Rock Thin Section Scale In-Situ Apatite U-Pb Dating Technique Discussion: A New Perspective on Ultramafic Rock Geochronology Analysis

Ultramafic rocks, as a major component of mantle rocks, hold significant importance for understanding the Earth's internal structure and dynamic processes. Due to the silicon undersaturation in ultramafic magmas, crystallization of zircon is challenging; instead, apatite, a common accessory mineral in ultramafic rocks, has emerged as a crucial target for geochronological studies owing to its unique crystallochemical characteristics. With advancements in in-situ microanalysis techniques, the U-Pb dating method for apatite has experienced marked improvements, significantly enhancing both precision and reliability. However, conducting in-situ apatite dating analyses on thin sections of ultramafic rocks still presents several challenges, such as the correction of common lead, genetic analysis of the minerals, and contamination control during the preparation of rock thin sections. This paper reviews the current state of geochronological research on ultramafic rocks, summarizes advancements in in-situ dating techniques and apatite U-Pb dating methodologies, discusses the prospects for the application of apatite U-Pb dating in the in-situ dating of ultramafic rocks, and outlines future research directions.