Hi Timothy, the detrital zircons can only provide you with a relative minimum age for the host sediment. In your example, if the youngest zircon crystals are dated at about 1.5Ga, you can infer that this sediment is not older than 1.5Ga, but you cannot exclude the possibility that it is younger.

Thanks Daniel. So, the detrital zircon method can only tell this sediment is not older than (zircon date), not the real forming age. Then, in such cases, what method can we used to have a closer dating?

Clastic sediments are difficult to date. You can try to date them in relative terms based on their stratigraphic relationships with the other rocks of the area (e.g. lithological contacts and cross-cutting relationships).

Dear Mr. Huang,

zircon, tourmaline and rutile are the most stable heavy minerals which are commonly used to normalize heavy mineral suites when it comes to the determination of supergene alteration of sedimentary rocks. They get easily reworked and therefore are not suitable for supporting the age of sedimentation. Zircon XX are, in places, zoned and it might happen under certain circumstance that the outer rim of zircon shows an interaction or contact zone with different detrital minerals nearby being thus indicative of an authigenic diagenetic process or even metamorphic overprinting. In a setting like that U/Pb ages of authigenic zircon may reflect a lithogenic processes most closely to the age of sedimentation

H.G.Dill

Hello Mr. Huang,

perhaps the detrital zircon U-Pb ages could be combined with Ar-Ar dating results for detrital muscovite and biotite flakes? This might help get a more comprehensive understanding of the depositional (and burial/exhimation) history of (clastic) sediments.

A short example is provided by Eric Tohver et al.:Conference Paper Thermochronological constraints on detrital sediments of the...

Then, one can also utilize (U-Th)/He ages of zircon (and apatite), sampling the lower-temperature regime.

Best,

Martin

Hello Mr. Huang,

there are wisely suggestions to you better the depositional evolution study. With focus on U-Pb detrital zircon I do recommend the Geherls's chapter of Basin Analisys Book. You will find good explanation of the U-Pb method applied.