High-Potash Dikes in The Homestake Mine, Lead, South Dakota
- Creators
- Noble, James A.
Abstract
Widely scattered bodies of Tertiary intrusive porphyry crop out in the northern Black Hills, in greatest abundance in a circular area of about 10-mile radius with Lead and the Homestake Mine at the center. Five rock types are represented: rhyolite; quartz monzonite; monzonite; grorudite; and phonolite. A swarm of rhyolite dikes in the Homestake Mine comprise rocks of two distinct compositional types: so-called low potash rocks with about equal parts of orthoclase, albite, and quartz; and high potash rocks which consist of orthoclase and quartz. There are no ferro-magnesian minerals in either type of rock. While only a few other occurrences of rocks of the high potash type have been described, it does not seem possible to dismiss this rock type from a genetic classification on the basis of inaccurate description. Three possible modes of origin for similar rocks have been proposed: selective assimilation of potash-rich wall rocks; hydrothermal introduction of potash; or, most probably, normal differentiation with strong reaction, followed by hindered reaction (Bowen, 1928).
Additional Information
© 1948 Geological Society of America. Manuscript received by the Secretary of the Society, August 19, 1947.Additional details
- Eprint ID
- 114073
- DOI
- 10.1130/0016-7606(1948)59[927:hdithm]2.0.co;2
- Resolver ID
- CaltechAUTHORS:20220325-703103300
- Created
-
2022-03-25Created from EPrint's datestamp field
- Updated
-
2022-03-25Created from EPrint's last_modified field
- Other Numbering System Name
- Caltech Division of Geological Sciences
- Other Numbering System Identifier
- 468