DOI: 10.1016/j.epsl.2019.116002
论文题名: Plate-driven micro-hotspots and the evolution of the Dragon Flag melting anomaly, Southwest Indian Ridge
作者: Yu X. ; Dick H.J.B.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2020
卷: 531 语种: 英语
中文关键词: heterogeneity
; magma evolution
; melting anomaly
; micro-hotspot
; ridge-hotspot interaction
; Southwest Indian Ridge
英文关键词: Isotopes
; Tectonics
; Trace elements
; Volcanoes
; Bathymetric trends
; heterogeneity
; Hot spot
; Isotopic composition
; Magma evolution
; Southwest Indian Ridge
; Tectonic stress fields
; Ultra-slow spreading
; Melting
; heterogeneity
; hot spot
; isotopic composition
; magma
; mantle
; melting
; plate tectonics
; trace element
; volcanism
; Indian Ocean
; Southwest Indian Ridge
英文摘要: Micro hotspots represent excess volcanism at the ultraslow spreading Southwest Indian Ridge (SWIR) unrelated to mantle hotspots, but to focused melt flow in the mantle, wide volcano spacing, and/or increased mantle fertility. Individual micro hotspot can reflect variations in regional mantle fertility, simultaneously affecting 100's of km of ridge, or extreme melt focusing to isolated segments in regions with unusually thick lithosphere. The Dragon Flag melting anomaly, erupting isotopically moderately depleted low-K tholeiite, is the best example of the former: an enormous ridge-centered volcano at 50.5°E. It is far from Crozet, and lies at the apex of a V-shaped trace consisting of ∼1 km anomalously elevated seafloor that extends ∼400 km to the northwest and southeast, indicating a sudden onset of excess volcanism at ∼11-8 Ma. This trend is opposite to that predicted by the hotspot framework, with inconsistent geochemistry. Narrowgate at 14.7°E is one of many micro hotspots that represent isolated large volcanic centers bounded by long amagmatic ridge sections. It also lies at the apex of an eastward V-shaped bathymetric trend, but erupts large volumes of alkali basalt. Both micro hotspot varieties are an order of magnitude smaller than Wilson's classic hotspots, and are not fixed in the hotspot referenced frame. They can grow and remain stationary for extended periods, or migrate freely with respect to each other; driven by the evolving plate tectonic stress field. Dragon Flag, represents a plate reorganization during a prolong period of enhanced melt supply. Narrowgate, on the other hand represents excess volcanism due to extreme deep melt focusing of low degree melt from an unusually wide region in the mantle to an isolated volcanic segment where thick lithosphere caps melting at great depth. To constrain the origins of the micro hotspots six examples are evaluated in terms of their major and isotopic composition, prior plate history, depth and extent of melting and tectonic context. This includes new major, trace element, and heavy isotope data for the Dragon Flag Supersegment, and unpublished data for the Joseph Mayes and Narrowgate segments. © 2019 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165371
Appears in Collections: 气候变化与战略
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作者单位: Key Laboratory of Submarine Geosciences, State Oceanic Administration, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, 310012, China; Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, United States
Recommended Citation:
Yu X.,Dick H.J.B.. Plate-driven micro-hotspots and the evolution of the Dragon Flag melting anomaly, Southwest Indian Ridge[J]. Earth and Planetary Science Letters,2020-01-01,531