Incomplete mixing of isotopically variable melts in the lower oceanic crust and its implications on mantle heterogeneity: Evidence from oceanic cumulates from Mid-Atlantic

doi:10.1016/j.chemgeo.2024.121940

IOCAS-IR

	Incomplete mixing of isotopically variable melts in the lower oceanic crust and its implications on mantle heterogeneity: Evidence from oceanic cumulates from Mid-Atlantic
	Wang, Jixin 1,2; Li, Bing 3,4; Zhang, Fangyi 1,2; Liao, Renqiang1,2 ; Gu, Xiaoyan 5; Li, Congying 1,2; Sun, Weidong1,2,6
	2024-03-20
发表期刊	CHEMICAL GEOLOGY
ISSN	0009-2541
卷号	648 页码:15
通讯作者	Wang, Jixin([email protected]) ; Li, Congying([email protected])
摘要	Abyssal peridotites and mid-ocean ridge basalts (MORB) offer only a partial glimpse into the mantle's composition and the magmatic process beneath the mid-ocean ridges. Recently, lower crustal cumulates have emerged as potential candidates for capturing a broader range of mantle heterogeneity and depicting a detailed process in MORB generating system. However, it remains uncertain to what extent the lower crustal cumulates can represent mantle source variability. In this study, we present detailed in-situ geochemical and isotopic data, including major and trace element compositions of minerals and in-situ Sr isotopic analysis on plagioclase from lower crustal cumulates collected at 14 degrees 45 ' N on the Mid-Atlantic Ridge (MAR). Trace element compositions of melt in equilibrium with clinopyroxenes from the lower crustal cumulates exhibit strong similarities to nearby MORBs. Exception is that the equilibrium melt of the core of a clinopyroxene oikocryst records a transitional MORB composition, different from the more enriched MORB composition at rims. This phenomenon, together with element changing in minerals from cores to rims, suggests a history of melt-rock interactions, during which more enriched melts transport through minerals that had previously crystallized from relatively more depleted melts. The in-situ 87Sr/86Sr ratios, which vary from 0.70249 to 0.70306, span the range of the global MORB Sr isotope values. Thus, both the trace element compositions and 87Sr/86Sr ratios of cumulate minerals confirm the coexistence of depleted and enriched melts. Our findings furtherly suggest that the melts from heterogenous mantle components underwent incomplete mixing in the lower oceanic crust, even in the crystal mush, thus preserving variable heterogeneities not seen in MORB. Through integrated analyses of geochemistry, isotopic data, and geophysical information from existing literature, we identify the most likely mantle components in the study area as depleted peridotites veined with recycled oceanic crust (pyroxenites).
关键词	Incomplete melt mixing Lower crustal gabbros In -situ plagioclase Sr isotopes Mid -Atlantic Ridge Pegmatites
DOI	10.1016/j.chemgeo.2024.121940
收录类别	SCI
语种	英语
资助项目	National Natural Science Foundation of China[NSFC 42006051]; National Natural Science Foundation of China[NSFC 42221005]; National Natural Science Foundation of China[NSFC 42176070]; Shandong Provincial Natural Science Foundation[ZR2020QD075]; Strategic Priority Research Program (B) of Chinese Academy of Sciences[XDB42020303]; State Key Laboratory of Marine Geology, Tongji University[MGK202006]
WOS研究方向	Geochemistry & Geophysics
WOS类目	Geochemistry & Geophysics
WOS记录号	WOS:001172939500001
出版者	ELSEVIER
WOS关键词	TRACE-ELEMENTS ; GEOCHEMICAL MORPHOLOGY ; DEPLETED MANTLE ; HF ISOTOPES ; RIDGE ; PB ; BASALTS ; SR ; BENEATH ; TEMPERATURE
引用统计
文献类型	期刊论文
条目标识符	http://ir.qdio.ac.cn/handle/337002/184841
专题	中国科学院海洋研究所
通讯作者	Wang, Jixin; Li, Congying
作者单位	1.Chinese Acad Sci, Inst Oceanog, Ctr Deep Sea Res, Qingdao 266071, Peoples R China 2.Deep Sea Multidisciplinary Res Ctr, Laoshan Lab, Qingdao 266237, Peoples R China 3.Minist Nat Resources, Metallogeny Inst Oceanog 1, Key Lab Marine Geol, Qingdao 266061, Peoples R China 4.Key Lab Deep Sea Mineral Resources Dev, Shandong Preparatory, Qingdao 266061, Peoples R China 5.Zhejiang Univ, Sch Earth Sci, Key Lab Geosci Big Data & Deep Resource Zhejiang P, Hangzhou 310058, Peoples R China 6.Univ Chinese Acad Sci, Beijing 100049, 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	Wang, Jixin,Li, Bing,Zhang, Fangyi,et al. Incomplete mixing of isotopically variable melts in the lower oceanic crust and its implications on mantle heterogeneity: Evidence from oceanic cumulates from Mid-Atlantic[J]. CHEMICAL GEOLOGY,2024,648:15.
APA	Wang, Jixin.,Li, Bing.,Zhang, Fangyi.,Liao, Renqiang.,Gu, Xiaoyan.,...&Sun, Weidong.(2024).Incomplete mixing of isotopically variable melts in the lower oceanic crust and its implications on mantle heterogeneity: Evidence from oceanic cumulates from Mid-Atlantic.CHEMICAL GEOLOGY,648,15.
MLA	Wang, Jixin,et al."Incomplete mixing of isotopically variable melts in the lower oceanic crust and its implications on mantle heterogeneity: Evidence from oceanic cumulates from Mid-Atlantic".CHEMICAL GEOLOGY 648(2024):15.