The Meteor Impact that Killed the Dinosaurs?

Key Investigator: Charles E. Duller

The northern Yucatan Peninsula is a region of geologically youthful limestone development controlled largely by fractures in its flat surface. These fractures also control ground water flow. Of the two main fracture systems in the northern Peninsula, the western system features a semi-circular boundary of fractured and unfractured rock, along which is found a chain of sink holes. This feature is the Cenote Ring ("Cenote" is the local Spanish word for sink hole, adapted from the Yucatec Maya word dz'onot. (See Figure 1.) The Cenote Ring was discovered with Landsat Thematic Mapper imagery during an archaeological remote sensing survey of ancient Mayan surface water sources in 1988 (Figure 2). The origin of this ring is now thought to be related to a buried impact crater.

The origin of the Cenote Ring must be a circular structural anomaly, for no combination of stresses from the region's fault systems could produce such a nearly perfect circular feature. A gravimetric and magnetic high lies at the center of the ring, while a gravimetric and magnetic low is found just outside the ring. The 170 kilometer diameter region within the Cenote Ring corresponds to the floor of the proposed buried crater. A subsequent study of subsurface geology and magnetic and gravimetric anomalies of the region supports the interpretation that the fracturing that created the Cenote Ring is related to underground slumping in the rim of a buried 200+ kilometer diameter impact crater dating geologically to the.boundary between the Cretaceous and Tertiary periods, roughly 65 million years ago.

An examination of data from nine exploratory oil wells in the vicinity of the ring showed that the ring interior corresponds with a Late Cretaceous structural low filled with Tertiary sediments. A large body of evidence now exists supporting the hypotheses that a major comet or asteroid struck the Caribbean region at this time (Figure 3). Such an impact is thought to be responsible for the mass extinction of many floral and faunal species, including the large dinosaurs, that mark the termination of the Cretaceous period. Previously, the remains of such an impact crater have escaped discovery. The Cenote Ring, discovered through NASA's remote sensing technology, offers a prime candidate for the impact site of a global catastrophic event.

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