This paper reports the discovery of shocked quartz grains within a well-dated upper Eocene marlstone at the Massignano outcrop (Ancona, Italy). The shocked quartz reaches a maximum concentration of 1.6 ± 0.4 grains per cubic centimetre of bulk rock. A modest Ir anomaly is also coincident with the shocked quartz, and together they strongly support an impact origin. Moreover, this impact layer has a precise interpolated radiometric age of 35.7 ± 0.4 Ma. Although impact evidence found throughout the world indicates that at least two large impacts did occur during this time, the actual number, timing, and environmental effects of these impact events remain unclear. The late Eocene was a critical time in Earth history because of significant climatic, biotic, and environmental crises.

This content is PDF only. Please click on the PDF icon to access.

First Page Preview

First page PDF preview
You do not have access to this content, please speak to your institutional administrator if you feel you should have access.