North American microtektites in Deep Sea Drilling Project cores from the Caribbean Sea and Gulf of Mexico

摘要

Several thousand microtektites (125 to 1,000 µm in diameter) have been found in cores from two Deep Sea Drilling Project sites: site 94 in the Gulf of Mexico and site 149 in the Caribbean Sea. The microtektites occur in upper Eocene sediments associated with the last occurrence of at least five species of Radiolaria. X-ray diffraction data, energy dispersive X-ray analysis, and petrographic studies indicate the presence of inclusions of quartz, cristobalite, and lechatelierite. Major-element compositions were determined for 57 of the microtektites using energy-dispersive X-ray analysis. The geographical location, age, petrography, and chemistry of the microtektites indicate that they belong to the North American tektite strewn field (34 m.y. old). Calculations indicate that there may be as much as 109 t (metric tons) of microtektites in this strewn field.