The petrogenesis of the topaz-rich ongonite and topazite dikes in the Flying W ranch area (Tonto basin, Arizona) was investigated, and the possible origin of the topaz in the Flying W rhyolite is discussed. The field, textural geochemical, and mineralogical characteristics of the topaz-bearing dikes in the Flying W ranch area all were found to support the genesis of the topaz-bearing bodies from a magma. The evidence obtained contradicts an origin for these rock types by greisenization or veining.
Abstract This chapter investigates where and in what form phosphorus occurs on Earth. It describes the major geological dimensions of phosphorus. It measures the quantities extractable phosphorus occurs and explores the past and current trends of phosphorus usage; looks into the prediction of future trends and determines the reliability; and discusses the role of economics in phosphorus reserves, and how resources are geologically determined. It also explains the issue of the shortage of phosphorus.
Phase relations involving genthelvite are studied on the basis of physical-chemical principles and natural occurrences. Stability diagrams and exchange operators are considered as well as an extended system, natural associations, and solid state relations. It is noted that the extremely high chalcophilicity of Zn explains, in part, why genthelvite is such as rare mineral. It is only somewhat more stable than willemite and is therefore restricted to the extremely low-S environments provided by alkaline granites and syenites.
Progress in Metamorphic and Magmatic Petrology comprises a collection of review articles summarising recent scientific achievements in the theory of petrology. The contributors include many prominent specialists in the field, such as A. Boettcher, A. Marakushev, I. Kushiro, B. Mysen, W. Schreyer, W. Ernst, E. Grew, P. Wyllie and E-an Zen. Their papers discuss developments in experimental work as well as in field geology. The book is divided into three main sections: section 1 covers general thermodynamics and mineral equilibria, section 2 covers metamorphic and metasomatic processes, and the final section covers the mantle and magmatic processes. The subjects covered include the general thermodynamics of geological processes, the thermodynamics of solid solutions, geothermometry and geobarometry, P-T-time paths, experimental and theoretical modelling of metasomatic processes, the genesis of anorthosites, island arc magmatic rocks and kimberlites, and the thermal areas around intrusive bodies. The book is dedicated to the memory of Professor D. S. Korzhinskiy, a founder of the theory of open systems with perfectly mobile components.
Research Article| March 01, 2008 Nanometer-scale complexity, growth, and diagenesis in desert varnish Laurence A.J. Garvie; Laurence A.J. Garvie 1School of Earth and Space Exploration, Arizona State University, Tempe, Arizona 85287-1404, USA Search for other works by this author on: GSW Google Scholar Donald M. Burt; Donald M. Burt 1School of Earth and Space Exploration, Arizona State University, Tempe, Arizona 85287-1404, USA Search for other works by this author on: GSW Google Scholar Peter R. Buseck Peter R. Buseck 2School of Earth and Space Exploration, Arizona State University, Tempe, Arizona 85287-1404, USA and Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287-1604, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Laurence A.J. Garvie 1School of Earth and Space Exploration, Arizona State University, Tempe, Arizona 85287-1404, USA Donald M. Burt 1School of Earth and Space Exploration, Arizona State University, Tempe, Arizona 85287-1404, USA Peter R. Buseck 2School of Earth and Space Exploration, Arizona State University, Tempe, Arizona 85287-1404, USA and Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287-1604, USA Publisher: Geological Society of America Received: 05 Sep 2007 Revision Received: 02 Nov 2007 Accepted: 07 Nov 2007 First Online: 02 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 The Geological Society of America, Inc. Geology (2008) 36 (3): 215–218. https://doi.org/10.1130/G24409A.1 Article history Received: 05 Sep 2007 Revision Received: 02 Nov 2007 Accepted: 07 Nov 2007 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Laurence A.J. Garvie, Donald M. Burt, Peter R. Buseck; Nanometer-scale complexity, growth, and diagenesis in desert varnish. Geology 2008;; 36 (3): 215–218. doi: https://doi.org/10.1130/G24409A.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Nanometer-scale element mapping and spectroscopy of desert varnish from the northern Sonoran Desert in southwestern Arizona reveal a dynamic disequilibrium system characterized by postdepositional mineralogical, chemical, and structural changes activated by liquid water. Lack of equilibrium is suggested by the large variety of coexisting Mn phases. Sparse secondary Ba and Sr sulfates also occur, as do carbonaceous particles. Individual Mn-oxide particles contain variable concentrations of Ba and Ce, reflecting their role as repositories of trace elements, presumably derived from atmospheric aerosols. Desert varnish is analogous to more familiar sediments in displaying authigenic and diagenetic structures, but with total sediment thicknesses <1 mm and structures at the nanometer scale. As such, it is neither a weathering rind nor patina, but a unique subaerial sediment that is in dynamic disequilibrium. Our results suggest continuing adjustment of varnish to changing environmental conditions. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.
The primary lithium aluminosilicates in pegmatites are spodumene (a-LiAlSizOe) and petalite (LiAlSi4Or0). These minerals are frequently replaced by fine-grained assemblages of eucryptite (a-LiAlSiO+), albite, micas, and clay minerals as a result of subsolidus cation exchange reactions with residual pegmatitic fluids. All three of the lithium aluminosilicates may be converted to albite in quartz-saturated, Na-rich environments, but in quartz-undersaturated environments (as within large single crystals of spodumene), the replacement assemblage eucryptite + albite is stabli to higtr values of the exchange potential pNoLi_,. The stability of the primary pegmatite assembhle quartz + albite + spodumene (or petalite) * amblygonite-montebrasite + lithiophilite means that lithiophilite or amblygonite-montebrasite cannot be altered to natrophilite (NaMnPor) or lacroixite (NaAlPoaF), respectively, until Na-Li exchange has locally converted all of the lithium aluminosilicates to albite. Of the three lithium aluminosilicates, eucryptite is the most susceptible to replacement by muscovite, but spodumene also may be converted directly to mica (killinite). In acidic fluids with a high capacity to hydrolyze solid phases and leach alkali cations, the lithium aluminosilicates may be altered to (or become unstable relative to) kaolinite, cookeite, muscovite, lepidolite, and topaz. The common late-stage assemblage topaz + lepidolite + quartz forms in KF- and HF-rich environments outside of the lithium aluminosilicate stability region. All of the lithium aluminosilicates are unstable relative to amblygonite (or montebrasite) + quartz in p- and F-rich environments, but spodumene is stable to higher activities of these acidic volatiles than are eucryptite and petalite.
Several types of mineralization appear to be related to the emplacement of fluorine-rich silicic lava flows and domes. An important example is the beryllium deposit at Spor Mountain, west-central Utah, where bertrandite, fluorite, amorphous silica, and Mn-Fe oxides replace dolomite fragments in tuffaceous surge deposits just beneath a topaz-bearing rhyolitic lava flow. The Be-mineralized zone is also highly enriched in F, Sn, W, Nb (and presumably Ta), Zn, Pb, and several other metals (but not in Mo). The uniform lateral character of the mineralization, the restriction of Be mineralization to the upper-most few meters of tuff, and the lack of...
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