Research Training Program

Bryan Cockrell
Princeton University
Princeton, New Jersey

Ed Vicenzi, Ph.D.
Supervising Scientist
Department of Mineral Sciences

"While I searched for carbonates, another mineral scientist analyzed samples from a comet, and another studied the results of Mars rover missions- needless to say, it was a striking experience to do research at NMNH."

The Origins of Layered Carbonates in Ancient Volcanic Rock

Depositions of carbonate compounds have been discovered in lava-coated foreign mantle rock that arose with the eruption of the Sverrefjell volcano through a glacier in Svalbard, Norway one million years ago during the Pleistocene epoch. This investigation has sought to explore how the carbonates were deposited. First, light microscopy helped to elucidate the environments of the globules, on the boundaries of mineral grains and at grain junctions. Then, an evaluation of the local chemistry of these globules was made using a scanning electron microscope and an electron microprobe. The layered globules were found to be rich in calcium-, iron-, and even lead- carbonate, all of which often surrounded a clay-like center. Iron and magnesium silicates were discovered in the layers in greater abundance than anticipated. Cathodoluminescence, a method through which electrons in a specimen are excited and emit light, helped to characterize the liquid that carried these carbonates into the rock. The liquid has been proposed as local water heated by the volcano. As a means of comparison, other occurrences of carbonate in Svalbard, such as in chimney-like columns, fault fillings, and terraces, were analyzed using similar methods. These layered carbonates are almost identical to ones discovered in a Martian meteorite and may have implications for studies of early life.

This research was supported by a grant from the Department of Mineral Sciences.

Letter of gratitude