ANALYSIS OF CARBONATE CONTENTS OF THE ILLINIOAN TITUSVILLE TILL, MAHONING COUNTY, OHIO

Pink calcareous diamict inclusions in the Illionian Titusville Till of the glaciated Allegheny Plateau have been noted by field mappers for over 50 years. A clue into the origin of these inclusions may lay in an examination of the distribution of carbonate in various size fractions of pink diamicts and their surrounding gray diamicts. Seventy-four samples of pink and gray diamicts were collected from a strip mine near North Lima, Ohio. Other diamict samples were partially oxidized to brown or a pink and brown mixture. Results from various color pairings were compared using F tests to test for similar variances and to determine which two-sample t test to use to compare sample means.

Fine-carbonate analysis of silt and clay fractions of samples was done gasometrically using a Chittick apparatus. Data from carbonate analysis of the silt and clay fractions were combined with carbonate analyses of sand fractions in the diamicts. Average carbonate contents of sand fractions in gray diamicts range from 7.8% to 24.3%, whereas those of pink diamicts range from 10.2% to 24.0%. Gray diamicts show a greater variation in carbonate content in medium- to very fine-sand fractions. Analysis of silt and clay fractions indicate that most carbonate is contained within silt fractions, having very little in clay fractions. Carbonate contents of silt fractions varied between 3.8% and 8.1% for gray diamicts and between 0% and 13.3% for pink diamicts. Gray diamicts averaged 0.8% calcite and 4.4% dolomite, whereas pink diamicts averaged 1.5% calcite and 5.1% dolomite. Means for various measures of carbonate are significantly different.

Frequency-distribution graphs, histograms, and squiggle graphs illustrate statistical differences in the carbonate samples. Plots of sand, silt, and clay fractions on a squiggle chart of a vertical section show distinct jumps where calcareous pink diamicts occur. Interpretations of carbonate data suggest that pink and gray diamicts have different sources. Larger variations in carbonate contents of the medium- to very fine-sand fractions of gray diamicts compared to those of pink diamicts suggest that carbonates of gray diamicts originated locally, whereas larger percentages of carbonate in fine fractions of pink diamicts suggest a more distant source.