The composition of nacre will tell about temperature of the ancient ocean

Scientists from the Wisconsin university in Madison (USA) found an unusual key to determination of temperature of the ancient ocean. Nacre — “brilliant, strong as nail biomineral” of which the milky-white external covering of pearls consists. Sometimes it is found in an internal covering of sinks of mollusks, such as a nautilus, a sea zhemchuzhnitsa, an abalone.

The team under the leadership of professor Pupy Gilbert found out that the stratified composition of nacre in a mollusk provides the precise report on temperature in a mineral heating-up period. Nacre is formed when in a mollusk aragonite layers like a bricklaying at each other keep within. “We can correlate very precisely nacre layer density to temperature” — Gilbert says.

Using the electronic scanning microscope, Gilbert and his team studied a cut of a sink and measured density of layers of nacre. Knowing what was ocean temperature in a nacre heating-up period in the modern sinks, researchers could calculate the ocean temperature at which ancient nacre was formed.

“You just measure the nacre layer density, distance between lines — they correspond to temperature — Gilbert says. — When temperature is higher, layers are thicker”. Scientists studied petrified exemplars of nacre an age of 200 million years.