DOI: 10.1016/j.epsl.2020.116386
论文题名: Mantle degassing of primordial helium through submarine ridge flank basaltic basement
作者: Lin H.-T. ; Lilley M.D. ; Lupton J.E. ; Rappé M.S.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2020
卷: 546 语种: 英语
中文关键词: 3He mantle degassing
; abiotic methane
; basement fluids
; deep subseafloor
; mantle-crust boundary
; ridge flank
英文关键词: Aquifers
; Basalt
; Buildings
; Degassing
; Heat flux
; Helium
; Methane
; Submarine geology
; Submarines
; Earth's interior
; High temperature
; Hydrothermal plume
; Hydrothermal system
; Mantle degassing
; Methane production
; Mid-ocean ridges
; Subduction zones
; Air
; basalt
; degassing
; heat flux
; helium
; hydrothermal fluid
; hydrothermal system
; hydrothermal vent
; mantle structure
; methane
; mid-ocean ridge
; subduction zone
; submarine ridge
; volcanism
; Juan de Fuca Ridge
; Pacific Ocean
英文摘要: The degassing of primordial gases from Earth's interior is evidenced by the high He3/4He ratios in submarine hydrothermal plumes, vent fluids, and rock samples with mantle origin from active hydrothermal systems in mid-ocean ridges (MOR) and subduction zone volcanism. As the largest aquifer on Earth, the uppermost 40-500 m of permeable submarine ridge flank basement (1-65 million-years-old, Myr) holds ∼2% of the ocean volume and accounts for 70% of the seafloor hydrothermal heat flux. However, the degassing of primordial gases through the oceanic ridge flank crust has not yet been directly quantified. Here, we show that high integrity hydrothermal (65 °C) fluids from the sediment-buried 3.5 Myr basaltic crust from the eastern flank of the Juan de Fuca Ridge (JdFR) contain elevated 3He. The He3/4He for the basaltic fluid is 4.5 ± 0.1 Ra (relative to the air ratio), which is greatly elevated when compared to deep seawater (1.05 Ra), but is half of that observed for high-temperature vent fluids (∼8 Ra) emitting from MOR. Only a small fraction of the 3He in ridge flank fluids is derived from the entrainment of high-temperature ridge-axis fluids and is better explained by degassing of the mantle through the mantle-crust boundary. The lower than MOR He3/4He ratios indicate that radiogenic 4He originates from aged uranium and thorium decay within the mantle as well as from the ridge-flank basalts. The 3He outgassing through warm ridge flanks (4.9 to 36 mol/yr) accounts for 0.7-6% of the global 3He outgassing, exceeded only by degassing through mid-ocean ridges and subduction volcanism. The presence of mantle 3He suggests that the abiogenic methane present in the ridge flank fluids might be mantle-derived. Based on the 3He outgassing flux, a possibly mantle-derived abiotic methane production rate at the ridge flank is estimated to be 0.3–35×108mol/yr. © 2020 Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165119
Appears in Collections: 气候变化与战略
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作者单位: Institute of Oceanography, National Taiwan University, No. 1, Sec. 4 Roosevelt Road, Taipei City, 10617, Taiwan; Department of Oceanography, School of Ocean and Earth Science and Technology, University of Hawaii, 1000 Pope Road, Honolulu, HI 96822, United States; School of Oceanography, University of Washington, Box 355351, 1503 NE Boat Street, Seattle, WA 98195, United States; Cooperative Institute of Marine Resources Studies (CIMRS), Oregon State University, Newport, OR 97365, United States; Hawaii Institute of Marine Biology, University of Hawaii, P.O. Box 1346, Kaneohe, HI 96744, United States
Recommended Citation:
Lin H.-T.,Lilley M.D.,Lupton J.E.,et al. Mantle degassing of primordial helium through submarine ridge flank basaltic basement[J]. Earth and Planetary Science Letters,2020-01-01,546