Reviews in Mineralogy & Geochemistry最新文献_第3页

Diffusion: Obstacles and Opportunities in Petrochronology 扩散:岩石年代学的障碍与机遇

1区地球科学

Reviews in Mineralogy & Geochemistry Pub Date : 2017-02-01 DOI: 10.2138/RMG.2017.83.4

M. Kohn, S. Penniston‐Dorland

{"title":"Diffusion: Obstacles and Opportunities in Petrochronology","authors":"M. Kohn, S. Penniston‐Dorland","doi":"10.2138/RMG.2017.83.4","DOIUrl":"https://doi.org/10.2138/RMG.2017.83.4","url":null,"abstract":"Many of the approaches in petrochronology are rooted in the assumption of equilibrium. Diffusion is an expression of disequilibrium: the movement of mass in response to chemical potential gradients, and isotopes in response to isotopic gradients. It is extremely important that we be aware of how the effects of diffusion can place obstacles across our path towards petrochronologic enlightenment. Conversely the effects of diffusion also provide opportunities for understanding rates, processes, and conditions experienced by rocks. The enormity of the field does not permit us to provide a comprehensive review of either the mathematics of diffusion or quantitative data that have been obtained relevant to the interpretation of diffusive processes in rocks and minerals. Many resources cover these topics, including RiMG volume 72 ( Diffusion in Minerals and Melts ; Zhang and Cherniak 2010) and several textbooks (Crank 1975; Glicksman 2000). Particularly relevant to the discussion of petrochronology are summaries of the theory and controls on diffusion (Brady and Cherniak 2010; Zhang 2010), as well as diffusion rates in feldspar (Cherniak 2010a), accessory minerals (Cherniak 2010b), garnet (Ganguly 2010), mica, pyroxene, and amphibole (Cherniak and Dimanov 2010), and melts (Zhang and Ni 2010; Zhang et al. 2010). Rather than duplicate that material, our goal is to explore the obstacles and opportunities presented by the effects of diffusion as they inform the rates of petrologic processes. To achieve this goal, we emphasize key principles and illustrative examples.\u0000\u0000Quantitative interpretation of the effects of diffusion assumes predictability of numerous factors that may affect chemical or isotopic transport, including temperature, initial and boundary conditions, water and oxygen fugacities, activities of other components, multiple mechanisms of diffusion, and crystal chemistry (‘coupling’ of the substitution of elements into different crystallographic sites). Additionally, the extraction of meaningful ages, durations of events, and temperatures requires …","PeriodicalId":49624,"journal":{"name":"Reviews in Mineralogy & Geochemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85434569","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 29

“Thy friendship makes us fresh”: Charles, King of France, Act III, Scene III (Henry VI, Part 1, by William Shakespeare) “你的友谊使我们精神焕发”——法国国王查理，第三幕，第三场(《亨利六世》第一部，威廉·莎士比亚)

1区地球科学

Reviews in Mineralogy & Geochemistry Pub Date : 2017-02-01 DOI: 10.2138/RMG.2017.83.0

M. Kohn, M. Engi, P. Lanari

引用次数: 3

Chronometry and Speedometry of Magmatic Processes using Chemical Diffusion in Olivine, Plagioclase and Pyroxenes 橄榄石、斜长石和辉石中化学扩散岩浆过程的计时和速度测定

1区地球科学

Reviews in Mineralogy & Geochemistry Pub Date : 2017-02-01 DOI: 10.2138/RMG.2017.83.16

R. Dohmen, K. Faak, J. Blundy

{"title":"Chronometry and Speedometry of Magmatic Processes using Chemical Diffusion in Olivine, Plagioclase and Pyroxenes","authors":"R. Dohmen, K. Faak, J. Blundy","doi":"10.2138/RMG.2017.83.16","DOIUrl":"https://doi.org/10.2138/RMG.2017.83.16","url":null,"abstract":"The magmatic processes that fuel volcanism, crustal growth, ore formation and discharge of volcanic gases and aerosols to the atmosphere occur across a range of timescales, from millions of years to just a few seconds. For example, the production of new oceanic crust at mid-ocean ridges is a near-continuous process that can operate in any one ocean basin on timescales of more than 100 m.y. However, the driving force for such processes is the spreading of the ocean plates that happens on a cm/yr timescale. At the other end of the spectrum, explosive volcanic eruptions involve the ascent and fragmentation of magma at velocities of the order of 100 m/s such that the journey from a magma chamber to an ash cloud may take place in a matter of minutes. In this case the driving force is the rapid expansion of magmatic gas in response to changes in pressure. At intermediate timescales magmatic processes may give rise to hydrothermal ore deposits on timescales of less than a million years for an individual deposit, while growth of giant granite batholiths may require piecemeal assembly of magma batches on timescales of a few million years. Although each of these processes has a characteristic, time-averaged timescale on which it operates, this is typically the end result of one or more natural processes that operate on much shorter timescales. For example, mid-ocean ridges do not extrude magma continuously onto the ocean floor, mineralising fluids do not discharge continuously through the shallow crust, and granitic magmas do not dribble continuously into evolving batholithic chambers. In some cases it is the long-term timescales that are important, for example the spreading rate of ocean basins, in others it is the short-term timescales that are important, for example the episodic growth of lava domes at active volcanoes. Although …","PeriodicalId":49624,"journal":{"name":"Reviews in Mineralogy & Geochemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86692997","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 35

Hadean Zircon Petrochronology

1区地球科学

Reviews in Mineralogy & Geochemistry Pub Date : 2017-02-01 DOI: 10.2138/RMG.2017.83.11

T. Harrison, E. Bell, P. Boehnke

{"title":"Hadean Zircon Petrochronology","authors":"T. Harrison, E. Bell, P. Boehnke","doi":"10.2138/RMG.2017.83.11","DOIUrl":"https://doi.org/10.2138/RMG.2017.83.11","url":null,"abstract":"The inspiration for this volume arose in part from a shift in perception among U–Pb geochronologists that began to develop in the late 1980s. Prior to then, analytical geochronology emphasized progressively lower blank analysis of separated accessory mineral aggregates (e.g., Krogh 1982; Parrish 1987), with results generally interpreted to reflect a singular moment in time. For example, a widespread measure of confidence in intra-analytical reliability was conformity to an MSWD (a form of χ2 test; Wendt and Carl 1991) of unity. This approach implicitly assumed that geological processes act on timescales that are short with respect to analytical errors (e.g., Schoene et al. 2015). As in situ methodologies (e.g., Compston and Pidgeon 1986; Harrison et al. 1997; Griffin et al. 2000) and increasingly well-calibrated double spikes (e.g., Amelin and Davis 2006; McLean et al. 2015) emerged, geochronologists began to move away from interpreting geological processes as a series of instantaneous episodes (e.g., Rubatto 2002). At about the same time, petrologists developed techniques that permitted in situ chemical analyses to be interpreted in terms of continuously changing pressure–temperature–time histories (e.g., Spear 1988). The recognition followed that specific mineral reactions yielded products that could be directly dated or interpreted in terms of protracted petrogenetic processes. Part of this shift was due to an appreciation that trace elements in accessory phases could identify the changing nature of modal mineralogy during crystal growth (e.g., Pyle et al. 2001; Kohn and Malloy 2004) and thus potentially relate petrogenesis to absolute time. The transition to petrochronology was complete upon recognition that high MSWDs were in fact the expected case for most metamorphic minerals (Kohn 2009).\u0000\u0000One of the great frontiers for fundamental discovery in the geosciences is earliest Earth (DePaolo et al. 2008). However, investigations of the first five …","PeriodicalId":49624,"journal":{"name":"Reviews in Mineralogy & Geochemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89111936","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 55

Petrochronology of Zircon and Baddeleyite in Igneous Rocks: Reconstructing Magmatic Processes at High Temporal Resolution 火成岩中锆石和坏长岩的岩石年代学:在高时间分辨率下重建岩浆过程

1区地球科学

Reviews in Mineralogy & Geochemistry Pub Date : 2017-02-01 DOI: 10.2138/RMG.2017.83.10

U. Schaltegger, J. Davies

{"title":"Petrochronology of Zircon and Baddeleyite in Igneous Rocks: Reconstructing Magmatic Processes at High Temporal Resolution","authors":"U. Schaltegger, J. Davies","doi":"10.2138/RMG.2017.83.10","DOIUrl":"https://doi.org/10.2138/RMG.2017.83.10","url":null,"abstract":"Zircon (ZrSiO4) and baddeleyite (ZrO2) are common accessory minerals in igneous rocks of felsic to mafic composition. Both minerals host trace elements substituting for Zr, among them Hf, Th, U, Y, REEs and many more. The excellent chemical and physical resistivity of zircon makes this mineral a perfect archive of chemical and temporal information to trace geological processes in the past, utilizing the outstanding power and temporal resolution of the U–Pb decay schemes. Baddeleyite is a chemically and physically much more fragile mineral. It preserves similar information only where it is shielded from dissolution and physical fragmentation as an inclusion in other minerals or in a fine-grained or non-reactive rock matrix. It offers the potential for dating the solidification of mafic rocks with high-precision through its crystallization in small pockets of Zr-enriched melt, after extensive olivine and pyroxene fractionation. Zircon and baddelelyite U–Pb dates are, for an overwhelming majority of cases and where we can assume a closed system, considered to reflect the time of crystallization.\u0000\u0000The development of the U–Pb dating tool CA-ID-TIMS (chemical abrasion-isotope dilution-thermal ionization mass spectrometry) since 2005 has led to unprecedented precision of better than 0.1% in 206Pb/238U dates (Bowring et al. 2005). Increased sensitivity of mass spectrometers and low laboratory blanks due to reduction of acid volumes allow routine U–Pb age determinations of micrograms of material at sufficiently high radiogenic/common lead ratios (see Schoene and Baxter 2017, this volume).\u0000\u0000In situ U–Pb age analysis using laser ablation or primary ion beam sputtering allows analysis of sub-microgram quantities of zircon material from polished internal sections or zircon surfaces with spot diameters ranging from ~30 μm for laser-ablation, inductively coupled plasma mass spectrometry (LA-ICP-MS) to 10 μm for secondary ion mass spectrometry (SIMS), lateral resolutions of 2–5 μm for NanoSIMS …","PeriodicalId":49624,"journal":{"name":"Reviews in Mineralogy & Geochemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74349424","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 77

Local Bulk Composition Effects on Metamorphic Mineral Assemblages 局部体积成分对变质矿物组合的影响

1区地球科学

Reviews in Mineralogy & Geochemistry Pub Date : 2017-02-01 DOI: 10.2138/RMG.2017.83.3

P. Lanari, M. Engi

{"title":"Local Bulk Composition Effects on Metamorphic Mineral Assemblages","authors":"P. Lanari, M. Engi","doi":"10.2138/RMG.2017.83.3","DOIUrl":"https://doi.org/10.2138/RMG.2017.83.3","url":null,"abstract":"Plate tectonic forcing leads to changes in the physical conditions that affect the lithosphere. In response to such changes, notably the local temperature ( T ) and pressure ( P ), rocks evolve dynamically. Processes mostly involve mineral transformations, i.e., solid-state reactions, but (hydrous) fluids are often involved, and partial melting may occur in the Earth’s middle and lower crust. While these chemical reactions reflect the tendency of natural systems to reduce their Gibbs free energy, metamorphic rocks commonly preserve textural and mineralogical relics, such as compositionally zoned minerals. Where relics are present, thermodynamic equilibrium clearly was not attained during the evolution of the rock.\u0000\u0000Petrochronology seeks to establish a temporal framework of petrologic evolution, and for this purpose it is essential to determine the P–T conditions prevailing at several stages. When analyzing a rock sample it is thus critical: \u0000\u00001. to recognize whether several stages of its evolution can be discerned,\u0000\u00002. to document the minerals that formed or were coexisting at each stage, and\u0000\u00003. to estimate at what physical conditions this happened.\u0000\u0000If (and only if) a chronometer then can be associated to one of these stages—or better yet several chronometers to different stages—then the power of petrochronology becomes realizable.\u0000\u0000This chapter is concerned with a basic dilemma that results directly from steps (b) and (c) above: P–T conditions are determined on the basis of mineral barometers and thermometers, which mostly rest on the assumption of chemical (or isotopic) equilibrium, yet the presence of relics is proof that thermodynamic equilibrium was not attained. One way out of the dilemma is to analyze reaction mechanisms and formulate a model based on non-equilibrium thermodynamics and kinetics (Lasaga 1998). While this can be fruitful for understanding fundamental aspects of metamorphic petrogenesis, there are more direct ways to address the limited scope needed for petrochronology. The alternative pursued …","PeriodicalId":49624,"journal":{"name":"Reviews in Mineralogy & Geochemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78889315","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 125

Secondary Ionization Mass Spectrometry Analysis in Petrochronology 岩石年代学中的二次电离质谱分析

1区地球科学

Reviews in Mineralogy & Geochemistry Pub Date : 2017-02-01 DOI: 10.2138/RMG.2017.83.7

A. Schmitt, J. Vazquez

{"title":"Secondary Ionization Mass Spectrometry Analysis in Petrochronology","authors":"A. Schmitt, J. Vazquez","doi":"10.2138/RMG.2017.83.7","DOIUrl":"https://doi.org/10.2138/RMG.2017.83.7","url":null,"abstract":"The goal of petrochronology is to extract information about the rates and conditions at which rocks and magmas are transported through the Earth’s crust. Garnering this information from the rock record greatly benefits from integrating textural and compositional data with radiometric dating of accessory minerals. Length scales of crystal growth and diffusive transport in accessory minerals under realistic geologic conditions are typically in the range of 1–10’s of μm, and in some cases even substantially smaller, with zircon having among the lowest diffusion coefficients at a given temperature (e.g., Cherniak and Watson 2003). Intrinsic to the compartmentalization of geochemical and geochronologic information from intra-crystal domains is the requirement to determine accessory mineral compositions using techniques that sample at commensurate spatial scales so as to not convolute the geologic signals that are recorded within crystals, as may be the case with single grain or large grain fragment analysis by isotope dilution thermal ionization mass spectrometry (ID-TIMS; e.g., Schaltegger and Davies 2017, this volume; Schoene and Baxter 2017, this volume). Small crystals can also be difficult to extract by mineral separation techniques traditionally used in geochronology, which also lead to a loss of petrographic context. Secondary Ionization Mass Spectrometry, that is SIMS performed with an ion microprobe, is an analytical technique ideally suited to meet the high spatial resolution analysis requirements that are critical for petrochronology (Table 1).\u0000\u0000View this table:\u0000\u0000Table 1 \u0000Advantages and limitations of in-situ SIMS analysis for petrochronology in comparison with other isotope selective methods\u0000\u0000\u0000\u0000In SIMS, bombardment of solid targets with an energetic ion beam removes atoms from the sample where primary ions are implanted into the target material to a depth of < 5–10 nm. Lateral resolution is controlled by primary ion beam dimensions (sub-μm to few 10’s of μm) with an upper limit set by the acceptance …","PeriodicalId":49624,"journal":{"name":"Reviews in Mineralogy & Geochemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79490527","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 29

Petrology and Geochronology of Rutile 金红石的岩石学和年代学

1区地球科学

Reviews in Mineralogy & Geochemistry Pub Date : 2017-02-01 DOI: 10.2138/RMG.2017.83.14

T. Zack, E. Kooijman

{"title":"Petrology and Geochronology of Rutile","authors":"T. Zack, E. Kooijman","doi":"10.2138/RMG.2017.83.14","DOIUrl":"https://doi.org/10.2138/RMG.2017.83.14","url":null,"abstract":"Rutile (TiO2) is an important accessory mineral that, when present, offers a rich source of information about the rock units in which it is incorporated. It occurs in a variety of specific microstructural settings, contains significant amounts of several trace elements and is one of the classical minerals used for U–Pb age determination. Here, we focus on information obtainable from rutile in its original textural context. We do not present an exhaustive review on detrital rutile in clastic sediments, but note that an understanding of the petrochronology of rutile in its source rocks will aid interpretation of data obtained from detrital rutile. For further information on the important role of rutile in provenance studies, the reader is referred to previous reviews (e.g., Zack et al. 2004b; Meinhold 2010; Triebold et al. 2012). Coarse rutile is the only stable TiO2 polymorph under all crustal and upper mantle conditions, with the exception of certain hydrothermal environments (Smith et al. 2009). As such, we will focus on rutile rather than the polymorphs brookite, anatase and ultrahigh-pressure modifications.\u0000\u0000In this chapter, we first review rutile occurrences, trace element geochemistry, and U–Pb geochronology individually to illustrate the insights that can be gained from microstructures, chemistry and ages. Then, in the spirit of petrochronology, we show the interpretational power of combining these approaches, using the Ivrea Zone (Italy) as a case study. Finally, we suggest some areas of future research that would improve petrochronologic research using rutile.\u0000\u0000Rutile is a characteristic mineral in moderate- to high pressure metapelitic rocks, in high pressure metamorphosed mafic rocks, and in sedimentary rocks (e.g., Force 1980; Frost 1991; Zack et al. 2004b; Triebold et al. 2012). Rutile also occurs rarely in magmatic rocks, e.g., anorthosites, as well as in some hydrothermal systems. Coarse-grained …","PeriodicalId":49624,"journal":{"name":"Reviews in Mineralogy & Geochemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84391323","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 92

Germanium Isotope Geochemistry 锗同位素地球化学

1区地球科学

Reviews in Mineralogy & Geochemistry Pub Date : 2017-01-01 DOI: 10.2138/RMG.2017.82.14

O. Rouxel, B. Luais

{"title":"Germanium Isotope Geochemistry","authors":"O. Rouxel, B. Luais","doi":"10.2138/RMG.2017.82.14","DOIUrl":"https://doi.org/10.2138/RMG.2017.82.14","url":null,"abstract":"Germanium (Ge) is a trace element in the Earth’s crust and natural waters, averaging about 1.6 ppm in rocks and minerals (El Wardani 1957; Bernstein 1985) and 75 picomol/L in seawater (Froelich and Andreae 1981). The naturally occurring oxidation states of Ge are +2 and +4, with the +4 state forming the principal common and stable compounds. Germanium has outer electronic structure 3 d 10 4 s 2 4 p 2 and mainly occurs in the quadrivalent state, although in some minerals it is octahedrally coordinated. Germanium is chemically similar to silicon (Si), both belonging to the IVA group in the periodic table, with Ge immediately above Si. Germanium is classified as a semimetal, whereas Si is a nonmetal element. Because of nearly identical ionic radii and electron configurations for Ge and Si, the crustal geochemistry of Ge is dominated by a tendency to replace Si in the lattice sites of minerals (Goldschmidt 1958; De Argollo and Schilling 1978b). These two elements exist in seawater as similar hydroxyacids, i.e., Ge(OH)4 and Si(OH)4 (Pokrovski and Schott 1998a) and the concentration profile of Ge is similar to that of Si (Froelich and Andreae 1981), thus making Ge/Si ratio an interesting tracer for biogenic silica cycling in the ocean. Although Ge and Si are geochemically similar, their behavior is different enough so that decoupling of Ge and Si can occur. Germanium commonly occurs in 4-fold (tetrahedral) coordination but in contrast to Si, Ge has a stronger tendency for the 6-fold coordination. Unlike Si, Ge also forms methylated compounds, and high concentrations of monomethyl- and dimethyl-germanium have been detected in ocean waters, accounting for > 70% of the total Ge (Lewis et al. 1985). Germanium is a particularly interesting element for geochemists since it exhibits siderophile, lithophile, chalcophile and …","PeriodicalId":49624,"journal":{"name":"Reviews in Mineralogy & Geochemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76582172","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 36

Kinetic Fractionation of Non-Traditional Stable Isotopes by Diffusion and Crystal Growth Reactions 非传统稳定同位素的扩散和晶体生长动力学分馏

1区地球科学

Reviews in Mineralogy & Geochemistry Pub Date : 2017-01-01 DOI: 10.2138/RMG.2017.82.4

J. Watkins, D. DePaolo, E. Watson

{"title":"Kinetic Fractionation of Non-Traditional Stable Isotopes by Diffusion and Crystal Growth Reactions","authors":"J. Watkins, D. DePaolo, E. Watson","doi":"10.2138/RMG.2017.82.4","DOIUrl":"https://doi.org/10.2138/RMG.2017.82.4","url":null,"abstract":"Natural variations in the isotopic composition of some 50 chemical elements are now being used in geochemistry for studying transport processes, estimating temperature, reconstructing ocean chemistry, identifying biological signatures, and classifying planets and meteorites. Within the past decade, there has been growing interest in measuring isotopic variations in a wider variety of elements, and improved techniques make it possible to measure very small effects. Many of the observations have raised questions concerning when and where the attainment of equilibrium is a valid assumption. In situations where the distribution of isotopes within and among phases is not representative of the equilibrium distribution, the isotopic compositions can be used to access information on mechanisms of chemical reactions and rates of geological processes. In a general sense, the fractionation of stable isotopes between any two phases, or between any two compounds within a phase, can be ascribed to some combination of the mass dependence of thermodynamic (equilibrium) partition coefficients, the mass dependence of diffusion coefficients, and the mass dependence of reaction rate constants. Many documentations of kinetic isotope effects (KIEs), and their practical applications, are described in this volume and are therefore not reviewed here. Instead, the focus of this chapter is on the measurement and interpretation of mass dependent diffusivities and reactivities, and how these parameters are implemented in models of crystal growth within a fluid phase. There are, of course, processes aside from crystal growth that give rise to KIEs among non-traditional isotopes, such as evaporation (Young et al. 2002; Knight et al. 2009; Richter et al. 2009a), vapor exsolution (Aubaud et al. 2004), thermal diffusion (Richter et al. 2009a, 2014b; Huang et al. 2010; Dominguez et al. 2011), mineral dissolution (e.g., Brantley et al. 2004; Wall et al. 2011; Pearce et al. 2012 …","PeriodicalId":49624,"journal":{"name":"Reviews in Mineralogy & Geochemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84869964","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 75