Christopher S. Swezey¹
(1) BP Amoco Exploration, Houston, TX

Abstract: Miocene-Pliocene stratigraphy of the Amberjack Field, Mississippi Canyon blocks 108-109, Gulf of Mexico

The Amberjack Fields, located in Mississippi Canyon blocks 108-109 (northern Gulf of Mexico), consists of muds and very fine sands of Miocene and Pliocene age. Hydrocarbon-bearing sands within this field have been designated as follows (from oldest to youngest): O, M, I, J, G, F, and E. The O Sand and older sediments are interpreted as upper continental slope deposits, and the younger sediments are interpreted as shelf-edge delta deposits. The J Sand is the “lower delta” and the G Sad is the “upper delta” previously described by Mayall et al. (1992).

Using dates from Berggren et al. (1995a, b), biostratigraphic data from the MC 108#1 well provide some constraints on the timing of the transition from older continental slope deposits to younger deltaic deposits. The Last Appearance Datum (LAD) of planktonic foraminifera Globigerina nepenthes occurs above the M Sand, suggesting that the M Sand is older than 4.2 million years. The LAD of calcareous nannofossil Discoaster quinqueramus occurs between the M and O Sands, suggesting that the M Sand is younger than 5.6 million years and that the O Sand is older than 5.6 million years. Age-diagnostic fossils were not identified below the O Sand. The transition from continental slope deposits to deltaic deposits is interpreted as a sequence boundary that formed by a eustatic fall in sea level sometime around 5.6 million years ago.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana