气候变化领域集成服务门户(CCPortal): Topography of the 410 and 660 km Discontinuities Beneath the Cenozoic Okavango Rift Zone and Adjacent Precambrian Provinces

CCPortal

DOI	10.1029/2019JB019290
	Topography of the 410 and 660 km Discontinuities Beneath the Cenozoic Okavango Rift Zone and Adjacent Precambrian Provinces
	Yu Y.; Gao S.S.; Liu K.H.
发表日期	2020
ISSN	21699313
卷号	125 期号:9
英文摘要	By taking advantage of the recent availability of a broadband seismic data set from Networks NR and BX covering the entire country of Botswana, we conduct a systematic receiver function investigation of the topography of the 410 and 660 km discontinuities beneath the incipient Okavango rift zone (ORZ) in northern Botswana and its adjacent Archean-Proterozoic tectonic provinces in southern Africa. Similar to a previous mantle transition zone (MTZ) discontinuity study using data from a 1-D profile traversing the ORZ, a normal MTZ thickness is observed in most parts of the study area. This is inconsistent with the existence of widespread positive thermal anomalies in the MTZ and further implies that active thermal upwelling from the lower mantle plays an insignificant role in the initiation of continental rifting. The results also suggest that cold temperature presumably associated with thick cratonic keels has indiscernible influence on the thermal structure of the MTZ. The expanded data set reveals several isolated areas of slight (~10 km or smaller) MTZ thinning. The largest of such areas has a NE-SW elongated shape and is mostly caused by relative deepening of the 410 km discontinuity rather than shallowing of the 660 km discontinuity. These characteristics are different from those expected for a typical mantle plume. We speculate that the thinner-than-normal MTZ may be induced by minor thermal upwelling associated with late Mesozoic-early Cenozoic lithospheric delamination, a recently proposed mechanism that might be responsible for the high elevation of southern Africa. © 2020. American Geophysical Union. All Rights Reserved.
英文关键词	Botswana; incipient rifting; mantle transition zone; Okavango rift; receiver function
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/187593
作者单位	State Key Laboratory of Marine Geology, Tongji University, Shanghai, China; Geology and Geophysics Program, Missouri University of Science and Technology, Rolla, MO, United States
推荐引用方式 GB/T 7714	Yu Y.,Gao S.S.,Liu K.H.. Topography of the 410 and 660 km Discontinuities Beneath the Cenozoic Okavango Rift Zone and Adjacent Precambrian Provinces[J],2020,125(9).
APA	Yu Y.,Gao S.S.,&Liu K.H..(2020).Topography of the 410 and 660 km Discontinuities Beneath the Cenozoic Okavango Rift Zone and Adjacent Precambrian Provinces.Journal of Geophysical Research: Solid Earth,125(9).
MLA	Yu Y.,et al."Topography of the 410 and 660 km Discontinuities Beneath the Cenozoic Okavango Rift Zone and Adjacent Precambrian Provinces".Journal of Geophysical Research: Solid Earth 125.9(2020).