Brügge reported in 2018 that the Chesapeake structure, with its age of 35.3 million years, is one of the most recent large impact crater on earth. However, seismic investigations and some "flat" boreholes in which breccias were drilled are not sufficient to confirm initial assumptions. In 2005, the final proof was to be provided by a deep borehole in the center of the structure. As part of the International Continental Scientific Drilling Program (ICDP), the U.S. Geological Survey induced the core drilling Eyreville, with a depth of 1766 m.
According to the scientific evaluation of the drill cores, it is confirmed that the Chesapeake Bay structure actually resulted from an impact event. This can be doubted, however, because once again was ignored a clearly existing magmatic melt. It was not recognized that the "melt-rich suevites" found in a depth range of 1397-1551 m are, in fact, breccias infiltrated with a dacitic-rhyolitic magma.
This is the result by Brugge's investigation of the many analyzes (BARTOSOVA et al.) of melts in this interval. They confirm a dacitic-rhyolitic composition of the pure melt. A wide range of deviating compositions of melts are the result of a mix of the dacitic-rhyolitic melt with molten breccias. A special feature are pure silica fractions (with very high SiO2 contents), as well as the cristobalite and tridymite crystals grown during the cooling.
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