| Description |
vii, 84 leaves : illustrations ; 29 cm |
| Summary |
"Regional structure and thickness of a single horizon, the M bed, have been studied in the Tri-State district by picking the top and base of the M bed in the logs of 557 selected drill holes and contouring this data together with the aid of local detailed structural information available for individual mining fields. Structures determined from these data were compared to the positions of mined mineralization to determine the control of regional structure upon the localization of ore. Variations in the M bed thickness were compared to the positions of fields of mineralization to examine possible spatial relationships which they might show. Among the 80 folds outlined in the fields of the Tri-State district, two-thirds of the synclines and one-third of the anticlines exhibit areally associated mineralization. The preference for synclines over anticlines suggests that the ore-forming solutions were moving downward at the time at which the ores were deposited. The M bed exhibits remarkable variations in thickness in the Tri-State district from as little as eight feet to as much as 110 feet. In the Picher field strikingly concentric isopachous zones show a progressive decrease in thickness toward the center of the field. The Galena, Melrose and possibly the Waco fields show similar but less well defined thinning of the M bed. This close relationship between the M bed thickness and the fields of mineralization is interpreted to have resulted from solution of the M bed limestone partly before mineralization and partly during the ore-forming process"--Abstract, leaves ii-iii. |
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