Добрый день, Коллеги. Важное сообщение, просьба принять участие. Музей Ферсмана ищет помощь для реставрационных работ в помещении. Подробности по ссылке
Growing evidence suggests that the mechanism of Palaeozoic continental growth in Central Asia was by subduction– accretion with punctuated collisions that produced ophiolitic sutures between accreted blocks. The Bayankhongor ophiolite is the largest ophiolite in Mongolia and possibly all of Central Asia, and is interpreted to mark the collisional suture between the Baidrag and Hangai continental blocks. New 207Pb/206Pb zircon evaporation ages for granite plutons and dykes that intrude the ophiolite and its neighbouring lithotectonic units suggest that the ophiolite was obducted at c. 540 Ma at the beginning of a collisional event that lasted until c. 450 Ma. The new data, combined with that of previous studies, indicate regional correlation of isotopic ages north-westward from Bayankhongor to southern Tuva. These data record oceanic crust formation at c. 570 Ma, followed by approximately 30 million years of subduction–accretion that culminated in obduction of ophiolites, collision related metamorphism, and magmatism in the period c. 540–450 Ma. Correlation of isotopic-age data for the ophiolites of western Mongolia and southern Tuva suggests that the ophiolites define a major collisional suture in the Central Asian Orogenic Belt (CAOB) that defines the southern and western margins of the Hangai continental block.
The siliceous rocks from structures of the junction zone of the Kokchetav massif and Stepnyak trough that occur in turbidites of the accretionary wedge, silica-volcanogenic sequence of the Stepnyak trough and syntectonic olistostrome were dated on the basis of findings of conodonts and radiolarians within the Middle-Upper Arenigian (conodont zones O. evae, B. navis—lower Par. originalis). This range of time is marked by a powerful tectonic rearrangement, involved with the rearrangement of the accretionary wedge and overriding of the Kokchetav massif upon the Stepnyak fore-arc trough.
Pregold mineralization at the Getchell Carlin-type gold deposit includes quartz and base metal vein mineralization associated with intrusion of a Cretaceous granodiorite stock. The veins contain minor pyrite and trace chalcopyrite, arsenopyrite, galena, and sphalerite. The pyrite is moderately coarse and, in thin section, has high relief, is well polished, and is fractured and locally cemented by the gold ore assemblage. White micas are associated with veins near the granodiorite intrusion. Gold was not observed or detected by fire assay analyses of samples or electron microprobe analyses of pyrites. Microprobe analyses show that pregold pyrites have near-stoichiometric compositions. Variable, low arsenic is present in pyrite in samples overprinted by gold mineralization. Secondary ion mass spectrometry (SIMS) analyses detected trace gold in the coarse, near-stoichiomet-ric pyrite in overprinted samples. The pregold vein assemblage was fractured and cemented by gold ore-stage mineralization
Ammonoids are the quintessential fossils, seemingly covering all the major themes of paleontology. Method and theory of stratigraphic correlation using fossils? Albert Oppel, whose concepts of zonation were explicated and applied by W. J. Arkell exhaustively in his monumental works on the Jurassic System, immediately spring to mind-works based virtually exclusively on the stratigraphic distributions of ammonoid species. Evolution? W. Waagen leaps to mind, applying the term “mutation” to his ammonoid lineages, and thus introducing the word to the scientific literature well before geneticists co-opted “mutation” for their own, starkly different, use. <...>
“Topics in Igneous Petrology: A Tribute to Professor Mihir K. Bose”, as the title appropriately suggests, is a Festschrift, ably edited by Professors Jyotisankar Ray, Gautam Sen and Dr. Biswajit Ghosh. It includes 18 scientific papers by 53 authors from around the globe. This Festschrift is indeed a welcome tribute, a true “festival of writing”, celebrating the life and works of the honoree, the admirable Professor Bose, by his students, colleagues and acquaintances. Unfortunately, Professor Bose passed away on October 1, 2009 before seeing these papers in print. The papers cover a broad range of topics and focus on igneous petrology that is bound to attract attentions of many igneous petrologist-geochemist, and certainly Professor Bose would have found himself drawn to many of these papers with utmost interest.
Topography is at once a fundamental and a subtle environmental factor. It wields large and small influences over all other factors of the ecosphere -climate, water storage and movement, soils, animals and plants, and human activities. Several conspicuous topographic influences are well known. Most readers will be aware that a hike up a mountain is the climatic equivalent of a trek from a lower to a higher latitude. They will also be familiar with the stark climatic and botanical contrasts between northfacing and south-facing slopes in the European Alps. Subtle influences are not so well known but are equally significant.
The Australasian Institute of Mining and Metallurgy (The AusIMM) has been one of the principal organisations behind the JORC Code, which has been adopted by the Australian Stock Exchange and the Australian Securities commission as the standard for reporting mineral resources and ore reserves. This is now starting to be recognised as the international standard, with the UK, the USA and Canada all examining some form of the JORC Code for their resource and reserve reporting guidelines. The AusIMM has now further taken the initiative to produce a major volume covering all aspects of world’s best practice in Mineral Resource and Ore Reserves estimation. This prestigious volume will be published in the year 2000. <...>
The Kapai Slate is a continuous, pyrite-rich carbonaceous shale horizon within the St. Ives Au district that is spatially related to high-grade Au mineralization. In situ laser ablation-inductively coupled mass spectrometry (LA-ICPMS) trace element analyses, in situ sensitive high resolution ion microprobe, stable isotope (SHRIMPSI) S isotope analyses, and optical microscopy pyrite texture analyses were used to examine the different pyrite types in the Kapai Slate and Au deposits. These data were also used to confirm that the trace element signature of sedimentary pyrite can be preserved in rocks that underwent upper to mid-greenschist facies metamorphism and significant hydrothermal overprint. The data were further utilized to gain a more detailed understanding of the ocean conditions during deposition of the Kapai Slate and determine whether some of the Au and S in the St. Ives district could have been sourced from the Kapai Slate.
Plant and soil form an integrated system. Technogenic contamination of soils with potentially toxic trace elements (PTE) are reflected in the functioning of plants and soil biota. Soil contamination by PTE has several implications for human health, as well as for the biosphere. Trace element “biogeogenic cycling” in the environment is an integral function of the ecosystem (aquatic, terrestrial, and atmospheric). Therefore, the aim of this collective work is to deal with the trace elements in the holistic environment, considering advancements in the state-of the-art analytical techniques, molecular biology, and contemporary biotechnology that enhance our knowledge of the behavior of trace elements in the biogeosphere and organismal levels, i.e., at the cellular and molecular levels. Various chapters of this book provide the background with appropriate examples to understanding the trace elements in the biogeosphere on bioavailability, biogeochemistry, biotechnology, bioremediation, and risk assessment. <...>
Chapter 1 A Study of Airborne Trace Elements in Belgrade Urban Area: Instrumental and Active Biomonitoring Approach M. Aničić, Z. Mijić, M. Kuzmanoski, A. Stojić, M. Tomašević, S. Rajšić and M. Tasić
Chapter 2 Flow Optosensing Applied to the Analysis of Trace Elements Antonio Ruiz-Medina and Eulogio J. Llorent-Martínez
Chapter 3 Trace Metals in Fruit and Vegetable and their Effects on Human Health Stefania Papa, Giovanni Bartoli and Antonietta Fioretto
