Student NameClaudia Banks
Faculty Mentor NameJoseph Meert
CollegeLiberal Arts and Sciences
Research InterestsGeochonology, Geochemistry
Academic AwardsNAGT Field Study Scholarship
OrganizationsAWG, Geoclubs, SEG
Hobbies and InterestsCamping, Tea, Dogs

Research Project

Geochronology of Hadean Zircons

The Singhbhum Craton (SC) is one of five Archean nuclei comprising Peninsular India. The SC is a composite Archean block that includes the Older Metamorphic Group, the Older Metamorphic Tonalite Gneisses, the Singhbhum Granite, and the Iron Ore Group. The ages of these components range in age from ~3.5 to ~3.1 Ga, although overlapping ages and lithologies confound their genetic relationships. Thus far, we have characterized age-signals and geochemical compositions of the SC via analysis of 207Pb/206Pb and 176Lu/177Hf isotopic ratios in individual zircon mineral grains with Nu Plasma II laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS). Our work has identified three discrete Archean age spectra at 3.62-3.55 Ga (5%), 3.50-3.22 Ga (87%), and 3.10-3.06 Ga (6%). In addition, we have identified a single concordant Hadean age grain. Together with our work, a total of seven Hadean-age zircon grains are recorded in the SC as either xenocrysts or detrital grains in either modern river detritus or in outcrop. Lu-Hf isotopic ratios provide a useful discrimination between crustal or mantle sources. While we do not have a good estimate for the potential yield of Hadean grains from the SC, the discovery of both detrital and xenocrystic zircons holds promise.