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Preliminary stratigraphy and facies analysis of the Upper Cretaceous Kaguyak Formation, including a brief summary of newly discovered oil stain, upper Alaska Peninsula

Alaska Division of Geological & Geophysical Surveys Preliminary Interpretive Report 2013-1F

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Abstract

The Alaska Division of Geological and Geophysical Surveys has an ongoing program aimed at evaluating the Mesozoic forearc stratigraphy, structure, and petroleum systems of lower Cook Inlet. Most of our field studies have focused on the Jurassic component of the petroleum system (this report). However, in late July and early August of 2012, we initiated a study of the stratigraphy and reservoir potential of the Upper Cretaceous Kaguyak Formation.


The Kaguyak Formation is locally well exposed on the upper Alaska Peninsula (fig. 25) and was named by Keller and Reiser (1959) for a sequence of interbedded siltstone and sandstone of upper Campanian to Maastrichtian age that they estimated to be 1,450 m thick.Subsequent work by Detterman and Miller (1985) examined 900 m of section and interpreted the unit as the record of a prograding submarine fan.This interpretation of deep-water deposition contrasts with other Upper Cretaceous rocks exposed along the Alaska Peninsula and lower Cook Inlet that are generally described as nonmarine to shallow marine (Detterman and others, 1996; LePain and others, 2012).Based on foraminifera and palynomorphs from the COST No. 1 well, Magoon (1986) concluded that the Upper Cretaceous rocks were deposited in a variety of water depths and environments ranging from upper bathyal to nonmarine. During our recent fieldwork west and south of Fourpeaked Mountain, we similarly encountered markedly varying lithofacies in the Kaguyak Formation (fig. 25), and we also found oil-stained rocks that are consistent with the existence of an active petroleum system in Upper Cretaceous rocks on the upper Alaska Peninsula and in lower Cook Inlet. These field observations are summarized below.

Study Area

Additional Publication Details

Publication type:
Report
Publication Subtype:
Other Government Series
Title:
Preliminary stratigraphy and facies analysis of the Upper Cretaceous Kaguyak Formation, including a brief summary of newly discovered oil stain, upper Alaska Peninsula
Series title:
Alaska Division of Geological & Geophysical Surveys Preliminary Interpretive Report
Series number:
2013-1F
Year Published:
2013
Language:
English
Publisher:
Alaska Division of Geological and Geophysical Surveys
Contributing office(s):
Geology, Minerals, Energy and Geophysics Science Center
Description:
8 p.
Larger Work Type:
Report
Larger Work Subtype:
Other Government Series
Larger Work Title:
Overview of 2012 field studies: Upper Alaska Peninsula and west side of lower Cook Inlet, Alaska (Alaska Division of Geological & Geophysical Surveys Preliminary Interpretive Report 2013-1)
First page:
25
Last page:
32
Country:
United States
State:
Alaska