Detrital zircon dating carbon cycle used dating artifacts
They can yield ages that are statistically significant, but geologically meaningless.
How confident are geologists in the ages of formations they study?
What we want to ask, now that this paper has shown a significant “unknown” in geological sample collection and testing, is what other unknowns are still out there? Do any of them really know how old their samples are?
Subduction along the southern margin of Alaska, USA, has been ongoing since at least the Jurassic.
Although larger values of are evidently fundamental for improving representativity and statistical accuracy (Pullen et al., 2014; Zhang et al., 2016; Nie et al., 2018), Thus, in order to improve the quantitative use and application of geochronologic-based detrital mineral provenance approaches, we must better our understanding of how zircon crystals pass through, and fractionate from, sedimentary systems (Hietpas et al., 2011), and use that understanding to inform our statistical treatments accordingly.
This is particularly critical as the number of publications including a component of detrital zircon provenance continues to grow, because this is inevitably driving the community toward a “big data” approach that will (by necessity) continue to increase its reliance on robust statistical treatments. How long have geologists been publishing papers about formations dated with detrital zircons?
Does statistical convergence necessarily translate into geological convergence? In a new paper in , six geologists tested a widely-used technique of gathering detrital zircons: crystals of zirconium that often contain uranium (U) and its daughter product lead (Pb), found in debris piles below a slope.
There are, however, two inconvenient and commonly ignored issues in geochronology-based sediment provenance: (1) detrital zircon U-Pb ages can cluster by grain size ; and (2) grain-size sorting is strongly influenced by the dynamics of sediment transport.Geologic processes and landscape evolution of the overriding plate were affected by these variations in subduction mode and are recorded in the forearc basin strata.We investigate the Cenozoic to modern sediment of the forearc Cook Inlet basin in south-central Alaska.The story often told is that radiometric dating produces dates that are super-reliable, because lab rates of radioactive decay don’t lie.The part of the story not told, though, is that many sources of bias can creep in. How many samples must be collected to converge on a reliable date? What should the geologist do with anomalous samples?