Oragesee5 with1QRFICGAL:USE ONLY page 6 Zonation. Correlation using these two benthic groups is critical because calcareous nannofossils a planktic foraminifers are absent in the lower Miocene strata. Biostratigraphic data from these boreholes delineate a thick (greater than 700 feet) sequence of upper Oligocene and lower Miocene strata corresponding to lower and upper Te zone. These strata document a major period of carbonate accumulation at Enewetak during the Late Oligocene and early Miocene (26 to 18 million years 801. Item KEYWORD (S) ago). ENIWETOK/geologic formations ;GEOLOGIC FORMATIONS/paleontology ; STRATIGRAPHY; PROTOZOA; BOREHOLES; MARSHALL ISLANDS; THICKNESS ; CARBONATES ; ENIWETOK; TERTIARY PERIOD; CORRELATIONS; EXPLORATION; AGE ESTIMATION; PALEONTOLOGY; ATOMIC EXPLOSIONS 11 PB--91-239061/XAB Calcareous nannofossils and planktic foraminifers from Enewetak Atoll, Western Pacific Ocean: Geologic and geophysical investigations of Enewetak Atoll, Republic of the Marshall Islands. Professional paper 150. 110. REPORT NUMBER PRIMARY TITLE (M) 72. 710. PERSONAL AUTHOR/AFFIL Bybell, L.M.; Poore, R.&Z@. CORPORATE SOURCE Geological Survey, Alexandria, 750. 371. PUBL.ANNOUNCEMENT PUB. DATE (YYMMDD) 34. CLASSIF. 950. ABSTRACT LEVEL TEXT VA (United States) GRA-91:11922;EDB-92:006530 910000 Unclassified Boring of the carbonate sequence at the northern end of Enewetak Atoll, was conducted in 1985, Republic of the Marshall Islands, as part of the Pacific Enewetak Atoll Crater Exploration (PEACE) Program. The overall goal of the program was to characterize physical effects of large-scale nuclear blasts, which were conducted in the early 1950's, on the sediments of the atoll. In the report the authors document the occurrences of stratigraphically diagnostic planktic microfossils in samples from Enewetak (generally referred to as core) and outline the rationale for incorporating all available diagnostic planktic assemblages into a 801. KEYWORD(S) composite sequence that was used to date the Enewetak benthic zonation. ENIWETOK/geologic surveys ;ATOMIC EXPLOSIONS/BLAST DAMAGE ; GEOPHYSICAL SURVEYS; SEDIMENTS; PACIFIC OCEAN; STRATIGRAPHY; CARBONATE ROCKS;MARSHALL ISLANDS; PROTOZOA; ENIWETORK Item 12 150. REPORT NUMBER NBS--6050 OFFICIAL USE ONLY