An improved U-Pb age dating method for detrital zircon by LA-MC-ICP-MS

Abstract

Detrital zircon U-Pb dating is a powerful tool to trace sources for sedimentary basin and to understand of geological history in structurally complex areas. This study established an analytical protocol for measurement of detrital zircon U-Pb age by LA-MC-ICP-MS. Because detrital zircons normally have a large Pb content variation (several ppm to hundred ppm), which leads to large variations for Pb signal intensity, two sets of detector arrays were used. For Pb-rich zircons, ²⁰⁶Pb was collected with Faraday cup detector array, while for Pb-poor zircons, ²⁰⁶Pb was collected with ion counter detector array. The results of ²⁰⁶Pb/²³⁸U age and ²⁰⁷Pb/²³⁵U age for six well-known and widely used zircon standards agree within 0.5% and 1% respectively of the preferred values measured by ID-TIMS. The precision of ²⁰⁶Pb/²³⁸U age and ²⁰⁷Pb/²³⁵U age of the six zircons vary from 0.6% to 2.3% and 0.9% to 2.3% (2SD), respectively.