Episodes 2005; 28(2): 93-104
Published online June 1, 2005
Copyright © International Union of Geological Sciences.
W.J. Kennedy1, I. Walaszczyk2, and W.A. Cobban3*
1Geological Collections, Oxford University Museum of Natural History, Parks Road, Oxford OX1 3PW, United Kingdom
2Institute of Geology of the University of Warsaw, Al. Zwirki I Wigury 93, 02-089 Warszawa, Poland
370 Estes Street, Lakewood, Colorado 80226, USA
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Following the recommendation of the International Commission on Stratigraphy (16 votes Yes [94%], 1 abstention, 2 votes not received), the Global boundary Stratotype Section and Point (GSSP) for the base of the Turonian Stage of the Cretaceous System is defined as the base of bed 86 of the Bridge Creek Limestone Member of the Greenhorn Limestone Formation at the western end of the Denver and Rio Grande Railroad cut near the north boundary of the Pueblo Reservoir State Park Recreation Area, west of Pueblo, Colorado, USA. This GSSP horizon is also exposed and protected in the adjacent state recreation area. It coincides with the first occurrence of the ammonite Watinoceras devonense, is in the middle of a global positive excursion in Carbon-13 isotopes, and is bracketed by widespread bentonites that have yielded ages of 93 to 93.5 Ma.