气候变化领域集成服务门户(CCPortal): The Transition Zone Beneath West Argentina-Central Chile Using P-to-S Converted Waves

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DOI	10.1029/2020JB019446
	The Transition Zone Beneath West Argentina-Central Chile Using P-to-S Converted Waves
	Bonatto L.; Piromallo C.; Cottaar S.
发表日期	2020
ISSN	21699313
卷号	125 期号:8
英文摘要	We investigate the mantle transition zone beneath the Chile-Argentina flat subduction region by means of P-to-S conversions at mantle discontinuities from teleseismic events recorded at 103 seismic stations. From the analysis of receiver functions, we obtain clear converted phases from the 410 and 660 discontinuities, and we identify a robust precursory signal to P660s, of negative amplitude, that we name P590s. We observe little frequency dependence in the amplitude of the P410s converted phase, while the P660s is less visible toward higher frequencies. The 410 is on average deeper than 410 km by 10 ± 1 km in the higher-frequency bands, and it is relatively sharp, being consistent with a 10% velocity jump over less than 20 km. The observed 660 depth varies with frequency; it is deeper by up to 18 ± 2 km for lower frequencies and close to reference at higher frequencies, being consistent with a 13% broad velocity gradient over 30–40 km, probably caused by a composite of multiple phase transitions. The transition zone thickness is controlled by the frequency-dependent depth variability of the 660. Our findings of relative depth, width, and velocity jump of the detected discontinuities, combined with tomographic images of the mantle transition zone, cannot be explained by thermal variations alone. Compositional constraints from mineral physics show that a near pyrolitic mantle is consistent with the ratio of the estimated velocity jumps. However, the negative P590s phase in this region could be signal from the velocity reduction due to basalt accumulation at the base of the transition zone. ©2020. American Geophysical Union. All Rights Reserved.
英文关键词	mantle transition zone; Pampean flat slab; receiver functions; seismic discontinuities; seismology; transition zone composition
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/187712
作者单位	Department of Physics, University of La Serena, La Serena, Región de Coquimbo, Chile; Istituto Nazionale di Geofisica e Vulcanologia, Rome, Italy; Department of Earth Sciences, University of Cambridge, Cambridge, United Kingdom
推荐引用方式 GB/T 7714	Bonatto L.,Piromallo C.,Cottaar S.. The Transition Zone Beneath West Argentina-Central Chile Using P-to-S Converted Waves[J],2020,125(8).
APA	Bonatto L.,Piromallo C.,&Cottaar S..(2020).The Transition Zone Beneath West Argentina-Central Chile Using P-to-S Converted Waves.Journal of Geophysical Research: Solid Earth,125(8).
MLA	Bonatto L.,et al."The Transition Zone Beneath West Argentina-Central Chile Using P-to-S Converted Waves".Journal of Geophysical Research: Solid Earth 125.8(2020).