Databases for China-Indochina Paleogeography

            Building paleogeographic maps requires team efforts to compile databases of regional sedimentary and volcanic facies, to validate and update information, and to develop visualization and computer projection methods. We have worked with experts on regional geologic systems to assemble cloud-based detailed lexicons of all geologic formations within China-Indochina regions (ca. 3000 formations as of March 2023; http://chinalex.geolex.org; vietlex.geolex.org; thailex.geolex.org). A parallel program through the past decade by the Geobiodiversity Database (GBDB) team has completed a detailed grid of outcrops and borehole stratigraphic-biostratigraphic columns for much of China (http://www.geobiodiversity.com). The GBDB had initially focused on the Early Paleozoic; for example, the Ordovician portion for the South China plate contains detailed stratigraphic information at biozone level from 750 exposed sections. The user interfaces for both projects include various search options, and map or stratigraphic navigation. Both of these database projects are now components of the paleogeography program of the IUGS Deep-time Digital Earth system (deep-time.org).            These databases enable display of all lithologies of a desired time horizon onto the modern geography or onto modeled plate reconstructions of that geologic age. For the interlinked Lexicon databases of China-Indochina (and the Indian Plate), the auto-merged output provides a visualization of all formations as polygons filled with a colored generalized facies pattern projected onto the dispersed Asian plates (Du et al., Geoscience Data Journal, 2023). The GBDB database produces very detailed isopach and paleogeographic depositional-facies reconstructions, for example the paleogeography and sediment patterns of South China for each Ordovician stage (Zhang, L.N., et al., Earth-Science Reviews, 2023).            The main coordinators for the China Lexicon database include Gao Linzhi (Precambrian), Shanchi Peng (Cambrian), Xiaofeng Wang (Ordovician-Silurian), Hongfei Hou (Devonian), Xiangdong Wang (Carboniferous), Rennong Wang (Permian), Jinnan Tong (Triassic), Jingeng Sha (Jurassic), Wan Xiaoqiao (Cretaceous) and Deng Tao (Cenozoic); and the details will be published in a forthcoming Stratigraphic Lexicon of China. For Vietnam, the team at Vietnam National University provided extensive updates and GeoJSONs to their previous published-book compilation by Tran Van Tri and Vu Khuc (Editors, 2011; Geology and Earth Resources of Viet Nam, General Dept. of Geology and Minerals of Viet Nam).