Pb-Sr-Nd isotopes in surficial materials at the Pebble Porphyry Cu-Au-Mo Deposit, Southwestern Alaska: can the mineralizing fingerprint be detected through cover?

The Cretaceous Pebble porphyry Cu-Au-Mo deposit is covered by tundra and glacigenic sediments. Pb-Sr-Nd measurements were done on sediments and soils to establish baseline conditions prior to the onset of mining operations and contribute to the development of exploration methods for concealed base metal deposits of this type. Pebble rocks have a moderate range for ²⁰⁶Pb/²⁰⁴Pb = 18.574 to 18.874, ²⁰⁷Pb/²⁰⁴Pb = 15.484 to 15.526, and ^208,Pb/²⁰⁴Pb = 38.053 to 38.266. Mineralized granodiorite shows a modest spread in ⁸⁷Sr/⁸⁶Sr (0.704354–0.707621) and ¹⁴³Nd/¹⁴⁴Nd (0.512639–0.512750). Age-corrected (89 Ma) values for the granodiorite yield relatively unradiogenic Pb (e.g., ²⁰⁷Pb/²⁰⁴Pb