Abstract
Late Cretaceous batholith, quartz monzonite ore, Precambrian isotope age, partial-melting source material model; Isotope ratios of Pb in feldspar range widely from pluton to pluton: 16.9-18.1 for 206/204, 15.4-15.7 for 207/204, and 37.7-38.5 for 208/204.Whole-rock initial Sr-87/Sr-86 is 0.706-0.709. Variation in Pb isotope ratios within Butte Quartz Monzonite, plus differences in ratios between megacryst and groundmass feldspars in Donald pluton suggest incomplete isotopic mixing; similarity of Butte ore Pb to feldspar Pb of Butte Quartz Monzonite, therefore, has genetic significance. Isotope data suggest that batholith rocks result from partial melting of lower crust or upper mantle; assimilation of upper crustal material is necessary if source material resembled oceanic tholeiites.
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.
