Discussion

Due to the limited detection of Ti and Hf, we are unable to interpret the thermal history and magmatic sources of the zircons with credibility. Hence, the optimization for the Ti and Hf sensitivity is needed. Enhanced sensitivity of Hf for a proper analysis can be done on a Multi-Collector ICP-MS (MC-ICP-MS). 

The Cl-Chondrite normalized pattern of the detrital zircon populations from sample 23ROM27 is divided among prominent age groups and compared to the expected general trend of the igneous chondrite normalized pattern, specifically the overall increasing trend of the REEs pattern with the enrichment of Ce and the depletion of Eu. trend of the chondrite REE pattern includes as observed in Rubatto, 2002.  The results are as follows.

1. The wide range of light REE concentration, as opposed to the narrow concentrations of heavy REEs. 
2. The general pattern of Ce enrichment (Ce anomaly) and Eu depletion (Eu anomaly).
3. There is no clear correlation between U-Pb age groups and REE patterns. The possible intermediate factors are magmatism, metamorphism, and different trace element concentrations differences due to geochemical or geological processes affecting the concentrations. 
4. We normalized our detrital zircons to Cl-Chondrites, but our results might differ if we normalized them to a different standard such as the North American Shale, which best represents the upper continental chondrites. We chose Cl-chondrites due to their igneous origin. Hf can help us resolve their specific origin such as crustal recycling or mantle-derived.
5. Our REE results for the FC-1 standard zircon indicate that there is no clear correlation between REE patterns and zircons, given that the FC-1 standards showed variability in the REE patterns, as did the 23ROM27 unknowns.

Another major aspect of this study was to identify igneous zircon REE pattern different from metamorphic zircon REE pattern. Due to the limited number of metamorphic zircons identified in our 23ROM27 sample based on the Th/U ratio, we were not able to produce a graph that demonstrates the REE patterns of the four metamorphic zircons. However, we suspect that the 4 metamorphic zircons should follow a general LREE depletion to HREE enrichment pattern according to Rubatto, 2002. Adding on, one of the metamorphic zircons is a FC-1 grain which means that there is another geochemical or geological process that is causing a depletion in Uranium in that grain leading to a Th/U less than -1. Similarly, the depletions in the REEs (except for Ce and Eu) in the 23ROM27 zircons, can be attributed to geochemical or geological processes that resulted in these depletions.

Additionally, our initial proposal looks drastically different from our final gameplan. At first, we planned on measuring and analyzing various trace elements besides the REEs, but unfortunately due to time, the focus of this project, and instrument sensitivity, we were unable to proceed with our original plan. However, we were able to measure the REEs in zircons and FC-1 and demonstrate the variability in the REE patterns amongst the unknowns and FC-1 zircon standards.