Abstract
The leads in feldspars from the main Tertiary intrusives in three mining districts are isotopically similar to the lead deposits immediately associated with them. The largest deposits are the least radiogenic in each region, and the smaller deposits the more radiogenic. 9The ore leads appear to be mixtures in various proportions of lead derived from the intrusive magma [assumed to have evolved along the primary growth curve] and a radiogenic lead component derived from the upper crustal rocks through which the mineralizing fluids passed.9 One of two alternative models requires only 1,650 m.y. and 2,400 m.y. events in the basement rocks.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
