Notes on the Tertiary stratigraphy of Margarita Island

Abstract

Micropalaeontological evidence is presented for a further refinement of the Tertiary stratigraphy of Margarita Island, Venezuela. The writer supports Bermudez & Gamez (1966) and Butterlin (1970) in determining the uppermost beds of the Punta Mosquito Formation as no younger than the Truncorotaloides rohri zone of the Middle Eocene. Caudri's (1974) evidence for possible deposition of Upper Eocene sediments is challenged. Micropalaeontological studies and field observations indicate the La Guica Formation to be a middle clay member of the Mio-Pliocene Cubagua Formation. Rich planktonic foraminiferal faunas from this horizon are identified as representing the Late Miocene Neogloboquadrina dutertrei zone of Bo[i & Bermudez (1965). The Los Bagres limestone is interpreted as allochthonous blocks of Paleocene or Early Eocene age within the conglomeratic facies of the Lower Eocene Las Bermudez Formation. The time gap represented by the Miocene-Eocene unconformity on the island can be demonstrated to extend through Late Eocene to Late Miocene time.