Retrograde reactions of an ultrahigh-pressure metamorphic spinel pyroxenite lens, northeast sulu UHP terrane, eastern China

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	Retrograde reactions of an ultrahigh-pressure metamorphic spinel pyroxenite lens, northeast sulu UHP terrane, eastern China
	Yang, TN (Yang, T. N.)4; Zeng, L (Zeng, L.); Zhao, ZR (Zhao, Z. R.); Liou, JG (Liou, J. G.)
刊名	INTERNATIONAL GEOLOGY REVIEW
	2008
卷号	50 期号:1 页码:32-47
ISSN号	0020-6814
英文摘要	A similar to 5 cm thick garnet-rich layer, with relict spinel grains in its center, is intercalated within garnet pyroxenite at Rongcheng. Both the garnetite layer and the host garnet pyroxenite underwent the same P-T evolution, but exhibit quite different mineral assemblages, microtextures, and associated mineral reactions. Microtextures and mineral compositions confirm our previous suggestion that the Rongcheng garnet pyroxenite recrystallized from a spinel pyroxenite cumulate derived from a gabbroie magma. The present study concludes that (1) The garnet-rich layer resulted from a net transfer reaction between primary spinel and clinopyroxene, Ca-1.5(FeMg)(0.5) Si2O6 + (FeMg)Al2O4 + TiO2 = Ca-1.5(FeMg)(1.5)Al-2(Si2Ti)O-12, and mass-balance reactions between clinopyroxene end-members, 2[Ca-0.75(FeMg)(0.25)][(FeMg)(0.5)Al-0.5](Si1.5Al0.5)O-6 = Ca-1.5(FeMg)(1.5)Al2Si3O12, under UHP conditions that produced garnet-1. (2) Garnet-I decomposed during exhumation of the UHP terrane, leading to the assemblage of Grt-II + Ilm + Cpx-II + Amp, ilmenites were partially released to the relict spinel along micro-fractures to form intergrowths of Spl-I + Ilm. A corona assemblage of Cpx-II + Spl-II + minor Amp developed along contacts between garnet and relict Spl-I at similar to 890 degrees C and similar to 9 kbar. And (3), during a later stage of retrogression, aqueous fluid infiltrated heterogeneously through the garnet-rich layer, leading to the formation of hydrous minerals. Parageneses and mineral compositional maps suggest that Ti may have substituted for Si and entered the T site in the garnet structure, represented by a garnet component such as M3Al2[Si(3-x)Tix]O-12, in addition to the commonly suggested M2+Ti4+ -> 2Al(3+) substitution (forming the garnet component M3-0.5x[Al2-xSi3O12). Heterogeneous microtextures and mineral compositions indicate that the domain equilibrium was controlled by mass transfer at least at the mineral-grain scale due to various degrees of fluid infiltration.
学科主题	变质岩岩石学
WOS关键词	GARNET-PYROXENITE ; OXIDE MINERALS ; ECLOGITE ; EVOLUTION ; RETROGRESSION ; CLINOPYROXENE ; KIMBERLITE ; TEXTURES ; ORIGIN ; MANTLE
WOS研究方向	Geology
语种	英语
出版者	BELLWETHER PUBL LTD
WOS记录号	WOS:000252289600003
内容类型	期刊论文
源URL	[http://119.78.100.197/handle/2HKVOGP0/38687]
专题	中国地质调查局
作者单位	1.[Yang, T. N. 2.Zeng, L. 3.Zhao, Z. R.] Chinese Acad Geol Sci, Inst Geol, Beijing 100037, Peoples R China [Liou, J. G.] Stanford Univ, Dept Geol & Environm Sci, Stanford, CA 94305 USA 4.中国地质科学院地质研究所
推荐引用方式 GB/T 7714	Yang, TN ,Zeng, L ,Zhao, ZR ,et al. Retrograde reactions of an ultrahigh-pressure metamorphic spinel pyroxenite lens, northeast sulu UHP terrane, eastern China[J]. INTERNATIONAL GEOLOGY REVIEW,2008,50(1):32-47.
APA	Yang, TN ,Zeng, L ,Zhao, ZR ,&Liou, JG .(2008).Retrograde reactions of an ultrahigh-pressure metamorphic spinel pyroxenite lens, northeast sulu UHP terrane, eastern China.INTERNATIONAL GEOLOGY REVIEW,50(1),32-47.
MLA	Yang, TN ,et al."Retrograde reactions of an ultrahigh-pressure metamorphic spinel pyroxenite lens, northeast sulu UHP terrane, eastern China".INTERNATIONAL GEOLOGY REVIEW 50.1(2008):32-47.