About This Item

Share This Item

The AAPG/Datapages Combined Publications Database

AAPG Bulletin

Abstract


Volume: 63 (1979)

Issue: 4. (April)

First Page: 686

Last Page: 687

Title: Mechanisms for Uranium Deposition in Grants Mineral Belt: ABSTRACT

Author(s): D. G. Brookins

Article Type: Meeting abstract

Abstract:

A polygenetic model for uranium deposition of much of the ore in the Grants mineral belt results from (a) spatial relations of orebodies, (b) geochronologic studies, (c) clay-mineral studies, (d) trace-element studies, and (e) theoretical considerations. Trend ore apparently formed from southeast-flowing solutions entirely in reduced ground with organic carbon (plus some hydrogen sulfide) acting as reductant; this is supported by evidence for organic carbon in calcite penecontemporaneous with ore, trace-element distribution, and other factors. Uplift, remobilization, and reprecipitation of some of the stratigraphically high ore in the Laguna district is somewhat similar to Wyoming roll-type deposits in terms of mineralization control by sulfide-sulfate equilibria and clay mineralogic variations. The effect of this event is not apparent in the deeper Ambrosia Lake ore. The Laramide orogeny resulted in the establishment of a redox front which, in turn, resulted in destruction and remobilization of some earlier trend ore and the formation

End_Page 686------------------------------

of stack ore. Virtually all zones of rock weakness are subjected to some mineralization near this front, and the sulfide-sulfate equilibria cause many of these stack deposits to resemble roll fronts. Roll geometry of some of this ore is due to encroachment of the front on reduced ground after the Laramide. Younger, but very local, solutions result in ore in oxidized ground, some of which is indicated by primary uranophane. Roll geometry is present for some of these deposits. The superimposition of the redox front on the older trend ore allows both carbon and sulfur to act as reductants, and orebody geometries are similar to Wyoming-type rolls in terms of uranium distribution but not necessarily for trace-element distribution.

End_of_Article - Last_Page 687------------

Copyright 1997 American Association of Petroleum Geologists