QUANTITATIVE VARIABILITY OF BURROW PERCENTAGE ESTIMATED FROM 2D VIEWS: EXAMPLE FROM THALASSINOIDES-BEARING STRATA, CENTRAL SAUDI ARABIA

This study examines computed tomography (CT) scans of a 15.24-cm diameter and 17.1-cm length core cut from Thalassinoides-bearing strata (Hanifa Formation, central Saudi Arabia) to explore the quantitative variability in burrow percentage when estimated using 2D views. A cropped quadrangular prism of this core allowed 202 2D slices in two vertical orientations and 165 horizontal 2D slices. Thalassinoides volume represents 20.0% (burrow percentage) of the total volume within this cropped quadrangular prism. The estimated burrow percentage by the 2D vertical slices varies from 11.8% to 30.3% with a mean value of 19.9% +/- 3.3% and 19.6% +/- 3.9%, and coefficients of variation of 17% and 20%, for the two vertical orientations. A wider range and slightly more variability arc found when estimated burrow percentage using the horizontal slices (burrow percentage range from 6.1% to 33.1% with a mean value of 19.8% +/- 6.5% and coefficient of variation of 33.1%). However, analysis of variance results indicated no statistically significant difference between the distribution of the burrow percentage among vertical and horizontal slices. A test of how randomly selected slices of the CT scan would represent the burrow percentage indicated that even five randomly selected slices could retain a mean comparable to the actual burrow percentage of the CT scan. Based on these results, we suggested a statistical way to quantify the uncertainty associated with estimating the burrow percentage from 2D views, an important step toward a complete understanding of variability in burrow percentage (and bioturbation intensity) when estimated from 2D views.

Automated summary

This study examines the quantitative variability in burrow percentage estimated using 2D views of a core from Thalassinoides-bearing strata in central Saudi Arabia. The results show that the estimated burrow percentage varies among different 2D views, but there is no significant difference between vertical and horizontal slices. The study also proposes a statistical method to quantify the uncertainty associated with estimating the burrow percentage from 2D views.