To celebrate SEPM’s 100th anniversary, and almost ten years of successful collaboration, Prof. Dashtgard at Simon Fraser University, Canada, and Prof. Löwemark, NTU, invited selected specialists to a scientific meeting dedicated to the sedimentology of convergent margins. From experience, most scientific interaction at meetings does not take place through the actual presentations, but happens during breaks, meals, or field trips. To capitalize on this insight, we structured the meeting around two symposia flanked by field trips to selected sites chosen to highlight different stages of the formation of Taiwan. In all, 17 sedimentologists from 10 different countries representing four continents presented their research and joined the two mini-buses for a tour around Taiwan.
The first symposium was held at the Department of Geosciences (NTU) and featured two keynote presentations. First out was Michael Hren from University of Connecticut, USA, who outlined how compound specific isotopes can be used to assess the altitude of the uplifting Taiwan orogen over the past 5–6 million years. Our second keynoter speaker, Annette George from University of Western Australia, gave an overview of the continent-arc collisions responsible for the formation of northern Thailand.
After the first symposium, we took the group for a two-and-a-half-day field trip to visit river sections in the Western Foothills, where the sedimentary rocks record the shift in the source of the sediments as Taiwan started to uplift. Before the collision started, sands and muds were delivered by long rivers from the Eurasian mainland onto a passive continental margin in a shallow marine to coastal environment. As the collision progressed, the sediment source shifted to the uplifting Taiwan mountain ranges, and the sediment delivered by short, steep rivers was deposited in a strait characterized by strong tidal currents which formed between the uplifting island and the Asian continent.
The second symposium was held at the Department of Earth Sciences (NCU), and featured two more keynote addresses. The first keynote was delivered by our local host, Prof. Andrew T-S Lin, who gave an overview of the formation of Taiwan and resulting strata. The final keynote address was given by Liz Hajek, Penn State University, USA, who explored how the interplay between sediment delivery and accommodation space influences the sedimentary structures preserved.
Following the second symposium, the group headed south, visited the spectacular badlands in Moon World, Tianliao, before crossing over to the East Coast. The Coastal Range, which stretches from Taitung in the south to Hualien in the north, consists of an uplifted volcanic island arc. In the sediments deposited on the sides of the volcanic islands, a record of the island arc gradually approaching and finally colliding with the Eurasian margin is preserved. Spectacular stops included the volcanoclastic rocks at Shitiping and overturned turbidites at Xiaoyehliu.
Our last day was spent on the NE Coast, where shallow marine strata from the past 30 million years or so expose snapshots of paleoenvironmental conditions of the different stages of the collision. For instance, at Yehliu Geopark we saw trace fossils that demonstrate how vertebrates such as stingrays hunted for shrimp and worms hiding deep in the sediment on the paleo-continental shelf.
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