Analcite-bearing intrusives from South Park, Colorado
- Creators
- Jahns, Richard H.
Abstract
Sills and dikes of analcite diabase and analcite syenite occur as low ridges on the flat floor of South Park, Colorado. The intrusions appear in Cretaceous shaly sandstone, and are probably Laramide in age. Certain features suggest a composite nature for the larger bodies, with the syenitic rock having been injected into pre-existing, but not yet completely solid diabase. Both types contain analcite, some of which is pyrogenetic. At least three mineral reaction series are well shown; all point to crystallization of an alkaline and water-rich magma at low temperatures, with development of a highly sodic residual liquid. The lack of any apparent break between the pyrogenetic and hydrothermal stages suggests for this rock a genetic nature tending in its end stages toward that of veins.
Additional Information
© 1938 American Journal of Science.Additional details
- Eprint ID
- 99651
- DOI
- 10.2475/ajs.s5-36.211.8
- Resolver ID
- CaltechAUTHORS:20191104-111658590
- Created
-
2019-11-04Created from EPrint's datestamp field
- Updated
-
2021-11-16Created from EPrint's last_modified field
- Other Numbering System Name
- Balch Graduate School of the Geological Sciences
- Other Numbering System Identifier
- 251