Journal of Petrology Advance Access originally published online on March 22, 2006
Journal of Petrology 2006 47(6):1245-1254; doi:10.1093/petrology/egl010
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Crystal Size Distributions Derived from 3D Datasets: Sample Size Versus Uncertainties
DEPARTMENT OF THE GEOPHYSICAL SCIENCES, THE UNIVERSITY OF CHICAGO, 5734 S. ELLIS AVE., CHICAGO, IL 60637, USA
RECEIVED JUNE 23, 2005; ACCEPTED FEBRUARY 21, 2006
Crystal size distributions (CSD) are the most commonly studied character in quantitative textural investigations of igneous rocks. The quality of CSD depends fundamentally on the sample size (i.e. total number of crystals). Here we use 3D X-ray tomographic datasets of two early erupted Bishop Tuff pumice clasts (comprising 849 and 446 quartz crystals) to investigate the effect of sample size on the quality of the quartz size distributions. Because CSD are obtained using a counting procedure, uncertainties related to counting statistics can be used as minimum estimates of error. Given that most natural samples are characterized by a decreasing number of crystals with increasing crystal size, uncertainties tend to increase markedly with crystal size, and the number of small crystals to be counted grows very quickly with increasing sample size. Accordingly, with as few as 100 crystals in total, it is possible to properly estimate the population densities for small size bins (20–80 µm). However, to obtain meaningful estimates across four bin sizes (20–320 µm), at least 
250 crystals, but preferably >400 crystals are needed. To minimize the total number of crystals counted, and keep the uncertainties on the larger size ranges within reasonable values, it becomes necessary to study multiple volumes at variable spatial resolution.
KEY WORDS: crystal size distributions; quantitative petrography; texture; X-ray tomography
* Corresponding author. Telephone: +1-773-702-8101. Fax: +1-773-702-9505. E-mail: ggualda{at}uchicago.edu
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  D. A. Jerram and V. M. Martin Understanding crystal populations and their significance through the magma plumbing system Geological Society, London, Special Publications, January 1, 2008; 304(1): 133 - 148. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R. Amenta, A. Ewing, A. Jensen, S. Roberts, K. Stevens, M. Summa, S. Weaver, and P. Wertz A modeling approach to understanding the role of microstructure development on crystal-size distributions and on recovering crystal-size distributions from thin slices American Mineralogist, November 1, 2007; 92(11-12): 1936 - 1945. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. A. Jerram and M. D. Higgins 3D Analysis of Rock Textures: Quantifying Igneous Microstructures Elements, August 1, 2007; 3(4): 239 - 245. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 B. O'Driscoll, C. H. Donaldson, V. R. Troll, D. A. Jerram, and C. H. Emeleus An Origin for Harrisitic and Granular Olivine in the Rum Layered Suite, NW Scotland: a Crystal Size Distribution Study J. Petrology, February 1, 2007; 48(2): 253 - 270. [Abstract] [Full Text] [PDF]
|
|