ID-TIMS U-Pb dating of zircons and Nb-Zr chronometry of two cumulate eucrites: constraints on the thermal history of the Vestan crust

Abstract

In this study, we investigated the thermal history of the Vestan crust using ID-TIMS U-Pb ages of zircons from the cumulate eucrites NWA 11455 and NWA 11247, along with a Nb-Zr age from NWA 11455. The zircon Pb-Pb ages range from 4539 to 4553 Ma, suggesting either prolonged crystallization or partial resetting due to a high-temperature reheating event. The Nb-Zr age is 50.6 ± 4.8 Ma after CAI formation (4516.7 Ma), and the relative order of these ages is consistent with their different closure temperatures. If the Pb-Pb ages reflect crystallization, an additional heat source or thermal insulation would be required. Alternatively, if the U-Pb system experienced partial resetting, the data imply a high-temperature event occurred between 4517 and 4539 Ma.