Abstract

The Concord area is a 65–70± square mile area around the City of Concord, in the Suisun Bay portion of the Sacramento Basin. The stratigraphic section present includes predominately marine shale and sandstone, late Cretaceous through Miocene age, and predominately non-marine sediments of Pliocene through Recent age. The structure of the area has been formed by compressive forces and is extremely complex. Three major anticlinal trends, running northwest-southeast across the area, are recognized. From northeast to southwest these are, respectively, the Los Medanos, Concord and City of Concord trends. Major and minor thrust, reverse and normal faults are ubiquitous along and across the anticlinal trends. The area is bounded on the southwest by the Concord fault, a strike-slip fault with right lateral movement, and on the southeast by the major Mount Diablo uplift. Drilling of wells within the area has resulted in the discovery of approximately 46 BCF of dry gas. These wells have provided valuable geological data.