Sublithosphere Mantle Crystallization and Immiscible Sulfide Melt Segregation in Continental Basalt Magmatism: Evidence from Clinopyroxene Megacrysts in the Cenozoic Basalts of Eastern China

doi:10.1093/petrology/egac001

IOCAS-IR > 海洋地质与环境重点实验室

	Sublithosphere Mantle Crystallization and Immiscible Sulfide Melt Segregation in Continental Basalt Magmatism: Evidence from Clinopyroxene Megacrysts in the Cenozoic Basalts of Eastern China
	Sun, Pu1,2 ; Niu, Yaoling 2,3,4; Guo, Pengyuan 1,2; Duan, Meng 1,2; Wang, Xiaohong 1,2; Gong, Hongmei 1,2
	2022-02-03
发表期刊	JOURNAL OF PETROLOGY
ISSN	0022-3530
卷号	63 期号:2 页码:27
通讯作者	Sun, Pu(pu.sun@gdio.ac.cn)
摘要	This study explores the effects of high-pressure crystallization and immiscible sulfide melt segregation under mantle conditions on the compositional variation of basaltic magmas, using clinopyroxene megacrysts in the Cenozoic basalts of eastern China. These clinopyroxene megacrysts are large (up to >10 cm in size) and homogeneous at the grain scale. They were crystallized from variably evolved parental magmas and then captured by their host basalts. The large and systematic variations of [Sm/Yb](N), Lu/Hf, Fe/Mn, Sc/La, Ni and Cu with Mg-# in the clinopyroxene megacrysts suggest their co-precipitation with garnet and with immiscibility between sulfide and silicate melts. This is consistent with the appearance of garnet megacrysts in the host basalts and abundant sulfide globules in the clinopyroxene megacrysts. The covariation between Ni contents of sulfide globules and Mg-# of the clinopyroxene megacrysts suggests a genetic relationship between sulfide globules and clinopyroxene megacrysts. High-pressure crystallization of clinopyroxene and garnet results in decrease of Mg-# and concentrations of CaO, MnO and heavy rare earth elements (e.g. Yb) and increase of Fe/Mn and [Sm/Yb](N) in the residual melts. Therefore, geochemical characteristics of low Mg-#, low CaO and MnO contents and high Fe/Mn and [Sm/Yb](N) in basalts do not necessarily indicate a pyroxenite mantle source. In addition, caution is needed when applying the olivine addition method to infer the primary compositions of alkali basalts without considering the effects of high-pressure crystallization of clinopyroxene and garnet. The calculated pressure (P) and temperature (T) conditions of the clinopyroxene megacrysts are close to those of the lithosphere-asthenosphere boundary (LAB) beneath eastern China, and the low primitive [Sm/Yb](N) (similar to 4.0) of melts parental to the clinopyroxene megacrysts suggests final equilibration at relatively low pressures most likely beneath the LAB. Hence, a melt-rich layer is expected close beneath the LAB. Melt pools in this melt-rich layer provide a stable and closed environment for the growth of compositionally homogeneous clinopyroxene megacrysts. As a result, melts in these melt pools are compositionally evolved with low and variable Mg-#. Subsequent pulses of melt aggregation/supply from depths with primitive compositions and high Mg-# will disturb these melt pools, cause magma mixing and trigger the eruption of magmas carrying clinopyroxene and garnet megacrysts.
关键词	Cenozoic basalts in continental eastern China clinopyroxene megacryst high-pressure crystallization lithosphere-asthenosphere boundary immiscibility between sulfide and silicate melts
DOI	10.1093/petrology/egac001
收录类别	SCI
语种	英语
资助项目	Shandong Provincial Natural Science Foundation[ZR2020MD029] ; National Natural Science Foundation of China (NSFC)[41630968] ; National Natural Science Foundation of China (NSFC)[42006049] ; NSFC-Shandong Joint Fund for Marine Science Research Centers[U1606401] ; Qingdao National Laboratory for Marine Science and Technology[2015ASKJ03] ; 111 Project[B18048]
WOS研究方向	Geochemistry & Geophysics
WOS类目	Geochemistry & Geophysics
WOS记录号	WOS:000755308100001
出版者	OXFORD UNIV PRESS
引用统计	被引频次：6[WOS] [WOS记录] [WOS相关记录]
文献类型	期刊论文
条目标识符	http://ir.qdio.ac.cn/handle/337002/178021
专题	海洋地质与环境重点实验室
通讯作者	Sun, Pu
作者单位	1.Chinese Acad Sci, Inst Oceanol, Key Lab Marine Geol & Environm, 7 Nanhai Rd, Qingdao 266071, Peoples R China 2.Qingdao Natl Lab Marine Sci & Technol, Lab Marine Geol, 168 Wenhai Rd, Qingdao 266061, Peoples R China 3.Univ Durham, Dept Earth Sci, Durham DH1 3LE, England 4.China Univ Geosci, Sch Earth Sci & Resources, 29 Xueyuan Rd, Beijing 100083, Peoples R China
第一作者单位	中国科学院海洋研究所
通讯作者单位	中国科学院海洋研究所
推荐引用方式 GB/T 7714	Sun, Pu,Niu, Yaoling,Guo, Pengyuan,et al. Sublithosphere Mantle Crystallization and Immiscible Sulfide Melt Segregation in Continental Basalt Magmatism: Evidence from Clinopyroxene Megacrysts in the Cenozoic Basalts of Eastern China[J]. JOURNAL OF PETROLOGY,2022,63(2):27.
APA	Sun, Pu,Niu, Yaoling,Guo, Pengyuan,Duan, Meng,Wang, Xiaohong,&Gong, Hongmei.(2022).Sublithosphere Mantle Crystallization and Immiscible Sulfide Melt Segregation in Continental Basalt Magmatism: Evidence from Clinopyroxene Megacrysts in the Cenozoic Basalts of Eastern China.JOURNAL OF PETROLOGY,63(2),27.
MLA	Sun, Pu,et al."Sublithosphere Mantle Crystallization and Immiscible Sulfide Melt Segregation in Continental Basalt Magmatism: Evidence from Clinopyroxene Megacrysts in the Cenozoic Basalts of Eastern China".JOURNAL OF PETROLOGY 63.2(2022):27.