Tropical cyclones (TCs) cause irreversible damage and thousands of deaths annually. Predicting future changes in the frequency and relative intensity of TCs is a timely problem that requires tracking their occurrence and recurrence in the rock record, and matching their cyclicity and impacts to climate and paleoclimate models. In Southeast Asia, one of the most populated places on Earth, TCs are the primary mechanism for sediment erosion and transport, delivering millions of tons of sediment annually from land to the surrounding oceans, and this is amplified in tectonically active areas such as Taiwan. Recent studies have identified sedimentological and geochemical expressions of past TCs from the Western Foreland Basin (WFB; Taiwan) and defined changes in sediment character as a function of precession-related coupled TC and monsoon intensity variations. Together, these recent results demonstrate the dominant influence of TCs during deposition in the WFB (Plio-Pleistocene), and the relatively young age of these strata allows comparison with depositional processes in the modern Taiwan Strait. The high sediment supply and high accommodation creation (due to high tectonic subsidence) occurring in the WFB enhanced the preservation potential of short-duration depositional processes and climate cycles, resulting in the preservation of relatively reliable climate archives in shallow-marine strata. Furthermore, Taiwan is located along the path of most of the TCs generated in the northwestern Pacific, including the strongest recorded on Earth; consequently, Taiwan and the WFB constitute the best natural laboratory to study the record of TCs. If this underscores the significant impact of climate and extreme weather events on sedimentation, several questions remain, and through my research, I aim to answer the following questions using multiple methodologies:

What is the long-term record of tropical cyclones over the past million years?

How do Earth's orbital parameters affect and modulate the intensity and frequency of TCs over short and long periods of climate oscillation?

How have TC frequencies and intensities responded to climate oscillations?

What do stratigraphic data tell us, and how can these data be used in prediction models?

Recognizing hybrid depositional systems in the sedimentary record is not trivial when one of the processes does not leave direct sedimentary traces that allow its identification. The facies models for wave-dominated and storm-dominated depositional environments are well established in the literature for both modern and fossil environments, providing a predictable zonation of sedimentary structures created by the collapse of wave orbits on the sea floor. However, wave-dominated and storm-dominated environments represent an end member of the three processes (rivers, tides, and waves) that influence coastal environments. A mixed coastal depositional system occurs when the dominant controlling process is overlapped by one of the other two. Recent studies have discussed the sedimentary organization of modern coastal systems under the influence of waves and tides, and similar systems certainly existed in the past, but only a few of them have been described in ancient sedimentary successions. Studies of modern and ancient coastal environments have focused on the shallowest parts of these mixed systems, the intertidal and shallow subtidal zones. The continuation of these systems offshore is poorly constrained, and very few models have been proposed that integrate such a sedimentary context from the shoreline to offshore. In wave- and storm-dominated sedimentary systems, the influence of tides is generally erased, and tide-related sedimentary structures have a much lower preservation potential than wave-related structures. Consequently, proving tidal influence in a wave-dominated sedimentary environment by identifying unique tidal structures may be difficult or infeasible. This difficulty probably explains why these types of environments have not been widely recognized in ancient sedimentary successions. Thus, through the combined analysis of ancient and modern environments, I try to provide new criteria for the recognition of ancient sedimentary successions. I focus mainly on systems under the influence of waves and tides.

Picture: Puncoviscana, Santa Rosita and Yacoraïte formations, Quebrada de Humahuaca, Argentina © Romain Vaucher