Using U-Th/He and Apatite fission track (AFT) geochronology to study the denudation history of Tasmanian dolerite will be part of my PhD thesis work. One of a senior student, Paul B. O'Sullivan had done some work in Tassie already. AFT data from wide range of outcrop and drillhole samples have been provided further constrain for thermal history and tectonics evolution of southeastern Australia. My work aims to further study one particular rock, dolerite, which is widespread and covers almost 2/3 of the whole island.
Dolerite was once believed a curse among Tasmanian. Its present had been made the fundamental construction, such as groundwater drilling, road building and mining problematic and frustrated. Thanks to the engineering technology, Tasmanian have known how to live with it and build it but not against it. Previous AFT analysis from dolerite showed ages <120 Ma which were much younger than the intrusive age (Jurassic). The results suggest at least two regional cooling episodes and imply that the intrusive body might intrude deeper than original expectation. The target of my fieldtrip is to obtain coarse-grained dolerite which is with higher possibility to get apatite to study the denudation history of Tasmania.
The trip was accomplished by me and a Korean student, Jaeryul, who studies marine terraces and geomorphology. Due to weather concern, Barry suggested me going fieldtrip in October. However, I came to know a sudden opportunity to have earlier fieldtrip with Jaeryul in early August. It’s a way to save money and time if we could work together. Moreover, I could get some help from him to collect rocks! So I decide to grab this chance although it totally disturbed my schedule. Jaeryul and I are both 1st year PhD student. We were surprised at the first moment that no other professors or senior students would go with us. But then I realized it’s an opportunity to get the experience of completing a project independently. Barry provided me some essential documents and information of previous studies. He also suggested some local institutions where I might be able to get support. I’ve contacted a geologist, Steve, in Mineral Resources of Tasmania (MRT) and have got very positive and helpful response. Not only provided me many possible sampling sites, Steve also helped me applied for the permit to sample in national parks. His assistance made me feel 50% ready to go to field!
Except for getting outcrop rocks, I also want to obtain core samples which are stored in the core shed of MRT. Pre-fieldtrip work was to read through hundreds of drill log documents to find the cores with coarse-grained dolerite. Thanks to Steve, I focused my search in some certain dolerite exposure regions and limited the reading to around a hundred documents. By reading through those files, I really appreciated those who wrote the reports and those who made them into e-file. I could easily access to the precious data even reported 50 years ago.
With limited preparing time, I was extremely anxious and irritable before the trip. One day before our departure, Jaeryul’s supervisor asked us: how much percentage you guys were ready? I said only 50% without thinking and felt regret immediately. However, he replied: Wow! That’s good. Most of the time I feel only 10% ready before going to field! Well, he might just try to make me feel better, but it did work! I just left the rest 50% to the field and decided to have a good sleep that night…