Date of Award
Master of Science (MS)
Detrital zircon (DZ) grains from 13 drainages across the South Island, New Zealand, were U-Pb dated to ascertain how accurately their ages reflect the geologic record of exposed bedrock. With the proliferation of inexpensive and easily accessible ion microprobes and laser ablation inductively coupled plasma mass spectrometers, DZ dating has become the dominant chronometer for elucidating tectonic systematics. Zircon’s physical and chemical resilience makes it an ideal candidate for U-Pb geochronometry, but is also a potential source of bias. Zircon’s resilience in sedimentary systems means it rarely occurs as first order detritus. N = 966 zircon grains from Modern alluvium were U-Pb dated and statistically scrutinized against sedimentary and plutonic bedrock grain-age compilations in the published literature. Cross-correlation, Likeness, Similarity, and Kolmogorov-Smirnoff tests were employed to better understand how well DZ in modern alluvium are representing the bedrock. Even with minimal analyses of populations, grain-age distributions in the modern alluvium are missing from the bedrock on the South Island, New Zealand. Thus, although DZ is a significant tool for constraining some aspects of tectonics and sedimentary provenance it needs to be interpreted cautiously in assuming a one-to-one relationship between potential bedrock source and sedimentary sink.
Fisher, Will Sparhawk, "Testing Detrital Zircon age Bias in Tectonic Provenance: Examples from Modern Alluvium in the South Island, New Zealand" (2022). Theses - ALL. 655.