Compositional zoning in dolomite from lawsonite-bearing eclogite (SW Tianshan, China): Evidence for prograde metamorphism during subduction of oceanic crust

doi:10.2138/am.2014.4507

	Compositional zoning in dolomite from lawsonite-bearing eclogite (SW Tianshan, China): Evidence for prograde metamorphism during subduction of oceanic crust
	Li, Ji-Lei 1; Klemd, Reiner 1; Gao, Jun 2; Meyer, Melanie 1
刊名	AMERICAN MINERALOGIST
	2014
卷号	99 期号:1 页码:206-217
关键词	Prograde zoning dolomite magnesite eclogite high pressure Tianshan
ISSN号	0003-004X
DOI	10.2138/am.2014.4507
文献子类	Article
英文摘要	Dolomite with compositional zoning was discovered in carbonate-lawsonite-bearing eclogites in the Tianshan (ultra-)high-pressure/low-temperature metamorphic belt, northwestern China. The eclogite-facies dolomite occurs as matrix porphyroblast and as inclusion in garnet, both of which display the same chemical zoning pattern. The dolomite contains inclusions of calcite (probably after aragonite), magnesite, glaucophane, lawsonite (and its pseudomorphs), allanite, epidote, paragonite, phengite, and omphacite. The chemical zoning in dolomite is well defined by a continuous core-to-rim Mg increase and Fe-Mn decrease. The concentrations of transition metal elements, REE, and Y also decrease from core to rim of the dolomite. Thermodynamic modeling demonstrates that the Fe-Mg zoning of dolomite is largely temperature dependent and, thus, is interpreted as prograde growth zoning, which developed during subduction of carbonate-bearing oceanic crust. It is suggested that dolomite in equilibrium with garnet formed as a result of changing matrix compositions due to increasing temperatures. In addition, thermodynamic modeling demonstrates that during subduction at high-pressure conditions prograde-formed aragonite and dolomite were transformed to dolomite and magnesite. Furthermore, Fe-rich magnesite inclusions in matrix dolomite and in dolomite inclusions in garnet are shown to have formed during high-pressure conditions prior to peak metamorphic conditions and, therefore caution is warranted using Fe-bearing magnesite occurrences in eclogite-facies rocks as an unambiguous ultrahigh pressure indicator as previously suggested.
WOS关键词	HIGH-PRESSURE METAMORPHISM ; FLUID-ROCK INTERACTION ; HP-LT ROCKS ; WESTERN TIANSHAN ; NW-CHINA ; PHASE-RELATIONS ; TECTONIC IMPLICATIONS ; COESITE INCLUSIONS ; AGE CONSTRAINTS ; DABIE MOUNTAINS
WOS研究方向	Geochemistry & Geophysics ; Mineralogy
语种	英语
出版者	MINERALOGICAL SOC AMER
WOS记录号	WOS:000329416700026
资助机构	Deutsche Forschungsgemeinschaft(KL692/17-3) ; Deutsche Forschungsgemeinschaft(KL692/17-3) ; National Natural Science Foundation of China(41025008) ; National Natural Science Foundation of China(41025008) ; Deutsche Forschungsgemeinschaft(KL692/17-3) ; Deutsche Forschungsgemeinschaft(KL692/17-3) ; National Natural Science Foundation of China(41025008) ; National Natural Science Foundation of China(41025008) ; Deutsche Forschungsgemeinschaft(KL692/17-3) ; Deutsche Forschungsgemeinschaft(KL692/17-3) ; National Natural Science Foundation of China(41025008) ; National Natural Science Foundation of China(41025008) ; Deutsche Forschungsgemeinschaft(KL692/17-3) ; Deutsche Forschungsgemeinschaft(KL692/17-3) ; National Natural Science Foundation of China(41025008) ; National Natural Science Foundation of China(41025008)
内容类型	期刊论文
源URL	[http://ir.iggcas.ac.cn/handle/132A11/86482]
专题	中国科学院地质与地球物理研究所
通讯作者	Li, Ji-Lei
作者单位	1.Univ Erlangen Nurnberg, GeoZentrum Nordbayern, D-91054 Erlangen, Germany 2.Chinese Acad Sci, Inst Geol & Geophys, Key Lab Mineral Resources, Beijing 100029, Peoples R China
推荐引用方式 GB/T 7714	Li, Ji-Lei,Klemd, Reiner,Gao, Jun,et al. Compositional zoning in dolomite from lawsonite-bearing eclogite (SW Tianshan, China): Evidence for prograde metamorphism during subduction of oceanic crust[J]. AMERICAN MINERALOGIST,2014,99(1):206-217.
APA	Li, Ji-Lei,Klemd, Reiner,Gao, Jun,&Meyer, Melanie.(2014).Compositional zoning in dolomite from lawsonite-bearing eclogite (SW Tianshan, China): Evidence for prograde metamorphism during subduction of oceanic crust.AMERICAN MINERALOGIST,99(1),206-217.
MLA	Li, Ji-Lei,et al."Compositional zoning in dolomite from lawsonite-bearing eclogite (SW Tianshan, China): Evidence for prograde metamorphism during subduction of oceanic crust".AMERICAN MINERALOGIST 99.1(2014):206-217.