A method for determining the age of high common lead zircons and the initial lead isotopic composition of the source region

Abstract

The invention belongs to the technical field of zircon age determination and source area tracing, and specifically discloses a method for determining the age of high-common lead zircons and the initial lead isotope composition of the source area, as follows: step 1, zircon age data selection; step 2, select 238 U / 204 Pb‑ 206 Pb / 204 Pb data and corresponding error; step 3, using the zircon age data in the above step 1, the 238 U / 204 Pb and 206 Pb / 204 Pb data and corresponding error, obtained 206 Pb‑ 238 U isochrone age, MSWD value and 206 Pb / 204 Pb initial lead isotopic composition information; step 4, select 235 U / 204 Pb‑ 207 Pb / 204 Pb data and corresponding error; step 5, using the age data in the above step 1, step 4 235 U / 204 Pb and 207 Pb / 204 Pb data and corresponding error, obtained 207 Pb‑ 235 U isochrone age, MSWD value and 207 Pb / 204 Pb initial lead isotopic composition information; step 6, compare above 206 Pb‑ 238 U isochron age and 207 Pb‑ 235 U isochrone age, calculate Concordant%, and complete the determination of zircon age and initial lead isotope composition in the source area. The method of the invention is helpful to revitalize the high common lead age data and improve the dating effect of specific lithology.

Description

technical field [0001] The invention belongs to the technical field of zircon age determination and source area tracing, and in particular relates to a method for determining the age of high-common lead zircons and the initial lead isotope composition of the source area. Background technique [0002] The zircon-uranium-lead age determination method is currently the most mature and reliable method for obtaining the age of geological bodies. It is widely used and plays a key role in solving major geoscience problems. However, the accurate determination of the age of high common lead zircons is still pending, mainly because common lead is difficult to accurately estimate and deduct. [0003] Highly common lead zircons are widely found in pegmatites and basic-ultrabasic rocks, and zircons of hydrothermal origin usually contain relatively high ordinary lead, which leads to the age change of zircons that accurately define this type of lithology or origin. more difficult. The cur...

AI Technical Summary

Problems solved by technology

At the same time, the trace information carried by high-common lead zircons is also lost. As far as hydrothermal zircons are concerned, studies have shown that their formation is closely related to mineralization. It is estimated that the key geological information such as the age of metallization and the source of metallogenic materials cannot be obtained.

[0004] At present, there is a lack of a reasonable method for calculating the age data of high common lead, resulting in a large amount of high common lead age data that cannot be used

Images