气候变化领域集成服务门户(CCPortal): Geochemical Characteristics of Volcanic Rocks from ODP Site 794, Yamato Basin: Implications for Deep Mantle Processes of the Japan Sea

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DOI	10.1111/1755-6724.12523
	Geochemical Characteristics of Volcanic Rocks from ODP Site 794, Yamato Basin: Implications for Deep Mantle Processes of the Japan Sea
	Chen Shuangshuang; Liu Jiaqi; Guo Zhengfu; Chen Shengsheng; Sun Chunqing
通讯作者	Liu, JQ (通讯作者)
发表日期	2015
ISSN	1000-9515
EISSN	1755-6724
起始页码	1189
结束页码	1212
卷号	89 期号:4
英文摘要	Deep mantle processes and the dynamic mechanism of magmatism in the Japan Sea Basin are important processes that have not been studied in detail. In this paper, systematic evaluation of basalt samples from the ocean drilling program Site 794 in the Japan Sea was performed, which included petrography, whole-rock major- and trace-element analysis, Sr-Nd-Pb isotopic composition, and electron microprobe analysis of plagioclase and clinopyroxene. These basalts belong to the tholeiitic series with porphyritic texture and massive Ca-rich plagioclase, clinopyroxene, and minor olivine phenocrysts. The basalts are characterized as flat rare earth elements and high-field-strength elements with remarkably low ratios of (La/Yb)(N) (0.75-2.51), significant positive anomalies of Ba, Sr, and Rb and no Eu anomaly (Eu = 0.99-1.36). The samples showed relatively high Sr-87/Sr-86 (0.70425-0.70522), Pb-207/Pb-204 (15.511-15.610), and Pb-208/Pb-204 (38.064-38.557) values and a low Nd-143/Nd-144 ratio (0.51271-0.51295). The basalts from Site 794 can be divided into upper, middle, and lower volcanic rocks (UVR, MVR, and LVR) on the basis of their stratigraphic level. The MVR was geochemically derived from the depleted mantle, whereas the UVR and LVR originated from a nondepleted and relatively enriched mantle source with contributions from subducted Pacific plate fluid and sediments. Use of geothermobarometers indicates that the crystallization pressure for the UVR and LVR (6.25-11.19 kbar) was significantly higher than that of the MVR (3.48-5.84 kbar). The UVR and LVR may have been derived from the low-degree (5%-10%) partial melting of spinel lherzolite, while the MVR originated from a shallower mantle source with a high degree (10%-20%) of partial melting. In addition, the geochemical characteristics of the samples are consistent with a younger age (13-17 Ma) and the depleted composition of the MVR and an older age (17-23 Ma) and slightly enriched composition of the UVR and LVR. Therefore, temporal changes in the mantle source from old and enriched to young and depleted and subsequently to old and nondepleted may have been associated with progressive lithospheric extension and thinning, as well as at least two episodes of diverse asthenospheric upwelling and pull-apart tectonic motion in the Yamato Basin.
关键词	PLAGIOCLASE-MELT EQUILIBRIA MIDOCEAN RIDGE BASALT EAST PACIFIC RISE TRACE-ELEMENT PALEOMAGNETIC EVIDENCE CRUSTAL CONTAMINATION CLINOPYROXENE COMPOSITION CHEMICAL CHARACTERISTICS ISOTOPIC COMPOSITIONS MAGMATIC EVOLUTION
英文关键词	Basalt; deep mantle process; geothermobarometer; Yamato Basin
语种	英语
WOS研究方向	Geology
WOS类目	Geosciences, Multidisciplinary
WOS记录号	WOS:000360495600010
来源期刊	ACTA GEOLOGICA SINICA-ENGLISH EDITION
来源机构	中国科学院青藏高原研究所
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/258460
推荐引用方式 GB/T 7714	Chen Shuangshuang,Liu Jiaqi,Guo Zhengfu,et al. Geochemical Characteristics of Volcanic Rocks from ODP Site 794, Yamato Basin: Implications for Deep Mantle Processes of the Japan Sea[J]. 中国科学院青藏高原研究所,2015,89(4).
APA	Chen Shuangshuang,Liu Jiaqi,Guo Zhengfu,Chen Shengsheng,&Sun Chunqing.(2015).Geochemical Characteristics of Volcanic Rocks from ODP Site 794, Yamato Basin: Implications for Deep Mantle Processes of the Japan Sea.ACTA GEOLOGICA SINICA-ENGLISH EDITION,89(4).
MLA	Chen Shuangshuang,et al."Geochemical Characteristics of Volcanic Rocks from ODP Site 794, Yamato Basin: Implications for Deep Mantle Processes of the Japan Sea".ACTA GEOLOGICA SINICA-ENGLISH EDITION 89.4(2015).