Positioning the zircon fission-track and zircon micro-Raman partial annealing zones

锆石是火成岩、变质岩和衍生碎屑沉积岩的常见成分。它是一种有价值的地质年代测定矿物，因为它的晶格中有U和Th的取代。它们的放射性衰变产生Pb、He、裂变产物和各种形式的晶格损伤。我的第一个目标是通过确定锆石裂变径迹时钟重置的地质条件来推进锆石裂变径迹定年。这包括定位锆石裂变径迹部分退火区（ZPAZ）。此外，自辐照造成的晶格损伤对裂变径迹的腐蚀和退火性能都有影响。在室内实验中研究了辐射损伤积累和修复的动力学。他们对地质时间尺度的外推预测，由于在~160℃以上的温度下损伤退火，锆石的非晶化减少或抑制。因此，我的第二个目标是为锆石辐射损伤退火带（ZRAZ）提供地质基准。这两个目标都可以通过检查Tiefbohrung大陆锆石的裂变径迹和辐射损伤记录来实现，Tiefbohrung大陆在9.1 km深度达到265°C。我预测它穿越了3至5公里深度的无隔离区和7至9公里深度的无隔离区。研究结果有助于评价锆石在高放核废料长期封存和热成因气勘探方面的潜力。

Zircon is a common constituent of igneous, metamorphic and derived clastic sedimentary rocks. It is a valuable mineral for geological age dating because of U and Th substitutions in its lattice. Their radioactive decay produces Pb, He, fission products and various forms of lattice damage. My first aim is to advance zircon fission-track dating by determining the geolog-ical conditions under which the zircon fission-track clock is reset. This involves locating the zircon fission-track partial annealing zone (ZPAZ). In addition, lattice damage from self-irradiation affects both the etching and annealing properties of the fission tracks. The kinetics of radiation-damage accumulation and repair have been studied in lab experiments. Their extrapolation to geological timescales predicts that the amorphization of zircon is reduced, or suppressed, due to damage annealing at temperatures above ~160 °C. My second aim is therefore to provide geological benchmarks for the zircon radiation-damage annealing zone (ZRAZ). Both aims can be realized by examining the fission-track and radiation-damage records of zircons from the Kontinentale Tiefbohrung, which reached 265 °C at 9.1 km depth. I predict that it traversed the ZRAZ between 3 and 5 km depth and the ZPAZ between 7 and 9 km depth. The results of this investigation could help to evaluate the potential of zircon for the long-term sequestration of high-level nuclear waste and for the exploration of thermogenic gas.