asteroid Ryugu by the Hayabusa2 mission. On average Ryugu particles consist of 50% phyllosilicate matrix, 41% porosity and 9% minor phases, including organic matter. The abundances of 70 elements from the particles are in close agreement with those of CI chondrites. Bulk Ryugu particles show higher δ18O, Δ17O, and ε54Cr values than CI chondrites. As such, Ryugu sampled the most primitive and least-thermally processed protosolar nebula reservoirs. Such a finding is consistent with multi-scale H-C-N isotopic compositions that are compatible with an origin for Ryugu organic matter within both the protosolar nebula and the interstellar medium. The analytical data obtained here, suggests that complex soluble organic matter formed during aqueous alteration on the Ryugu progenitor planetesimal (several 10’s of km), <2.6 Myr after CAI formation. Subsequently, the Ryugu progenitor planetesimal was fragmented and evolved into the current asteroid Ryugu through sublimation

<所内学術研究成果報告>H. 「環境保全・地球環境温暖化防止をターゲットとする新パルプ資源ケナフの栽培と利用に関する研究」

本研究は, エコマテリアルとしての非木材繊維資源に最も適切である一年生植物ケナフ(Hibiscus cannabinus L.)の栽培とその利用を目的に, 1993年より開始した研究である。従来の成果は, すでに本年報1992,\u2794,\u2795,\u2796,\u2797,\u2798,および\u2799年に報告した。特に従来のケナフ栽培の成果の総決算として, 1998年より平塚市および平塚ケナフ普及協会との共同研究が行われてきた。特に, 平塚市では休耕田対策としてケナフの栽培を推奨し, 現在, 栽培したケナフのパルプ化と紙製造を行って市政に還元している。この現状はさらに展開し, 平塚市のみならず日本全国にその輪が広がり大きな活動となっている。これらの栽培や利用は最も基礎的な指導と, より学術的な研究成果の提供が常に必要であり, この点を最も重要な課題としている。さらに, 環境教育に対する展開を学校, 公民館などを中心に行い, 2000年度は, 平塚キャンパスで市内6小学校の生徒28名のケナフ教育を行った。まお, 研究室内では, 栽培研究の他に, a)種子の発芽阻害実験, b)海水による阻害実験, c)生長に伴うクロロフィル量および水分量の測定実験, d)光合成測定実験, e)花の成分(色素)研究, f)葉など各器官の成分研究などを行っている。取り扱った種類も, ローゼル(H. sabdariffa L.)類も加えると30種に近い

A Noise Reduction Method for Graphical Analyses with KL-Expansion during Transient Equilibrium Condition

Objectives: Graphical analyses have advantages in unnecessary for the assumption of the number of compartments and fast computation. However, there is a large noise-induced bias or variability in the estimationof total volume of distribution (VT) [1]. Principal component analysis based method (mPCA) was proposed for a noise reduction in Logan graphical analysis (LGA) [2], which might lead to a deformation of kinetics of timeactivity curves (TACs). This study proposes a new noise reduction method for graphical analyses by Karhunen- Lo&egrave;ve expansion (mKLE), which aims to maintain kinetics of voxel-based TACs.\nMethods: mKLE is based on the assumption that the ratio of a TAC to the input function is approximately constant after a certain time (t*) (transient equilibrium condition). Then the TAC after t* can be represented by one basis function. The basis function is expressed as an axis which passes across the origin and minimizesthe distance from TACs in feature space. mKLE was applied to a set of TACs to calculate the basis function. The noise-reduced TACs were obtained by projecting voxel-based TACs onto the basis function. mKLE was tested on human PET data of [11C]TMSX, an adenosine A2A antagonist radioligand [3]. Dynamic PET scans were acquired for 1 hour, and metabolite-corrected arterial input function was obtained. We tested 3 versions: without noise reduction and with mKLE or mPCA. The dynamic data were analyzed by LGA and multilinear analysis (MA1) to calculate the parametric VT images. The regional mean value of VT was calculated from the striatum drawn on the summed PET image. For all graphical methods, t* was set to be 30 min postinjection.\nResults: Figure (A) shows a typical example of TAC from a voxel: an original TAC, the noise-reduced TACs by mKLE and mPCA, and the ROI-averaged TAC. The mKLE estimated TAC agreed well with the ROI-averaged TAC. Figure (B) shows the VT images from the same subject of Fig. (A). In the ROI-averaged TAC, the estimated VT values of LGA and MA1 were the same as 1.23 mL/cm3. The lowest value of VT was given byLGA without noise-reduction (1.12 +- 0.17 mL/cm3). Both mKLE and mPCA similarly improved VT values estimated with LGA (1.23 +- 0.19 mL/cm3 for mKLE, 1.24 +- 0.18 mL/cm3 for mPCA). On the other hand, only mKLE improved VT estimated with MA1 (1.24 +- 0.18 mL/cm3), while mPCA caused overestimation and large variability (1.37 +- 3.21 mL/cm3).\nConclusions: The experimental results suggest that the proposed method is promising for noise reduction of VT imaging by graphical analyses.[pic_01]\nReferences:[1] Slifstein, et al., J Nucl Med 41, 2083-2088, 2000.[2] Joshi, et al., J Cereb Blood Flow Metab 28, 852-865, 2008.[3] Ishiwata, et al., J Nucl Med, 41:345-354, 2000.Brain\u2709 & BrainPET\u270