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The Eocene-Oligocene Transition: Events and Boundary

1986; Elsevier BV; Linguagem: Inglês

10.1016/s0920-5446(08)70090-6

2352-2852

Charles Pomerol, Isabello Premoli Silva,

Geological and Geochemical Analysis

The Eocene–Oligocene boundary is not characterized by a single event either catastrophic or other in origin. Most of the numerous and important changes that characterized the Eocene– Oligocene transition have their origin as far back as the late Middle Eocene or the early Late Eocene. This chapter discusses several Eocene–Oligocene transition events, such as (1) biostratigraphic events, (2) geochemical events, (3) magnetostratigraphic events, (4) trace elements events, (5) sedimentologic events, (6) tectonic and volcanic events, and (7) cosmic events. A generalized event was a marked cooling registered in all realms that culminated in a drop of temperature about 5°C some 300,000 y. later than the extinction level among the Eocene planktonic foraminifera. It is testified by a positive shift of 18O in the oceans.