Tsunamis Struck Coasts of Triassic Oceans and Seas: Brief Summary of the Literary Evidence

Abstract

Studying palaeotsunamis is important to the comprehensive understanding of these events and their role in the geological evolution of the coasts of oceans and seas. The present work aims at summarizing the published information on Triassic tsunamis to document their spatiotemporal distribution and the related knowledge gaps and biases. A bibliographical survey was undertaken to collect the literature sources, and their content was examined to extract the principal information about palaeotsunamis. The certainty of the literary evidence for particular localities and regions is addressed by checking the consistency of the published interpretations. It is found that tsunamis were discussed commonly in different parts of the world for the Permian–Triassic transition and the end-Triassic. However, the certainty of the literary evidence is questionable in both cases. Some interpretations of palaeotsunamis were disputed, and storm versus tsunami interpretations were offered in several cases. A few tsunamis were also reported from the Olenekian–Carnian interval but with the same quality of literary evidence. Taking into account the frequency of tsunamis in the historical times and the Holocene, as well as the presence of their possible triggers in the Triassic, it is proposed that the analyzed literary evidence is significantly incomplete, and, thus, our knowledge about Triassic tsunamis is imperfect. Further research should aim at studying them in a bigger number of localities, paying attention to the Olenekian–Norian interval and trying to relate them to different triggers.

Ordovician Tsunamis: Summary of Hypotheses and Implications for Geoheritage Resources

“…In other words, we know no more than 0.00001% of them. The significant incompleteness of the knowledge of ancient tsunamis is established for the much younger periods [27]. As noted above, the sources of this incompleteness can be both objective and subjective [24][25][26][27][28].…”

“…The significant incompleteness of the knowledge of ancient tsunamis is established for the much younger periods [27]. As noted above, the sources of this incompleteness can be both objective and subjective [24][25][26][27][28]. Tsunami deposits are not necessarily preserved, and even when so, it is very difficult to identify and interpret them correctly (for instance, they can easily be misinterpreted as storm deposits or anything else).…”

“…In regard to what is known about the common scarcity of information about pre-Quaternary tsunamis [24][25][26][27][28], one can conclude that Ordovician tsunamis are known more or less appropriately (at least, in regard to the present level of the development of geology). They were reported from all epochs of the period (Figure 1) and from many major palaeotectonic domains (Figure 2).…”

“…They can be interpreted on the basis of the careful analysis of sedimentary structures or the modeling of tsunami-triggering processes. Nonetheless, the evidence of pre-Quaternary tsunamis is very limited due to their poor preservation, the methodological difficulties, and, probably, the unawareness of geologists about their indicators in the sedimentary successions [24][25][26][27][28]. In particular, Pratt [29] stated that the tsunami horizons could occur more widely in the stratigraphical successions than expected.…”

“…This is why it appears very important to gather it together and systematize it. Moreover, Ruban [27] explained that it is really important to pay attention to the quality (better put, certainty) of the evidence of ancient tsunamis. In some cases, they were proposed too briefly and without detailed argumentation, or the researchers were unable to choose between tsunamis and severe storms.…”