气候变化领域集成服务门户(CCPortal): Lateral Variations in Thermochemical Structure of the Eastern Canadian Shield

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DOI	10.1029/2019JB018734
	Lateral Variations in Thermochemical Structure of the Eastern Canadian Shield
	Eeken T.; Goes S.; Petrescu L.; Altoe I.
发表日期	2020
ISSN	21699313
卷号	125 期号:7
英文摘要	The origin of 3-D seismic heterogeneity in Precambrian lithosphere has been enigmatic, because temperature variations in old stable shields are expected to be small and seismic sensitivity to major-element compositional variations is limited. Previous studies indicate that metasomatic alteration may significantly affect average 1-D structure below shields. Here, we perform a grid search for 3-D thermochemical structure, including variations in alteration, to model published Rayleigh wave phase velocities between 20 and 160 s for the eastern part of the Archean Superior and Canadian Proterozoic Grenville Provinces. We find that, consistent with constraints from surface heat flow and xenoliths, the lithosphere is coolest (Moho heat flow 12–17 mW/m2) and the thermal boundary layer thickest (>250 km) in the northeastern Superior and warmest in the southeastern Grenville (Moho heat flow 20–25 mW/m2, thermal boundary thickness 160–200 km). Compositionally, the phase velocities for most of the Superior within our study region require little alteration, but in a few regions, fast velocities need to overlie slower velocities. These can be modeled with an eclogite layer in the midlithosphere, consistent with active seismic and xenolith evidence for remnants of subducted Archean crust. The phase velocities from the Grenville Province require significant metasomatic modification to explain the relatively low velocities of the shallow lithosphere, and the required intensity of alteration is highest in parts of the Grenville associated with arc accretion. Thus, the composition of the northeastern Canadian Shield appears to reflect different stages and styles of craton assembly. ©2020. American Geophysical Union. All Rights Reserved.
英文关键词	craton; geotherm; lithosphere; metasomatic alteration; Rayleigh wave dispersion
语种	英语
来源期刊	Journal of Geophysical Research: Solid Earth
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/187793
作者单位	Department of Earth Science and Engineering, Imperial College London, London, United Kingdom; Istituto Nazionale di Geofisica e Vulcanologia, Bologna, Italy; Now at National Institute for Earth Physics, Bucharest, Romania
推荐引用方式 GB/T 7714	Eeken T.,Goes S.,Petrescu L.,et al. Lateral Variations in Thermochemical Structure of the Eastern Canadian Shield[J],2020,125(7).
APA	Eeken T.,Goes S.,Petrescu L.,&Altoe I..(2020).Lateral Variations in Thermochemical Structure of the Eastern Canadian Shield.Journal of Geophysical Research: Solid Earth,125(7).
MLA	Eeken T.,et al."Lateral Variations in Thermochemical Structure of the Eastern Canadian Shield".Journal of Geophysical Research: Solid Earth 125.7(2020).