U thhe dating of phosphates apatite monazite and xenotime rules for women and online dating
A large body of major element data exists demonstrating sufficient homogeneity (1 to 5% RSD) at the 10 µm level.The Durango apatite might therefore have considerable potential as a suitable standard for trace element microanalysis of phosphates.Back-scatter electron images and X-ray maps of monazite reveal distinct core, intermediate and rim compositional domains.Monazite–xenotime thermometry from the intermediate and rim domains yields temperatures of 405–470°C (±50°C) and 500–520°C (±50°C), respectively, consistent with the prograde to peak metamorphic growth of monazite.Kyanite and fibrolite are strongly deformed; some prismatic sillimanite, and all andalusite are relatively undeformed.Monazite occurs as inclusions within kyanite, mats of sillimanite and centimetre-scale porphyroblasts of andalusite, and is typically aligned subparallel to the dominant regional foliation (S).They propose that regional amphibolite to near-granulite facies metamorphism and north-vergent folding and thrusting was related to the Mazatzal Orogeny (∼1650 Ma).
Because these minerals tend, to varying degrees, to partition U and Th into their structures they can often contain the majority of those elements in a rock.
We will present the results of a detailed geochemical study that investigated the trace element homogeneity of a euhedral, highly transparent, and inclusion-free Durango apatite crystal.
After crushing, an aliquot of this crystal has been analysed for the bulk trace element content by solution ICP-MS.
These three phases, again to varying degrees, tend not to incorporate significant amounts of Pb during crystallization and thus were early candidates for utilization as U-Th-Pb geochronometers.
The ideal U-Th-Pb geochronometer would be a phase that is stable over all possible environmental conditions and is quantitatively retentive of parent and daughter isotopes.
However, the limit of zircon as an ideal chronometer lies only in its limited resistance to auto-irradiation damage that can render it metamict.