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BACKGROUND: Scientists have long been driven by the desire to describe, organize, classify, and compare objects using taxonomies and/or ontologies. In contrast to biology, geology, and many other scientific disciplines, the world of chemistry still lacks a standardized chemical ontology or taxonomy. Several attempts at chemical classification have been made; but they have mostly been limited to either manual, or semi-automated proof-of-principle applications. This is regrettable as comprehensive chemical classification and description tools could not only improve our understanding of chemistry but also improve the linkage between chemistry and many other fields. For instance, the chemical classification of a compound could help predict its metabolic fate in humans, its druggability or potential hazards associated with it, among others. However, the sheer number (tens of millions of compounds) and complexity of chemical structures is such that any manual classification effort would prove to be near impossible. RESULTS: We have developed a comprehensive, flexible, and computable, purely structure-based chemical taxonomy (ChemOnt), along with a computer program (ClassyFire) that uses only chemical structures and structural features to automatically assign all known chemical compounds to a taxonomy consisting of >4800 different categories. This new chemical taxonomy consists of up to 11 different levels (Kingdom, SuperClass, Class, SubClass, etc.) with each of the categories defined by unambiguous, computable structural rules. Furthermore each category is named using a consensus-based nomenclature and described (in English) based on the characteristic common structural properties of the compounds it contains. The ClassyFire webserver is freely accessible at http://classyfire.wishartlab.com/. Moreover, a Ruby API version is available at https://bitbucket.org/wishartlab/classyfire_api, which provides programmatic access to the ClassyFire server and database. ClassyFire has been used to annotate over 77 million compounds and has already been integrated into other software packages to automatically generate textual descriptions for, and/or infer biological properties of over 100,000 compounds. Additional examples and applications are provided in this paper. CONCLUSION: ClassyFire, in combination with ChemOnt (ClassyFire's comprehensive chemical taxonomy), now allows chemists and cheminformaticians to perform large-scale, rapid and automated chemical classification. Moreover, a freely accessible API allows easy access to more than 77 million "ClassyFire" classified compounds. The results can be used to help annotate well studied, as well as lesser-known compounds. In addition, these chemical classifications can be used as input for data integration, and many other cheminformatics-related tasks.

The evaluation of the abundances of chemical elements in the Earth’s crust is a pivotal geochemical problem. Its first solutions in the early 20th century formed the empirical groundwork for geochemistry and justified concepts about the unity of the material of the Universe, the genesis of the chemical elements, and the geochemical differentiation of the Earth. The accumulation of newly obtained data called for the revision of this problem, and a series of papers by A.P. Vinogradov, which were published in Geokhimiya in 1956–1962, presented reevaluated contents of elements in the continental crust. In these papers, A.P. Vinogradov relied on the classic idea of the geochemical balance of the sedimentary process. These generalizations provided the foundation for the quantitative characterization of the geochemical background of the biosphere and allowed Vinogradov to formulate the principles of the melting and degassing of material in the outer Earth’s shells during the geologic history, a concept that became universally acknowledged in modern geochemistry and geology. The composition of the Earth’s crust can also be evaluated based not on the principle of geochemical balance in the sedimentary process but on data on the actual abundances of major magmatic, metamorphic, and sedimentary rock types. The possibility of this solution was provided after the extensive research of A.B. Ronov, who managed to develop a quantitative model for the structure of the Earth’s sedimentary shell. Based on these data, A.B. Ronov, A.A. Yaroshevsky, and A.A. Migdisov published a series of papers in Geokhimiya in 1967–1985 that presented a model for the chemical structure of the Earth’s crust with regard for the material composing not only the upper part of the continental crust but also its deep-seated granulite-basite layer and the oceanic crust. The quantitative estimates thus obtained led the authors to important conclusions: first, it was demonstrated that the estimated abundances of elements in the granite-metamorphic layer of the continental crust presented in the classic works by A.P. Vinogradov are confirmed by independent materials, which are based on data on the actual abundance of rocks. Second, incredible as it was, the principle of geochemical balance in the sedimentary process in application to Ca and carbonates appeared to be invalid. This problem remains unsettled as of yet and awaits its resolution.

Research Article| May 01, 1976 Mechanism of burial metamorphism of argillaceous sediment: 1. Mineralogical and chemical evidence JOHN HOWER; JOHN HOWER 1Department of Earth Sciences, Case Western Reserve University, Cleveland, Ohio 44106 Search for other works by this author on: GSW Google Scholar ERIC V. ESLINGER; ERIC V. ESLINGER 2Department of Geology, West Georgia College, Carrollton, Georgia 30117 Search for other works by this author on: GSW Google Scholar MARK E. HOWER; MARK E. HOWER 3Department of Mathematics, Middlebury College, Middlebury, Vermont 05753 Search for other works by this author on: GSW Google Scholar EDWARD A. PERRY EDWARD A. PERRY 4Department of Geology, University of Massachusetts, Amherst, Massachusetts 01002 Search for other works by this author on: GSW Google Scholar Author and Article Information JOHN HOWER 1Department of Earth Sciences, Case Western Reserve University, Cleveland, Ohio 44106 ERIC V. ESLINGER 2Department of Geology, West Georgia College, Carrollton, Georgia 30117 MARK E. HOWER 3Department of Mathematics, Middlebury College, Middlebury, Vermont 05753 EDWARD A. PERRY 4Department of Geology, University of Massachusetts, Amherst, Massachusetts 01002 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1976) 87 (5): 725–737. https://doi.org/10.1130/0016-7606(1976)87<725:MOBMOA>2.0.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation JOHN HOWER, ERIC V. ESLINGER, MARK E. HOWER, EDWARD A. PERRY; Mechanism of burial metamorphism of argillaceous sediment: 1. Mineralogical and chemical evidence. GSA Bulletin 1976;; 87 (5): 725–737. doi: https://doi.org/10.1130/0016-7606(1976)87<725:MOBMOA>2.0.CO;2 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 SocietyGSA Bulletin Search Advanced Search Abstract A detailed mineralogical and chemical investigation has been made of shale cuttings from a well (Case Western Reserve University Gulf Coast 6) in Oligocene-Miocene sediment of the Gulf Coast of the United States. The <0.1-, 0.1- to 0.5-, 0.5- to 2-, 2- to 10-, and >10-µm fractions from the 1,250- to 5,500-m stratigraphic interval were analyzed by x-ray diffraction. Major mineralogic changes with depth take place over the interval 2,000 to 3,700 m, after which no significant changes are detectable. The most abundant mineral, illite/smectite, undergoes a conversion from less than 20 percent to about 80 percent illite layers over this interval, after which the proportion of illite layers remains constant. Over the same interval, calcite decreases from about 20 percent of the rock to almost zero, disappearing from progressively larger size fractions with increasing depth; potassium feldspar (but not albite) decreases to zero; and chlorite appears to increase in amount. Variations in the bulk chemical composition of the shale with depth show only minor changes, except for a marked decrease in CaO concomitant with the decrease in calcite. By contrast, the <0.1-µm fraction (virtually pure illite/smectite) shows a large increase in K2O and Al2O3 and a decrease in SiO2 The atomic proportions closely approximate the reaction smectite + Al+3 + K+ = illite + Si+4. The potassium and aluminum appear to be derived from the decomposition of potassium feldspar (and mica?), and the excess silicon probably forms quartz. We interpret all the major mineralogical and chemical changes as the response of the shale to burial metamorphism and conclude that the shale acted as a closed system for all components except H2O, CaO, Na2O, and CO2. Compositional changes in the shale as a function of metamorphic grade closely parallel compositional changes in shale as a function of geologic age. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

The Origin of Porosity and Permeability. Ground-Water Movement. Main Equations of Flow, Boundary Conditions, and Flow Nets. Ground Water in the Basin Hydrologic Cycle. Hydraulic Testing: Models, Methods, and Applications. Ground Water as a Resource. Stress, Strain, and Pore Fluids. Heat Transport in Ground-Water Flow. Solute Transport. Principles of Aqueous Geochemistry. Chemical Reactions. Colloids and Microorganisms. The Equations of Mass Transport. Mass Transport in Natural Ground-Water Systems. Mass Transport in Ground-Water Flow: Geologic Systems. Introduction to Contaminant Hydrogeology. Modeling the Transport of Dissolved Contaminants. Multiphase Fluid Systems. Remediation: Overview and Removal Options. In Situ Destruction and Risk Assessment. Answers to Problems. Appendices. References. Index.

Abstract Potassium–argon dating, field relations, geochemical and strontium-isotope compositions are reported for the island of Pantelleria (Strait of Sicily, Italy). These data support the following model for the genesis and evolution through time of the volcanic system: the peralkaline rocks originated from mantle-derived parental magmas; the trachytic magma differentiated in a low pressure magma chamber by crystal–liquid fractionation. This process led to a chemically zoned magma chamber tapped at different levels by successive eruptions. During low-pressure differentiation the 87 Sr/ 86 Sr ratios of some of the most evolved Sr-poor rhyolitic magmas increased from 0.703 up to 0.708 by contamination with crustal material. The chemical variation displayed by the products of each of the defined eruptive cycles in the last 50000 years suggests an open system behaviour of the magma chamber which is episodically refilled by more mafic parent magma, differentiated at high rate and episodically erupted.

Introduction 3 Purpose and scope of report 4 Acknowledgments 5 Properties of water 5 Composition of the earth's crust 6 Water as a geochemical agent The role of water in erosion Chemistry of weathering processes Collection of quality-of-water data Collection of water samples Surface-water sampling Ground-water sampling Completeness of sample coverage Analyses of water samples Field testing of water Electric logs as indicators of ground-water quality Laboratory procedures Expression of water analyses Analyses reported in terms of hypothetical combinations Analyses expressed in terms of ions Determinations included in analyses Units used in reporting analyses Weight-per-weight units Weight-per-volume units Equivalent-weight units Composition of anhydrous residue Parts per million as calcium carbonate Comparison of units of expression Significance of properties and constituents reported in water analyses_ _ Specific electrical conductance Units for reporting conductance Physical basis of conductance Range of conductance values Accuracy and reproducibility of conductance values Hydrogen-ion concentration (pH) Hydrolysis Buffered solutions Interpretation of pH data Range of pH values Accuracy and reproducibility of pH values Color Sources and significance of color in water 49 Residue on evaporition 49 Theoretical basis of determination 50 Range of concentration 51 Accuracy and reproducibility of results 51 III Significance of properties and constituents reported in water analyses-Continued Acidity Sources of acidity of natural water Chemistry of acidity determination Range of concentration Reproducibility of acidity data Sulfate Sources of sulfate in natural water Chemistry of sulfate in natural water Range of concentration Accuracy and reproducibility of results Chloride Sources of chloride in water Chemistry of chloride in natural water Oceanic chloride Juvenile chloride Cyclic chloride Range of concentration Accuracy and reproducibility of results Fluoride Source of fluoride in water Chemistry of fluoride in natural water Range of concentration Accuracy and reproducibility of results Nitrate Source of nitrate in water Chemistry of nitrate in natural water 116 Range of concentration Accuracy and reproducibility of results Phosphate Sources of phosphate Chemistry of phosphate in natural water 119 Range of concentration 120 Accuracy and reproducibility of results 120 Boron 120 Sources of boron 120 Chemistry of boron in natural water Range of concentration 122 Accuracy and reproducibility of results 122 Trace or minor constituents-Cations 124 Heavy metals 124 Titanium 124 Chromium 124 Zinc 125 Nickel and cobalt 126 Copper 126 Tin 127 Lead 127 Cadmium 128 Mercury 128 Arsenic 129 Selenium 130 Significance of properties and constituents reported in water analyses-Continued Trace or minor constituents-Cations-Continued Alkaline-earth metals Beryllium Strontium Barium Alkali metals and ammonium Lithium Rubidium Cesium Ammonium Radioactive components Uranium Radium Radon Thorium Trace or minor constituents-Anions Bromide Iodide Sulfite and thiosulf ate Total dissolved solids-Computed Chemistry of dissolved solids determination Accuracy and reproducibility of results Dissolved gases Biochemical oxygen demand Hardness Utilization Range of concentration Accuracy and reproducibility of results Percent sodium Sodium-adsorption ratio Density Organization and study of water-analysis data Evaluation of water analyses Tabulation Study techniques Inspection and comparison Use of ratios Use of averages 156 Palmer's geochemical classification 162 Graphical representation 164 Scatter diagrams 165 Ionic-concentration diagrams 168 Percentage-composition diagrams Frequency diagrams Chemical analyses plotted against nonchemical variables 186 Hydrographs 186 Dissolved-solids rating curves 188 Water-quality profiles 192 Quality-of-water maps 192 Selection of study techniques 10. Effect of temperature on solubility of calcium carbonate (calcite) in water in the presence of CO2 VIII CONTENTS Page FIGURE 11. Solubility of magnesium carbonate in water at 25C in the presence of CO2 81 12. Relation of conductance to chloride, hardness, and sulfate concentrations, Gila River at Bylas, Ariz., Oct. 1, 1943 to Sept. 30, 1944 13. Sodium-chloride relationship, Gila River at Bylas, Ariz., Oct. 1, 1943, to Sept. 30, 1944 14. Analyses represented by vertical bar graphs of equivalents per million 15. Analyses represented by bar graphs of parts per million 16. Bar graph of equivalents per million which also shows hardness values in parts per million 17. Analyses in equivalents per million represented by vectors__ _ 18. Analyses represented by patterns based on equivalents per million 19. Analyses represented by linear plotting of cumulative percentage composition based on parts per million 20. Analyses represented by logarithmic plotting of concentrations in parts per million 21. Analyses represented by circular diagrams subdivided on the basis of percent of total equivalents per million 22. Analyses represented by bar-patterns based on percent of total equivalents per million 23. Analyses represented by patterns drawn on radial coordinates.. 24. Analyses represented by three points plotted in trilinear diagram (after A. M. Piper) 25. Number of samples having percent sodium within ranges indicated, San Simon artesian basin, Ariz 26. Cumulative frequency curve of specific conductance, Allegheny, Monongahela and Ohio River waters, Pittsburgh area, Pennsylvania, 1944-50 27. Specific conductance of daily samples and daily mean discharge, San Francisco River at Clifton, Ariz., Oct. 1, 1943 to Sept. 30, 1944 28. Bicarbonate, sulfate, hardness, and pH of samples collected in cross section of Susquehanna River at Harrisburg, Pa., July 8, 1947 29. Temperature and dissolved solids of water in Lake Mead in Virgin and Boulder Canyons, 1948 194 30. Total concentration and hardness of water from deeper wells in Prairie Creek Unit, Nebr 31. Ratio of alkalinity to sulfate in water from unconsolidated deposits in the Torrington area, Nebr 32. Map of portions of Apache and Navajo counties, Ariz., showing mineral content of ground water in the Coconino sandstone_ 198 33. Analyses of waters associated with igneous rocks 206 34. Analyses of waters associated with resistate sediments 209 35. Analyses of waters associated with hydrolyzate sediments_ _ _ 36. Weighted-average analyses for Rio Grande at San Acacia, N. Mex., for two periods in the 1945-46 water year 212 37. Analyses of waters associated with precipitate-type sediments.. 38. Analyses of waters associated with evaporate sediments 215 39. Analyses of waters associated with metamorphic rocks 217 40. Diagram for use in interpreting the analysis of irrigation water_ 251 2 CHEMICAL CHARACTERISTICS OF NATURAL WATER

Chemical reaction simulations are considerably used to quantitatively assess the long-term geologic carbon sequestration (GCS), such as CO2 sequestration capacity estimations, leakage pathway analyses, enhanced oil recovery (EOR) efficiency studies, and risk assessments of sealing formations (caprocks), wellbores, and overlying underground water resources. All these require a deep understanding of the CO2 -associated chemical reactions. To ensure long-term, safe CO2 sequestration in the intended formations, modeling is the only way to plausibly assess the CO2 flow, reaction, and transport over thousands of years. This review summarizes the multiple methodologies for describing homogeneous and heterogeneous chemical reaction patterns and multiscale application examples, the recent progress and current status of chemical reaction simulations for GCS, and the impact of such simulations on geological CO2 sequestration performance. Technical gaps and future challenges are also discussed for further study. The trends and challenges of such studies include: (1) the combination of coupled chemical, mechanical, and transport processes with calibrated experiments and associated uncertainty/risk assessments; (2) enhancement of the ability to simulate detailed geophysical and geochemical equations to mimic in situ conditions; and (3) characterization of multiscale subsurface systems with detailed conceptual models and assignment of suitable boundary conditions for field-scale sequestration fields. One major issue remaining is the current lack of accurate (or scale-justified) kinetic and equilibrium chemical reaction parameters under reservoir conditions. Advanced models that couple chemical, mechanical, and transport processes with scale-justified parameters, from lab to field-scale experiments, are required for quantitative assessments of sequestration capacity and the long-term safety of GCS projects.

Alan Turing was neither a biologist nor a chemist, and yet the paper he published in 1952, 'The chemical basis of morphogenesis', on the spontaneous formation of patterns in systems undergoing reaction and diffusion of their ingredients has had a substantial impact on both fields, as well as in other areas as disparate as geomorphology and criminology. Motivated by the question of how a spherical embryo becomes a decidedly non-spherical organism such as a human being, Turing devised a mathematical model that explained how random fluctuations can drive the emergence of pattern and structure from initial uniformity. The spontaneous appearance of pattern and form in a system far away from its equilibrium state occurs in many types of natural process, and in some artificial ones too. It is often driven by very general mechanisms, of which Turing's model supplies one of the most versatile. For that reason, these patterns show striking similarities in systems that seem superficially to share nothing in common, such as the stripes of sand ripples and of pigmentation on a zebra skin. New examples of 'Turing patterns' in biology and beyond are still being discovered today. This commentary was written to celebrate the 350th anniversary of the journal Philosophical Transactions of the Royal Society.

Research Article| July 01, 1992 Chemical subdivision of the A-type granitoids:Petrogenetic and tectonic implications G. Nelson Eby G. Nelson Eby 1Department of Earth Sciences, University of Massachusetts, Lowell, Massachusetts 01854 Search for other works by this author on: GSW Google Scholar Author and Article Information G. Nelson Eby 1Department of Earth Sciences, University of Massachusetts, Lowell, Massachusetts 01854 Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1992) 20 (7): 641–644. https://doi.org/10.1130/0091-7613(1992)020<0641:CSOTAT>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation G. Nelson Eby; Chemical subdivision of the A-type granitoids:Petrogenetic and tectonic implications. Geology 1992;; 20 (7): 641–644. doi: https://doi.org/10.1130/0091-7613(1992)020<0641:CSOTAT>2.3.CO;2 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 The A-type granitoids can be divided into two chemical groups. The first group (A1) is characterized by element ratios similar to those observed for oceanic-island basalts. The second group (A2) is characterized by ratios that vary from those observed for continental crust to those observed for island-arc basalts. It is proposed that these two types have very different sources and tectonic settings. The A1 group represents differentiates of magmas derived from sources like those of oceanic-island basalts but emplaced in continental rifts or during intraplate magmatism. The A2 group represents magmas derived from continental crust or underplated crust that has been through a cycle of continent-continent collision or island-arc magmatism. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Abstract The sequestration of CO 2 in the deep geosphere is one potential method for reducing anthropogenic emissions to the atmosphere without a drastic change in our energy-producing technologies. Immediately after injection, the CO 2 will be stored as a free phase within the host rock. Over time it will dissolve into the local formation water and initiate a variety of geochemical reactions. Some of these reactions could be beneficial, helping to chemically contain or ‘trap’ the CO 2 as dissolved species and by the formation of new carbonate minerals; others may be deleterious, and actually aid the migration of CO 2 . It will be important to understand the overall impact of these competing processes. However, these processes will also be dependent upon the structure, mineralogy and hydrogeology of the specific lithologies concerned and the chemical stability of the engineered features (principally, the cement and steel components in the well completions). Therefore, individual storage operations will have to take account of local geological, fluid chemical and hydrogeological conditions. The aim of this paper is to review some of the possible chemical reactions that might occur once CO 2 is injected underground, and to highlight their possible impacts on long-term CO 2 storage.

Research Article| July 01, 1965 Chemical Characteristics of Oceanic Basalts and the Upper Mantle A. E. J ENGEL; A. E. J ENGEL Dept. Earth Sciences, University of California, La Jolla, Calif Search for other works by this author on: GSW Google Scholar CELESTE G ENGEL; CELESTE G ENGEL U. S. Geological Survey, La Jolla, Calif Search for other works by this author on: GSW Google Scholar R. G HAVENS R. G HAVENS U. S. Geological Survey, Denver, Colo Search for other works by this author on: GSW Google Scholar Author and Article Information A. E. J ENGEL Dept. Earth Sciences, University of California, La Jolla, Calif CELESTE G ENGEL U. S. Geological Survey, La Jolla, Calif R. G HAVENS U. S. Geological Survey, Denver, Colo Publisher: Geological Society of America Received: 21 Dec 1964 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Copyright © 1965, The Geological Society of America, Inc. Copyright is not claimed on any material prepared by U.S. government employees within the scope of their employment. GSA Bulletin (1965) 76 (7): 719–734. https://doi.org/10.1130/0016-7606(1965)76[719:CCOOBA]2.0.CO;2 Article history Received: 21 Dec 1964 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation A. E. J ENGEL, CELESTE G ENGEL, R. G HAVENS; Chemical Characteristics of Oceanic Basalts and the Upper Mantle. GSA Bulletin 1965;; 76 (7): 719–734. doi: https://doi.org/10.1130/0016-7606(1965)76[719:CCOOBA]2.0.CO;2 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 SocietyGSA Bulletin Search Advanced Search Abstract Tholeiitic basalts (oceanic tholeiites) that form most of the deeply submerged volcanic features in the oceans are characterized by extremely low amounts of Ba, K, P, Pb, Sr, Th, U, and Zr as well as Fe2O3/FeO < 0.2 and Na/K > 10 in unaltered samples. Oceanic tholeiites also have rare earth abundance-distribution patterns and ratios of K/Rb (1300) and Sr87/Sr86 (0.702) similar to or overlapping those of calcium-rich (basaltic) achondritic meteorites. The close compositional similarities between the oceanic tholeiites and calcium-rich achondrites indicates the relatively primitive nature of the oceanic tholeiites.In contrast, the alkali-rich basalts that cap submarine and island volcanoes are relatively enriched in Ba, K, La, Nb, P, Pb, Pb206, Rb, Fe2O3, Sr, Sr87, Ti, Th, U, and Zr; i.e. in the same elements and isotopes that are concentrated in the sialic continental crusts by factors of 5 to 1000 more than the amounts readily inferred in the upper mantle.These analytical data coupled with the field relationships indicate that the alkali-rich basalts are derivative rocks, fractionated from the oceanic tholeiites by processes of magmatic differentiation, and that the oceanic tholeiites are the principal or only primary magma generated in the upper mantle under the oceans.Studies of the abundances and compositions of continental basalts show that essentially identical tholeiitic lavas, contaminated with Si, K, and the chemically coherent trace elements and radiogenic isotopes from the sial, also have been the predominant or only magma generated in the mantle under the continents.The chemical properties of oceanic tholeiites suggest that the upper mantle probably contains less than (in parts per million): Ba, 10; K, 1000; Pb, 0.4; Rb, 10; Th, 0.2; and U, 0.1. The Sr87/Sr86 must be less than 0.7015; Th/U about 2; K/Rb about 1500–2000; and Fe2O3/FeO less than 0.1.The integration of field and petrochemical data with seismic, density, and shock-wave studies suggests that the oceanic tholeiites are either complete melts of the upper mantle or are generated from a mix of this tholeiite and a magnesium-rich peridotite or dunite in proportions up to perhaps 1:4.The Mohorovičić discontinuity under the oceans appears to mark the transition downward from a largely tholeiitic oceanic crust to either tholeiite reconstituted to blueschist or greenschist or to the ultramafic residue left after expulsion of oceanic tholeiite. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Nature's photosynthesis uses the sun's energy with chlorophyll in plants as a catalyst to recycle carbon dioxide and water into new plant life. Only given sufficient geological time can new fossil fuels be formed naturally. In contrast, chemical recycling of carbon dioxide from natural and industrial sources as well as varied human activities or even from the air itself to methanol or dimethyl ether (DME) and their varied products can be achieved via its capture and subsequent reductive hydrogenative conversion. The present Perspective reviews this new approach and our research in the field over the last 15 years. Carbon recycling represents a significant aspect of our proposed Methanol Economy. Any available energy source (alternative energies such as solar, wind, geothermal, and atomic energy) can be used for the production of needed hydrogen and chemical conversion of CO(2). Improved new methods for the efficient reductive conversion of CO(2) to methanol and/or DME that we have developed include bireforming with methane and ways of catalytic or electrochemical conversions. Liquid methanol is preferable to highly volatile and potentially explosive hydrogen for energy storage and transportation. Together with the derived DME, they are excellent transportation fuels for internal combustion engines (ICE) and fuel cells as well as convenient starting materials for synthetic hydrocarbons and their varied products. Carbon dioxide thus can be chemically transformed from a detrimental greenhouse gas causing global warming into a valuable, renewable and inexhaustible carbon source of the future allowing environmentally neutral use of carbon fuels and derived hydrocarbon products.

Nature's photosynthesis uses the sun's energy with chlorophyll in plants as a catalyst to recycle carbon dioxide and water into new plant life. Only given sufficient geological time, millions of years, can new fossil fuels be formed naturally. The burning of our diminishing fossil fuel reserves is accompanied by large anthropogenic CO(2) release, which is outpacing nature's CO(2) recycling capability, causing significant environmental harm. To supplement the natural carbon cycle, we have proposed and developed a feasible anthropogenic chemical recycling of carbon dioxide. Carbon dioxide is captured by absorption technologies from any natural or industrial source, from human activities, or even from the air itself. It can then be converted by feasible chemical transformations into fuels such as methanol, dimethyl ether, and varied products including synthetic hydrocarbons and even proteins for animal feed, thus supplementing our food chain. This concept of broad scope and framework is the basis of what we call the Methanol Economy. The needed renewable starting materials, water and CO(2), are available anywhere on Earth. The required energy for the synthetic carbon cycle can come from any alternative energy source such as solar, wind, geothermal, and even hopefully safe nuclear energy. The anthropogenic carbon dioxide cycle offers a way of assuring a sustainable future for humankind when fossil fuels become scarce. While biosources can play a limited role in supplementing future energy needs, they increasingly interfere with the essentials of the food chain. We have previously reviewed aspects of the chemical recycling of carbon dioxide to methanol and dimethyl ether. In the present Perspective, we extend the discussion of the innovative and feasible anthropogenic carbon cycle, which can be the basis of progressively liberating humankind from its dependence on diminishing fossil fuel reserves while also controlling harmful CO(2) emissions to the atmosphere. We also discuss in more detail the essential stages and the significant aspects of carbon capture and subsequent recycling. Our ability to develop a feasible anthropogenic chemical carbon cycle supplementing nature's photosynthesis also offers a new solution to one of the major challenges facing humankind.

There has been considerable controversy concerning the role of chemical weathering in the regulation of the atmospheric partial pressure of carbon dioxide, and thus the strength of the greenhouse effect and global climate. Arguments center on the sensitivity of chemical weathering to climatic factors, especially temperature. Laboratory studies reveal a strong dependence of mineral dissolution on temperature, but the expression of this dependence in the field is often obscured by other environmental factors that co-vary with temperature. In the field, the clearest correlation is between chemical erosion rates and runoff, indicating an important dependence on the intensity of the hydrological cycle. Numerical models and interpretation of the geologic record reveal that chemical weathering has played a substantial role in both maintaining climatic stability over the eons as well as driving climatic swings in response to tectonic and paleogeographic factors.

Research Article| October 01, 1954 AVERAGE CHEMICAL COMPOSITIONS OF SOME IGNEOUS ROCKS S. R NOCKOLDS S. R NOCKOLDS DEPARTMENT OF MINERALOGY AND PETROLOGY, CAMBRIDGE, ENGLAND Search for other works by this author on: GSW Google Scholar Author and Article Information S. R NOCKOLDS DEPARTMENT OF MINERALOGY AND PETROLOGY, CAMBRIDGE, ENGLAND Publisher: Geological Society of America Received: 19 Aug 1953 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Copyright © 1954, The Geological Society of America, Inc. Copyright is not claimed on any material prepared by U.S. government employees within the scope of their employment. GSA Bulletin (1954) 65 (10): 1007–1032. https://doi.org/10.1130/0016-7606(1954)65[1007:ACCOSI]2.0.CO;2 Article history Received: 19 Aug 1953 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation S. R NOCKOLDS; AVERAGE CHEMICAL COMPOSITIONS OF SOME IGNEOUS ROCKS. GSA Bulletin 1954;; 65 (10): 1007–1032. doi: https://doi.org/10.1130/0016-7606(1954)65[1007:ACCOSI]2.0.CO;2 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 SocietyGSA Bulletin Search Advanced Search Abstract Average chemical compositions are given for the common plutonic rock types and their volcanic equivalents. An attempt has been made also to give the general average chemical compositions of silicic, intermediate, subsilicic and ultramafic igneous rocks This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Steroids are used to illustrate some of the significant advances that have been made in recent years in understanding the biological origin and geological fate of the organic compounds in sediments. The precursor sterols are transformed, initially by microbial activity and later by physicochemical constraints, into thermodynamically more stable saturated and aromatic hydrocarbons in mature sediments and petroleums. The steps in this transformation result in a complex web linking biogenesis, diagenesis, and catagenesis. Indeed, the complexity and variety of biological lipids such as the steroids are evidently matched in the corresponding geolipids. The extent of preservation of the biochemical imprint in the structures and stereochemistry of these geolipids, even over hundreds of millions of years, is startling, as is the systematic and sequential nature of the geochemical changes they evidently undergo. This new understanding of molecular organic geochemistry has applications in petroleum geochemistry, where biological marker compounds are valuable in the assessment of sediment maturity and in correlation work.