Faculty Sponsor: Michael Wizevich
GSC Newsletter Article Project Summary
Zircons were then handpicked from the non-magnetic portion of the sample. Approximately 100 zircon grains were picked per sample and sent to the LaserChron Center (University of Arizona) for U-Pb age-dating on a LA-ICPMS. Several samples were “double dated,” where age-dates were taken on the core and rims of the same zircon. SEM cathodoluminescence (CL) was utilized to distinguish rims and cores of the zircon (Figure 2).
In addition to the overwhelmingly complex geology surrounding the Mesozoic basins, multiple source areas, metamorphic alterations and recycling of zircons make pinpointing provenance a challenge. Overall, the samples contain diverse populations of zircons, primarily reflecting source areas affected by one or more orogeny: Alleghanian (270-320 Ma), Acadian (340-400 Ma), Taconic (420-490 Ma), Peri-Gondwanan (550-640 Ma), and Grenville (980-1320 Ma). Examinations of the results of this study show several notable features:
Figure 2: Detailed CL images of detrital zircons showing laser ablation pits, oscillatory zoning and metamorphic overgrowths of various ages.