| Description |
vii, 147 leaves : illustrations ; 29 cm |
| Summary |
"Scope and Purpose: The Lead Belt area of southeast Missouri, which is nearly 40 km. long and 10 km. wide, is considered, at the present time, the most important lead district in the world. Lead has been mined in this area by the natives prior to 1720, and almost continuously up to the present day. A variety of sulphides are mined from different places in the district. The sulphide deposits in the Lead Belt are considered to be typical examples of the Mississippi Valley Type Deposits, which are distributed all over the world. As in practically all the Mississippi Valley Type Deposits, the problems involved in the genesis of the southeast Missouri sulphide deposits have been and still are a matter of controversy. Different opinions and theories have been postulated to explain the mode of their formation. The iron-cobalt-nickel-lead-zinc sulphide deposit, a section of which has been studied in the present thesis, is considered to be one of the important deposits in the district. It is located 2 km. to the southeast of Fredericktown, in the Fredericktown Quadrangle, Madison County, Missouri, U. S. A. In this thesis an attempt is made to correlate data from previous work with new observations. The main purpose of the study was to formulate a reasonable hypothesis for the genesis of the deposit, on the basis of the study of both large and small scale features, with special emphasis on the small scale geometric features. Those features and patterns are considered to be important. As will be shown, the literature contains very little on small scale properties of this type of deposit in the Lead Belt. Four steps have been used to approach the problem: 1. A review of previous work through a detailed study of the published literature on the geology, general setting, and the character of the deposit in question, and on other deposits of similar character. 2. Field observations of the relation between the sulphides and the surrounding rooks in three dimensions as available in the mine. 3. A study of the relation between the sulphide masses and crystals of the enclosing rook in hand or "foot" specimens. 4. A study of the relation between the sulphides themselves and also the surrounding rock matter under the microscope, in both polished and thin sections. Through these four steps, it was possible to relate the large scale observations to the smaller scale features, and to allow a better understanding of the problem of genesis of the deposit in question, and its relation to the other rock types present in the area. The conclusions reached through this type of study differ from the previous interpretations regarding the genesis of the studied deposit"--Introduction, leaves 1-2. |
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