Historical Geology from Late Neogene Planktonic Foraminifera: ABSTRACT

Abstract

Study of the JOIDES, Deep Sea Drilling Project, Leg 1, Gulf of Mexico Sites 02 and 03; study of Texas AM and study of the Jamaica surface localities of E. Robinson (SEPM 1969 field trip) reveal a complete late Neogene history. Marine planktonic histories are synchronous in the Gulf of Mexico, the Caribbean, and the Pacific. Across these geographic provinces from the tropics to the poles, however, the synchronous climatic events are expressed by differing and commonly unique assemblages of temperature sensitive planktonic foraminifers. Mirror image analogs of the tropical history are represented by warmer (right coiling) and cooler (left coiling) pachyderma group biostratigraphic records in the late Neogene of Alaska and New Zealand. These paleoclimatic events of several million years duration, based on K/A dating, are described as follows. (1) The end of the middle Miocene warm climatic event approximately 15 m. y. ago coincides with the extinction of the fohsi group at the top of the Montpellier Formation of Jamaica and the Cipero Formation of Trinidad. (2) The relatively cooler late Miocene recorded 2 cooler and 2 warmer events characterized by the nepenthes group and ended approximately 11 m. y. ago. (3) A worldwide early Pliocene warm climax 7 m.y. ago was preceded by an intense cooler event of extinction and coiling changes, the Sigsbee zone. End_Page 361------------------------------ (4) Progressively cooling and fluctuating climates typify the late Pliocene (with Globorotalia tosaensis) which ended with the cold climax of the first intense Pleistocene glaciation and extreme low sea level stand. End_of_Article - Last_Page 362------------