Geochronology double dating

However, the composition of detrital zircons is not entirely controlled by the crystallization of the zircon mineral.In fact, many of them are modified by later processes in the sedimentary cycle.The main strength of zircons resides in the fact that they are capable of surviving multiple phases of physical and chemical weathering, erosion, and deposition.The increased use of multicollector-laser ablation-inductively coupled plasma–mass spectrometry (MC-LA-ICPMS) in recent years is a significant advancement in the application of U-Pb geochronology to provenance and tectonic problems, because the technique can efficiently generate a large number of analyses (Gehrels et al., 2008).A total of 2,330 zircon grains yielded ages with acceptable precision and concordance for geochronologic interpretation.Together with sandstone petrography, the detrital zircons indicate that the primary source of detritus in the basin from ~113 to 54 Ma was the Gangdese magmatic arc.The common pre-conditions for application of these methods are: (1) the source areas are characterized by rocks with different tectonic histories recorded by distinctive crystallization and cooling ages, and (2) the source rocks contain the selected mineral.Whereas zircons occur in most magmatic, metamorphic, and sedimentary rocks, other minerals, such as apatite, monazite, and white mica, are less abundant.

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It has become increasingly popular in geological studies from the 2000s mainly due to the advancement in radiometric dating techniques.

Zircon is a common accessory or trace mineral constituent of most granite and felsic igneous rocks.

Due to its hardness, durability and chemical inertness, zircon persists in sedimentary deposits and is a common constituent of most sands.

Depending on the degree of physical sorting, mechanical abrasion and dissolution, a detrital zircon grain may lose some of its inherent features and gain some over-printed properties like rounded shape and smaller size.

On a larger scale, two or more tribes of detrital zircons from different origins may deposit within the same sedimentary basin.


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