岩石学报  2019, Vol. 35 Issue (1): 16-30, doi: 10.18654/1000-0569/2019.01.02   PDF    
假蓝宝石(Sapphirine)的矿物学特征及其在超高温变质作用研究中的应用
焦淑娟1 , 郭敬辉1,2     
1. 中国科学院地质与地球物理研究所岩石圈演化国家重点实验室, 北京 100029;
2. 中国科学院大学地球与行星科学学院, 北京 100049
摘要:假蓝宝石是Mg-Al质麻粒岩中一种特殊的高温矿物,对超高温变质作用的研究有重要的意义。本文通过对全球66个超高温麻粒岩中47个含假蓝宝石麻粒岩地区的文献调研,总结了几种最常见的含假蓝宝石矿物组合产出的结构位置和变质反应关系,以及假蓝宝石的矿物化学特征。假蓝宝石的化学成分一般位于7:9:3端元左右,XMg大于0.7,XFe3+变化范围很宽,为0~0.7。含假蓝宝石矿物组合的形成和演化指示了岩石经历的P-T轨迹。岩石中保留的假蓝宝石取代尖晶石、Grt/Opx+Sil取代Spr+Qz组合,以及随后的Spr+Crd±Opx后成合晶取代Grt/Opx+Sil组合的结构,一般可能指示了逆时针P-T轨迹中冷却和随后减压的部分;岩石中Grt/Opx+Sil/Ky或富Mg十字石反应形成Spr+Qz组合的结构可能指示了顺时针P-T轨迹中减压升温的部分。超高温变质岩不同的P-T轨迹暗示着它们的成因机制并不单一,前者可能是幔源基性岩浆底侵或增生作用的结果,后者可能与长期的热造山作用相关。
关键词: 假蓝宝石     超高温变质作用     矿物组合     矿物学特征     富Mg-Al质    
Mineralogical characteristics of sapphirine and application in investigating ultrahigh-temperature (UHT) metamorphism
JIAO ShuJuan1, GUO JingHui1,2     
1. State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;
2. College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
Abstract: Sapphirine is a specific high-temperature mineral in Mg-Al-rich granulites, and it is of significance in investigating ultrahigh-temperature (UHT) metamorphism. This study has tracked 47 sapphirine-bearing granulite localities among the worldwide 66 UHT granulite localities, and summarized the textural settings and metamorphic reaction sequences of several most commonly-observed sapphirine-bearing mineral assemblages, as well as the typical features of sapphirine mineral chemistry. Sapphirine compositions are usually localized close to the 7:9:3 end-member, and their XMg is usually higher than 0.7, and XFe3+ shows a large range of 0~0.7. Formation and evolution of the sapphirine-bearing mineral assemblages in the rocks indicate the experienced P-T paths. Textures of sapphirine replacing spinel, Grt/Opx+Sil replacing Spr+Qz assemblage, and subsequent Spr+Crd±Opx symplectite replacing Grt/Opx+Sil assemblage, generally indicate the cooling and subsequent decompression parts of an anticlockwise P-T path. Whereas, the texture of Grt/Opx+Sil/Ky or Mg-rich staurolite producing Spr+Qz assemblage, suggests that the rocks have probably experienced the heating and decompression stages in a clockwise P-T path. Different shapes of P-T paths imply that the origin mechanism of the UHT metamorphism is multiple, with the former probably resulting from underplating or accretion of the mantle-derived mafic magma, and the latter probably related to the long-lived hot orogenesis.
Key words: Sapphirine     UHT metamorphism     Mineral assemblage     Mineralogical feature     Mg-Al-rich    

假蓝宝石(sapphirine)是一种很少见的矿物,常发育在富Mg-Al质的高级变质岩中,而富Mg-Al质麻粒岩一般以团块状或条带状位于大面积的变泥质岩内。假蓝宝石的保存和识别对研究高温-超高温变质作用的热演化历史有重要的意义,尤其是假蓝宝石和石英的共生组合是岩石经历了超高温变质作用的标志(>900℃, Harley,1998a, 2008; Kelsey, 2008)。Dallwitz (1968)首次在Nature杂志报道了南极洲恩德比地区阿姆斯坦湾东部42英里处出露的麻粒岩(或蓝色石英岩)中Spr+Qz组合(矿物名称缩写参见Whitney and Evans, 2010)。样品是由澳大利亚矿产资源局I. R. McLeod采集。此后,全球陆续有含假蓝宝石麻粒岩或石英岩的报道,如加拿大威尔逊湖地区(Leong and Moore, 1972)、乌干达Labwor山地区(Nixon et al., 1973)、以及美国纽约皮克斯基尔科特兰地体(Caporuscio and Morse, 1978)。到目前为止,据作者不完全统计全球约有66个超高温变质岩地体的报道,其中的58个已在Kelsey (2008)Kelsey and Hand (2015)中介绍,新增的8个超高温变质岩地体或露头见表 1。在统计的66个超高温变质岩中,共有47个含有假蓝宝石,这其中24个发育Spr+Qz的组合(图 1),尤其发育在几个冈瓦纳大陆地体,如印度南部、斯里兰卡、马达加斯加和东南极等。实际上,报道的含假蓝宝石麻粒岩的数量不止于此,由于传统地质温度计存在后期扩散平衡的问题(Fitzsimons and Harley, 1994; Pattison et al., 2003),采用该方法得到的变质温度一般偏低50℃或更多,导致文献作者认为这些假蓝宝石麻粒岩并没有经历超高温变质作用,因而可能低估了假蓝宝石或其组合的形成温度,如印度南部达瓦尔克拉通东部含假蓝宝石麻粒岩不在统计之列(Prakash et al., 2013; Prakash and Singh, 2014)。假蓝宝石一方面对于识别超高温变质作用的发生有重要的作用,另一方面含假蓝宝石矿物组合的形成和分解对解析这些变质高级地体曾经历的P-T演化轨迹起到关键的约束作用。

表 1 全球范围内超高温变质岩出露情况(补充) Table 1 Worldwide occurrences of the UHT metamorphic rocks (Supplement)

图 1 全球范围内已报道的超高温变质岩的分布情况 数据库基于Kelsey (2008)Kelsey and Hand (2015)以及表 1 Fig. 1 Worldwide occurrences of reported UHT metamorphic rocks The database is from Kelsey (2008), Kelsey and Hand (2015) and Table 1

假蓝宝石和石英直接接触的现象比较少见,多数情况下它们之间形成堇青石或复式Sil+Grt/Opx冠状体,其中夕线石靠近假蓝宝石生长,石榴石或紫苏辉石一般靠近石英生长。这些冠状体的形成指示了Spr+Qz组合的分解反应,一般发生在中下地壳层位、近等压冷却(IBC: isobaric cooling)的变质过程(Ellis, 1980; Sandiford, 1985; Bose and Das, 2007)。假蓝宝石和石英之间或后来形成的紫苏辉石和夕线石之间堇青石环带的形成,以及石榴石和夕线石间堇青石±尖晶石组合的形成,一般暗示着随后的近等温减压过程(ITD: isothermal decompression)。相比在含石英的岩石中,假蓝宝石在硅不饱和岩石或者微域内更为发育,可形成粗粒的变斑晶与紫苏辉石共生,或与紫苏辉石、堇青石或斜长石构成后成合晶取代早期的石榴石、紫苏辉石或夕线石/蓝晶石(Raith et al., 1997; Ouzegane et al., 2003; Guo et al., 2012; Jiao et al., 2015, 2017)。这些含假蓝宝石后成合晶一般认为形成于峰期变质后、高温或超高温条件下的减压阶段(Droop, 1989; Bhattacharya and Kar, 2002; Raith et al., 1997; Ouzegane et al., 2003; Sajeev and Osanai, 2004; Karmakar and Schenk, 2015; 等等)。此外,假蓝宝石冠状体常围绕尖晶石生长或者粗粒的假蓝宝石内部含残余的尖晶石包体,暗含着它们的反应关系和先后生长次序。

上述假蓝宝石一般认为形成于中下地壳层位、干体系和极高温的变质条件(约20~30km)。除此之外,幔源成因的假蓝宝石也时有报道(Griffin and O’Reilly, 1986; Giovanardi et al., 2013),暗示着假蓝宝石可以在上地幔富Ca-Al-Mg的岩石中稳定存在,例如,澳大利亚新南威尔士玄武质角砾岩中的单斜辉石(含尖晶石和斜长石)堆晶体(Griffin and O’Reilly, 1986)、意大利西部阿尔卑斯金云母-橄榄岩岩体(Giovanardi et al., 2013)、以及我国汉诺坝和建德地区新生代玄武岩中的单斜辉石岩捕掳体/晶(Su et al., 2012; Xiao et al., 2018)。这类假蓝宝石常呈冠状体围绕尖晶石生长,与上述壳源成因的假蓝宝石发育的结构特征类似(Santosh et al., 2009; Guo et al., 2012; Jiao et al., 2017)。这种现象一般解释为原始的单斜辉石±尖晶石±斜长石堆晶体在15kbar形成后经历了近等压冷却过程,温度从大于1400℃降低到约1000℃(Griffin and O’Reilly, 1986)。

本文通过对全球典型超高温变质岩地区的文献调研,结合作者多年来在华北克拉通孔兹岩带高温-超高温变质作用的研究心得,着重介绍超高温麻粒岩中假蓝宝石常见的结构位置、矿物组合、化学成分以及假蓝宝石形成和分解的化学反应对超高温变质作用和演化历史的指示意义,为初入超高温变质作用研究领域的读者提供一份素材。幔源成因的假蓝宝石在此文中不再详细展开。

1 假蓝宝石的结构位置与矿物组合

假蓝宝石属于单斜晶系,其中β=100°30′,Ng=1.705~1.745,Nm=1.703~1.741,Np=1.701~1.731,Ng-Np=0.005~0.007,2V=(-)47°~(+)80°,r < v,b轴与Nm平行,a轴与Np夹角为12°~18°,c轴与Ng夹角为1°30′~7°,光轴面与(010)平行,假蓝宝石沿(010)呈板状或粒状结晶,解理{010}较完全,{100}和{001}不完全(摘自常丽华等, 2006)。假蓝宝石在手标本中呈墨水蓝色,有时为灰色、粉灰色,镜下呈无色到蓝色,有时为淡粉红色,其多色性Ng为宝石蓝至暗蓝色、绿蓝色、浅绿色,Nm为天蓝、蓝绿、淡紫兰、灰蓝色,Np为无色、浅红、浅黄绿、灰绿色,吸收性为Ng >Nm >Np,正高突起,折射率随Fe含量的增加而增大,干涉色为一级灰白,斜消光,二轴晶(摘自常丽华等, 2006)。

在富Mg-Al麻粒岩中,假蓝宝石可以以粗粒变斑晶形式存在,与紫苏辉石、石英等矿物平衡共生(图 2a, b),但多数情况下,假蓝宝石常以包体形式位于石榴石、夕线石、紫苏辉石等变斑晶矿物内(图 2c, d)、呈冠状体围绕尖晶石或刚玉等矿物生长(图 2e, f)、与石英、紫苏辉石、堇青石、或斜长石等构成后成合晶,取代早期的矿物或矿物组合(图 2g, h)。以下介绍假蓝宝石常见的几种矿物组合及其产出的结构位置,有些含假蓝宝石的矿物组合部分重叠,如Spr+Qz+Opx、Spr+Opx+Crd、Spr+Spl+Crd、及Spr+Crd+Pl等。在研究深入的典型地区的含假蓝宝石麻粒岩中,同一露头甚至同一样品中可以观察到多种含假蓝宝石的矿物组合,如南极洲恩德比地内皮尔地体、加拿大拉布拉多威尔逊湖地区、印度东高支山地体、印度南部麻粒岩地体、斯里兰卡高地地体、苏格兰南哈里斯地体、阿尔及利亚In Ouzzal地体等(相关文献见Kelsey (2008)Kelsey and Hand (2015)所列,以及表 1所列文献)。因此,这些典型的超高温变质岩地区将会在下面介绍不同的含假蓝宝石矿物组合时重复出现。

图 2 含假蓝宝石矿物组合的岩相学特征 (a)南极洲内皮尔地体恩德比Mount Rüser-Larsen地区Spr+Qz+Opx组合,样品由Simon Harley提供;(b)挪威西南部罗加兰地区发育的Spr+Opx组合;(c、d)华北克拉通集宁地体天皮山露头早期Spr+Qz组合被Grt+Sil组合分开;(e)华北克拉通集宁地体天皮山露头条纹长石中假蓝宝石冠状体围绕尖晶石生长,斜长石冠状体围绕假蓝宝石和尖晶石生长;(f)华北克拉通大青山地体东坡露头假蓝宝石冠状体围绕尖晶石生长;(g)巴西巴尼亚北部Caraiba Complex中Spr+Crd组合构成的交生体,可能取代了早期的夕线石或蓝晶石,岩石中其他粗粒的变斑晶矿物为紫苏辉石;(h)华北克拉通大青山地体东坡露头石榴石和黑云母之间发育的Spr+Pl交生体组合 Fig. 2 Petrographic features of the Spr-bearing mineral assemblages (a) Spr+Qz+Opx assemblage in Napier Complex, Mount Rüser-Larsen, Enderby Land, Antarctica, and sample was supplied by Simon Harley; (b) Spr+Opx assemblage in Rogaland area, SW Norway; (c, d) Spr+Qz assemblage separated by Grt+Sil assemblage at the Tianpishan outcrop of the Jining Terrane, North China Craton; (e) sapphirine corona growing around spinel and plagioclase corona growing around both sapphirine and spinel in perthite at the Tianpishan outcrop of the Jining Terrane, North China Craton; (f) sapphirine corona growing around spinel at the Dongpo outcrop of the Daqingshan Terrane, North China Craton; (g) Spr+Crd intergrowth possibly replacing a pre-existing sillimanite or kyanite from the Caraiba Complex, northern Bahia, Brazil, and the other coarse-grained porphyroblast is orthopyroxene in the rock; (h) Spr+Pl intergrowth growing between garnet and biotite at the Dongpo outcrop of the Daqingshan Terrane, North China Craton
1.1 假蓝宝石+石英

在本文统计的66个出露超高温变质岩地区中,共24个发育Spr+Qz的共生组合。假蓝宝石与石英呈变斑晶形式直接接触(图 2a, b),共生的矿物可能还有尖晶石、磁铁矿和紫苏辉石,典型实例如南极洲恩德比地内皮尔杂岩的麻粒岩和石英岩(Dallwitz, 1968; Grew, 1980; Harley and Motoyoshi, 2000图 2; Hokada et al., 2004图 2; Grew et al., 2006图 4)、美国纽约皮克斯基尔科特兰地体(Caporuscio and Morse, 1978中图片1)、印度东高支山含假蓝宝石石英岩(Kamineni and Rao, 1988)和假蓝宝石麻粒岩(Mohan et al., 1997图 1; Rao and Chmielowski, 2011图 3; Prakash et al., 2015中图 7)、印度南部麻粒岩地体(Prakash et al., 2018图 3)、加拿大拉布拉多地区威尔逊湖地体(Korhonen et al., 2012)、巴西Anápolis-Itauçu地体(Moraes et al., 2002图 2; Baldwin et al., 2005图 3)、阿拉伯联合酋长国赛迈尔蛇绿岩地体(Gnos and Kurz, 1994图 4-图 5)、以及秘鲁安第斯山脉莫延多-卡马纳地块(Martignole and Marlelat, 2003中图 20)等。假蓝宝石和石英呈复式包体位于石榴石内,如斯里兰卡高地地体(Sajeev and Osanai, 2004图 4; Osanai et al., 2006图 3)、埃及东Sahara Ghost克拉通(Karmakar and Schenk, 2015图 4)等。在印度南部麻粒岩地体,Tsunogae and Santosh(2006, 2011总结了几种Spr+Qz共生组合的结构位置:1)Spr+Qz交生体发育在石榴石包体内(Tsunogae and Santosh, 2006图 2-图 3; Braun et al., 2007图 3; Tsunogae and Santosh, 2010图 3-图 4);2)假蓝宝石发育在尖晶石和石英包体之间(Tsunogae and Santosh, 2006图 3);3)粗粒假蓝宝石包裹少量石英的包体(Kondou et al., 2009图 2);4)Spr+Qz组合为石榴石内富Mg十字石的反应边(Nishimiya et al., 2010图 3; Tsunogae and Santosh, 2011图 3-图 4)。

图 3 SiO2-FeAl2O4-MgAl2O4三角图中含假蓝宝石矿物组合的稳定域和演化过程(据Prakash et al., 2015修改) Fig. 3 Stability and evolution of the Spr-bearing mineral assemblages in SiO2-FeAl2O4-MgAl2O4 triangular diagram (modified after Prakash et al., 2015)

图 4 假蓝宝石的化学成分特征 Fig. 4 Chemical compositions of sapphirine

图 5 自长石投影的AFM(Al2O3-FeO-MgO)三角图图中阴影区代表高Mg的全岩化学成分 Fig. 5 AFM compatibility diagram plotting from feldspar Shadow area representing high-Mg bulk compositions

多数情况下,假蓝宝石和石英没有直接接触,而被Grt+Sil或Opx+Sil±Grt组合构成的复合冠状体分开,其中夕线石一般靠近假蓝宝石,石榴石或紫苏辉石靠近石英,如南极洲内皮尔地体(Ellis, 1980图 1; Grew, 1980; Grew et al., 2006图 3-图 4; Shimizu et al., 2013图 2-图 3)、印度东高支山地体(Sengupta et al., 1990图 4; Dasgupta and Ehl, 1993图 5; Mohan et al., 1997图 2; Bose et al., 2000图 4; Bose and Das, 2007图 3; Prakash et al., 2015图 5-图 7)、和巴西Anápolis-Itauçu地体(Moraes et al., 2002图 2; Baldwin et al., 2005图 3)等。其次,假蓝宝石和石英呈独立的包体位于石榴石、堇青石或夕线石等内(图 2c, d),如上述印度东高支山地体(Rao and Chmielowski, 2011图 2)和我国华北孔兹岩带集宁地体土贵乌拉露头(Santosh et al., 2007图 4)等。假蓝宝石和石英被堇青石所分离的实例如意大利中阿尔卑斯Gruf地体(Droop and Bucher-Nurminen, 1984图 5)。假蓝宝石和石英组合间也常发育Pl+Kfs复式冠状体,其中斜长石靠近假蓝宝石,钾长石靠近石英一侧,如内皮尔杂岩地体(Shimizu et al., 2013图 2-图 3)。Spr+Qz±Spl/Opx组合也以交生体的形式出现,是早期矿物分解的产物,如上述介绍的印度南部麻粒岩地体、内皮尔杂岩地体(Motoyoshi and Hensen, 1989图 1; Harley and Motoyoshi, 2000图 2)、东高支山地体(Bose and Das, 2007图 3; Rao and Chmielowski, 2011图 3)、以及阿尔及利亚In Ouzzal地体(Guiraud et al., 1996图 2; Adjerid et al., 2013图 3)等。

1.2 假蓝宝石+紫苏辉石

在石英岩或含石英的麻粒岩中,Spr+Opx+Qz组合的介绍见上面一节。在硅不饱和体系中,假蓝宝石也可呈自形的变斑晶与紫苏辉石共生(图 2b),其他矿物可能还有铝直闪石、石榴石、夕线石、刚玉、堇青石或尖晶石等。典型实例如印度东高支山地体,粗粒紫苏辉石和假蓝宝石变斑晶被后期夕线石、堇青石、或Opx2+Sil/Spr2组合取代(Bose et al., 2000图 4; Rickers et al., 2001图 3-图 4; Prakash et al., 2015图 5-图 7)、印度南部麻粒岩地体(Sajeev et al., 2001图 1)、斯里兰卡高地地体(Sajeev and Osanai, 2004图 4; Osanai et al., 2006图 3)等。在挪威罗加兰地区发育的假蓝宝石麻粒岩中,细粒的尖晶石+堇青石后成合晶或内环为尖晶石外环为堇青石的冠状体常取代假蓝宝石,或发育在假蓝宝石和紫苏辉石变斑晶之间(Drüppel et al., 2013中的图 4Blereau et al., 2017图 6)。Spr+Opx±Crd组合也常呈交生体取代其他矿物,如石榴石和早期的紫苏辉石,实例如印度东高支山地体(Rickers et al., 2001图 3)、印度南部麻粒岩地体Spr/Spl+Opx±Pl/Crd交生体取代石榴石(Brown and Raith, 1996图 2; Raith et al., 1997图 3; Sajeev et al., 2001图 1; Sajeev et al., 2004图 3; Tamashiro et al., 2004图 5-图 7; Braun et al., 2007图 3; Kondou et al., 2009图 2; Brandt et al., 2011图 4; Tsunogae and Santosh, 2010图 3; Tsunogae and Santosh, 2011图 3; Prakash et al., 2018图 3-图 4)、南极洲Rauer Group(Harley and Fitzsimons, 1991图 2; Harley, 1998b图 5; Kelsey et al., 2007图 3)、南哈里斯地体(Baba, 2003图 4、图 8)、中阿尔卑斯Gruf地体(Droop and Bucher-Nurminen, 1984图 4)、巴西Anápolis-Itauçu地体(Moraes et al., 2002图 2)、阿尔及利亚In Ouzzal地体中Spr+Opx+Crd/Sil/Qz交生体取代石榴石(Bertrand et al., 1992图 3; Guiraud et al., 1996图 2; Mouri et al., 1996图 2; Adjerid et al., 2013图 4)、斯里兰卡高地地体Spr+Opx±Crd组合取代石榴石(Kriegsman and Schumacher, 1999图 3; Sajeev and Osanai, 2004图 5; Osanai et al., 2006图 3; Osanai et al., 2016图 5-图 6)、以及我国秦岭-桐柏造山带中Spr+Opx+Pl组合(Xiang et al., 2014图 2)等。在纳米比亚西北部埃普帕地体(Brandt et al., 2007图 3)和澳大利亚斯特兰韦斯地区(Goscombe, 1992图 3),文献既报道了变斑晶状的假蓝宝石和紫苏辉石,也报道了围绕早期紫苏辉石发育的Spr+Opx后成合晶。在阿尔及利亚In Ouzzal地体,文献报道了取代早期黑云母的Spr+Opx+Crd+Kfs后成合晶,其中堇青石常发育在假蓝宝石与钾长石或紫苏辉石之间(Ouzegane et al., 2003图 5)。

1.3 假蓝宝石+尖晶石±刚玉

含石英的岩石或微域内,假蓝宝石和尖晶石一般都与石英共生,如“1.1假蓝宝石+石英”中的描述。在硅不饱和的岩石或微域内,平衡共生的Spr+Spl组合较少,它们一般发育在石榴石包体内,呈复式包体或相邻的独立包体,如斯里兰卡高地地体(Dharmapriya et al., 2017图 2-图 3)。相比而言,假蓝宝石呈冠状体围绕尖晶石生长的现象更为常见(图 2e, f),在同时含尖晶石、刚玉和假蓝宝石的超高温麻粒岩中,详细的岩相学工作常能发现这种假蓝宝石围绕尖晶石或刚玉生长的现象(文献见Kelsey, 2008; Kelsey and Hand, 2015; 表 1所列文献)。代表性实例如印度东高支山地体(Mohan et al., 1997图 1; Bose et al., 2000图 4; Prakash et al., 2015中图 7)、印度南部麻粒岩地体(Santosh and Sajeev, 2006图 3; Prakash and Sharma, 2008图 2; Nishimiya et al., 2010图 3; Brandt et al., 2011图 4; Tsunogae and Santosh, 2011图 3; Prakash et al., 2018图 3)、斯里兰卡高地地体(Kriegsman and Schumacher, 1999图 3)、苏格兰西北部南哈里斯地体(Baba, 2003图 2)、巴西Anápolis-Itauçu地体(Moraes et al., 2002图 2)、南非林波波活动带(Horrocks, 1983图 2-图 4)、纳米比亚西北部埃普帕地体(Brandt et al., 2007图 3)、马达加斯加南部Sakena河床(Raith et al., 2008图 2-图 3)、我国华北克拉通孔兹岩带集宁和大青山地体(Santosh et al., 2007图 5; Santosh et al., 2009图 4-图 5; Tsunogae et al., 2011图 3; Guo et al., 2012图 6; Jiao et al., 2017图 4)、以及我国秦岭-桐柏造山带(Xiang et al., 2014图 2)。在阿尔及利亚In Ouzzal地体文献报道了围绕刚玉生长的粗粒假蓝宝石,而假蓝宝石又被夕线石包裹,且夕线石和粗粒假蓝宝石随后反应形成Spr+Crd后成合晶(Bertrand et al., 1992图 2; Ouzegane et al., 2003图 3)。在意大利中阿尔卑斯Gruf地体假蓝宝石麻粒岩中,文献报道了假蓝宝石围绕尖晶石生长的结构,还观察到尖晶石围绕假蓝宝石这一相反的结构(Droop and Bucher-Nurminen, 1984)。在南非林波波带,文献报道了尖晶石围绕刚玉,假蓝宝石围绕尖晶石生长的结构,假蓝宝石随后被堇青石将其与石榴石或铝直闪石分开(Horrocks, 1983图 2-图 3; Windley et al., 1984图 2; Droop, 1989图 4-图 5)。

1.4 假蓝宝石+堇青石

假蓝宝石+堇青石和尖晶石+堇青石的矿物组合常以交生体或后成合晶发育在Sil/Ky周围,有时完全取代它们,只留下夕线石或蓝晶石的晶形(即假晶;图 2g),如苏格兰南哈里斯地体(Baba, 2003图 6、图 8)、南极洲Rauer Group(Harley, 1998b图 6; Tong and Wilson, 2006图 5)、印度南部麻粒岩地体(Brown and Raith, 1996图 2; Raith et al., 1997图 2; Santosh and Sajeev, 2006图 4-图 5; Kanazawa et al., 2009图 4; Brandt et al., 2011图 4; Shazia et al., 2012图 3)、斯里兰卡高地地体(Kriegsman and Schumacher, 1999图 3)、挪威南部的Bamble麻粒岩地体(Kihle and Bucher-Nurminen, 1992中图 9)、中阿尔卑斯Gruf地体(Droop and Bucher-Nurminen, 1984图 3-图 4)、纳米比亚西北部埃普帕地体(Brandt et al., 2007图 3)、秘鲁安第斯山脉莫延多-卡马纳地块(Martignole and Marlelat, 2003中图 20)等;或生长在紫苏辉石、石榴石边部,如印度东高支山地体(Bose et al., 2000图 4; Bose et al., 2016图 4)。在巴西Anápolis-Itauçu地体假蓝宝石麻粒岩中,文献报道了取代夕线石的Spr+Crd组合,还发现石榴石和夕线石之间发育的Spr+Crd+Pl交生体(Moraes et al., 2002图 2)。在印度南部麻粒岩地体,文献还报道了Spr+Crd后成合晶发育在铝直闪石周围,可能与其分解有关(Santosh and Sajeev, 2006图 6)。粗粒的假蓝宝石和堇青石变斑晶在该带也有报道(Sajeev et al., 2004图 3)。在In Ouzzal地体,可观察到细粒Spr+Crd交生体发育在夕线石和紫苏辉石之间,和发育在粗粒假蓝宝石或夕线石边部或它们之间(Bertrand et al., 1992图 2图 4; Mouri et al., 1996图 2; Ouzegane and Boumaza, 1996图 3; Ouzegane et al., 2003图 3图 6)。在林波波带,Spr+Crd组合不仅发育在紫苏辉石和夕线石之间,还常位于钠柱晶石和铝直闪石周围,暗示它们可能也是形成假蓝宝石后成合晶的反应物(Windley et al., 1984图 2; Droop, 1989图 4-图 5)。在该带,还可以观察到晚期的Spl+Crd组合构成的交生体取代早期Spr+Crd交生体的结构(Droop, 1989图 3)。粗粒假蓝宝石和堇青石变斑晶常被晚期冠状体或后成合晶分开,如Opx+Sil组合,实例如印度东高支山地体(Bose et al., 2000图 4; Prakash et al., 2015图 5-图 6)。

图 6 FMAS体系下P-T相图中(据Kelsey et al., 2004修改)含假蓝宝石矿物组合可能的演化轨迹 Fig. 6 Possible metamorphic paths of the Spr-bearing mineral assemblage in P-T projection for the FMAS system (modified after Kelsey et al., 2004)
1.5 假蓝宝石+斜长石

假蓝宝石+斜长石组合与上述假蓝宝石+堇青石组合一样,常围绕夕线石、蓝晶石、黑云母或石榴石生长(图 2h),斜长石的形成与体系中含Ca矿物如石榴石的分解有关。典型研究实例如印度南部麻粒岩地体(Sajeev et al., 2004图 3; Brandt et al., 2011图 2图 4)、我国大青山地体东坡和沙尔沁露头(Tsunogae et al., 2011图 3; Guo et al., 2012图 6; Jiao et al., 2015图 4-图 6; Jiao et al., 2017图 4)、加拿大亚大巴斯卡东糜棱岩三角区(Baldwin et al., 2007图 6-图 7; Baldwin et al., 2015图 2图 5)、德国Saxon麻粒岩地体(Rötzler and Romer, 2001图 2)、以及斯里兰卡高地地体(Kriegsman and Schumacher, 1999图 3)等。

1.6 含假蓝宝石的其他矿物组合

在南非林波波带,文献报道了富Mg十字石和假蓝宝石的组合,可观察到在石榴石包体内,假蓝宝石围绕十字石和紫苏辉石生长(Tsunogae and van Reenen, 2006图 2-图 3)。从上述结构可判断假蓝宝石可能是十字石、紫苏辉石与石榴石变质反应的产物。在林波波带中还发现粗粒的假蓝宝石与钠柱晶石的交生体组合,后期又被细粒的Spr+Crd组合取代(Droop, 1989图 2)。在斯里兰卡高地杂岩中,石榴石包体内发现相接触的假蓝宝石和蓝晶石,以及假蓝宝石、尖晶石和铝直闪石包体相邻(Hiroi et al., 1994图 3; Dharmapriya et al., 2017图 2-图 3)。文献解释Spr+Ky组合可能是富Mg十字石分解的产物,但从提供的照片看,不规则的假蓝宝石发育在粗粒的蓝晶石边部,因此我们认为假蓝宝石和蓝晶石更像是反应关系。在我国华北克拉通集宁和大青山地体(Santosh et al., 2007图 5; Jiao et al., 2015图 4-图 5)、斯里兰卡高地地体(Dharmapriya et al., 2015图 3)、苏格兰西北部南哈里斯地体(Baba, 2003图 6),文献报道了石榴石包体内共生的假蓝宝石和磁铁矿组合(图 2d)。在印度南部麻粒岩地体,文献报道了围绕石榴石并包裹刚玉的Spr+Ged±St交生体(Kanazawa et al., 2009图 4; Nishimiya et al., 2010图 3; Tsunogae and Santosh, 2011图 3)和Spr+Sil交生体(Santosh and Sajeev, 2006图 4)。此外,在印度南部麻粒岩地体(Brandt et al., 2011图 4)、华北克拉通集宁地体(Santosh et al., 2007图 4)等地,假蓝宝石还常生长在钾长石内,有时它们之间发育斜长石的反应边结构(图 2e)。

自夕线石投影的SiO2-FeAl2O4-MgAl2O4三角图中,标出了上述介绍的四种常见含假蓝宝石矿物组合的稳定域和可能的演化过程,如Spr+Qz±Spl/Opx、Spr+Opx、Spr+Spl和Spr+Crd或它们间的组合(图 3)。这些含假蓝宝石矿物组合的演化所指示的温压条件及其变化(P-T轨迹)将在最后一节讨论。

2 假蓝宝石的矿物化学特征

假蓝宝石的化学成分主要含Al2O3、MgO、SiO2、FeOT和少量Cr2O3,其化学式大致为(Mg, Fe)16-nAl32+2nSi8-nO80,其中n=0~2.5(Schreyer and Abraham, 1975)。由电子探针分析得到的假蓝宝石的化学成分一般根据20个氧原子进行标准化,其中Fe2O3含量由化学计量平衡法计算得到。图 4为11个典型超高温变质岩地区中假蓝宝石的化学成分特征,详细数据和参考文献见电子版附表 1。表中搜集了这些超高温变质岩地体不同结构位置的假蓝宝石共99个分析数据,原始文献中总量偏高(>101.5)或偏低(< 98.5)的数据已删除。

附表1 假蓝宝石的化学成分(wt%) AppendixTable1 Chemical compositions of sapphirine (wt%)

这些地区的假蓝宝石化学成分大都重叠,XMg(=Mg/(Mg+Fe2+))全部大于0.70(附表 1)。我国华北克拉通集宁和大青山地体、印度东高支山地体以及纳米比亚西北部埃普帕地体中假蓝宝石的XMg偏低,为0.70~0.80,巴西Anápolis-Itauçu地体中假蓝宝石的XMg相对集中为0.76~0.82;其他地体中假蓝宝石的化学成分变化较大,尤其是印度南部麻粒岩地体。这是由于这些地体中包含不同参考文献中采自不同露头的含假蓝宝石麻粒岩(附表 1)。在同一文献中这些假蓝宝石的XMg相对集中,如印度南部麻粒岩地体Madurai地区Ganguvarpatti村的一处小矿坑中假蓝宝石的XMg为0.71~0.75(Sajeev et al., 2004),而巴尔卡德-高韦里河剪切带内卡鲁尔镇北北西约25km处Panangad露头的假蓝宝石的XMg为0.86~0.91(Nishimiya et al., 2010)。这些地体中假蓝宝石的XFe3+(=Fe3+/(Fe3++Fe2+))变化范围很宽,最低接近0值,最高可达0.7。我国华北克拉通大青山地体、纳米比亚西北部埃普帕地体、印度南部东高支山地体和南极洲内皮尔地体中假蓝宝石的XFe3+相对集中,数值依次增加,分别为0.04~0.14、0.12~0.20、0.20~0.30和0.15~0.40,可能反应了它们不同的氧化还原状态。其他地体中假蓝宝石的XFe3+变化较分散,尤其是印度南部麻粒岩地体,最低为0.03~0.05,最高为0.36~0.70,暗示着同一地体中不同露头或样品之间截然不同的氧化还原状态。在图 4中,多数假蓝宝石成分点投影在理想的切尔迈克取代线上((Mg, Fe)2++Si4+=Al3++Al3+),横跨在7:9:3((Mg, Fe)O:Al2O3+Fe2O3+Cr2O3:SiO2)端元两侧,但斯里兰卡高地地体两个与石英共生的假蓝宝石成分投影在靠近2:2:1的端元,也有个别数据投影在理想的切尔迈克取代线之下。

高温高压实验岩石学在1400℃和15kbar条件下合成的假蓝宝石富硅,靠近2:2:1端元(Taylor, 1973),但自然界高温-超高温麻粒岩中的假蓝宝石化学成分一般靠近7:9:3端元,或者更富铝,位于7:9:3和3:5:1端元之间(图 4)。同一地体内假蓝宝石化学成分的变化,如印度南部麻粒岩地体,除了体现了不同变质阶段假蓝宝石成分之间的差异外,如早期石榴石或铝硅酸盐矿物包体内、或与石英共生的假蓝宝石一般富硅,而晚期与堇青石、紫苏辉石等呈后成合晶状发育的假蓝宝石一般富铝(图 4),全岩或微区化学成分的不同也会对假蓝宝石的成分有很大的影响。

3 含假蓝宝石的矿物组合对超高温变质作用研究的意义 3.1 Spr+Qz组合与超高温变质作用

FMAS体系的实验岩石学研究和热力学理论模拟得到Spr+Qz组合至少指示了1000℃和7kbar的温压条件(Hensen and Green, 1971, 1972, 1973; Bertrand et al., 1991)。借助与Spr+Qz共生的其他矿物组合的温压计,如Grt+Crd、Grt+Opx温压计、紫苏辉石中Al含量温度计,还可以间接证实该组合形成的极端温度条件(Grew, 1980; Horrocks, 1983; Harley, 1998b)。因此,Harley (2008)认为Spr+Qz组合是岩石经历了超高温变质作用的指示性矿物组合之一,其他指示性组合如Opx+Sil+Qz、Grt/Opx/Spl+Osm等。然而,在氧化的体系中,尤其与磁铁矿甚至赤铁矿共生的假蓝宝石,其晶格中可容纳大量的Fe3+(XFe3+=0~0.7),有时可能出溶磁铁矿或赤铁矿条纹,这时Spr+Qz组合稳定域的温度会极大地降低(Grew, 1982; Hensen, 1986; Powell and Sandiford, 1988; Gnos and Kurz, 1994; Taylor-Jones and Powell, 2010; Wheller and Powell, 2014)。阿拉伯联合酋长国赛迈尔蛇绿岩地体发育的麻粒岩具有很高的氧逸度,峰期矿物组合为Spr+Spl+Mag+钛铁-Hem+Pl+En+Qz和Spr+Crn+钛铁-Hem+Phl+Pl,原文利用二辉石温度计得到含假蓝宝石麻粒岩周围石英岩和角闪石的温度分别为830℃和835℃(Gnos and Kurz, 1994)。由于受到扩散作用的影响,这些传统温度计得到的结果可能偏低100℃以上(Pattison et al., 2003),即便如此,赛迈尔蛇绿岩地体发育的高氧逸度、含假蓝宝石麻粒岩可能的峰期温度仍比实验限定的结果低100℃左右。

一般来说,含Mag+Ilm组合的体系指示氧化的环境,而含Rt+Ilm的体系指示较还原的状态(Wheller and Powell, 2014)。氧化体系中Spr+Qz组合稳定域的温度下限较还原体系中的低30℃,分别为920℃和950℃(Wheller and Powell, 2014)。此外,在相同温压条件下,氧化和还原条件下和假蓝宝石共生的矿物组合有所不同,例如,在1000℃和7.5kbar的AFM体系中,还原条件下的共生矿物组合为Spr+Sil+Opx(+Rt+Ilm),而氧化条件下的共生组合为Spr+Spl+Grt(+Mag+Ilm)(Taylor-Jones and Powell, 2010; Wheller and Powell, 2014)。在KFMASHTO体系下,假蓝宝石新的a-x活度模型的标定,使得我们可以准确确定氧化条件下Spr+Qz组合稳定的温压范围(Taylor-Jones and Powell, 2010; Wheller and Powell, 2014)。因此,对体系中Spr+Qz组合稳定性的判断及其温压条件的计算要充分考虑系统的氧化还原状态的影响,采用包含Fe2O3较全的组分体系进行视剖面图计算。T/P-M(O)(=XFe3+)视剖面图可评估体系中氧逸度变化对共生矿物组合的影响(Korhonen et al., 2012)。加拿大拉布拉多地区威尔逊湖地体的麻粒岩具有很高的氧逸度,副矿物有钛赤铁矿和磁铁矿,根据FMAS体系下的实验岩石学结果,Spr+Mag+Qz(+Opx+Sil+Ky+Crn+Spl)组合的温压条件高于1100℃和11kbar,甚至达到1150℃和13kbar(Morse and Talley, 1971)。在NCKFMASHTO体系下,视剖面图计算得到的该区Spr+Qz组合的峰期温压条件则为960~935℃和10~8.6kbar(Korhonen et al., 2012)。在我国华北克拉通孔兹岩带天皮山露头,假蓝宝石常与磁铁矿接触共生,NCKFMASHTO体系下视剖面图模拟结果限定峰期含Spr+Qz组合的温压条件为>950℃和>7.5kbar(Shimizu et al., 2013)。假蓝宝石端元组分的热力学性质和a-x活度模型仍需要进一步实验标定和不断完善以便更加准确地限定自然界中Spr+Qz组合以及其他含假蓝宝石矿物组合的温压条件。

此外,有些看似相接触的假蓝宝石和石英并非共生组合,石英可能是后期熔体冷却结晶的产物(Harley, 2008),这需要我们仔细分辨石英是否是早期熔体的假象,比如呈尖尖的、很小的二面角发育在其他矿物颗粒之间,石英和假蓝宝石之间是否有平直的接触关系。

含假蓝宝石矿物组合的发育除了与体系的温压条件有很大的关系外,与岩石有效化学成分也有关系。假蓝宝石是一种富Mg-Al的矿物,从以上统计的数据看,其XMg大多数大于0.70,因此假蓝宝石一般发育在富Mg的岩石或微域内(全岩XMg大于0.50;图 3图 5)。前人研究表明以包体形式存在的假蓝宝石一般出现在XMg较高的微域,由假蓝宝石和其他矿物构成的后成合晶微域内的XMg一般较低,作者认为前者形成于变质作用早期XMg较高的环境,而后者形成于变质作用晚期,并且全岩化学成分所有调整,全岩XMg降低(Baba, 2003)。含假蓝宝石矿物组合随全岩化学成分的变化可反映在AFM三角图中,以挪威罗加兰、阿尔及利亚In Ouzzal地体、和印度南部麻粒岩地体(含)假蓝宝石麻粒岩为代表,多数富Mg-Al麻粒岩投影在图中高Mg的阴影区,发育Spr+Opx±Crd组合,但当假蓝宝石在岩石中含量很低且局部出现时,岩石的主体矿物组合为Opx+Crd,而发育Spr微域内的化学成分应与全岩化学成分有所不同(图 5)。局部稍富Fe的微域可能会出现Spr+Spl±Opx的矿物组合,局部富集Al的微域还可能发育Spr+Spl+Sil/Crn、Spr+Sil/Crn±Crd、Spr+Crd组合。

3.2 假蓝宝石形成和分解指示的P-T轨迹

尽管对于具体的岩石来说,目前已有很复杂的P-T相图(如KFMASH、FMASTO、KFMASHTO)和NCKFMASHTO体系下的视剖面图来精确模拟含假蓝宝石麻粒岩的变质演化过程(Kelsey et al., 2004; Taylor-Jones and Powell, 2010; Wheller and Powell, 2014; Kelsey and Hand, 2015),但FMAS体系的P-T成岩格子仍是解释这些富Al、Mg和Fe的含假蓝宝石矿物组合最简单和有效的方法,尤其是当用于概述全岩成分不同的麻粒岩发育的相同矿物组合的演化过程。图 6Kelsey et al. (2004)利用在硅饱和以及不饱和体系下都兼容的、新的假蓝宝石的a-x活度模型计算得到的FMAS体系下的P-T相图,其中不变点[Spl]、[Qz]和[Opx]位于较低的温压条件,即约6.5kbar和960~990℃范围内,而最初实验岩石学确定的FMAS体系的P-T相图中(Hensen and Green, 1971, 1972, 1973),它们位于8~10kbar和950~1070℃范围内。在FMASH体系下,这些不变点的位置将随着水活度的增加沿着Crd缺失的单变线向高温和高压方向移动(Kelsey et al., 2004),因此Hensen and Green(1971, 1972, 1973)可能是在较高水活度条件下得到的FMAS体系P-T相图。

假蓝宝石围绕尖晶石生长的现象,指示着尖晶石的分解和假蓝宝石的生长,可能对应着FMAS体系中Spl+Qz+Opx=Grt+Spr的变质反应。也有学者认为在富含刚玉和钙长石的Ca-Al质岩石中这种冠状体的形成可能与流体交代作用有关(Raith et al., 2008)。假蓝宝石中紫苏辉石和夕线石的包体,以及石榴石内交生状的Spr+Qz复合包体指示了FMAS体系中Opx+Sil=Grt+Spr+Qz和Grt+Sil=Spl+Spr+Qz的变质反应。这些反应一般具有正的dP/dT斜率,因此向左穿过这些反应指示了冷却的变质过程,可能还伴随着升压过程,而向右穿过这些反应一般指示了升温减压的进变质过程。假蓝宝石、尖晶石和石英常呈独立的包体位于石榴石、夕线石或紫苏辉石中,并且夕线石和石榴石/紫苏辉石复合冠状体常围绕假蓝宝石生长,这些结构指示了假蓝宝石的分解反应,即向左穿过上述FMAS反应。

围绕粗粒变斑晶如石榴石、紫苏辉石、夕线石生长的含假蓝宝石后成合晶组合是Mg-Al质、尤其是硅不饱和麻粒岩中常见的结构,如Spr+Crd+Opx交生状后成合晶是早期高Al紫苏辉石或石榴石完全分解的产物(Brandt et al., 2007)。紫苏辉石和夕线石之间发育的Spr/Spl+Crd交生体,指示了紫苏辉石和夕线石的分解反应,如Opx+Sil=Crd+Spr+Grt,一般发生在近等温减压的变质阶段。然而,最近的研究表明这些含假蓝宝石的后成合晶组合可以形成于减压或者升温阶段,或同时减压升温的变质过程(Dumond et al., 2017; Jiao et al., 2017)。假蓝宝石与紫苏辉石、堇青石或斜长石构成的后成合晶的形成很难体现在FMAS P-T相图的变质反应中,这需要我们对具体的岩石进行更细致的复杂体系下的视剖面图模拟,来解析含假蓝宝石后成合晶的形成是否同时伴随着升温过程。假蓝宝石被堇青石或含堇青石的矿物组合所取代,如Opx+Spr+Qz=Grt+Crd、Spr+Qz=Crd+Grt+Sil、Spr+Qz+Grt=Crd+Spl,一般认为指示了近等温减压过程。据文献报道其他矿物分解形成堇青石或含堇青石的矿物组合的变质反应同样一般指示了减压过程,如Grt+Sil=Spr/Spl+Crd、Grt+Sil+Qz=Crd、Grt+Qz=Opx+Crd(Harley, 1998b),尽管有些学者认为堇青石的形成可能反映了体系中水活度的变化,而非大规模的减压过程(Kelsey et al., 2004; Baldwin et al., 2005)。

除此之外,在富Mg-Al的高温-超高温岩石中,早期残留的含水矿物铝直闪石((Mg, Fe)5Al2[Si6Al2O22](OH)2)的保存和识别,可以限定超高温进变质过程。铝直闪石常以包体形式位于紫苏辉石、石榴石、假蓝宝石等高温-超高温矿物中,或假蓝宝石围绕铝直闪石生长,指示铝直闪石是早期变质阶段的矿物(Droop, 1989; Goscombe, 1992; Kriegsman and Schumacher, 1999; Tsunogae and van Reenen, 2006; Kanazawa et al., 2009)。在MASH体系中存在Spr+Crd=Ged+Sil的变质反应(Windley et al., 1984)。但是由于它含水的性质,其稳定性与体系的水活度有很大关系,温压条件不易限定。在澳大利亚中部斯特兰韦斯地区的麻粒岩中,含铝直闪石矿物组合(如铝直闪石+夕线石+紫苏辉石+黑云母+斜长石+石英)的温压条件在固相线以下,为670~750℃和6~7.5kbar,该体系的水活度约为0.2(Diener et al., 2008)。在另一个水活度较低的例子中,即印度南部巴尔卡德-高韦里剪切带(Palghat-Cauvery Shear Zone system)的富Mg-Al麻粒岩中(岩石富集原生的CO2流体包裹体),含钠质铝直闪石矿物组合的温度为900~990℃(Kanazawa et al., 2009)。在阿尔及利亚In Ouzzal地体的麻粒岩中,含Ged+Grt+Sil峰期矿物组合的温压条件为850~900℃和7~9kbar,体系的水活度在0.4~0.7之间。因此,在具体岩石中含铝直闪石温压条件精确的限定取决于体系中水含量及其变化。

根据前面统计的世界范围内含假蓝宝石矿物组合的保存和演化信息,我们将Mg-Al质麻粒岩可能经历的P-T轨迹大致归为两类,如图 6中A、B所示。如果岩石中保存了尖晶石被假蓝宝石取代,假蓝宝石和石英被石榴石、紫苏辉石和夕线石取代,而后者又被堇青石取代的变质反应结构,那么这些岩石很可能经历了一个超高温峰期后近等压冷却和极高温下的减压过程,即A型P-T轨迹。A型P-T轨迹中温度峰期早于压力峰期出现,很可能是一个完整的逆时针P-T轨迹的一部分。超高温变质作用的难点在于强烈的高温扩散作用和后期矿物组合的叠加,使得早期进变质过程难以确定。但仔细的岩相学观察常发现一些Mg-Al质麻粒岩中保存了进变质阶段矿物或变质反应结构,如石榴石或紫苏辉石内形成Spr+Qz交生状组合的反应可能指示了与A型P-T轨迹相反的过程,即B型P-T轨迹(图 6)。在斯里兰卡高地,印度南部和苏格兰南哈里斯地体,文献还报道了超高温峰期变质前残留的高压矿物,如蓝晶石、富Mg的十字石(Hiroi et al., 1994; Baba, 1999, 2003; Nishimiya et al., 2010; Brandt et al., 2011 etc),在加拿大亚大巴斯卡东糜棱岩三角区,文献报道了早期的榴辉岩随后经历了超高温变质作用(Dumond et al., 2017)。这些研究实例指示着超高温变质作用之前发生的高压麻粒岩相或榴辉岩相变质作用。图 6中B型P-T轨迹可能是一个完整的顺时针P-T轨迹的一部分。超高温变质作用不同的P-T轨迹形状暗示着它们的成因机制并不单一,逆时针型P-T轨迹可解释为同期的幔源基性岩浆底侵或增生作用的热效应,据此很难判断超高温变质作用是否与造山作用相关;顺时针型P-T轨迹,尤其是早期高压变质作用的保存,可解释为热造山带快速伸展或垮塌带来的热弛豫效应,或者造山带内叠加了幔源基性岩浆的加热效应。超高温麻粒岩一般是二次或叠加变质作用的结果,只记录了整个P-T轨迹的片段信息,解析超高温进变质过程,探讨超高温变质作用与早期进变质作用的联系(是连续的或独立的构造热事件?)是解决其成因机制的关键,也是我们今后着力突破的研究方向。

4 结论

本文着重论述了世界典型超高温麻粒岩中常见的几种含假蓝宝石矿物组合和他们产出的结构位置以及假蓝宝石的矿物化学特征,总结了这些岩石中普遍存在的假蓝宝石的形成与分解的变质演化过程,和可能指示的温压条件和P-T轨迹。含假蓝宝石的矿物组合,尤其是Spr+Qz组合,对于指示超高温变质作用的发生,定性确定其温压条件和变质演化历史有重要的意义。Spr+Qz组合虽是超高温变质作用指示性的矿物组合,但其稳定的温压条件取决于体系的氧化还原状态。根据含假蓝宝石矿物组合的演化规律,本文总结了超高温麻粒岩常见的两种P-T轨迹,两种截然不同的演化轨迹说明超高温变质作用的成因并不单一,可能与幔源基性岩浆活动或者长期的热造山作用有关。解决超高温变质作用成因机制的关键是详细解析其进变质过程。细致的岩相学观察以寻找早期残留的矿物或其组合,分析粗粒变斑晶如石榴石的微量元素成分环带,不同结构位置,尤其是粗粒变斑晶内的独居石和锆石原位高精度和高分辨率年代学和地球化学研究也许能提供超高温早期变质作用的信息。

谨以此文祝贺叶大年院士八十华诞。叶大年院士在矿物学和岩石学领域取得的科研成就令人叹服;他精益求精、不折不挠的治学精神使人肃然起敬;他对晚辈学生孜孜不倦的教导和精心的培养使之终身受益;他胸怀家国天下的情怀值得我们终身学习。

参考文献
Adjerid Z, Godard G, Ouzegane KH and Kienast JR. 2013. Multistage progressive evolution of rare osumilite-bearing assemblages preserved in ultrahigh-temperature granulites from In Ouzzal (Hoggar, Algeria). Journal of Metamorphic Geology, 31(5): 505-524. DOI:10.1111/jmg.2013.31.issue-5
Baba S. 1999. Sapphirine-bearing orthopyroxene-kyanite/sillimanite granulites from South Harris, NW Scotland:Evidence for proterozoic UHT metamorphism in the Lewisian. Contributions to Mineralogy and Petrology, 136(1-2): 33-47. DOI:10.1007/s004100050522
Baba S. 2003. Two stages of sapphirine formation during prograde and retrograde metamorphism in the Palaeoproterozoic Lewisian complex in South Harris, NW Scotland. Journal of Petrology, 44(2): 329-354. DOI:10.1093/petrology/44.2.329
Baldwin JA, Powell R, Brown M, Moraes R and Fuck RA. 2005. Modelling of mineral equilibria in ultrahigh-temperature metamorphic rocks from the Anápolis-Itauçu Complex, central Brazil. Journal of Metamorphic Geology, 23(7): 511-531. DOI:10.1111/j.1525-1314.2005.00591.x
Baldwin JA, Powell R, Williams ML and Goncalves P. 2007. Formation of eclogite, and reaction during exhumation to mid-crustal levels, Snowbird tectonic zone, western Canadian Shield. Journal of Metamorphic Geology, 25(9): 953-974. DOI:10.1111/j.1525-1314.2007.00737.x
Baldwin JA, Powell R, White RW and Štípská P. 2015. Using calculated chemical potential relationships to account for replacement of kyanite by symplectite in high pressure granulites. Journal of Metamorphic Geology, 33(3): 311-330. DOI:10.1111/jmg.12122
Bertrand P, Ellis DJ and Green DH. 1991. The stability of sapphirine-quartz and hypersthene-sillimanite-quartz assemblages:An experimental investigation in the system FeO-MgO-Al2O3-SiO2 under H2O and CO2 conditions. Contributions to Mineralogy and Petrology, 108(1-2): 55-71. DOI:10.1007/BF00307326
Bertrand P, Ouzegane K and Kienast JR. 1992. P-T-X relationships in the Precambrian Al-Mg-rich granulites from in Ouzzal, Hoggar, Algeria. Journal of Metamorphic Geology, 10(1): 17-31. DOI:10.1111/jmg.1992.10.issue-1
Bhattacharya S and Kar R. 2002. High-temperature dehydration melting and decompressive P-T path in a granulite complex from the Eastern Ghats, India. Contributions to Mineralogy and Petrology, 143(2): 175-191. DOI:10.1007/s00410-001-0341-6
Blereau E, Johnson TE, Clark C, Taylor RJM, Kinny PD and Hand M. 2017. Reappraising the P-T evolution of the Rogaland-Vest Agder Sector, southwestern Norway. Geoscience Frontiers, 8(1): 1-14.
Bose S, Fukuoka M, Sengupta P and Dasgupta S. 2000. Evolution of high-Mg-Al granulites from Sunkarametta, Eastern Ghats, India:Evidence for a lower crustal heating-cooling trajectory. Journal of Metamorphic Geology, 18(3): 223-240.
Bose S and Das K. 2007. Sapphirine+quartz assemblage in contrasting textural modes from the Eastern Ghats Belt, India:Implications for stability relations in UHT metamorphism and retrograde processes. Gondwana Research, 11(4): 492-503. DOI:10.1016/j.gr.2006.07.003
Bose S, Das K, Torimoto J, Arima M and Dunkley DJ. 2016. Evolution of the Chilka Lake granulite complex, northern Eastern Ghats Belt, India:First evidence of~780Ma decompression of the deep crust and its implication on the India-Antarctica correlation. Lithos, 263: 161-189. DOI:10.1016/j.lithos.2016.01.017
Brandt S, Will TM and Klemd R. 2007. Magmatic loading in the proterozoic Epupa Complex, NW Namibia, as evidenced by ultrahigh-temperature sapphirine-bearing orthopyroxene-sillimanite-quartz granulites. Precambrian Research, 153(3-4): 143-178. DOI:10.1016/j.precamres.2006.11.016
Brandt S, Schenk V, Raith MM, Appel P, Gerdes A and Srikantappa C. 2011. Late neoproterozoic P-T evolution of HP-UHT granulites from the Palni Hills (South India):New constraints from phase diagram modelling, LA-ICP-MS zircon dating and in-situ EMP monazite dating. Journal of Petrology, 52(9): 1813-1856. DOI:10.1093/petrology/egr032
Braun I, Cenki-Tok B, Paquette JL and Tiepolo M. 2007. Petrology and U-Th-Pb geochronology of the sapphirine-quartz-bearing metapelites from Rajapalayam, Madurai Block, Southern India:Evidence for polyphase Neoproterozoic high-grade metamorphism. Chemical Geology, 241(1-2): 129-147. DOI:10.1016/j.chemgeo.2007.02.010
Brown M and Raith M. 1996. First evidence of ultrahigh-temperature decompression from the granulite province of southern India. Journal of the Geological Society, 153(6): 819-822. DOI:10.1144/gsjgs.153.6.0819
Caporuscio FA and Morse SA. 1978. Occurrence of sapphirine plus quartz at Peekskill, New York. American Journal of Science, 278(9): 1334-1342. DOI:10.2475/ajs.278.9.1334
Chang LH, Chen MY, Jin W, Li SC and Yu JJ. 2006. Handbook for Identification of Transparent Minerals under Microscope. Beijing: Geological Publishing House: 198-199.
Dallwitz WB. 1968. Co-existing sapphirine and quartz in granulite from Enderby Land, Antarctica. Nature, 219(5153): 476-477. DOI:10.1038/219476a0
Dasgupta S and Ehl J. 1993. Reaction textures in a spinel-sapphirine granulite from the Eastern Ghats, India, and their implications. European Journal of Mineralogy, 5(3): 537-543. DOI:10.1127/ejm/5/3/0537
Dharmapriya PL, Malaviarachchi SPK, Santosh M, Tang L and Sajeev K. 2015. Late-Neoproterozoic ultrahigh-temperature metamorphism in the Highland Complex, Sri Lanka. Precambrian Research, 271: 311-333. DOI:10.1016/j.precamres.2015.10.010
Dharmapriya PL, Malaviarachchi SPK, Kriegsman LM, Sajeev K, Galli A, Osanai Y, Subasinghe ND and Dissanayake CB. 2017. Distinct metamorphic evolution of alternating silica-saturated and silica-deficient microdomains within garnet in ultrahigh-temperature granulites:An example from Sri Lanka. Geoscience Frontiers, 8(5): 1115-1133. DOI:10.1016/j.gsf.2016.11.008
Diener JFA, White RW and Powell R. 2008. Granulite facies metamorphism and subsolidus fluid-absent reworking, Strangways Range, Arunta Block, central Australia. Journal of Metamorphic Geology, 26(6): 603-622. DOI:10.1111/jmg.2008.26.issue-6
Droop GTR and Bucher-Nurminen K. 1984. Reaction textures and metamorphic evolution of sapphirine-bearing granulites from the Gruf Complex, Italian Central Alps. Journal of Petrology, 25(3): 766-803. DOI:10.1093/petrology/25.3.766
Droop GTR. 1989. Reaction history of garnet-sapphirine granulites and conditions of Archaean high-pressure granulite-facies metamorphism in the Central Limpopo Mobile Belt, Zimbabwe. Journal of Metamorphic Geology, 7(3): 383-403. DOI:10.1111/jmg.1989.7.issue-3
Drüppel K, Elsäßer L, Brandt S and Gerdes A. 2013. Sveconorwegian mid-crustal ultrahigh-temperature metamorphism in Rogaland, Norway:U-Pb LA-ICP-MS geochronology and pseudosections of sapphirine granulites and associated paragneisses. Journal of Petrology, 54(2): 305-350. DOI:10.1093/petrology/egs070
Dumond G, Williams ML, Baldwin JA and Jercinovic MJ. 2017. Backarc origin for Neoarchean ultrahigh-temperature metamorphism, eclogitization, and orogenic root growth. Geology, 45(10): 943-946. DOI:10.1130/G39254.1
Ellis DJ. 1980. Osumilite-sapphirine-quartz granulites from Enderby Land, Antarctica:P-T conditions of metamorphism, implications for garnet-cordierite equilibria and the evolution of the deep crust. Contributions to Mineralogy and Petrology, 74(2): 201-210. DOI:10.1007/BF01132005
Fitzsimons ICW and Harley SL. 1994. The influence of retrograde cation exchange on granulite P-T estimates and a convergence technique for the recovery of peak metamorphic conditions. Journal of Petrology, 35(2): 543-576. DOI:10.1093/petrology/35.2.543
Giovanardi T, Morishita T, Zanetti A, Mazzucchelli M and Vannucci R. 2013. Igneous sapphirine as a product of melt-peridotite interactions in the Finero phlogopite-peridotite massif, Western Italian Alps. European Journal of Mineralogy, 25(1): 17-31.
Gnos E and Kurz D. 1994. Sapphirine-quartz and sapphirine-corundum assemblages in metamorphic rocks associated with the Semail ophiolite (United Arab Emirates). Contributions to Mineralogy and Petrology, 116(4): 398-410. DOI:10.1007/BF00310907
Goscombe B. 1992. Silica-undersaturated sapphirine, spinel and kornerupine granulite facies rocks, Ne Strangways Range, Central Australia. Journal of Metamorphic Geology, 10(2): 181-201. DOI:10.1111/jmg.1992.10.issue-2
Grew ES. 1980. Sapphirine+quartz association from Archean rocks in Enderby Land, Antarctica. American Mineralogist, 65(9-10): 821-836.
Grew ES. 1982. Osumilite in the sapphirine-quartz terrane of Enderby Land, Antarctica:Implications for osumilite petrogenesis in the granulite facies. American Mineralogist, 67(7-8): 762-787.
Grew ES, Yates MG, Shearer CK, Hagerty JJ, Sheraton JW and Sandiford M. 2006. Beryllium and other trace elements in paragneisses and anatectic veins of the ultrahigh-temperature napier complex, Enderby Land, East Antarctica:The role of sapphirine. Journal of Petrology, 47(5): 859-882. DOI:10.1093/petrology/egi098
Griffin WL and O'Reilly SY. 1986. Mantle-derived sapphirine. Mineralogical Magazine, 50(358): 635-640. DOI:10.1180/minmag.1986.050.358.08
Guiraud M, Powell R and Cottin JY. 1996. Hydration of orthopyroxene-cordierite-bearing assemblages at Laouni, central Hoggar, Algeria. Journal of Metamorphic Geology, 14(4): 467-476. DOI:10.1046/j.1525-1314.1996.06016.x
Guo JH, Peng P, Chen Y, Jiao SJ and Windley BF. 2012. UHT sapphirine granulite metamorphism at 193~1.92Ga caused by gabbronorite intrusions:Implications for tectonic evolution of the northern margin of the North China Craton.. Precambrian Research: 124-223.
Harley SL and Fitzsimons ICW. 1991. Pressure-temperature evolution of metapelitic granulites in a polymetamorphic terrane:The Rauer Group, East Antarctica. Journal of Metamorphic Geology, 9(3): 231-243. DOI:10.1111/jmg.1991.9.issue-3
Harley SL. 1998a. On the occurrence and characterization of ultrahigh-temperature crustal metamorphism. In: Treloar PJ and O'Brien PJ (eds.). What Drives Metamorphism and Metamorphic Reactions? Geological Society, London, Special Publication, 81-107
Harley SL. 1998b. Ultrahigh temperature granulite metamorphism (1050℃, 12 kbar) and decompression in garnet (Mg70)-orthopyroxene-sillimanite gneisses from the Rauer Group, East Antarctica. Journal of Metamorphic Geology, 16(4): 541-562. DOI:10.1111/j.1525-1314.1998.00155.x
Harley SL and Motoyoshi Y. 2000. Al zoning in orthopyroxene in a sapphirine quartzite:Evidence for >1120℃ UHT metamorphism in the Napier Complex, Antarctica, and implications for the entropy of sapphirine. Contributions to Mineralogy and Petrology, 138(4): 293-307. DOI:10.1007/s004100050564
Harley SL. 2008. Refining the P-T records of UHT crustal metamorphism. Journal of Metamorphic Geology, 26(2): 125-154. DOI:10.1111/jmg.2008.26.issue-2
Hensen BJ and Green DH. 1971. Experimental study of the stability of cordierite and garnet in pelitic compositions at high pressures and temperatures.Ⅰ. compositions with excess alumino-silicate. Contributions to Mineralogy and Petrology, 33(4): 309-330. DOI:10.1007/BF00382571
Hensen BJ and Green DH. 1972. Experimental study of the stability of cordierite and garnet in pelitic compositions at high pressures and temperatures.Ⅱ. Compositions without excess alumino-silicate. Contributions to Mineralogy and Petrology, 35(4): 331-354. DOI:10.1007/BF00371314
Hensen BJ and Green DH. 1973. Experimental study of the stability of cordierite and garnet in pelitic compositions at high pressures and temperatures.Ⅲ. synthesis of experimental data and geological applications. Contributions to Mineralogy and Petrology, 38(2): 151-166. DOI:10.1007/BF00373879
Hensen BJ. 1986. Theoretical phase relations involving cordierite and garnet revisited:The influence of oxygen fugacity on the stability of sapphirine and spinel in the system Mg-Fe-Al-Si-O. Contributions to Mineralogy and Petrology, 92(3): 362-367. DOI:10.1007/BF00572165
Hiroi Y, Ogo Y and Namba K. 1994. Evidence for prograde metamorphic evolution of Sri Lankan pelitic granulites, and implications for the development of continental crust. Precambrian Research, 66(1-4): 245-263. DOI:10.1016/0301-9268(94)90053-1
Hokada T, Misawa K, Yokoyama K, Shiraishi K and Yamaguchi A. 2004. SHRIMP and electron microprobe chronology of UHT metamorphism in the Napier Complex, East Antarctica:Implications for zircon growth at >1, 000℃. Contributions to Mineralogy and Petrology, 147(1): 1-20. DOI:10.1007/s00410-003-0550-2
Horrocks PC. 1983. A corundum and sapphirine paragenesis from the Limpopo Mobile Belt, Southern Africa. Journal of Metamorphic Geology, 1(1): 13-23. DOI:10.1111/jmg.1983.1.issue-1
Jacob JB, Scott JM, Turnbull RE, Tarling MS and Sagar MW. 2017. High-to ultrahigh-temperature metamorphism in the lower crust:An example resulting from Hikurangi Plateau collision and slab rollback in New Zealand. Journal of Metamorphic Geology, 35(8): 831-853. DOI:10.1111/jmg.2017.35.issue-8
Jiao SJ, Guo JH, Wang LJ and Peng P. 2015. Short-lived high-temperature prograde and retrograde metamorphism in Shaerqin sapphirine-bearing metapelites from the Daqingshan terrane, North China Craton. Precambrian Research, 269: 31-57. DOI:10.1016/j.precamres.2015.08.002
Jiao SJ, Fitzsimons ICW and Guo JH. 2017. Paleoproterozoic UHT metamorphism in the Daqingshan Terrane, North China Craton:New constraints from phase equilibria modeling and SIMS U-Pb zircon dating. Precambrian Research, 303: 208-227. DOI:10.1016/j.precamres.2017.03.024
Kamineni DC and Rao AT. 1988. Sapphirine-bearing quartzite from the Eastern Ghats Granulite Terrain, Vizianagaram, India. Journal of Geology, 96(2): 209-220. DOI:10.1086/629210
Kanazawa T, Tsunogae T, Sato K and Santosh M. 2009. The stability and origin of sodicgedrite in ultrahigh-temperature Mg-Al granulites:A case study from the Gondwana suture in southern India. Contributions to Mineralogy and Petrology, 157(1): 95-110. DOI:10.1007/s00410-008-0322-0
Karmakar S and Schenk V. 2015. Neoarchean UHT metamorphism and Paleoproterozoic UHT reworking at Uweinat in the East Sahara Ghost Craton, SW Egypt:Evidence from petrology and texturally controlled in situ monazite dating. Journal of Petrology, 56(9): 1703-1742. DOI:10.1093/petrology/egv051
Karmakar S and Schenk V. 2016. Mesoproterozoic UHT metamorphism in the Southern Irumide Belt, Chipata, Zambia:Petrology and in situ monazite dating. Precambrian Research, 275: 332-356. DOI:10.1016/j.precamres.2016.01.018
Kelsey DE, White RW, Holland TJB and Powell R. 2004. Calculated phase equilibria in K2O-FeO-MgO-Al2O3-SiO2-H2O for sapphirine-quartz-bearing mineral assemblages. Journal of Metamorphic Geology, 22(6): 559-578. DOI:10.1111/jmg.2004.22.issue-6
Kelsey DE, Hand M, Clark C and Wilson CJL. 2007. On the application of in situ monazite chemical geochronology to constraining P-T-t histories in high-temperature (>850℃ polymetamorphic granulites from Prydz Bay, East Antarctica. Journal of the Geological Society, 164(3): 667-683. DOI:10.1144/0016-76492006-013
Kelsey DE. 2008. On ultrahigh-temperature crustal metamorphism. Gondwana Research, 13(1): 1-29. DOI:10.1016/j.gr.2007.06.001
Kelsey DE and Hand M. 2015. On ultrahigh temperature crustal metamorphism:Phase equilibria, trace element thermometry, bulk composition, heat sources, timescales and tectonic settings. Geoscience Frontiers, 6(3): 311-356. DOI:10.1016/j.gsf.2014.09.006
Kihle J and Bucher-Nurminen K. 1992. Orthopyroxene-sillimanite-sapphirine granulites from the Bamble granulite terrane, southern Norway. Journal of Metamorphic Geology, 10(5): 671-693. DOI:10.1111/jmg.1992.10.issue-5
Kondou N, Tsunogae T, Santosh M and Shimizu H. 2009. Sapphirine+quartz assemblage from Ganguvarpatti:Diagnostic evidence for ultrahigh-temperature metamorphism in central Madurai Block, southern India. Journal of Mineralogical and Petrological Sciences, 104(5): 285-289. DOI:10.2465/jmps.090607
Korhonen FJ, Powell R and Stout JH. 2012. Stability of sapphirine+quartz in the oxidized rocks of the Wilson Lake terrane, Labrador:Calculated equilibria in NCKFMASHTO. Journal of Metamorphic Geology, 30(1): 21-36. DOI:10.1111/j.1525-1314.2011.00954.x
Kriegsman LM and Schumacher JC. 1999. Petrology of sapphirine-bearing and associated granulites from central Sri Lanka. Journal of Petrology, 40(8): 1211-1239. DOI:10.1093/petroj/40.8.1211
Leong KM and Moore JM. 1972. Sapphirine-bearing rocks from Wilson Lake, Labrador. The Canadian Mineralogist, 11(4): 777-790.
Liu JZ, Qiang XK, Liu XS and Ouyang ZY. 2000. Dynamics and genetic grids of sapphirine-bearing spinel gneiss in Daqing Mountain orogen zone, Inner Mongolia. Acta Petrologica Sinica, 16(2): 245-255.
Martignole J and Martelat JE. 2003. Regional-scale Grenvillian-age UHT metamorphism in the Mollendo-Camana Block (basement of the Peruvian Andes). Journal of Metamorphic Geology, 21(1): 99-120. DOI:10.1046/j.1525-1314.2003.00417.x
Mohan A, Tripathi P and Motoyoshi Y. 1997. Reaction history of sapphirine granulites and a decompressional P-T path in a granulite complex from the Eastern Ghats. Proceedings of the Indian Academy of Sciences-Earth and Planetary Sciences, 106(3): 115-129.
Moraes R, Brown M, Fuck RA, Camargo MA and Lima TM. 2002. Characterization and P-T evolution of melt-bearing ultrahigh-temperature granulites:An example from the Anapolis-Itaucu Complex of the Brasilia Fold Belt, Brazil. Journal of Petrology, 43(9): 1673-1705. DOI:10.1093/petrology/43.9.1673
Morse SA and Talley JH. 1971. Sapphirine reactions in deep-seated granulites near Wilson Lake, Central Labrador, Canada. Earth and Planetary Science Letters, 10(3): 325-328. DOI:10.1016/0012-821X(71)90037-9
Motoyoshi Y and Hensen BJ. 1. Sapphirine-quartz-orthopyroxene symplectites after cordierite in the Archaean Napier Complex, Antarctica:Evidence for a counterclockwise P-T path?. European Journal of Mineralogy, 3: 467-472.
Mouri H, Guiraud M and Hensen BJ. 1996. Petrology of phlogopite-sapphirine-bearing Al-Mg granulites from Ihouhaouene, In Ouzzal, Hoggar, Algeria:An example of phlogopite stability at high temperature. Journal of Metamorphic Geology, 14(6): 725-738. DOI:10.1111/jmg.1996.14.issue-6
Nishimiya Y, Tsunogae T and Santosh M. 2010. Sapphirine+quartz corona around magnesian (XMg~0.58) staurolite from the Palghat-Cauvery Suture Zone, southern India:Evidence for high-pressure and ultrahigh-temperature metamorphism within the Gondwana suture. Lithos, 114(3-4): 490-502.
Nixon PH, Reedman AJ and Burns LK. 1973. Sapphirine-bearing granulitcs from Labwor, Uganda. Mineralogical Magazine, 39(304): 420-428. DOI:10.1180/minmag.1973.039.304.05
Osanai Y, Sajeev K, Owada M, Kehelpannala KVW, Prame WKB, Nakano N and Jayatileke S. 2006. Metamorphic evolution of high-pressure and ultrahigh-temperature granulites from the Highland Complex, Sri Lanka. Journal of Asian Earth Sciences, 28(1): 20-37. DOI:10.1016/j.jseaes.2004.09.013
Osanai Y, Sajeev K, Nakano N, Kitano I, Kehelpannala WKV, Kato R, Adachi T and Malaviarachchi SPK. 2016. UHT granulites of the Highland Complex, Sri Lanka I:Geological and petrological background. Journal of Mineralogical and Petrological Sciences, 111(3): 145-156. DOI:10.2465/jmps.151227
Ouzegane K and Boumaza S. 1996. An example of ultrahigh-temperature metamorphism:Orthopyroxene-sillimanite-garnet, sapphirine-quartz and spinel-quartz parageneses in Al-Mg granulites from In Hihaou, In Ouzzal, Hoggar. Journal of Metamorphic Geology, 14(6): 693-708. DOI:10.1111/jmg.1996.14.issue-6
Ouzegane K, Guiraud M and Kienast JR. 2003. Prograde and retrograde evolution in high-temperature corundum granulites (FMAS and KFMASH systems) from In Ouzzal terrane (NW Hoggar, Algeria). Journal of Petrology, 44(3): 517-545. DOI:10.1093/petrology/44.3.517
Pattison DRM, Chacko T, Farquhar J and McFarlane CRM. 2003. Temperatures of granulite-facies metamorphism:Constraints from experimental phase equilibria and thermobarometry corrected for retrograde exchange. Journal of Petrology, 44(5): 867-900. DOI:10.1093/petrology/44.5.867
Powell R and Sandiford M. 1988. Sapphirine and spinel phase relationships in the system FeO-MgO-Al2O3-SiO2-TiO2-O2 in the presence of quartz and hypersthene. Contributions to Mineralogy and Petrology, 98(1): 64-71. DOI:10.1007/BF00371910
Prakash D and Sharma IN. 2008. Reaction textures and metamorphic evolution of quartz-free granulites from Namlekonda (Karimnagar), Andhra Pradesh, Southern India. International Geology Review, 50(11): 1008-1021. DOI:10.2747/0020-6814.50.11.1008
Prakash D, Singh P and Hokada T. 2013. A new occurrence of sapphirine-spinel-corundum-bearing granulite from NE of Jagtiyal, Eastern Dharwar Craton, Andhra Pradesh. Journal of the Geological Society of India, 82(1): 5-8. DOI:10.1007/s12594-013-0115-6
Prakash D and Singh PC. 2014. New finding of sillmanite in sapphirine-bearing granulites from Pedapalli, NE part of the Eastern Dharwar Craton, India. Journal of the Geological Society of India, 84(1): 29-34. DOI:10.1007/s12594-014-0107-1
Prakash D, Deepak, Singh PC, Singh CK, Tewari S, Arima M and Frimmel HE. 2015. Reaction textures and metamorphic evolution of sapphirine-spinel-bearing and associated granulites from Diguva Sonaba, Eastern Ghats Mobile Belt, India. Geological Magazine, 152(2): 316-340. DOI:10.1017/S0016756814000399
Prakash D, Yadav R, Tewari S, Frimmel HE, Koglin N, Sachan HK and Yadav MK. 2018. Geochronology and phase equilibria modelling of ultra-high temperature sapphirine+quartz-bearing granulite at Usilampatti, Madurai Block, Southern India. Geological Journal, 53(1): 139-158. DOI:10.1002/gj.v53.1
Raith M, Karmakar S and Brown M. 1997. Ultra-high-temperature metamorphism and multistage decompressional evolution of sapphirine granulites from the Palni Hill Ranges, southern India. Journal of Metamorphic Geology, 15(3): 379-399. DOI:10.1111/j.1525-1314.1997.00027.x
Raith MM, Rakotondrazafy R and Sengupta P. 2008. Petrology of corundum-spinel-sapphirine-anorthite rocks (sakenites) from the type locality in southern Madagascar. Journal of Metamorphic Geology, 26(6): 647-667. DOI:10.1111/jmg.2008.26.issue-6
Rao CVD and Chmielowski RM. 2011. New constraints on the metamorphic evolution of the Eastern Ghats Belt, India, based on relict composite inclusions in garnet from ultrahigh-temperature sapphirine granulites. Geological Journal, 46(2-3): 240-262. DOI:10.1002/gj.1251
Rickers K, Raith M and Dasgupta S. 2001. Multistage reaction textures in xenolithic high-MgAl granulites at Anakapalle, Eastern Ghats Belt, India:Examples of contact polymetamorphism and infiltration-driven metasomatism. Journal of Metamorphic Geology, 19(5): 563-582. DOI:10.1046/j.0263-4929.2001.00329.x
Romer RL and Rötzler J. 2001. P-T-t evolution of ultrahigh-temperature granulites from the Saxon Granulite Massif, Germany. Part Ⅱ:Geochronology. Journal of Petrology, 42(11): 2015-2032.
Rötzler J and Romer RL. 2001. P-T-t evolution of ultrahigh-temperature granulites from the Saxon Granulite Massif, Germany. Part Ⅰ:Petrology. Journal of Petrology, 42(11): 1995-2013.
Sajeev K, Osanai Y and Santosh M. 2001. Ultrahigh-temperature stability of sapphirine and kornerupine in Ganguvarpatti granulite, Madurai Block, Southern India. Gondwana Research, 4(4): 762-766. DOI:10.1016/S1342-937X(05)70553-0
Sajeev K and Osanai Y. 2004. Ultrahigh-temperature metamorphism (1150℃, 12 kbar) and multistage evolution of Mg-, Al-rich granulites from the central Highland Complex, Sri Lanka. Journal of Petrology, 45(9): 1821-1844. DOI:10.1093/petrology/egh035
Sajeev K, Osanai Y and Santosh M. 2004. Ultrahigh-temperature metamorphism followed by two-stage decompression of garnet-orthopyroxene-sillimanite granulites from Ganguvarpatti, Madurai block, southern India. Contributions to Mineralogy and Petrology, 148(1): 29-46. DOI:10.1007/s00410-004-0592-0
Sandiford M. 1985. The metamorphic evolution of granulites at Fyfe hills; Implications for Archaean crustal thickness in Enderby Land, Antarctica. Journal of Metamorphic Geology, 3(2): 155-178. DOI:10.1111/jmg.1985.3.issue-2
Santosh M and Sajeev K. 2006. Anticlockwise evolution of ultrahigh-temperature granulites within continental collision zone in southern India. Lithos, 92(3-4): 447-464. DOI:10.1016/j.lithos.2006.03.063
Santosh M, Tsunogae T, Li JH and Liu SJ. 2007. Discovery of sapphirine-bearing Mg-Al granulites in the North China Craton:Implications for Paleoproterozoic ultrahigh temperature metamorphism. Gondwana Research, 11(3): 263-285. DOI:10.1016/j.gr.2006.10.009
Santosh M, Sajeev K, Li JH, Liu SJ and Itaya T. 2009. Counterclockwise exhumation of a hot orogen:The Paleoproterozoic ultrahigh-temperature granulites in the North China Craton. Lithos, 110(1-4): 140-152. DOI:10.1016/j.lithos.2008.12.010
Schreyer W and Abraham K. 1975. Peraluminous sapphirine as a metastable reaction product in kyanite-gedrite-talc schist from Sar E Sang, Afghanistan. Mineralogical Magazine, 40(310): 171-180. DOI:10.1180/minmag.1975.040.310.06
Sengupta P, Dasgupta S, Bhattacharya PK, Fukuoka M, Chakraborti S and Bhowmick S. 1990. Petro-tectonic imprints in the sapphirine granulites from Anantagiri, Eastern Ghats Mobile Belt, India. Journal of Petrology, 31(5): 971-996. DOI:10.1093/petrology/31.5.971
Shazia JR, Santosh M and Sajeev K. 2012. Peraluminous sapphirine-cordierite pods in Mg-rich orthopyroxene granulite from southern India:Implications for lower crustal processes. Journal of Asian Earth Sciences, 58: 88-97. DOI:10.1016/j.jseaes.2012.06.020
Shimizu H, Tsunogae T and Santosh M. 2013. Petrology and phase equilibrium modeling of sapphirine+quartz assemblage from the Napier Complex, East Antarctica:Diagnostic evidence for Neoarchean ultrahigh-temperature metamorphism. Geoscience Frontiers, 4(6): 655-666. DOI:10.1016/j.gsf.2012.09.001
Su BX, Zhang HF, Hu Y, Santosh M, Tang YJ and Xiao Y. 2012. The genesis of mantle-derived sapphirine. American Mineralogist, 97(5-6): 856-863. DOI:10.2138/am.2012.3859
Tamashiro I, Santosh M, Sajeev K, Morimoto T and Tsunogae T. 2004. Multistage orthopyroxene formation in ultrahigh-temperature granulites of Ganguvarpatti, southern India:Implications for complex metamorphic evolution during Gondwana assembly. Journal of Mineralogical and Petrological Sciences, 99(5): 279-297. DOI:10.2465/jmps.99.279
Taylor HCJ. 1973. Melting relations in the system MgO-Al2O3-SiO2 at 15kb. GSA Bulletin, 84(4): 1335-1348. DOI:10.1130/0016-7606(1973)84<1335:MRITSM>2.0.CO;2
Taylor-Jones K and Powell R. 2010. The stability of sapphirine+quartz:Calculated phase equilibria in FeO-MgO-Al2O3-SiO2-TiO2-O. Journal of Metamorphic Geology, 28(6): 615-633. DOI:10.1111/(ISSN)1525-1314
Tong LX and Wilson CJL. 2006. Tectonothermal evolution of the ultrahigh temperature metapelites in the Rauer Group, East Antarctica. Precambrian Research, 149(1-2): 1-20. DOI:10.1016/j.precamres.2006.04.004
Tsunogae T and Santosh M. 2006. Spinel-sapphirine-quartz bearing composite inclusion within garnet from an ultrahigh-temperature pelitic granulite:Implications for metamorphic history and P-T path. Lithos, 92(3-4): 524-536. DOI:10.1016/j.lithos.2006.03.060
Tsunogae T and van Reenen DD. 2006. Corundum plus quartz and Mg-staurolite bearing granulite from the Limpopo Belt, southern Africa:Implications for a P-T path. Lithos, 92(3-4): 576-587. DOI:10.1016/j.lithos.2006.03.052
Tsunogae T and Santosh M. 2010. Ultrahigh-temperature metamorphism and decompression history of sapphirine granulites from Rajapalaiyam, southern India:Implications for the formation of hot orogens during Gondwana assembly. Geological Magazine, 147(1): 42-58. DOI:10.1017/S0016756809990100
Tsunogae T and Santosh M. 2011. Sapphirine+quartz assemblage from the Southern Granulite Terrane, India:Diagnostic evidence for ultrahigh-temperature metamorphism within the Gondwana collisional orogen. Geological Journal, 46(2-3): 183-197. DOI:10.1002/gj.1244
Tsunogae T, Liu SJ, Santosh M, Shimizu H and Li JH. 2011. Ultrahigh-temperature metamorphism in Daqingshan, Inner Mongolia Suture Zone, North China Craton. Gondwana Research, 20(1): 36-47. DOI:10.1016/j.gr.2011.03.001
Wheller CJ and Powell R. 2014. A new thermodynamic model for sapphirine:Calculated phase equilibria in K2O-FeO-MgO-Al2O3-SiO2-H2O-TiO2-Fe2O3. Journal of Metamorphic Geology, 32(3): 287-299. DOI:10.1111/jmg.2014.32.issue-3
Whitney DL and Evans BW. 2010. Abbreviations for names of rock-forming minerals. American Mineralogist, 95(1): 185-187. DOI:10.2138/am.2010.3371
Windley BF, Ackermand D and Herd RK. 1984. Sapphirine/kornenipine-bearing rocks and crustal uplift history of the Limpopo Belt, Southern Africa. Contributions to Mineralogy and Petrology, 86(4): 342-358. DOI:10.1007/BF01187139
Xiang H, Zhang L, Zhong ZQ, Santosh M, Zhou HW, Zhang HF, Zheng JP and Zheng S. 2012. Ultrahigh-temperature metamorphism and anticlockwise P-T-t path of Paleozoic granulites from north Qinling-Tongbai orogen, Central China. Gondwana Research, 21(2-3): 559-576. DOI:10.1016/j.gr.2011.07.002
Xiang H, Zhong ZQ, Li Y, Qi M, Zhou HW, Zhang L, Zhang ZM and Santosh M. 2014. Sapphirine-bearing granulites from the Tongbai orogen, China:Petrology, phase equilibria, zircon U-Pb geochronology and implications for Paleozoic ultrahigh temperature metamorphism. Lithos, 208-209: 446-461.
Xiao Y, Zhang HF, Liang Z, Su BX, Zhu B and Sakyi PA. 2018. Origin of sapphirine-and garnet-bearing clinopyroxenite xenoliths entrained in the Jiande basalts, SE China. Lithos, 304-307: 95-108.
Yang C and Wei CJ. 2017. Ultrahigh temperature (UHT) mafic granulites in the East Hebei, North China Craton:Constraints from a comparison between temperatures derived from REE-based thermometers and major element-based thermometers. Gondwana Research, 46: 156-169. DOI:10.1016/j.gr.2017.02.017
常丽华, 陈曼云, 金巍, 李世超, 于介江. 2006. 透明矿物薄片鉴定手册. 北京: 地质出版社: 198-199.
刘建忠, 强小科, 刘喜山, 欧阳自远. 2000. 内蒙古大青山造山带含假蓝宝石尖晶石片麻岩的成因网格及动力学. 岩石学报, 16(2): 245-255.