DIRECTLY DATING GEOLOGIC EVENTS: U-Pb DATING OF CARBONATES

Carbonates are ubiquitous, forming in a variety of settings including caves, soils, the oceans, during burial from hydrothermal fluids, and along faults. U-Pb dating of carbonates is applicable to almost the entire geologic time scale, with results from Pleistocene speleothems showing great promise for dating records < 1 Ma old. Here we review studies of U-Pb dating of carbonates from a range of depositional and diagenetic environments and consider published results with regard to stratigraphic associations and the behavior of U and Pb in various fluids. We detail the steps required to select suitable samples, summarize current laboratory techniques, and provide directions for improvement of analytical protocols. The U-Pb dating of carbonates has tremendous potential for dating events of geologic interest and is virtually untapped.