Cathodoluminescence images of representative zircons from sample XING988.

<p>Ellipses on the analyzed zircon grains show the positions of U-Pb analytical sites.</p

U-Pb concordia diagram showing secondary ion mass spectrometry analytical data for zircons from sample XING988 obtained from a bentonite layer in K₂n.

<p>Data-point error ellipses are 2σ.</p

Stratigraphy of borehole X1-4.

<p>Fig 2 was created by CorelDRAW X8 (<a href="http://www.coreldraw.com/us/pages/free-download" target="_blank">http://www.coreldraw.com/us/pages/free-download</a>). Copyright (c) 2018 [Huaiyu He] and its licensors. All rights reserved.</p

Secondary ion mass spectrometry zircon U-Pb data.

<p>Secondary ion mass spectrometry zircon U-Pb data.</p