التفاصيل البيبلوغرافية
| العنوان: |
Single-shot laser ablation split stream (SS-LASS) petrochronology deciphers multiple, short-duration metamorphic events. |
| المؤلفون: |
Viete, Daniel R.1,2 daniel.viete@gmail.com, Kylander-Clark, Andrew R.C.2, Hacker, Bradley R.2 |
| المصدر: |
Chemical Geology. Nov2015, Vol. 415, p70-86. 17p. |
| مصطلحات موضوعية: |
*METAMORPHISM (Geology), *LASER ablation, *GEOLOGICAL time scales, *URANIUM-lead dating, *ZIRCON |
| مستخلص: |
Single-shot laser ablation split stream (SS-LASS) petrochronology offers spatial resolution of < 1 μm per (surface) analysis. This enables the technique to interrogate metamorphic zircon overgrowths that are very thin, or that preserve a composite age structure. To demonstrate the advantages of SS-LASS, the technique was applied to metamorphic zircon overgrowths in five rocks from the Cordillera de la Costa, Venezuela. In these rocks, SS-LASS was able to decipher discrete, short-duration (< 10 6 yr) zircon growth events at c. 33.0, c. 28.3, c. 23.0 and c. 18.2 Ma. Comparison with existing geo-/thermochronology suggests that the SS-LASS dates represent (hydro)thermal events that mark distinct episodes of tectonism affecting the northern margin of South America. With an external error of 5% incorporated into isotope ratios (as required to achieve satisfactory analytical precision), SS-LASS dates for reference materials were accurate to within 1.5% of published values. The SS-LASS technique is thus, in favorable cases, capable of providing < 10 6 yr resolution for Cenozoic rocks. Methods in ‘geospeedometry’—which employ forward models to reproduce observed diffusion length scales—have obtained anomalously short time scales of 10 4 –10 6 yr for metamorphism. The high spatial and temporal resolution of SS-LASS offers tremendous promise for investigating the veracity of these claims. [ABSTRACT FROM AUTHOR] |
| قاعدة البيانات: |
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