Bunker Gas Field is in Solano County, T. 6 N., R. 1 and 2 E.,
Mount Diablo base and meridian, in the Sacramento Valley, the northern
part of the Great Valley of California.
Subsurface structure contour maps of the field indicate a north-west-
trending, faulted, domal to anticlinal fold which plunges to the
southeast.
Paleotopographic maps of the Bunker Gas Field demonstrate that:
1. The direction of the paleofluvial valleys and paleoslope
during Late Cretaceous time was generally in a south-south-
westerly direction and the sediment source was in
the north-northeast.
2. The direction of the paleofluvial valleys and paleoslope
during late Paleocene time was generally to the west
and the sediment source was to the east of the field.
This paleotopography is inferred to have persisted
during early Eocene time.
Lithologic characteristics (such as grain size, sorting, etc.)
and stratigraphic sequence illustrate that subsurface deposystems in
the Bunker Gas Field were predominantly of the shelf-facies type.
Both progradational and retrogradational suites of strata occur within
the stratigraphic sequence. The occurrence of a shallow regressive
and transgressive sea was the prominent paleogeographic feature
within the study area.
In Late Cretaceous the study area was covered by a shallow regressive
sea and was characterized by deltaic conditions during the
period that the Mokelumne sand/shale lithesome was deposited. In
early late Paleocene the study area was covered by a shallow transgressive
sea and a mid-neritic environment prevailed during the
period that the McCormick sandstone was deposited. In late late Paleocene
the area was covered by a shallow regressive sea and exhibited
a littoral environment at the time when the Martinez shale was
deposited. In early Eocene the study area was covered by a shallow
transgressive sea and was characterized by a nearshore environment
during the period that the Hamilton sandstone was deposited.
Description:
Includes bibliographical references (pages 46-48)
California State University, Northridge. Department of Geological Sciences.