J.B. Plescia, J. Cahill, B. Greenhagen, P. Hayne, P. Mahanti, M.S. Robinson, P.D. Spudis, M. Siegler, A. Stickle, J.P. Williams, M. Zanetti, N. Zellner
The modern surface of the Moon is primarily influenced by impact processes. While volcanism was active until perhaps 3.0 Ga and tectonic activity may still persist, it is the integrated effects of impacts that have produced the primary topography and controlled the physical properties of the surface materials (the regolith). Impact processes per se are discussed elsewhere (Osinski et al. 2023, this volume); here we focus on the regolith that has been produced by those impacts, its physical properties and its evolution.Regolith (Fig. 1) is the fragmental layer of debris that covers the lunar surface...
{"title":"Lunar Surface Processes","authors":"J.B. Plescia, J. Cahill, B. Greenhagen, P. Hayne, P. Mahanti, M.S. Robinson, P.D. Spudis, M. Siegler, A. Stickle, J.P. Williams, M. Zanetti, N. Zellner","doi":"10.2138/rmg.2023.89.15","DOIUrl":"https://doi.org/10.2138/rmg.2023.89.15","url":null,"abstract":"The modern surface of the Moon is primarily influenced by impact processes. While volcanism was active until perhaps 3.0 Ga and tectonic activity may still persist, it is the integrated effects of impacts that have produced the primary topography and controlled the physical properties of the surface materials (the regolith). Impact processes per se are discussed elsewhere (Osinski et al. 2023, this volume); here we focus on the regolith that has been produced by those impacts, its physical properties and its evolution.Regolith (Fig. 1) is the fragmental layer of debris that covers the lunar surface...","PeriodicalId":501196,"journal":{"name":"Reviews in Mineralogy and Geochemistry","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138548437","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Lisa R. Gaddis, Katherine H. Joy, Ben J. Bussey, James D. Carpenter, Ian A. Crawford, Richard C. Elphic, Jasper S. Halekas, Samuel J. Lawrence, Long Xiao
Exploration of the Moon has been a goal of humankind for millennia, and in recent decades enormous advances in lunar knowledge have resulted from orbital, landed, robotic, and human exploration and sample return (Spudis 2001; National Research Council 2007; Jaumann et al. 2012; Crawford and Joy 2014; Lunar Exploration Analysis Group 2016a). The Moon still retains the marks of human footprints, and these and other artifacts can now be seen with amazing clarity in images returned from the NASA Lunar Reconnaissance Orbiter Cameras (LROC; Robinson et al. 2010). The six U.S. Apollo missions...
{"title":"Recent Exploration of the Moon: Science from Lunar Missions Since 2006","authors":"Lisa R. Gaddis, Katherine H. Joy, Ben J. Bussey, James D. Carpenter, Ian A. Crawford, Richard C. Elphic, Jasper S. Halekas, Samuel J. Lawrence, Long Xiao","doi":"10.2138/rmg.2023.89.01","DOIUrl":"https://doi.org/10.2138/rmg.2023.89.01","url":null,"abstract":"Exploration of the Moon has been a goal of humankind for millennia, and in recent decades enormous advances in lunar knowledge have resulted from orbital, landed, robotic, and human exploration and sample return (Spudis 2001; National Research Council 2007; Jaumann et al. 2012; Crawford and Joy 2014; Lunar Exploration Analysis Group 2016a). The Moon still retains the marks of human footprints, and these and other artifacts can now be seen with amazing clarity in images returned from the NASA Lunar Reconnaissance Orbiter Cameras (LROC; Robinson et al. 2010). The six U.S. Apollo missions...","PeriodicalId":501196,"journal":{"name":"Reviews in Mineralogy and Geochemistry","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138547849","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
One of the key scientific questions about diamonds is “how are they formed?” To answer this question, we need to know the diamond-forming reactions and the physicochemical conditions under which these reactions take place. The pressure (P) and temperature (T) of diamond formation are an essential part of this knowledge and their assessment is pivotal to develop predictive scenarios of diamond distribution in the Earth interior. These scenarios may contribute to our understanding of global Earth processes, such as the long-term carbon cycle, and might also eventually improve our capability to select potential targets for diamond exploration (Shirey et al. 2013; Nimis et al. 2020).The evaluation of the P and T of diamond formation can be carried out at two levels of investigation. The first is concerned with formation conditions for individual diamonds or small populations of diamonds from specific sources. This approach has been so far the most widely practiced. The second level considers the statistical distribution of P–T conditions for diamond formation at either local or global scale. This type of investigation is hampered by the difficulty of obtaining large sets of suitable samples from a specific locality or for a statistically significant number of localities, and is therefore unavoidably affected to some degree by sampling bias. Despite inherent limitations, the latter approach is the most appropriate to reveal systematics in diamond P–T distributions and, ultimately, in diamond depth distribution within the Earth.Early reviews of P–T distributions for lithospheric diamonds were made by Nimis (2002), based on thermobarometry of chromian diopside inclusions, and by Stachel and Harris (2008) and Stachel (2014), using a more comprehensive set of thermobarometers. More recently, Nimis et al. (2020) investigated diamond depth distributions for a set of South African kimberlites and provided evidence for systematic trends of likely global significance. The depth distribution for sublithospheric diamonds worldwide was reviewed by Harte (2010). In this contribution, I first describe the methods that can be used to estimate the P–T conditions of diamond formation, highlighting their respective strengths and weaknesses. I then review existing diamond P–T data and their implications for diamond distribution with depth from both a local and a global perspective.Thermobarometry of diamonds can be carried out by estimating P–T conditions of chemical or elastic equilibrium of mineral inclusions contained within them. With some assumptions, the aggregation state of nitrogen substituting for carbon in the diamond lattice can also be used as a thermometer. In some cases, it is possible to derive both P and T estimates for a diamond by combining independent thermobarometric methods. In most instances, however, either P or T estimates can be directly retrieved with sufficient confidence. Below is a list of currently available methods for diamond thermobarome
这构成了钻石弹性气压计的基础。这种方法的原理、问题和持续发展在Angel等人(2022年，本卷)中有详细描述。投影到地热上。当由于缺乏合适的气压计而只能获得温度估计时，可以通过在参考地热上投射温度估计来获得压力的暂定估计。这将最方便地通过拟合来自同一金伯利岩源的地幔捕虏体或异晶的P-T数据得到地热。Mather等人(2011)的FITPLOT计算软件为从捕虏体P-T数据中模拟地热提供了有用的帮助。一些用于建模的输入参数可能存在显著的不确定性，特别是上下地壳的厚度和产热以及地幔的位温，但在大多数情况下，这些不确定性不会显著影响岩石圈钻石窗内的地热形状，这将主要受到捕虏体P-T数据的限制。然而，假设不同的地幔位温会影响岩石圈厚度的估计和地热传导部分的深度范围。这可能与一些古老的高t钻石有关，因为地幔的潜在温度可能随地质时间而变化。如果不考虑这种变化，测温估计可能会不适当地投影到地热的绝热部分，并导致对现今地幔势温及其随时间变化的p值的严重高估，可以在Katsura et al.(2010)和Ganne and Feng(2017)中找到。描述模型地热相关部分的输出数据可以方便地通过多项式表达式进行拟合，从而推导出P作为t的函数。最终的P - t估计值将由该多项式与所选温度计所描述的等温线相交得到。注意，这条等温线在P-T图中通常不会是一条平坦的线，因为温度计通常具有显著的p依赖性(图4)。这种方法的基本假设是，包裹体在喷发时位于地幔地热的P-T条件下最后达到平衡。对于接触包裹体对，这通常是可以接受的，它可以以与接触捕虏体中的矿物相同的方式重新平衡(但请参阅下面专门讨论接触与非接触包裹体的注意事项)，而对于非接触包裹体，这种情况就不那么明显了。对来自同一来源的包裹体和捕虏体的P-T估计的比较表明，该假设通常也适用于非接触包裹体(Nimis 2002)。尽管如此，也有证据表明一些钻石包裹体记录的条件比捕虏体地热明显更热或更冷(Griffin et al. 1993;Sobolev and Yefimova 1998;Nimis 2002;Stachel et al. 2003, 2004;Weiss et al. 2018;Nimis et al. 2020)。此外，单个钻石内的多个非接触内含物可能记录了一系列条件，表明钻石生长历史中的热波动(Griffin et al. 1993)。因此，对地热的投影应谨慎使用，并应允许相对较大的不确定性。假设捕虏岩地热的最大可能温差为~250°C，这与使用单斜辉石(Nimis and Taylor 2000)、单石榴石(Canil 1999)和正辉石-石榴石(Harley 1984)温度计对钻石的现有估计一致。对典型克拉通地热的投影可能导致P不确定性高达~1.5 GPa(图4)。对地幔地热绝热部分的投影可能为弹性气压测量方法在岩石圈下钻石的应用提供必要的独立约束(例如，Anzolini et al. 2019)。矿物的稳定。岩石圈地幔仅根据矿物组合的稳定性来估计金刚石形成条件的机会很少。例如，在整个钻石窗口中，唯一显著的矿物学变化是橄榄岩中尖晶石向石榴石的转变。尖晶石-石榴石的反应不是一成不变的，在Cr/Al强烈升高的枯竭克拉通橄榄岩中，尖晶石+石榴石组合可能在很大范围的P-T条件下持续存在(例如，MacGregor 1970;Webb and Wood 1986;Klemme 2004;Ziberna et al. 2013)。一般来说，尖晶石在更难熔、富cr和贫al的大块成分中稳定在更高的压力下。这使得镁铬铁矿可以作为包裹体掺入在非常深的难熔环境中形成的钻石中(例如，6.5 GPa，对应深度超过200公里，来自西伯利亚Udachnaya金伯利岩的钻石;Nestola et al. 2019a)。 矿物稳定性在岩石圈下地幔中变得更加有趣，在那里发生了许多特征矿物学变化(Harte 2010;Harte and Hudson 2013)。尽管这些变化不允许将P-T条件与传统的温压计的分辨率相媲美，但在某些情况下，它们将钻石的形成限制在特定的地幔深度区域内。例如，含铁方长石与顽辉石共存，被解释为倒桥辉石(以前称为mgsi -钙钛矿)，长期以来为一些钻石形成于下地幔深处提供了证据(Scott Smith et al. 1984;Moore et al. 1986)。即使在没有方长石的情况下，下地幔的倒菱辉石也可以很容易地与上地幔的顽辉石区分开来，因为它们的镍含量非常低(Stachel et al. 2000)。在巴西Juina的一颗钻石中发现了罕见的环伍德石包裹体，明确地证明了它起源于地幔过渡带(Pearson et al. 2014)。此外，重建的Juina钻石中一套脱溶包裹体的成分与预计在下地幔玄武岩系统中形成的矿物非常匹配(Walter et al. 2011)。然而，使用钻石包裹体中发现的不完整矿物组合作为深度标记并不总是没有歧义。例如，白晶石包裹体(以前称为CaSi-walstromite)长期以来被认为代表深度大于~600 km的后退casio3钙钛矿(例如，Harte et al. 1999;Joswig et al. 1999)，但有令人信服的证据表明，至少有一些白晶石包裹体起源于上地幔较浅的深度(Brenker et al. 2005;Anzolini et al. 2016)。Woodland et al.(2020)最近为白晶石可能的上地幔起源提供了实验支持。此外，含铁方长石是解释的下地幔起源中最常见的包裹体(Kaminsky 2012)，但有证据表明，含铁方长石参与了跨越上地幔-下地幔边界的矿物共生(Hutchison et al. 2001)，它可能是在过渡带甚至上覆上地幔中可能发生的钻石形成反应的副产物(Thomson et al. 2016;Bulatov et al. 2019)。数据质量。精确和准确的化学分析是可靠的热气压测定法的一个有时被低估的先决条件。钻石中的内含物通常很小，它们的化学分析可能具有挑战性。此外，有些温度计可能对临界浓度水平下元素的分析不确定度特别敏感。例如，Ziberna等人(2016)使用Nimis和Taylor(2000)的单斜云石气压计探索了分析误差对P估计的传播，并发现常规的电子探针分析条件可能不足以对钻石中的许多内含物进行有意义的气压测定。显然，不仅计数统计数据不准确，而且样品制备不当和标准化不当也可能是一个问题，并可能导致错误的结果。一项对岩石圈钻石中600多个斜辉石包裹体的公开化学数据的调查表明，其中约30%的氧化物总重量百分比< 98.5%或> 101%，或阳离子总和< 3.98或> 4.03原子/公式单位，因此，质量肯定不是很好!请注意，上述截止值充分考虑了在电子探针分析中将所有铁都视为Fe2+可能产生的影响。当研究从共存的矿物相中分离出来的包裹体时，下一个关键步骤是定义它们的原始共生。即使单矿物温压计经常会派上用场，它们也总是假定所研究的矿物最后与特定的其他矿物达到平衡。至于斜辉石和石榴石，它们是几种类型地幔岩石的主要成分，基于主要或微量元素浓度的简单成分筛选可能有
{"title":"Pressure and Temperature Data for Diamonds","authors":"Paolo Nimis","doi":"10.2138/rmg.2022.88.10","DOIUrl":"https://doi.org/10.2138/rmg.2022.88.10","url":null,"abstract":"One of the key scientific questions about diamonds is “how are they formed?” To answer this question, we need to know the diamond-forming reactions and the physicochemical conditions under which these reactions take place. The pressure (P) and temperature (T) of diamond formation are an essential part of this knowledge and their assessment is pivotal to develop predictive scenarios of diamond distribution in the Earth interior. These scenarios may contribute to our understanding of global Earth processes, such as the long-term carbon cycle, and might also eventually improve our capability to select potential targets for diamond exploration (Shirey et al. 2013; Nimis et al. 2020).The evaluation of the P and T of diamond formation can be carried out at two levels of investigation. The first is concerned with formation conditions for individual diamonds or small populations of diamonds from specific sources. This approach has been so far the most widely practiced. The second level considers the statistical distribution of P–T conditions for diamond formation at either local or global scale. This type of investigation is hampered by the difficulty of obtaining large sets of suitable samples from a specific locality or for a statistically significant number of localities, and is therefore unavoidably affected to some degree by sampling bias. Despite inherent limitations, the latter approach is the most appropriate to reveal systematics in diamond P–T distributions and, ultimately, in diamond depth distribution within the Earth.Early reviews of P–T distributions for lithospheric diamonds were made by Nimis (2002), based on thermobarometry of chromian diopside inclusions, and by Stachel and Harris (2008) and Stachel (2014), using a more comprehensive set of thermobarometers. More recently, Nimis et al. (2020) investigated diamond depth distributions for a set of South African kimberlites and provided evidence for systematic trends of likely global significance. The depth distribution for sublithospheric diamonds worldwide was reviewed by Harte (2010). In this contribution, I first describe the methods that can be used to estimate the P–T conditions of diamond formation, highlighting their respective strengths and weaknesses. I then review existing diamond P–T data and their implications for diamond distribution with depth from both a local and a global perspective.Thermobarometry of diamonds can be carried out by estimating P–T conditions of chemical or elastic equilibrium of mineral inclusions contained within them. With some assumptions, the aggregation state of nitrogen substituting for carbon in the diamond lattice can also be used as a thermometer. In some cases, it is possible to derive both P and T estimates for a diamond by combining independent thermobarometric methods. In most instances, however, either P or T estimates can be directly retrieved with sufficient confidence. Below is a list of currently available methods for diamond thermobarome","PeriodicalId":501196,"journal":{"name":"Reviews in Mineralogy and Geochemistry","volume":"63 8","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138511251","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Michael J. Walter, Andrew R. Thomson, Evan M. Smith
Minerals included in diamonds provide direct information about the petrologic and chemical environment of diamond crystallization. They record information relating to local and regional mantle processes and provide important contextual information for global-scale tectonic interpretations (Stachel et al. 2005; Stachel and Harris 2008; Harte 2010; Shirey et al. 2013, 2019). Most mined inclusion-bearing diamonds originate in sub-continental, cratonic mantle lithosphere but a small percentage host mineral inclusions consistent with an origin beneath the lithosphere (~1%, Stachel and Harris 2008). Key among these inclusions are silicate and oxide minerals that provide either direct (e.g., majoritic garnet, ringwoodite) or circumstantial (e.g., CaSiO3-rich and MgSiO3-rich phases; ferropericlase) evidence for a high-pressure origin deep in the convecting mantle; we refer to these diamonds as “sublithospheric” although they are also commonly called “superdeep”. Studies over the past four decades have provided a wealth of information to draw upon to interrogate the origins of sublithospheric diamonds and their inclusions and to speculate on broader geologic and geodynamic implications.In the 1980s researchers began to recognize that some diamonds carry inclusions indicative of an origin beneath continental lithosphere, extending to depths even into the lower mantle (Scott-Smith et al. 1984; Moore et al. 1986; Wilding et al. 1991; Harte and Harris 1994; Harris et al. 1997; Stachel et al. 1998a; Harte et al. 1999). Paramount among these are inclusions with (Mg,Fe)O and (Mg,Fe)SiO3 stoichiometry, and on the basis of co-occurrence in the same diamond they were interpreted as ferropericlase and retrograde Mg-silicate perovskite (bridgmanite) from the shallow lower mantle. Discoveries of inclusions with CaSiO3 stoichiometry, sometimes also co-occurring with MgSiO3-rich phases and/or ferropericlase and interpreted as retrograde Ca-silicate perovskite, supported the view of a lower mantle genesis related to mantle peridotite (Harte et al. 1999; Joswig et al. 1999; Stachel et al. 2000b; Kaminsky et al. 2001; Hayman et al. 2005). Garnet inclusions with excess octahedrally coordinated silicon per formula unit (Moore and Gurney 1985, 1989; Moore et al. 1991; Stachel and Harris 1997; Stachel et al. 1998a) provided further evidence for a sublithospheric origin on the basis of experiments that revealed the pressure dependence of elemental substitutions (Akaogi and Akimoto 1977).Over several decades numerous studies have uncovered many new examples of sublithospheric diamonds hosting these key indicator phases while also identifying a wide variety of other mineral inclusions interpreted to have an origin in the deep upper mantle to lower mantle, including but not limited to ringwoodite, stishovite, CF-phase, NAL-phase, K-hollandite, CAS phase, and phase Egg (Wirth et al. 2007; Bulanova et al. 2010; Walter et al. 2011; Thomson et al. 2014; Zedgenizov et al. 2015). The re
金刚石中所含的矿物为金刚石结晶的岩石学和化学环境提供了直接的信息。它们记录了有关局部和区域地幔过程的信息，并为全球尺度的构造解释提供了重要的背景信息(Stachel et al. 2005;Stachel and Harris 2008;哈特2010;Shirey et al. 2013, 2019)。大多数开采的含包裹体钻石起源于次大陆、克拉通地幔岩石圈，但一小部分含有与岩石圈下起源一致的矿物包裹体(~1%，Stachel和Harris 2008)。这些包裹体中的关键是硅酸盐和氧化物矿物，它们提供直接(如多数石榴石、环woodite)或间接(如富casio3和富mgsio3)相;铁长石)在对流地幔深部高压成因的证据;我们称这些钻石为“地下岩石圈”，尽管它们通常也被称为“超深”。过去四十年的研究提供了丰富的信息，可以用来询问岩石圈下钻石及其内含物的起源，并推测更广泛的地质和地球动力学含义。在20世纪80年代，研究人员开始认识到一些钻石携带的内含物表明其起源在大陆岩石圈之下，甚至延伸到下地幔深处(Scott-Smith et al. 1984;Moore et al. 1986;Wilding et al. 1991;Harte and Harris 1994;Harris et al. 1997;Stachel et al. 1998a;Harte et al. 1999)。其中最重要的包裹体具有(Mg,Fe)O和(Mg,Fe)SiO3的化学计量，根据它们在同一颗金刚石中的共现，它们被解释为铁长石和来自下地幔浅层的逆行镁硅酸盐钙钛矿(桥菱铁矿)。含有CaSiO3化学计量的包裹体的发现，有时也与富mgsio3相和/或铁镁长石共存，并被解释为逆行钙硅酸盐钙钛矿，支持了与地幔橄榄岩有关的下地幔成因的观点(Harte et al. 1999;Joswig et al. 1999;Stachel et al. 2000b;Kaminsky et al. 2001;Hayman et al. 2005)。每个分子式单位含有过量八面体配位硅的石榴石内含物(Moore和Gurney 1985, 1989;Moore et al. 1991;Stachel and Harris 1997;Stachel et al. 1998a)在揭示元素置换对压力依赖的实验基础上，为岩石圈下起源提供了进一步的证据(Akaogi and Akimoto 1977)。几十年来，大量的研究发现了岩石圈下钻石具有这些关键指示阶段的许多新例子，同时也发现了各种各样的其他矿物包裹体，这些包裹体被解释为起源于深部上地幔到下地幔，包括但不限于ringwoodite, stishovite, CF-phase, NAL-phase, K-hollandite, CAS phase和phase Egg (Wirth et al. 2007;Bulanova et al. 2010;Walter et al. 2011;Thomson et al. 2014;Zedgenizov et al. 2015)。读者可以参考最近的几篇综述论文，这些论文提供了岩石圈下钻石包裹体类型的清单(Stachel and Harris 2008;哈特2010;Kaminsky 2012;Shirey et al. 2013, 2019)。根据矿物学、岩石学和地球化学资料，越来越明显地发现许多岩石圈下钻石记录过程与岩石圈板块俯冲有关(Stachel et al. 2000a,b;Stachel 2001;Walter et al. 2008;Tappert et al. 2009;Bulanova et al. 2010;Kiseeva et al. 2013;Thomson et al. 2014;Burnham et al. 2015;Ickert et al. 2015;Shirey et al. 2019)。多数石榴石相和富钛casio3相的主要元素和微量元素地球化学特征表明其成因涉及俯冲玄武岩洋壳，稀有包裹体的存在解释为逆行的cf相和nal相。钻石中普遍存在的轻碳同位素和寄主包裹体中的重氧同位素为这一假设提供了额外的支持证据(Burnham et al. 2015;Ickert et al. 2015)。岩石圈下钻石的氮含量明显较低，约70%为ⅱ型(如< ~ 20at)。ppm N)和< 100 at的> 90%。测得的N高度聚集，以B中心为主(~87% > 50% B)，与高温下地幔的储存一致。岩石圈钻石的N值较高，一般为I型，平均为~250 at。ppm N，但扩展到> 1000 at。ppm N，并与< 20%低氮II型。岩石圈钻石在其报告的化学分析中也通常表现出聚集不良的N(例如，3si pfu)。与之前的许多研究不同，我们采用了Thomson等人的方法。 这些作者还发现了一个低压稳定场，其温度低于10 GPa，与其低压相相一致。3个高铝单相包裹体与铁方长石包裹体共生，还有1个富钠包裹体和5个长辉锌矿包裹体共生。图12显示了富mgsio3包体的三元组份图(Mg+Fe2+) - (Si+Ti) - (Al+Cr+Fe3+)。低铝包裹体分布在一个明确的区域，部分重叠在变质橄榄岩组合中合成的实验桥辉石场。然而，大多数实验用原始地幔成分制成的桥菱石具有比包裹体更高的三价阳离子。许多低铝包裹体与用碳素质体组成合成的桥辉石有相似之处，也与橄榄岩体组成合成的橄榄辉石有重叠;阿基莫托石是一种钛铁矿结构的富mgsio3相，在过渡带底部附近的变橄榄岩中稳定存在于有限的压力-温度范围内(图16;Stixrude and Lithgow-Bertelloni 2011)。相比之下，高铝包裹体表现出相当大的成分变化，图12显示，6个复合包裹体(青色钻石)和杰弗长包裹体(绿色钻石)在该投影上与变质玄武岩中产生的桥辉石大致相似，而3个单相包裹体(蓝色钻石;II型MgSiO3包裹体(Hutchison et al. 2021)介于实验变质橄榄岩和变质玄武岩桥辉岩之间。四种富na (~ 4-6 wt% Na2O)包裹体(红钻;Hutchison等人(2021)的III型MgSiO3包裹体不同于任何实验菱镁石或其他富MgSiO3包裹体。图13显示了富mgsio3包裹体的mg#与在同一颗钻石中共存的铁方长石包裹体的mg#。还显示了在可育橄榄岩的大块组成和黑铅矿组成的实验中，桥辉石和铁方长石平衡在一起的区域。镁镁长石小于~0.8的铁镁长石在变质橄榄岩或变质黑锰矿组合中不符合与共生桥锰矿的平衡。在含有Mg#s大于0.8的铁方长石的钻石中，很少有包裹体对位于肥沃的变质橄榄岩中。许多低铝桥辉石-铁方长石包裹体对与元辉石区域重叠或靠近，富mgsio3包裹体趋向于具有很高的mg# s。三个单相高铝mgsio3 -铁周长石对和两个长辉石-铁周长石对恰好位于或靠近实验变质橄榄岩场。Low-Al夹杂物。图14显示了富mgsio3包裹体(钻石)中NiO、Al2O3和CaO与Mg#的对比，以及在橄榄岩体组成实验中合成的桥菱石。低铝包裹体(白色钻石)出现在~ 0.86
{"title":"Geochemistry of Silicate and Oxide Inclusions in Sublithospheric Diamonds","authors":"Michael J. Walter, Andrew R. Thomson, Evan M. Smith","doi":"10.2138/rmg.2022.88.07","DOIUrl":"https://doi.org/10.2138/rmg.2022.88.07","url":null,"abstract":"Minerals included in diamonds provide direct information about the petrologic and chemical environment of diamond crystallization. They record information relating to local and regional mantle processes and provide important contextual information for global-scale tectonic interpretations (Stachel et al. 2005; Stachel and Harris 2008; Harte 2010; Shirey et al. 2013, 2019). Most mined inclusion-bearing diamonds originate in sub-continental, cratonic mantle lithosphere but a small percentage host mineral inclusions consistent with an origin beneath the lithosphere (~1%, Stachel and Harris 2008). Key among these inclusions are silicate and oxide minerals that provide either direct (e.g., majoritic garnet, ringwoodite) or circumstantial (e.g., CaSiO3-rich and MgSiO3-rich phases; ferropericlase) evidence for a high-pressure origin deep in the convecting mantle; we refer to these diamonds as “sublithospheric” although they are also commonly called “superdeep”. Studies over the past four decades have provided a wealth of information to draw upon to interrogate the origins of sublithospheric diamonds and their inclusions and to speculate on broader geologic and geodynamic implications.In the 1980s researchers began to recognize that some diamonds carry inclusions indicative of an origin beneath continental lithosphere, extending to depths even into the lower mantle (Scott-Smith et al. 1984; Moore et al. 1986; Wilding et al. 1991; Harte and Harris 1994; Harris et al. 1997; Stachel et al. 1998a; Harte et al. 1999). Paramount among these are inclusions with (Mg,Fe)O and (Mg,Fe)SiO3 stoichiometry, and on the basis of co-occurrence in the same diamond they were interpreted as ferropericlase and retrograde Mg-silicate perovskite (bridgmanite) from the shallow lower mantle. Discoveries of inclusions with CaSiO3 stoichiometry, sometimes also co-occurring with MgSiO3-rich phases and/or ferropericlase and interpreted as retrograde Ca-silicate perovskite, supported the view of a lower mantle genesis related to mantle peridotite (Harte et al. 1999; Joswig et al. 1999; Stachel et al. 2000b; Kaminsky et al. 2001; Hayman et al. 2005). Garnet inclusions with excess octahedrally coordinated silicon per formula unit (Moore and Gurney 1985, 1989; Moore et al. 1991; Stachel and Harris 1997; Stachel et al. 1998a) provided further evidence for a sublithospheric origin on the basis of experiments that revealed the pressure dependence of elemental substitutions (Akaogi and Akimoto 1977).Over several decades numerous studies have uncovered many new examples of sublithospheric diamonds hosting these key indicator phases while also identifying a wide variety of other mineral inclusions interpreted to have an origin in the deep upper mantle to lower mantle, including but not limited to ringwoodite, stishovite, CF-phase, NAL-phase, K-hollandite, CAS phase, and phase Egg (Wirth et al. 2007; Bulanova et al. 2010; Walter et al. 2011; Thomson et al. 2014; Zedgenizov et al. 2015). The re","PeriodicalId":501196,"journal":{"name":"Reviews in Mineralogy and Geochemistry","volume":"62 51","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138511252","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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