Geochemistry and Migration of Meteoric and Connate Waters as Related to Geologic Structure: ABSTRACT

Abstract

Data obtained during geologic and geochemical studies in several areas of the Sacramento Valley have suggested correlation between subsurface structure and the occurrence of a type of saline water in the shallow water-bearing deposits. Sufficient data have been collected to permit construction of subsurface contours on the base of fresh water. These contours, which reflect general structure in the Sacramento-San Joaquin Delta area, represent the interface between fresh water and a specific type of saline water. This connate water contains high concentrations of sodium and chloride ions, low concentrations of sulphate and nitrate ions, and approximately equal concentrations of iodide and bromide. Under hydrodynamic conditions, fresh water in the foothills with considerable head has apparently flushed the saline waters out of a part of the marine sediments. In the Delta area this connate water has been forced upward from the marine sediments to the surface along faults and from truncated marine sediments on anticlinal structures. There are numerous other ground-water anomalies which may indicate the presence of buried structural features. A characteristic type of water apparently associated with faulting may be noted in the shallow water-bearing deposits. This water commonly has higher temperatures and greater concentrations of silica and boron than the normal ground water. Further geochemical studies of this type may be of value to the petroleum industry. End_of_Article - Last_Page 431------------