globalchange  > 气候变化与战略
DOI: 10.1016/j.epsl.2021.117006
Long-lived low Th/U Pacific-type isotopic mantle domain: Constraints from Nd and Pb isotopes of the Paleo-Asian Ocean mantle
Author: Liu X.; Xu J.-F.; Castillo P.R.; Xiao W.; Shi Y.; Zhang Z.; Wang X.-C.; Ao S.; Wang B.; Hu R.; Shi X.; Yu H.; Liu P.; Song Y.
Source Publication: Earth and Planetary Science Letters
ISSN: 0012821X
Publishing Year: 2021
Volume: 567
Language: 英语
keyword in Chinese: ophiolite ; Pacific and Indian mantle domains ; Paleo-Asian Ocean ; Paleo-Pacific Ocean ; Pb isotope
Keyword: Oceanography ; Continental materials ; Domain constraint ; Large-scales ; Neoproterozoic ; Ophiolite ; Pacific and indian mantle domain ; Paleo-Asian Ocean ; Paleo-pacific ocean ; Pb isotopes ; Upper mantle ; Isotopes ; geodynamics ; heterogeneity ; igneous geochemistry ; igneous intrusion ; isotopic composition ; lead isotope ; mantle chemistry ; mid-ocean ridge ; neodymium isotope ; paleoceanography ; plate tectonics ; Proterozoic ; provenance ; Rodinia ; tectonic setting ; upper mantle ; India ; Tethys
English Abstract: The presence of Pacific-type and Indian-type mid-ocean ridge (MORB) isotopic source domains in the upper mantle is a clear manifestation of global-scale mantle compositional heterogeneities. The Indian-type mantle domain is a long-lived feature that can be traced back to, at least, the Palaeozoic Tethyan mantle domain. Few temporal constraints currently exist, however, regarding the longevity of Pacific-type mantle domain. The extinct Paleo-Asia Ocean (PAO), a subsidiary ocean of the Panthalassic Ocean that formed during the breakup of the Rodinia supercontinent in Mesoproterozoic to Neoproterozoic, can provide a solution to this dilemma. Here, we report the first complete geochemical and Sr, Nd and high-precision Pb isotopic data set for representative mafic rock samples from ophiolites representing remnants of the PAO basement ranging in age from 275 to 624 Ma to constrain the composition of their mantle provenance. Data suggest that the sub-PAO mantle has a similar long time-integrated, high Sm/Nd ratio as the global depleted upper mantle, but also shows typical Pacific MORB-like Pb isotopic compositions with lower 207Pb/204Pb(t) and 208Pb/204Pb(t) for given 206Pb/204Pb(t) ratios, and low radiogenic 208Pb*/206Pb*, indicating a long time-integrated, low Th/U ratio. Thus, the Pacific-type mantle domain, like the Indian-type mantle domain, is a long-lived secular mantle domain that can be traced back to early Paleozoic or even to the Neoproterozoic. Data further indicate that the Nd and Pb isotopic distinction between such two large-scale and long-term mantle domains is due to the different evolutionary and tectonic histories of the circum-Pacific (PAO, Paleo- and modern Pacific) and sub-Tethys-Indian oceanic mantle realms. Our results indicate that the high Sm/Nd and low Th/U ratio of Pacific-type mantle domain most likely are an inherited, long-standing intrinsic feature of the depleted upper mantle derived from the Earth's primordial mantle with less contamination of continental materials. In contrast, the large-scale and long-lived Indian-type mantle heterogeneity is produced by plate tectonic-driven continental material circulation in the upper mantle. Such a genetic link between plate tectonics and mantle chemical geodynamics is crucial to our understanding of how the Earth system works. © 2021 Elsevier B.V.
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Document Type: 期刊论文
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Affiliation: Guangxi Key Laboratory of Hidden Metallic Ore Deposits Exploration, College of Earth Sciences, Guilin University of Technology, Guilin, 541004, China; State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing, 100083, China; Xinjiang Research Center for Mineral Resources, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, 830011, China; Scripps Institution of Oceanography, UCSD, La Jolla, CA 92093, United States; State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029, China; School of Earth Sciences, Yunnan University, Kunming, 650500, China; Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266061, China; Collaborative Innovation Center for Exploration of Nonferrous Metal Deposits and Efficient Utilization of Resource, Guilin University of Technology, Guilin, 541004, China

Recommended Citation:
Liu X.,Xu J.-F.,Castillo P.R.,et al. Long-lived low Th/U Pacific-type isotopic mantle domain: Constraints from Nd and Pb isotopes of the Paleo-Asian Ocean mantle[J]. Earth and Planetary Science Letters,2021-01-01,567
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