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What was the Hawke Bay event in Cambrian stratigraphy?

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Cambrian paleogeography — Cambrian Period Distribution of landmasses, mountainous regions, shallow seas, and deep ocean basins during the late Cambrian Period. Included in the paleogeographic reconstruction are the locations of the interval's subduction zones.

In Cambrian stratigraphy, the Hawke Bay event refers to a period of global sea-level decline that resulted in extensive unconformities—interruptions in the deposition of sedimentary rock—within sectors of the continents of Laurentia and Baltica that bordered the Iapetus Ocean.1

This event is significant because it coincides with the extinction or severe geographic restriction of several characteristic early Cambrian animal groups in shallow-shelf environments. Notably, this included the disappearance of olenellid trilobites near Laurentia, holmiids at the margins of Baltica, redlichiids near Gondwana, and the loss of diverse archaeocyathans from most low-latitude, warm-water continental shelves. While some regions, such as parts of western North America, do not show a clear coeval unconformity, this may be due to localized shelf subsidence following earlier tectonic activity.1