Please use this identifier to cite or link to this item:
Authors: Cloetingh, Sierd* 
Koptev, Alexander* 
Lavecchia, Alessio* 
Kovács, István János* 
Beekman, Fred* 
Title: Fingerprinting secondary mantle plumes
Journal: Earth and Planetary Science Letters 
Series/Report no.: /597 (2022)
Publisher: Elsevier
Issue Date: Sep-2022
DOI: 10.1016/j.epsl.2022.117819
Keywords: plume-lithosphere interaction
secondary plumes
hydrous plumes
lithosphere rheology
mantle transition zone
numerical modelling
Abstract: Many vertical seismic velocity anomalies observed below different parts of the Eurasian plate are rooted in the transition zone between the upper and lower mantle (410–660 km), forming so-called secondary plumes. These anomalies are interpreted as the result of thermal effects of large-scale thermal upwelling (primary plume) in the lower mantle or deep dehydration of fluid-rich subducting oceanic plates. We present the results of thermo-mechanical numerical modelling to investigate the dynamics of such small-scale thermal and chemical (hydrous) anomalies rising from the lower part of the Earth’s upper mantle. Our objective is to determine the conditions that allow thermo-chemical secondary plumes of moderate size (initial radius of 50 km) to penetrate the continental lithosphere, as often detected in seismo-tomographic studies. To this end, we examine the effect of the following parameters: (1) the compositional deficit of the plume density due to the presence of water and hydrous silicate melts, (2) the width of the weak zone in the overlying lithosphere formed because of plume-induced magmatic weakening and/or previous tectonic events, and (3) a tectonic regime varied from neutral to extensional. In our models, secondary plumes of purely thermal origin do not penetrate the overlying plate, but flatten at its base, forming “mushroom”-shaped structures at the level of the lithosphere-asthenosphere boundary. On the contrary, plumes with enhanced density contrast due to a chemical (hydrous) component are shown to be able to pass upwards through the lithospheric mantle to shallow depths near the Moho when (1) the compositional density contrast is ≥ 100 kg m−3 and (2) the width of the lithospheric weakness zone above the plume is ≥ 100 km. An extensional tectonic regime facilitates plume penetration into the lithosphere but is not mandatory. Our findings can explain observations that have long remained enigmatic, such as the “arrow”-shaped zone of low seismic velocities below the Tengchong volcano in south-western China and the columnar (“finger”-shaped) anomaly within the lithospheric mantle discovered more than two decades ago beneath the Eifel volcanic fields in north-western Germany. It appears that a chemical component is a characteristic feature not only of conventional hydrous plumes located over presently downgoing oceanic slabs, but also of upper mantle plumes in other tectonic settings.
Appears in Collections:Article published / in press

Files in This Item:
File Description SizeFormat
Cloetingh et al 2022.pdfOpen Access published article3.45 MBAdobe PDFView/Open
Show full item record

Page view(s)

checked on Mar 25, 2023


checked on Mar 25, 2023

Google ScholarTM