The complex life cycle of oceanic lithosphere: A study of Yarlung-Zangbo ophiolitic peridotites, Tibet
The complex life cycle of oceanic lithosphere: A study of Yarlung-Zangbo ophiolitic peridotites, Tibet
复制标题
大洋岩石圈的复杂生命周期：西藏雅鲁藏布江蛇绿橄榄岩研究
DOI：
10.1016/j.gca.2020.03.024
复制
发表时间：
2020-05
影响因子：
5
通讯作者：
D.G. Pearson
中科院分区：
文献类型：
--
作者：
Yong Xu;Jingao Liu;Qing Xiong;Ben-Xun Su;James M. Scott;Bo Xu;Di-Cheng Zhu;D.G. Pearson
西藏雅鲁藏布江蛇绿岩(YZO)沿印度与亚洲缝合带的超镁铁质地幔剖面保存了先前夹杂大洋岩石圈的地幔历史。来自普朗、白岗和泽当三个地区的5 2个蛇绿橄榄岩揭示，这些岩石包括中生代亏损地幔(峰型187Os/188Os=0.126)，与更古老的地幔域(187Os/188Os：0.113-0.121，模式年龄高达2.2Ga)混合，可能是在旧岩石圈重新封装到中生代大洋岩石圈之前俯冲或拆沉。全岩主量元素和微量元素特征表明，该复合地幔岩石圈在二叠纪-三叠纪经历了中-高度(∼10-30%)的部分熔融，可能是由于东冈瓦那北缘弧后盆地的裂谷和新特提斯的打开所致。然而，基本平坦的原始上地幔标准化的高度亲铁元素模式与贫化的亲石元素特征不匹配。近垂向(Pd/Ir)N-Al_2O_3的变化，加上不同数量的间隙贱金属硫化物(BMS)的出现，以及与(Pd/Ir)N、Cu含量的相关性，表明该大洋岩石圈有S饱和(或富BMS)熔体或流体的加入。这可能发生在∼13 0~12 0 Ma的新一幕新特提斯俯冲过程中，在此期间产生了S饱和的弧前玄武岩岩浆，并随后叠加了上复的橄榄岩岩石圈地幔。西藏YZO阐明了与多期区域构造事件有关的蛇绿橄榄岩复杂的生命周期，并为理解地球上地幔的地球动力学机制提供了见解。
Abstract The ultramafic mantle sections of the Yarlung-Zangbo ophiolites (YZO) along the suture of India and Asia in Tibet preserve the mantle history of the formerly intervening oceanic lithosphere. Fifty-two ophiolitic peridotites from three localities (Purang, Baigang and Zedang) reveal that these rocks comprise Mesozoic depleted mantle (peak mode 187Os/188Os = 0.126), mixed with more ancient mantle domains (187Os/188Os: 0.113–0.121, with model ages up to 2.2 Ga), probably through subduction or delamination of older lithosphere prior to its re-encapsulation into Mesozoic oceanic lithosphere. Whole-rock major and trace elements indicate that this composite mantle lithosphere experienced moderate to high degrees (∼10–30%) of partial melting in the Permian-Triassic, possibly due to the rifting of the back-arc basin in the northern margin of East Gondwana and the opening of Neo-Tethys. However, the generally flat primitive upper mantle-normalized highly siderophile element patterns do not match the depleted lithophile element characteristics. Sub-vertical (Pd/Ir)N-Al2O3 variations, coupled with the occurrence of variable amounts of interstitial base metal sulfides (BMS) and correlations with (Pd/Ir)N and Cu contents, indicate the addition of S-saturated (or BMS-rich) melts or fluids into this oceanic lithosphere. This may have occurred at ∼130–120 Ma during a new episode of Neo-Tethyan subduction, during which S-saturated forearc basaltic magmas were produced and subsequently overprinted the overlying peridotitic lithospheric mantle. The Tibetan YZO illustrate the complex life cycle of ophiolitic peridotites related to multi-stage regional tectonic events, and provide insights into understanding geodynamic mechanisms that have operated in the Earth’s upper mantle.
登录
查看更多内容
影响因子：
5.3
作者：
Jingao Liu;J. Scott;Candace E Martin;D. Pearson
通讯作者：
Jingao Liu;J. Scott;Candace E Martin;D. Pearson
影响因子：
14.9
作者：
S. Shirey;R. Walker
通讯作者：
S. Shirey;R. Walker
影响因子：
3.5
作者：
Chuan-Zhou Liu;Chang Zhang;Liu Yang;L. Zhang;Weiqiang Ji;Fu-Yuan Wu
通讯作者：
Chuan-Zhou Liu;Chang Zhang;Liu Yang;L. Zhang;Weiqiang Ji;Fu-Yuan Wu
DOI：
10.1144/gsl.sp.2003.218.01.11
发表时间：
2003
期刊：
Geological Society, London, Special Publications
影响因子：
--
作者：
J. Malpas;Mei‐Fu Zhou;P. Robinson;P. Reynolds
通讯作者：
J. Malpas;Mei‐Fu Zhou;P. Robinson;P. Reynolds
影响因子：
2.9
作者：
G. Stampfli;C. Hochard;C. Vérard;C. Wilhem;J. vonRaumer
通讯作者：
G. Stampfli;C. Hochard;C. Vérard;C. Wilhem;J. vonRaumer