Reviews in Mineralogy & Geochemistry最新文献

{"title":"Distribution and Processing of Highly Siderophile Elements in Cratonic Mantle Lithosphere","authors":"S. Aulbach, J. Mungall, D. G. Pearson","doi":"10.2138/RMG.2016.81.5","DOIUrl":"https://doi.org/10.2138/RMG.2016.81.5","url":null,"abstract":"Cratonic lithospheric mantle is composed of predominantly refractory materials that formed at higher mantle potential temperatures ( T P) than recorded in non-cratonic peridotites. It also shows stronger depletion and fractionation of Pd and Pt from Ru, Os and Ir than oceanic, supra-subduction zone or off-cratonic lithospheric mantle, as well as some of the lowest Se and Te contents. The varied response of the highly siderophile elements (HSE: Os, Ir, Ru, Rh, Pt, Pd, Re, Au), and their embedded radioactive decay systems, to changes in oxygen fugacity ( f O2), sulfur fugacity ( f S2) and pressure ( P )—in particular through the impact of these parameters on the stability of the main HSE-bearing sulfide and alloy phases makes them potentially powerful tracers of their melting environment. Therefore, investigation of the HSE systematics of cratonic mantle peridotites, in combination with information from Re–Os isotopes on time-integrated enrichment or depletion, can help us to understand processes leading to mantle differentiation and continental lithosphere formation in the Archean, which are controversial subjects despite decades of research. The longevity of the cratonic lithosphere implies that there was ample opportunity for secondary overprint, obscuring our view of earlier processes. For example, destabilization of platinum-group element (PGE: Os, Ir, Ru, Rh, Pt, Pd) alloy leading to depletions in the compatible PGE, and perhaps Pt, in some cratonic mantle samples may occur in an oxidizing mantle wedge or through interaction with oxidizing small-volume, volatile-rich melts that typically invade cratonic roots. Such melts may eventually deposit S, Pd, Pt and Re and also capture remaining PGE alloys, consistent with the anomalous S-rich character of many kimberlite-borne xenoliths. Their basalt-borne counterparts show additional late effects of subaerial degassing that can deplete volatile elements (S, Re, Os). Basaltic melts can also scavenge PGE alloys at depth, while still sulfide-undersaturated. Such melts, may, …","PeriodicalId":49624,"journal":{"name":"Reviews in Mineralogy & Geochemistry","volume":"60 1","pages":"239-304"},"PeriodicalIF":0.0,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89177325","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}

{"title":"Experimental Results on Fractionation of the Highly Siderophile Elements (HSE) at Variable Pressures and Temperatures during Planetary and Magmatic Differentiation","authors":"J. Brenan, N. Bennett, Z. Zajacz","doi":"10.2138/RMG.2016.81.1","DOIUrl":"https://doi.org/10.2138/RMG.2016.81.1","url":null,"abstract":"The platinum-group elements (PGEs; Os, Ir, Ru, Rh, Pt, Pd), along with rhenium and gold, are grouped together as the highly siderophile elements (HSEs), defined by their extreme partitioning into the metallic, relative to the oxide phase (> 104). The HSEs are highly refractory, as gauged by their high melting and condensation temperatures, and were therefore relatively concentrated in the feedstock for the terrestrial planets, as defined by the composition of chondritic meteorites (e.g., Anders and Ebihara 1982; Horan et al. 2003; Fischer-Godde et al. 2010). However, the planetary formation and differentiation process has since acted on this chemical group to produce a rich variety of absolute and relative inter-element fractionations. For example, analysis of iron meteorites suggests a significant decoupling of the HSE in the cores of planetesimals, and likely Earth’s core, with Os, Ir, Ru (IPGE-group) and Re concentrated in the metal phase, and Pt, Rh, Pd (PPGE-group) plus Au usually concentrated in the residual liquid (Goldstein et al. 2009). In terms of the silicate Earth, analysis of mantle rocks reveals very low levels of the HSE, but relative abundances similar to chondrites (see review by Day et al. 2016, this volume), in part reflecting HSE segregation into core-forming iron (Ringwood 1966; Ganapathy et al. 1970). This is in contrast to mantle-derived melts, whose HSE abundances are highly fractionated, with relative depletions in the IPGE-group compared to PPGE-group, as well as Re and Au (Barnes et al. 1985). Resulting Re/Os and Pt/Os fractionation also influence the long-term evolution of the 187Re to 187Os and 190Pt to 186Os decay systems, and, hence, the development of distinctive Os-isotope reservoirs (Walker et al. 1997; Shirey and Walker 1998; Day 2013). The emplacement of mantle-derived magmas into Earth’s crust results in …","PeriodicalId":49624,"journal":{"name":"Reviews in Mineralogy & Geochemistry","volume":"1 1","pages":"1-87"},"PeriodicalIF":0.0,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82964699","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}

{"title":"Mantle Sulfides and their Role in Re–Os and Pb Isotope Geochronology","authors":"J. Harvey, J. Warren, S. Shirey","doi":"10.2138/RMG.2016.81.10","DOIUrl":"https://doi.org/10.2138/RMG.2016.81.10","url":null,"abstract":"Mantle sulfides (Fe–Ni–Cu-rich base metal sulfides or BMS; Fig. 1) play a crucial role in the distribution of Re, Os, and Pb in mantle rocks and are thus fundamental to obtaining absolute ages by direct geochronology using the Re–Os and Pb–Pb isotope systems on mantle samples. Mantle samples exist as hundreds of exposures of peridotites, pyroxenites and diamonds, either brought to the surface as accidental xenoliths and xenocrysts during kimberlitic or alkali basaltic volcanism (for comprehensive reviews, see Pearson et al. 2014; Aulbach et al. 2016, this volume; Luguet and Reisberg 2016, this volume), or as orogenic, ophiolitic and abyssal peridotite obducted at convergent margins and drilled / dredged from oceanic basins (e.g., Bodinier and Godard 2014; Becker and Dale 2016, this volume). This chapter reviews the occurrence of BMS in mantle samples and the role that they play in controlling the Re–Os and Pb isotope systematics of the mantle. Included in this review is a discussion of the role BMS plays in recording the multiple depletion / enrichment / metasomatic events that the mantle has undergone and the preservation of chemical heterogeneities that are inherently created by these processes. Along with discussions of the utility of Re–Os and Pb isotope measurements, this review will also consider the potential pitfalls and some of the surprises that can arise when analyzing these BMS micro-phases. Specifically excluded from this review is the extensive literature on Re–Os and Pb for the geochronology of sulfide systems in magmatic ores. This study is another field entirely from the study of sulfides in their native mantle hosts because of the complicated magmatic concentration processes occurring at crustal levels. Figure 1 Backscattered electron and chemical maps of typical mantle BMS grains. (a) Enclosed; (b) interstitial BMS, both from Mt Gambier peridotites, SE Australia (Alard …","PeriodicalId":49624,"journal":{"name":"Reviews in Mineralogy & Geochemistry","volume":"19 1","pages":"579-649"},"PeriodicalIF":0.0,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86588958","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}

{"title":"Analytical Methods for the Highly Siderophile Elements","authors":"T. Meisel, M. Horan","doi":"10.2138/RMG.2016.81.02","DOIUrl":"https://doi.org/10.2138/RMG.2016.81.02","url":null,"abstract":"The highly siderophile elements (HSE) include the fifth-period transition metals ruthenium (Ru), rhodium (Rh), palladium (Pd), and the sixth-period transition metals rhenium (Re), osmium (Os), iridium (Ir), platinum (Pt) and gold (Au). In addition to being iron-loving, these elements are also resistant to oxidation, have high melting temperatures and are important as industrial catalysts. HSE abundances in geologic materials vary significantly, ranging from ~1 mg/g in ore materials down to a few pg/g in basalts (Table 1). These elements comprise two long-lived radiometric decay schemes: 187Re decays to 187Os, and 190Pt decays to 186Os. View this table: Table 1 Range of HSE abundances, in ng/g, in selected rock types and in model upper mantle. The HSE have been targeted to address a wide variety of geochemical and cosmochemical questions. Early work suggested HSE concentrations can constrain Hadean mantle evolution (Chou 1978) and showed the geochronologic potential of the Re/Os isotope system (Herr and Merz 1955; Herr et al. 1961; Markey et al. 1998). More recent applications combine the Re–Os decay system with abundance data for the HSE to investigate the evolution of the planets and the moon (Day et al. 2010, 2016, this volume), the terrestrial mantle (Rehkamper et al. 1997; Aulbach et al. 2016, this volume; Harvey et al. 2016, this volume; Luguet and Reisberg 2016, this volume), impact craters (Koeberl and Shirey 1993), geochemistry and geochronology of ore formation (Markey et al. 1998; Barnes and Ripley 2016, this volume), tektites (Koeberl and Shirey 1993), as well as the formation and evolution of the continental curst (e.g., Peucker-Ehrenbrink and Jahn 2001). Non-mass dependent isotope variations in Re, Os, Ru, Pt and Pd are also present in some meteorites and lunar samples and arise from nucleosynthesis and cosmogenic radiation (Yokoyama and …","PeriodicalId":49624,"journal":{"name":"Reviews in Mineralogy & Geochemistry","volume":"79 1","pages":"89-106"},"PeriodicalIF":0.0,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88989386","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}

{"title":"Highly Siderophile and Strongly Chalcophile Elements in Magmatic Ore Deposits","authors":"S. Barnes, E. Ripley","doi":"10.2138/RMG.2016.81.12","DOIUrl":"https://doi.org/10.2138/RMG.2016.81.12","url":null,"abstract":"An ore deposit by definition must be economically viable, that is to say it must contain sufficient material at high enough grade to make it possible to mine and process it at a profit (Bates and Jackson 1987). This requires the elements to be collected and concentrated by some phase and for them to be deposited close to the surface of the earth. At the oxygen fugacities found in the crust, native Fe is not normally stable and thus the highly siderophile elements (defined as Ru, Rh, Pd, Re, Os, Ir, Pt, and Au) cannot behave as siderophile elements except in rare cases such as on Disko Island (Klock et al. 1986) where the magma is sufficiently reduced for native Fe to be present. However, if mafic magmas become saturated in a base-metal-sulfide liquid, the highly siderophile elements behave as highly chalcophile elements (Table 1). Thus these elements are generally found in association with base-metal-sulfide minerals which crystallized from a magmatic sulfide liquid, namely pyrrhotite, pentlandite, chalcopyrite, cubanite ± pyrite. An exception to this is Au. Although Au is strongly chalcophile and is produced as a by-product from many platinum-group element (PGE) deposits (Table 2), most primary Au deposits consist of native Au (Groves et al. 1998). These will not be discussed in this chapter. There are many PGE-deposits (i.e., accumulations of PGE minerals and base metal sulfides containing PGE; Bates and Jackson 1987) around the world, but most of these do not constitute PGE ore deposits, because they are either too small or their grade is too low, or other political or infrastructure factors prevent the economic exploitation of the deposit (Bates and Jackson 1987) For the purpose of this work we have defined PGE ore deposits as those which have significant production (> 2% of the annual world …","PeriodicalId":49624,"journal":{"name":"Reviews in Mineralogy & Geochemistry","volume":"23 1","pages":"725-774"},"PeriodicalIF":0.0,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88556119","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}

{"title":"Re–Pt–Os Isotopic and Highly Siderophile Element Behavior in Oceanic and Continental Mantle Tectonites","authors":"Tectonites, H. Becker, C. Dale","doi":"10.2138/RMG.2016.81.7","DOIUrl":"https://doi.org/10.2138/RMG.2016.81.7","url":null,"abstract":"Tectonically emplaced mantle rocks, such as ophiolites, abyssal peridotites, and orogenic peridotite massifs, provide a principle constraint on the composition of and processes in the Earth’s upper mantle (Bodinier and Godard 2003). In the past, these ‘mantle tectonites’ have sometimes received different names because their history and origin has been unclear. Mantle tectonites are now understood to reflect a range of geologic environments regarding their emplacement and their origin (e.g., Dilek and Furnes 2014). The advantage of these rocks compared to mantle xenoliths is the large-scale exposure of textural and compositional relations between different rock types that can be used to identify processes such as melting, magma or fluid transport, chemical reactions, mixing or deformation at a range of spatial scales. A disadvantage of most mantle tectonites is that they commonly display substantial chemical modification of some elements, resulting from widespread serpentinization at low temperatures. In some cases, this may also affect abundances of several of the highly siderophile elements (HSE: Re, Au, PGE: Os, Ir, Ru, Rh, Pt, Pd), however, this can be tested by comparison with unaltered rocks of similar composition. As is discussed in Luguet and Reisberg (2016, this volume), Harvey et al. (2016, this volume) and Aulbach et al. (2016, this volume), peridotite xenoliths have their own alteration issues regarding sulfides and chalcophile elements. Numerous studies have obtained Os isotope and/or highly siderophile element abundance data on many different types of mantle tectonites. Some of these studies have focused on large-scale chemical and isotopic variations, others on grain size-scale compositional variations to understand small-scale distribution processes. These studies have, together, significantly advanced the understanding of the processes that fractionate the HSE in the mantle at different spatial scales and have provided insights into the behavior of sulfide in the mantle—the phase that typically …","PeriodicalId":49624,"journal":{"name":"Reviews in Mineralogy & Geochemistry","volume":"70 1","pages":"369-440"},"PeriodicalIF":0.0,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86296991","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}

{"title":"Highly Siderophile Element and 187Os Signatures in Non-cratonic Basalt-hosted Peridotite Xenoliths: Unravelling the Origin and Evolution of the Post-Archean Lithospheric Mantle","authors":"A. Luguet, L. Reisberg","doi":"10.2138/RMG.2016.81.06","DOIUrl":"https://doi.org/10.2138/RMG.2016.81.06","url":null,"abstract":"The highly siderophile elements (HSE) consist of the Platinum Group Elements (PGE: Ru, Rh, Pd, Os, Ir, Pt) along with rhenium and gold. These transition elements show relative chemical inertness and high market values, which respectively earned them the additional names of noble metals and precious metals. The HSE show a very pronounced affinity for iron metal, which translates into metal/silicate partition coefficients similar to or higher than 10,000 over large ranges of both pressure and temperature (e.g., O’Neill et al. 1995; Borisov and Palme 2000; Ertel et al. 1999, 2001, 2006, 2008; Fortenfant et al. 2003, 2006; Brenan et al. 2005; Cottrell and Walker 2006; Brenan and McDonough 2009; Laurenz et al. 2010; Mann et al. 2012; see Brenan et al. 2016, this volume for detailed review). Consequently, the HSE are thought to have been efficiently sequestered within the metallic core of our planet during the metal–silicate differentiation of Earth, leaving the silicate counterpart almost HSE-barren. Investigations of mantle peridotites since the 1970s revealed ng.g−1 level abundances as well as close-to-chondritic proportions of the HSE (Chou 1978; Jagoutz et al. 1979; Mitchell and Keays 1981; McDonough and Sun 1995; Becker et al. 2006; Fischer-Godde et al. 2011). Such abundances and inter-HSE fractionations are not predicted for the silicate Earth left after separation of the metallic core for low- or high-pressure core–mantle differentiation (see Brenan et al. 2016, this volume). The close agreement between the osmium isotopic compositions of fertile mantle peridotites and those of chondritic meteorites (Walker et al. 2002a), which requires nearly identical Re/Os ratios in these two reservoirs, provides particularly convincing evidence that the mantle’s HSE content cannot simply represent the residue left after core formation. …","PeriodicalId":49624,"journal":{"name":"Reviews in Mineralogy & Geochemistry","volume":"27 1","pages":"305-367"},"PeriodicalIF":0.0,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82304567","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}

{"title":"Highly Siderophile Elements in Earth, Mars, the Moon, and Asteroids.","authors":"James M D Day, Alan D Brandon, Richard J Walker","doi":"10.2138/rmg.2016.81.04","DOIUrl":"10.2138/rmg.2016.81.04","url":null,"abstract":"The highly siderophile elements (HSE: Os, Ir, Ru, Rh, Pt, Pd, Re, Au) are key tracers of planetary accretion and differentiation processes due to their affinity for metal relative to silicate. Under low-pressure conditions the HSE are defined by having metal–silicate partition coefficients in excess of 104 (e.g., Kimura et al. 1974; Jones and Drake 1986; O’Neill et al. 1995; Borisov and Palme 1997; Mann et al. 2012). The HSE are geochemically distinct in that, with the exception of Au, they have elevated melting points relative to iron (1665 K), low vapour pressures, and are resistant to corrosion or oxidation. Under solar nebular conditions, Re, Os, Ir, Ru, Rh, and Pt, along with the moderately siderophile elements (MSE) Mo and W, condense as refractory-metal alloys. Palladium and Au are not as refractory and condense in solid solution with FeNi metal (Palme 2008). Assuming abundances of the HSE in materials that made up the bulk Earth were broadly similar to modern chondrite meteorites, mass balance calculations suggest that >98% of these elements reside in the metallic core (O’Neill and Palme 1998). In practical terms, the resultant low HSE abundance inventories in differentiated silicate crusts and mantles enables the use of these elements in order to effectively track metallic core formation and the subsequent additions of HSE-rich impactors to planets and asteroids (Fig. 1). In detail, the absolute and relative abundances of the HSE in planetary materials are also affected by mantle and crustal processes including melting, metasomatism, fractional crystallization, and crust-mantle remixing, as well as later impact processing, volatility of Re under oxidizing conditions, and low-temperature secondary alteration (cf., Day 2013; Gannoun et al. 2016, this volume). In the absence of metal, the HSE are chalcophile, so these elements are also affected by processes …","PeriodicalId":49624,"journal":{"name":"Reviews in Mineralogy & Geochemistry","volume":"81 1","pages":"161-238"},"PeriodicalIF":0.0,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2138/rmg.2016.81.04","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"37216558","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nucleosynthetic Isotope Variations of Siderophile and Chalcophile Elements in the Solar System.","authors":"Tetsuya Yokoyama, Richard J Walker","doi":"10.2138/rmg.2016.81.03","DOIUrl":"10.2138/rmg.2016.81.03","url":null,"abstract":"Numerous investigations have been devoted to understanding how the materials that contributed to the Solar System formed, were incorporated into the precursor molecular cloud and the protoplanetary disk, and ultimately evolved into the building blocks of planetesimals and planets. Chemical and isotopic analyses of extraterrestrial materials have played a central role in decoding the signatures of individual processes that led to their formation. Among the elements studied, the siderophile and chalcophile elements are crucial for considering a range of formational and evolutionary processes. Consequently, over the past 60 years, considerable effort has been focused on the development of abundance and isotopic analyses of these elements in terrestrial and extraterrestrial materials (e.g., Shirey and Walker 1995; Birck et al. 1997; Reisberg and Meisel 2002; Meisel and Horan 2016, this volume).\u0000\u0000In this review, we consider nucleosynthetic isotopic variability of siderophile and chalcophile elements in meteorites. Chapter 4 provides a review for siderophile and chalcophile elements in planetary materials in general (Day et al. 2016, this volume). In many cases, such variability is denoted as an “isotopic anomaly”; however, the term can be ambiguous because several pre- and post- Solar System formation processes can lead to variability of isotopic compositions as recorded in meteorites. Here we strictly define the term “isotopic anomaly” as referring to an isotopic deviation from the terrestrial composition resulting from the incorporation of varying proportions of elements with diverse nucleosynthetic origins into a meteorite component or parent body. The term will not be used here to refer to isotopic variations that result from mass-dependent isotopic fractionation, radioactive decay in the Solar System, or spallation effects.\u0000\u0000Based on astronomical observations and physical modelling, the formation of the Solar System has generally been thought to have initiated by the collapse of a dense molecular cloud …","PeriodicalId":49624,"journal":{"name":"Reviews in Mineralogy & Geochemistry","volume":"81 1","pages":"107-160"},"PeriodicalIF":0.0,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2138/rmg.2016.81.03","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"36975582","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Petrogenesis of the Platinum-Group Minerals","authors":"B. O’Driscoll, J. González-Jiménez","doi":"10.2138/RMG.2016.81.09","DOIUrl":"https://doi.org/10.2138/RMG.2016.81.09","url":null,"abstract":"The platinum-group minerals (PGM) are a diverse group of minerals that concentrate the platinum-group elements (PGE; Os, Ir, Ru, Rh, Pt, and Pd). At the time of writing, the International Mineralogical Association database includes 135 named discrete PGM phases. Much of our knowledge of the variety and the distribution of these minerals in natural systems comes from ore deposits associated with mafic and ultramafic rocks and their derivatives (see also Barnes and Ripley 2016, this volume). Concentrations of PGM can be found in layered mafic–ultramafic intrusions. Although they don’t typically achieve ore grade status, supra-subduction zone upper mantle (preserved in ophiolite) lithologies (i.e., chromitite [> 60 vol.% Cr-spinel], pyroxenite) characteristically host a diversity of PGM assemblages as well (Becker and Dale 2016, this volume). Occurrences of the PGM in layered intrusions, ophiolites, and several other important settings will all be described in this review. In keeping with the general theme of this volume, the focus of this chapter is on relatively high-temperature (magmatic) settings. This is not a straightforward distinction to make, as PGM assemblages that begin as high-temperature parageneses may be modified at much lower temperatures during metamorphism, hydrothermal processes or surficial weathering (e.g., Hanley 2005). However, the vast majority of the published literature on PGM petrogenesis is based on occurrences from magmatic environments, an understandable bias given the importance of the major ore deposits that occur in some layered mafic–ultramafic intrusions, for example. For that reason, the emphasis of this review will be on high-temperature magmatic settings, with the understanding that lower temperature (sub-solidus; < 600 °C) processes can modify primary PGM assemblages. The geochemical behavior of the platinum-group elements (PGE) in magmatic settings is highly chalcophile and not, as might be expected, highly siderophile. This is because most terrestrial magmatic systems are relatively oxidized, such …","PeriodicalId":49624,"journal":{"name":"Reviews in Mineralogy & Geochemistry","volume":"67 1","pages":"489-578"},"PeriodicalIF":0.0,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78346415","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}