DOI: 10.1038/s41561-020-0609-y
论文题名: Preferential localized thinning of lithospheric mantle in the melt-poor Malawi Rift
作者: Hopper E. ; Gaherty J.B. ; Shillington D.J. ; Accardo N.J. ; Nyblade A.A. ; Holtzman B.K. ; Havlin C. ; Scholz C.A. ; Chindandali P.R.N. ; Ferdinand R.W. ; Mulibo G.D. ; Mbogoni G.
刊名: Nature Geoscience
ISSN: 17520894
出版年: 2020
卷: 13, 期: 8 起始页码: 584
结束页码: 589
语种: 英语
英文关键词: crustal thinning
; extensional tectonics
; high temperature
; lithosphere
; magma
; mantle
; melting
; rifting
; seismic wave
; tectonic plate
; thermochemistry
; Malawi
英文摘要: The forces required to initiate rifting in cratonic plates far exceed the available tectonic forces. High temperatures and resultant melts can weaken the lithosphere, but these factors do not readily explain the extension of old and strong lithosphere in magma-poor rifts, such as the Malawi Rift. Here, new seismic converted-wave imaging shows that even in this magma-poor rift, upper-crustal rift basins are associated with localized preferential thinning of the lithospheric mantle. We calculated the beta factor, the ratio between current and prerift thickness, beneath the rift axis and found crustal beta of 1.7 ± 0.3 and lithospheric-mantle beta of 3.8 ± 1.7. Purely mechanical stretching cannot explain the preferential lithospheric mantle thinning—instead, thinning of the rheological lithosphere was probably augmented by thermochemical rejuvenation and erosion. Although local surface-wave-derived shear-wave velocities preclude a substantially elevated temperature and partial melt today, fusible materials preserved in the lower lithosphere that underlie the Ubendian Belt and its bounding subduction-related sutures in which the Malawi Rift nucleated may have provided an early supply of melt that enabled localized lithospheric alteration and/or removal. A plume-related or other asthenospheric perturbation would preferentially melt the more fusible lithospheric materials and the rising melts would heat and weaken progressively shallower parts of the lithosphere, which spatially localizes weakening (hence the lithospheric-mantle thinning) and enables the onset of rifting. © 2020, The Author(s), under exclusive licence to Springer Nature Limited. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/169617
Appears in Collections: 气候变化与战略
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作者单位: Lamont-Doherty Earth Observatory, Palisades, NY, United States; Northern Arizona University, Flagstaff, AZ, United States; Pennsylvania State University, State College, PA, United States; Syracuse University, Syracuse, NY, United States; Geological Survey of Malawi, Zomba, Malawi; University of Dar es Salaam, Dar es Salaam, Tanzania; Geological Survey of Tanzania, Dodoma, Tanzania
Recommended Citation:
Hopper E.,Gaherty J.B.,Shillington D.J.,et al. Preferential localized thinning of lithospheric mantle in the melt-poor Malawi Rift[J]. Nature Geoscience,2020-01-01,13(8)