Chromium in the olivine lattice: Chromium-rich olivines and their implication of deep mantle origin in the Luobusa mantle peridotite and chromitite, Tibet

	Chromium in the olivine lattice: Chromium-rich olivines and their implication of deep mantle origin in the Luobusa mantle peridotite and chromitite, Tibet
	Liang FengHua 2; Yang JingSui ; Xu ZhiQin ; Zhao JiaNan
刊名	ACTA PETROLOGICA SINICA
	2014
卷号	30 期号:8 页码:2125-2136
关键词	Chromium-rich Olivine Mantle peridotite Chromitite Luobusa ophiolite Tibet
ISSN号	1000-0569
英文摘要	Chromium-rich included olivines and chromite exsolution rod-rich deformed porphyroclast olivines occur in the Luobusa mantle peridotite and chromitite in the Yarlung Zangbo ophiolite, Tibet. Included olivines are subhedral to hedral with size up to 50 mu m and occur in spinels or chromites in harzburgite, dunite, disseminated chromitite, nodular chromitite and massive chromitite. Deformed porphyroclast olivines are coarse-grained (up to lOmm), undulatory extincted, kink banded and recrystallized. Amounts of chromite exsolution rods a.rrange parallelly with light-white, color and extremely narrow width of < 3 tim. In each sample, no matter what lithology, included olivines contain obviously higher Cr2O3 and lower FeO than other olivines. Parts of those included olivines contain by far the highest CO, (up to 1. 49%) in the world and much higher than those in lunar and chondrite olivines (similar to 0. 7%). Except for a weak negative correlation of Cr2O, vs. FeO for those included olivines, no other correlation of Cr2O3 vs. MnO and of Cr2O3 vs. MgO was observed, distinguishing from those chromium-rich olivines in lunar basalts (Cr varies inversely with Fe) and from those in St. Mesmin chondrite (Cr varies positively with Fe) Aluminum is near background levels and minors of manganese (similar to 0. 1%) and nickel (0. 3% similar to 0. 5%) were detected in included olivines. Combing with previous studies, we analyzed the valence state and substitution of chromium in Cr-rich olivine or its precursor phase. Cr' is believed to be the controlled valence in the octahedral site of olivine since an in-situ moissanite in one of samples studied here has been discoveried. A possible vacancy substitution mechanism is proposed to explain the uncorrelated characteristic between Cr and other metal elements. According to lots of findings of ultra-high pressure and extremely reductive minerals reported by previous studies, that the chromium-rich olivines in the Luobusha mantle peridotite and chromitite might originate from mantle transition zone or lower mantle and their precursor phase might be wadsleyite or ringwoodite.
学科主题	火成岩岩石学
WOS关键词	PODIFORM CHROMITITES ; SOUTHERN TIBET ; HIGH-PRESSURE ; DIAMOND-BEARING ; OPHIOLITE ; EXSOLUTION ; MOISSANITE ; ROCK ; EMPLACEMENT ; INCLUSIONS
WOS研究方向	Geology
语种	中文
出版者	SCIENCE PRESS
WOS记录号	WOS:000340023300002
内容类型	期刊论文
源URL	[http://119.78.100.197/handle/2HKVOGP0/40565]
专题	中国地质科学院地质研究所
作者单位	1.CAGS, CARMA, Inst Geol, State Key Lab Continental Tecton & Dynam, Beijing 100037, Peoples R China 2.中国地质科学院地质研究所
推荐引用方式 GB/T 7714	Liang FengHua,Yang JingSui,Xu ZhiQin,et al. Chromium in the olivine lattice: Chromium-rich olivines and their implication of deep mantle origin in the Luobusa mantle peridotite and chromitite, Tibet[J]. ACTA PETROLOGICA SINICA,2014,30(8):2125-2136.
APA	Liang FengHua,Yang JingSui,Xu ZhiQin,&Zhao JiaNan.(2014).Chromium in the olivine lattice: Chromium-rich olivines and their implication of deep mantle origin in the Luobusa mantle peridotite and chromitite, Tibet.ACTA PETROLOGICA SINICA,30(8),2125-2136.
MLA	Liang FengHua,et al."Chromium in the olivine lattice: Chromium-rich olivines and their implication of deep mantle origin in the Luobusa mantle peridotite and chromitite, Tibet".ACTA PETROLOGICA SINICA 30.8(2014):2125-2136.