Seafloor massive sulfides from mid-ocean ridges: Exploring the causes of their geochemical variability with multivariate analysis

The neovolcanic zones of mid-ocean ridges are host to seawater-derived hydrothermal systems forming seafloor massive sulfide (SMS) deposits. These deposits have high concentrations of base metals and potentially economic enrichment of a wide range of trace elements. The factors controlling this enrichment are currently poorly understood. We have investigated the main factors controlling SMS compositional variability through robust principal component analysis and robust factor analysis of published and newly obtained bulk geochemical data for samples collected from SMS deposits worldwide. We found that a large part of the observed variability is produced by a combination of three independent factors, which are interpreted to reflect (in order of importance): (1) the temperature of deposition, (2) the ridge spreading rate, and (3) zone refining. The first and the third factors are mostly related to processes operating near the seafloor, such as conductive cooling, mixing of the hydrothermal fluids with seawater and metal remobilization, and determine the relative proportions of the main minerals and, thus, of Cu and Zn (Co, Se, Sb, Pb). The ridge spreading rate influences the structure of the oceanic lithosphere, which exerts a major control on the length and depth of the hydrothermal convection cell and on the rock-to-water ratios in the reaction zone, which in turn control the behavior of the precious metals Au and Ag and elements including Ni (Mo, Se). Despite the obvious role of substrate rocks as metal sources, their composition (specifically mafic vs. ultramafic) does not emerge as a statistically significant independent factor

New properties of scalar field dynamics in brane isotropic cosmological models

Several aspects of scalar field dynamics on a brane which differs from corresponding regimes in the standard cosmology are investigated. We consider asymptotic solution near a singularity, condition for inflation and bounces and some detail of chaotic behavior in the brane model. Each results are compared with those known in the standard cosmology.Comment: 13 pages with 2 eps figures, submitted to Astronomy Letter

Гранулематоз с полиангиитом: астмаподобное и псевдопневмоническое начало болезни

A case of granulomatosis with polyangiitis is described in the article. The patient experienced 3year paroxysmal asthmalike syndrome with granulomatous lesion of the subglottic portion of the larynx that further developed into multifocal destructive lesions of the lungs without clinical signs of glomerulonephritis and with positive response to combined therapy with cytostatic agents, rituximab and systemic steroids. The main criteria of granulomatosis with polyangiitis in this patient were high levels of ANCA and antiproteinase3 antibodies. Therefore, granulomatosis with polyangiitis is characterized by polymorphic onset of lung disease with coexisting paroxysmal respiratory syndrome, infiltrative and destructive pulmonary lesions.Представлено описание случая гранулематоза с полиангиитом, характеризовавшегося трехлетним пароксизмальным астмаподобным симптомокомлексом (на фоне гранулематозных изменений в подскладочном пространстве гортани), последующей трансформацией в многофокусное деструктивное поражение легких (при отсутствии клинических признаков гломерулонефрита) с положительным терапевтическим ответом при назначении комбинированного лечения цитостатическим препаратом, ритуксимабом, системными глюкокортикостероидами

Легочный амилоидоз

Amyloidosis is an orphan disease. Amyloidosis is uncommonly associated with respiratory disorders. The present article is a review of recently published data on pulmonary amyloidosis and a case report of alveolar and septal amyloid lung injury. Clinical heterogeneity of lung lesions in systemic and limited AL amyloidosis (precursor proteins are light chains of immunoglobulins, λ dimer and κ monomer), AA amyloidosis (inflammatory acute-phase proteins), and ATTR amyloidosis (senile and inherited amyloidosis; precursor protein is transthyretin) have been discussed. One chart of the review has been devoted to the pathogenesis of diffuse parenchymatous (unilateral and bilateral) amyloidosis, nodular and tracheobronchial amyloidosis (with amyloid deposits in proximal, medium and distal airways, intrathoracic lymph node involvement (amyloid lymphadenopathy), amyloidosis of the pleura and the diaphragm, and differential diagnosis of these types of pulmonary amyloidosis.Амилоидоз относится к классу орфанных заболеваний. Среди других систем организма с амилоидозом в наименьшей степени ассоциирована дыхательная система. Современные данные по проблеме легочного амилоидоза представлены на основе литературного обзора и авторского описания редкого примера альвеолярно-септальной формы поражения легких; рассмотрены вопросы клинической неоднородности пульмонологической патологии при системном и местном амилоидозе (AL – белок-предшественник – легкие цепи иммуноглобулинов, димер λ и мономер κ; АА – воспалительные острофазовые белки; ATTR – старческий и наследственный, белок-предшественник транстиретин). Один из разделов посвящен патогенезу диффузного паренхиматозного (одностороннего и двустороннего), узлового и трахеобронхиального (с депозитами амилоида в проксимальных, средних или дистальных отделах бронхиального дерева) вариантов болезни, вовлечению в процесс внутригрудных лимфатических узлов (амилоидная аденопатия), плевры и диафрагмы, вопросам дифференциальной диагностики данных вариантов легочного амилоидоза

Cu–(Ni–Co–Au)-bearing massive sulfide deposits associated with mafic–ultramafic rocks of the Main Urals Fault, South Urals: Geological structures, ore textural and mineralogical features, comparison with modern analogs

Cu-rich massive sulfide deposits associated with mafic–ultramafic rocks in the southern portion of the Main Urals Fault (MUF) are characterized by variable enrichments in Ni (up to 0.45 wt.%), Co (up to 10 wt.%) and Au (up to 16 ppm in individual hand-specimens). The Cu (Ni–Co)-rich composition of MUF deposits, as opposed to the Cu (Zn)-rich composition of more eastward massive sulfide deposits of broadly similar age along the western flank of the Magnitogorsk arc, reflects the abundance of seafloor-exposed, Ni–Co-rich ultramafic rocks in the most external portion of the Early-Devonian Magnitogorsk forearc. Morphological, textural, and compositional differences between individual deposits are interpreted to be the result of the sulfide deposition style and, in part, of the original subseafloor lithology. One deposit produced by dominantly on-seafloor hydrothermal processes is characterized by pyrite–marcasite>>pyrrhotite, not so low Zn grades (occasionally up to 2 wt.%), abundant clastic facies and periodical superficial oxidation. Deposits produced by dominantly subseafloor hydrothermal processes are characterized by pyrrhotite>pyrite, very low Zn (generally < to << 0.1 wt.%), volumetrically minor clastic facies, and multi-layer deposit morphology. Very low Ni/Co ratios in the on-seafloor deposit may indicate a dominant metal contribution from a mafic rather than ultramafic source. The sulfide mineralization was associated with extensive hydrothermal alteration of the host ultramafic and mafic rocks, leading to formation of abundant talc, talc–carbonate and chlorite rocks.Occurrence of large volumes of such altered lithotypes in ophiolitic belts may be considered as a potential searching criteria for MUF-type (Cu, Co, Ni)-deposits. In spite of the contrasting geodynamic environment, geological, geochemical, textural and mineralogical peculiarities of the MUF deposits in many respects are similar to those of ultramafic-hosted massive sulfide deposits along the Mid-Atlantic Ridge. In geological time, supra subduction-zone settings appear to have been more effective than mid-ocean ridge settings for preservation of ultramafic-hosted massive sulfide deposits