DOI: 10.1016/j.epsl.2018.01.032
Scopus记录号: 2-s2.0-85044252834
论文题名: Formation of fast-spreading lower oceanic crust as revealed by a new Mg–REE coupled geospeedometer
作者: Sun C. ; Lissenberg C.J.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2018
卷: 487 起始页码: 165
结束页码: 178
语种: 英语
英文关键词: clinopyroxene
; cooling rate
; crystallization temperature
; Hess Deep
; oceanic crust
; plagioclase
Scopus关键词: Accelerometers
; Exploratory geochemistry
; Feldspar
; Magnesium
; Silica
; Stratigraphy
; Structural geology
; Thermometers
; Clinopyroxenes
; Cooling rates
; Crystallization temperature
; Hess Deep
; Oceanic crust
; plagioclase
; Cooling
英文摘要: A new geospeedometer is developed based on the differential closures of Mg and rare earth element (REE) bulk-diffusion between coexisting plagioclase and clinopyroxene. By coupling the two elements with distinct bulk closure temperatures, this speedometer can numerically solve the initial temperatures and cooling rates for individual rock samples. As the existing Mg-exchange thermometer was calibrated for a narrow temperature range and strongly relies on model-dependent silica activities, a new thermometer is developed using literature experimental data. When the bulk closure temperatures of Mg and REE are determined, respectively, using this new Mg-exchange thermometer and the existing REE-exchange thermometer, this speedometer can be implemented for a wide range of compositions, mineral modes, and grain sizes. Applications of this new geospeedometer to oceanic gabbros from the fast-spreading East Pacific Rise at Hess Deep reveal that the lower oceanic crust crystallized at temperatures of 998–1353 °C with cooling rates of 0.003–10.2 °C/yr. Stratigraphic variations of the cooling rates and crystallization temperatures support deep hydrothermal circulations and in situ solidification of various replenished magma bodies. Together with existing petrological, geochemical and geophysical evidence, results from this new speedometry suggest that the lower crust formation at fast-spreading mid-ocean ridges involves emplacement of primary mantle melts in the deep section of the crystal mush zone coupled with efficient heat removal by crustal-scale hydrothermal circulations. The replenished melts become chemically and thermally evolved, accumulate as small magma bodies at various depths, feed the shallow axial magma chamber, and may also escape from the mush zone to generate off-axial magma lenses. © 2018 The Authors Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/110001
Appears in Collections: 影响、适应和脆弱性 气候变化事实与影响
There are no files associated with this item.
作者单位: Department of Earth, Environmental and Planetary Sciences, Rice University, United States; Department of Geology and Geophysics, Woods Hole Oceanographic Institution, United States; School of Earth and Ocean Sciences, Cardiff University, United Kingdom
Recommended Citation:
Sun C.,Lissenberg C.J.. Formation of fast-spreading lower oceanic crust as revealed by a new Mg–REE coupled geospeedometer[J]. Earth and Planetary Science Letters,2018-01-01,487