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标题：Accretion of the cratonic mantle lithosphere via massive regional relamination
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作者：Zhensheng Wang ; Fabio A. Capitanio ; Zaicong Wang 等
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2022
卷号：119
期号：39
DOI：10.1073/pnas.2201226119
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Significance The continental lithospheric mantle contains regionally distinct domains with different ages, compositions, and sources, recording diverse formation mechanisms. Geodynamics modeling demonstrates that the delamination of depleted older and unrelated exotic continental lithospheric mantle allows sinking and mixing with the mantle. The multiscale heterogeneities formed retain most of the original chemical buoyancy and are embedded beneath distant plates in massive regional relamination (MRR) events. MRR events occurred episodically for tens to hundreds of Myr and likely contributed to the formation of most of the continental lithospheric mantle . The models provide constraints on the distribution, size, transportation, timescale, mixing, and relamination of different continental lithospheric mantle relicts throughout Earth’s history. Continental, orogenic, and oceanic lithospheric mantle embeds sizeable parcels of exotic cratonic lithospheric mantle (CLM) derived from distant, unrelated sources. This hints that CLM recycling into the mantle and its eventual upwelling and relamination at the base of younger plates contribute to the complex structure of the growing lithosphere. Here, we use numerical modeling to investigate the fate and survival of recycled CLM in the ambient mantle and test the viability of CLM relamination under Hadean to present-day mantle temperature conditions and its role in early lithosphere evolution. We show that the foundered CLM is partially mixed and homogenized in the ambient mantle; then, as thermal negative buoyancy vanishes, its long-lasting compositional buoyancy drives upwelling, relaminating unrelated growing lithospheric plates and contributing to differentiation under cratonic, orogenic, and oceanic regions. Parts of the CLM remain in the mantle as diffused depleted heterogeneities at multiple scales, which can survive for billions of years. Relamination is maximized for high depletion degrees and mantle temperatures compatible with the early Earth, leading to the upwelling and underplating of large volumes of foundered CLM, a process we name massive regional relamination (MRR). MRR explains the complex source, age, and depletion heterogeneities found in ancient cratonic lithospheric mantle, suggesting this may have been a key component of the construction of continents in the early Earth.
关键词：encratonlithospheric mantlemantle heterogeneitiesrelamination