DOI: 10.1038/ngeo2170
论文题名: Earth's earliest evolved crust generated in an Iceland-like setting
作者: Reimink J.R. ; Chacko T. ; Stern R.A. ; Heaman L.M.
刊名: Nature Geoscience
ISSN: 17520894
出版年: 2014
卷: 7, 期: 7 起始页码: 529
结束页码: 533
语种: 英语
Scopus关键词: continental crust
; crustal evolution
; gneiss
; igneous geochemistry
; igneous rock
; magmatism
; oceanic crust
; outcrop
; silica
; tectonic setting
; tonalite
; Arctic
; Canada
; Greenland
; Iceland
; Acasta
英文摘要: It is unclear how the earliest continental crust formed on an Earth that was probably originally surfaced with oceanic crust. Continental crust may have first formed in an ocean island-like setting, where upwelling mantle generates magmas that crystallize to form new crust. Of the oceanic plateaux, Iceland is closest in character to continental crust, because its crust is anomalously thick1 and contains a relatively high proportion of silica-rich (sialic) rocks2. Iceland has therefore been considered a suitable analogue for the generation of Earth's earliest continental crust3. However, the geochemical signature of sialic rocks from Iceland4-7 is distinct from the typical 3.9- to 2.5-billion-year-old Archaean rocks discovered so far8. Here we report the discovery of an exceptionally well-preserved, 4.02-billion-year-old tonalitic gneiss rock unit within the Acasta Gneiss Complex in Canada. We use geochemical analyses to show that this rock unit is characterized by iron enrichment, negative Europium anomalies, unfractionated rare-earth-element patterns, and magmatic zircons with low oxygen isotope ratios. These geochemical characteristics are unlike typical Archaean igneous rocks, but are strikingly similar to those of the sialic rocks from Iceland and imply that this ancient rock unit was formed by shallow-level magmatic processes that include assimilation of rocks previously altered by surface waters. Our data provide direct evidence that Earth's earliest continental crust formed in a tectonic setting comparable to modern Iceland. © 2014 Macmillan Publishers Limited. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/106467
Appears in Collections: 气候减缓与适应 科学计划与规划
There are no files associated with this item.
作者单位: Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, AB, T6G 2E3, Canada; Canadian Centre for Isotopic Microanalysis, University of Alberta, Edmonton, AB, T6G 2E3, Canada
Recommended Citation:
Reimink J.R.,Chacko T.,Stern R.A.,et al. Earth's earliest evolved crust generated in an Iceland-like setting[J]. Nature Geoscience,2014-01-01,7(7)