Abstract
The lead isotope composition of three Cu-Zn-Pb sulfide deposits and one Au deposit in the Early Proterozoic Svecofennian of central Sweden reveals the existence of two distinct lead sources in the region. Rockliden and Enstern contain lead of upper crustal affinity and are isotopically homogeneous. Lead in these deposits probably originates from Archean-derived detritus which was well homogenized by sedimentary processes and deposited over large areas as a component in Early Proterozoic sedimentary and tuffaceous rocks. Lead isotopic homogeneity within the Tjarnberget and Enasen deposits is less pronounced, and the less radiogenic character of the lead suggests a source of mantle affinity. In areas where metasedimentary rocks are absent or contain very little Archean-derived material the isotopic signature of mantle-derived volcanic rocks is reflected in the ore lead. This approach is also applicable to other Svecofennian deposits. Together with deposits in west-central Finland the Rockliden deposit constitutes the northern boundary for lead of upper-crustal affinity, i.e., Archean-derived lead, in Svecofennian sulfide deposits. Despite these differences the isotope ratios of the four deposits indicate that they formed roughly contemporaneously with other Svecofennian deposits in Sweden and Finland.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: 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.