Abstract

A state-of-the-art mobile Apatite Fission Track (AFT) laboratory is operational at Diné College on the Navajo Nation. For outreach to local Junior High School students, AFT analysis was applied to samples related to a Tertiary dike intruded into Lower Jurassic Navajo Sandstone, near Boundary Butte, southern Utah, Navajo Nation. AFTs in the dike and adjacent reset sandstone constrain post-intrusion time-temperature (t-T) paths. AFTs in one nearby sample constrain heating due to dike intrusion to between 275-325°C (assuming 1-2 months duration). AFTs far from the dike constrain pre-intrusion and post-intrusion t-T paths. Ms. White will provide several Chinle Junior High School 7th Grade students the AFT-based t-T histories summarized above and an Excel workbook containing Visual Basic source code that solves the infinite sheet heat flow equation (Carslaw and Jaeger's (1959, Equation 9, page 56). The students will be tasked with matching the AFT-based and heat-flow-equation-based t-T histories. Student and professional experiences with this project are being documented and will be polled. Lessons for students will reflect the Arizona Beyond Textbooks standards as an afterschool extracurricular project. The ultimate objective of this project is to demonstrate to these curious students links between AFT sciences and the rich natural history of the Navajo Nation. Fieldwork on the Navajo Nation was conducted under a permit from the Navajo Nation Minerals Department. Any person(s) wishing to conduct geologic investigations on the Navajo Nation must first apply for and receive a permit from the Navajo Nation Minerals Department, P.O. Box 1910, Window Rock, Arizona 86515, USA, and Telephone No. +1 (928) 871-6587. Junior High School Science Club Project Due to COVID-19 restrictions, Ms. White's Science Club at Chinle Junior High School will begin this project in September 2023. This AFT study is intended to engage students with Science, Technology, Engineering, and Mathematics subjects. The students will receive background information that place the samples in their geological context. A second field trip to the sample site is planned for October 2023 so the students can view first-hand and measure field relations (dike width, distance of sandstone samples to the dike) and to collect additional rocks for further analysis (sandstone samples CJHS-3A and CJHS-3B). Students will receive scaffolded information about apatite fission track data and how time-temperature histories are predicted using those data. Additionally, students will receive an Excel file (Figure 2) with Visual Basic code that solves Carslaw and Jaeger's infinite sheet analysis equation (1959; Equation 9, page 56). The students will be tasked with learning and modifying this Visual Basic code and with matching the AFT-based time-temperature predictions. Lastly, students will receive ongoing guidance by experts whilst sharing enthusiasm about the fields of geology and geological heat flow. The ultimate objective of this project is to help curious students make the link between state-of-the-art data gathered for this project and the sciences used with the rich natural history of the Navajo Nation. It is hoped that the students enter this project in a Science Fair competition during Spring 2024. Student and professional experiences with this project are being documented and will be polled. Lessons for students will reflect the Arizona Beyond Textbooks standards as an afterschool extracurricular project. Table 1. AFT data summary (analyst Ray Donelick). Figure 3. Colored by apatite UPb age (left), REE profiles for 381 standard apatite grains (center) and 396 apatite grains (right) from this study.