Figure - PMC

Skip to main content

An official website of the United States government

Here's how you know

Here's how you know

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

View full-text article in PMC

. 2019 Mar 14;9:4495. doi: 10.1038/s41598-019-40819-9

Search in PMC
Search in PubMed
View in NLM Catalog
Add to search

© The Author(s) 2019

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

PMC Copyright notice

Weathering-induced micro-fracturing. As biotite weathers, Fe(II) is oxidized to Fe(III), causing expansion and weathering-induced fractures. The top two images show a typical back-scattered electron microscope image of the protolith at 50 m depth with no observed cracking around biotite (Bt). The bottom two images from weathered/fractured bedrock at 32 m depth show oxidized biotite (Bio) that has expanded along cleavage planes (dark black parallel lines, marked by red arrow, inside Bio grain) and cracking in neighboring grains (red arrow in potassium feldspar (Kspar) grain). The expansion of biotite is sometimes accommodated in the rock by larger microfractures as shown in bottom right image. These microfractures open the rock to meteoric fluids and enhance weathering. (Labels: Clt or Chl = chlorite; Qtz = quartz; Pl = plagioclase; Ap = apatite; Zrn = zircon).