Insight on the formation of Pacific guyots from ODP Leg 144



Guyots are flat-topped seamounts that are most common on Mesozoic-age Pacific oceanic crust. Dredging of the Pacific guyots, of which over 300 are known, commonly revealed the existence of mid-Cretaceous rudist reefs and other shallow-water carbonate facies, now submerged to depths on the order of 1000-1500 m, capping volcanic edifices [Lincoln et al., 1993].

The intriguing question of how guyots originate played a major role in the development of concepts of seafloor spreading, hot spots, thermal subsidence and crustal thinning, and superswells [e.g., Hess, 1962; Detrick and Crough, 1978; Menard, 1964, 1984]. However, key questions remain, such as why a tropical carbonate platform would suddenly cease to keep pace with subsidence after constructing a massive carbonate cap up to 1000-m thick and tens of kilometers in diameter, or why the apparent ages of the underlying volcano and of the shallow-water carbonate cap as determined from dredge samples appeared to lack the coherent patterns predicted from hot-spot and subsidence theories.