Approach to trace hidden paleo-weathering of basaltic crust through decoupled Mg-Sr and Nd isotopes recorded in volcanic rocks

doi:10.1016/j.chemgeo.2019.01.019

CORC > 地质与地球物理研究所 > 中国科学院地质与地球物理研究所 > 中国科学院地球与行星物理重点实验室

	Approach to trace hidden paleo-weathering of basaltic crust through decoupled Mg-Sr and Nd isotopes recorded in volcanic rocks
	Tian, Heng-Ci 1,2; Yang, Wei 1,2; Li, Shu-Guang 3; Wei, Hai-Quan 4; Yao, Zhuo-Sen 5; Ke, Shan 3
刊名	CHEMICAL GEOLOGY
	2019-03-30
卷号	509 页码:234-248
关键词	Hidden paleo-weathering of crust Sr-Nd-Mg isotopes AFC processes Chemical weathering Changbaishan volcanic rocks
ISSN号	0009-2541
DOI	10.1016/j.chemgeo.2019.01.019
英文摘要	On Earth, chemical weathering of basaltic rocks not only modulates the climate change, but also plays a crucial role on the ocean oxygenation and ecosystem evolution. Records of paleo-weathered crusts are a challenge to identify because they are obscured by subsequent alteration processes and buried by the newly formed volcanic lavas. However, late formed volcanic rocks theoretically could record previously weathered crust via their assimilation and fractional crystallization (AFC) processes. Here, we present a systematic study on major, trace elements and Sr-Nd-Mg isotopes in a suite of Changbaishan early formed basalts and late erupted trachytes from Northeast China. Detailed evidence of field observation, geochemical signature and rhyolite-MELTS simulations suggest that trachytes mainly originated from deep fractional crystallization of basaltic melts. The low abundant trachytes from the stratigraphic layer above the basalts display decoupled Mg-Sr and Nd isotopes. delta Mg-26 and Sr-87/Sr-86 in trachytes range from - 0.27 up to + 0.94 parts per thousand (the heaviest isotopic composition ever reported for Mg in the igneous rocks) and 0.70490 to 0.71065, respectively, which are significantly elevated relative to that of their mantle source. However, they preserved mantle source-like Nd-143/Nd-144 (0.512584 to 0.512656) ratios. These unusual characteristics cannot be explained by thermal diffusion, fractional crystallization or simple crustal contamination processes. Specifically, delta Mg-26 correlates positively with SiO2 and Sr-87/Sr-86, and negatively with MgO, CaO, Al2O3, Sr and Nb/U indicators. The highly elevated Mg and Sr isotopes but limited Nd isotopic changes in trachytes require a component to be the relatively younger weathering residue of basaltic rocks. Taking this component as a wall rock endmember, the well-developed above correlations can be best modelled by AFC processes. This reflects that some trachytes in the aftermath of AFC processes almost fully lost their primary source characteristics, but inherited the intense chemical weathering signature of basalts. This event probably occurred in the middle Miocene as studies of paleosols showed humid and warm climate during that period after the initial eruption of Changbaishan basalts. Therefore, our study as a specific case for the first time provides an efficient way to explore paleo-weathering of basaltic crusts buried in the Earths surface, through comprehensive investigating Mg, Sr and Nd isotopes of volcanic rocks developed in the late stage of a volcano cone.
资助项目	Strategic Priority Research Program of the Chinese Academy of Sciences[XDB18000000] ; National Natural Science Foundation of China[41730214] ; National Postdoctoral Program[2018M631566] ; National Postdoctoral Program for Innovative Talents[BX201700237]
WOS关键词	CHANGBAISHAN-TIANCHI VOLCANO ; ATMOSPHERIC CARBON-DIOXIDE ; CHINA/NORTH KOREA ; MAGMA EVOLUTION ; BAEKDUSAN CHANGBAISHAN ; RIVER GEOCHEMISTRY ; MANTLE XENOLITHS ; NORTHEAST CHINA ; TIBETAN PLATEAU ; GLOBAL CLIMATE
WOS研究方向	Geochemistry & Geophysics
语种	英语
出版者	ELSEVIER SCIENCE BV
WOS记录号	WOS:000459780600016
资助机构	Strategic Priority Research Program of the Chinese Academy of Sciences ; Strategic Priority Research Program of the Chinese Academy of Sciences ; Strategic Priority Research Program of the Chinese Academy of Sciences ; Strategic Priority Research Program of the Chinese Academy of Sciences ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; National Postdoctoral Program ; National Postdoctoral Program ; National Postdoctoral Program ; National Postdoctoral Program ; National Postdoctoral Program for Innovative Talents ; National Postdoctoral Program for Innovative Talents ; National Postdoctoral Program for Innovative Talents ; National Postdoctoral Program for Innovative Talents ; Strategic Priority Research Program of the Chinese Academy of Sciences ; Strategic Priority Research Program of the Chinese Academy of Sciences ; Strategic Priority Research Program of the Chinese Academy of Sciences ; Strategic Priority Research Program of the Chinese Academy of Sciences ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; National Postdoctoral Program ; National Postdoctoral Program ; National Postdoctoral Program ; National Postdoctoral Program ; National Postdoctoral Program for Innovative Talents ; National Postdoctoral Program for Innovative Talents ; National Postdoctoral Program for Innovative Talents ; National Postdoctoral Program for Innovative Talents ; Strategic Priority Research Program of the Chinese Academy of Sciences ; Strategic Priority Research Program of the Chinese Academy of Sciences ; Strategic Priority Research Program of the Chinese Academy of Sciences ; Strategic Priority Research Program of the Chinese Academy of Sciences ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; National Postdoctoral Program ; National Postdoctoral Program ; National Postdoctoral Program ; National Postdoctoral Program ; National Postdoctoral Program for Innovative Talents ; National Postdoctoral Program for Innovative Talents ; National Postdoctoral Program for Innovative Talents ; National Postdoctoral Program for Innovative Talents ; Strategic Priority Research Program of the Chinese Academy of Sciences ; Strategic Priority Research Program of the Chinese Academy of Sciences ; Strategic Priority Research Program of the Chinese Academy of Sciences ; Strategic Priority Research Program of the Chinese Academy of Sciences ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; National Natural Science Foundation of China ; National Postdoctoral Program ; National Postdoctoral Program ; National Postdoctoral Program ; National Postdoctoral Program ; National Postdoctoral Program for Innovative Talents ; National Postdoctoral Program for Innovative Talents ; National Postdoctoral Program for Innovative Talents ; National Postdoctoral Program for Innovative Talents
内容类型	期刊论文
源URL	[http://ir.iggcas.ac.cn/handle/132A11/90701]
专题	地质与地球物理研究所_中国科学院地球与行星物理重点实验室
通讯作者	Tian, Heng-Ci; Li, Shu-Guang
作者单位	1.Chinese Acad Sci, Inst Geol & Geophys, Key Lab Earth & Planetary Phys, Beijing 100029, Peoples R China 2.Chinese Acad Sci, Inst Earth Sci, Beijing 100029, Peoples R China 3.China Univ Geosci, State Key Lab Geol Proc & Mineral Resources, Beijing 100083, Peoples R China 4.China Earthquake Adm, Inst Geol, Beijing 100029, Peoples R China 5.Chinese Acad Sci, Inst Geol & Geophys, Key Lab Mineral Resources, Beijing 100029, Peoples R China
推荐引用方式 GB/T 7714	Tian, Heng-Ci,Yang, Wei,Li, Shu-Guang,et al. Approach to trace hidden paleo-weathering of basaltic crust through decoupled Mg-Sr and Nd isotopes recorded in volcanic rocks[J]. CHEMICAL GEOLOGY,2019,509:234-248.
APA	Tian, Heng-Ci,Yang, Wei,Li, Shu-Guang,Wei, Hai-Quan,Yao, Zhuo-Sen,&Ke, Shan.(2019).Approach to trace hidden paleo-weathering of basaltic crust through decoupled Mg-Sr and Nd isotopes recorded in volcanic rocks.CHEMICAL GEOLOGY,509,234-248.
MLA	Tian, Heng-Ci,et al."Approach to trace hidden paleo-weathering of basaltic crust through decoupled Mg-Sr and Nd isotopes recorded in volcanic rocks".CHEMICAL GEOLOGY 509(2019):234-248.