Cookies

We use cookies to ensure that we give you the best experience on our website. By continuing to browse this repository, you give consent for essential cookies to be used. You can read more about our Privacy and Cookie Policy.


Durham Research Online
You are in:

The evolution and ascent paths of mantle xenolith-bearing magma : observations and insights from Cenozoic basalts in Southeast China.

Sun, Pu and Niu, Yaoling and Guo, Pengyuan and Cui, Huixia and Ye, Lei and Liu, Jinju (2018) 'The evolution and ascent paths of mantle xenolith-bearing magma : observations and insights from Cenozoic basalts in Southeast China.', Lithos., 31-311 . pp. 171-181.

Abstract

Studies have shown that mantle xenolith-bearing magmas must ascend rapidly to carry mantle xenoliths to the surface. It has thus been inferred inadvertently that such rapid ascending melt must have undergone little crystallization or evolution. However, this inference is apparently inconsistent with the widespread observation that xenolith-bearing alkali basalts are variably evolved with Mg# ≤ 72. In this paper, we discuss this important, yet overlooked, petrological problem and offer new perspectives with evidence. We analyzed the Cenozoic mantle xenolith-bearing alkali basalts from several locations in Southeast China that have experienced varying degrees of fractional crystallization (Mg# = ~ 48–67). The variably evolved composition of host alkali basalts is not in contradiction with rapid ascent, but rather reflects inevitability of crystallization during ascent. Thermometry calculations for clinopyroxene (Cpx) megacrysts give equilibrium temperatures of 1238–1390 °C, which is consistent with the effect of conductive cooling and melt crystallization during ascent because TMelt > TLithosphere. The equilibrium pressure (18–27 kbar) of these Cpx megacrysts suggests that the crystallization takes place under lithospheric mantle conditions. The host melt must have experienced limited low-pressure residence in the shallower levels of lithospheric mantle and crust. This is in fact consistent with the rapid ascent of the host melt to bring mantle xenoliths to the surface.

Item Type:Article
Full text:(AM) Accepted Manuscript
Available under License - Creative Commons Attribution Non-commercial No Derivatives.
Download PDF
(13468Kb)
Status:Peer-reviewed
Publisher Web site:https://doi.org/10.1016/j.lithos.2018.04.015
Publisher statement:© 2018 This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/
Date accepted:17 April 2018
Date deposited:24 April 2018
Date of first online publication:22 April 2018
Date first made open access:22 April 2019

Save or Share this output

Export:
Export
Look up in GoogleScholar