Petrogenesis of the garnet peridotite and garnet-free peridotite of the Zhimafang ultramafic body in the Sulu ultrahigh-pressure metamorphic belt, eastern China

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	Petrogenesis of the garnet peridotite and garnet-free peridotite of the Zhimafang ultramafic body in the Sulu ultrahigh-pressure metamorphic belt, eastern China
	Yang, JS (Yang, J. . S.); Zhang, RY (Zhang, R. Y.); Li, TF (Li, T. F.); Zhang, ZM (Zhang, Zh. M.); Liou, JG (Liou, J. G.)
刊名	JOURNAL OF METAMORPHIC GEOLOGY
	2007
卷号	25 期号:2 页码:187-206
关键词	CCSD-PP1 garnet peridotite mantle Sulu UHP
ISSN号	0263-4929
英文摘要	The CCSD-PP1 drillhole penetrated a 110-m-thick sequence of the Zhimafang ultramafic body in the Sulu ultrahigh-pressure (UHP) metamorphic belt, east China. The sequence consists of interlayered garnet-bearing (Grt) and garnet-free (GF) peridotite. Eleven layers of Grt-peridotite, ranging from 1.2 to 9.5 m in thickness, have an aggregate thickness of 54.49 m, whereas eight layers of GF-peridotite, ranging from 2.2 to 14.2 m in thickness, have a total thickness of 57.53 m. The boundaries between the two rock types are gradational. The Grt-peridotites have slightly higher contents of Al(2)O(3), CaO and SiO(2), and lower Mg(#)s (0.90-0.92) than the GF-peridotites (Mg(#)s 0.91-0.93). Both contain low TiO(2) (< 0.05 wt%) and have higher modal abundances of enstatite (average 10 vol.%) than diopside (1-5 vol.%), typical of depleted-type upper mantle. The diopside in these rocks has high and relatively uniform Mg(#) members (0.93-0.95), but highly variable Al(2)O(3) (0.2-2.3 wt%), Na(2)O (0.5-2.5 wt%) and Cr(2)O(3) (0.38-2.09 wt%). Enstatite (En(92-93)) contains very low Al(2)O(3) (0-0.3 wt%). Both porphyroblastic and equigranular garnet are present. The equigranular varieties are zoned, from core to rim in Cr(2)O(3) (3.4-4.2 wt%), MgO (18.4-17.5 wt%) and Al(2)O(3) (21.1-20.1 wt%). Titania is very low in all the garnet, mostly < 0.05 wt%. Chromite or chromium (Cr)-spinel occur both in the Grt- and GF-peridotite, and are characterized by high contents of Cr(2)O(3) (49-58 wt%) and FeO (24-43 wt%), similar to that in iron-rich Alpine-type peridotites. Based on the bulk-rock MgO-FeO compositions, the Zhimafang Grt-peridotite probably underwent 20-30% partial melting, whereas the GF-peridotite may have undergone as much as 35-40% partial melting, suggesting that the two rock types owe their differences to different degrees of partial melting rather than to pressure differences during metamorphism.
学科主题	变质岩岩石学
WOS关键词	ORTHO-PYROXENE EQUILIBRIA ; FERRIC IRON ; FEO-MGO-AL2O3-SIO2-CR2O3 SYSTEM ; JIANGSU PROVINCE ; DABIE MOUNTAINS ; UHP TERRANE ; BEARING ; MANTLE ; ROCKS ; COESITE
WOS研究方向	Geology
语种	英语
出版者	WILEY-BLACKWELL PUBLISHING, INC
WOS记录号	WOS:000244277000008
内容类型	期刊论文
源URL	[http://119.78.100.197/handle/2HKVOGP0/38466]
专题	中国地质调查局
作者单位	Chinese Acad Geol Sci, Inst Geol, Key Lab Continental Dynam, Beijing 100037, Peoples R China Stanford Univ, Dept Geol & Environm Sci, Stanford, CA 94305 USA
推荐引用方式 GB/T 7714	Yang, JS ,Zhang, RY ,Li, TF ,et al. Petrogenesis of the garnet peridotite and garnet-free peridotite of the Zhimafang ultramafic body in the Sulu ultrahigh-pressure metamorphic belt, eastern China[J]. JOURNAL OF METAMORPHIC GEOLOGY,2007,25(2):187-206.
APA	Yang, JS ,Zhang, RY ,Li, TF ,Zhang, ZM ,&Liou, JG .(2007).Petrogenesis of the garnet peridotite and garnet-free peridotite of the Zhimafang ultramafic body in the Sulu ultrahigh-pressure metamorphic belt, eastern China.JOURNAL OF METAMORPHIC GEOLOGY,25(2),187-206.
MLA	Yang, JS ,et al."Petrogenesis of the garnet peridotite and garnet-free peridotite of the Zhimafang ultramafic body in the Sulu ultrahigh-pressure metamorphic belt, eastern China".JOURNAL OF METAMORPHIC GEOLOGY 25.2(2007):187-206.