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#           Preliminary interpretation of industry two-dimensional seismic data from Susitna Basin, south-central Alaska      

      July 30, 2015    

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Located approximately 80 kilometers northwest of Anchorage, Alaska, the Susitna Basin is a complex sedimentary basin whose tectonic history has been poorly understood. Recent interpretation of two-dimensional seismic reflection data integrated with well, aeromagnetic, and gravity data provides new insights into the structural and stratigraphic nature of the basin.

This report presents an interpretation of 41 two-dimensional seismic reflection lines, acquired by industry from the 1960s to the 1980s. Our interpretation of the seismic data focused mainly on picking two Eocene stratigraphic units and a presumed base of Tertiary horizon. Based on our interpretation of the seismic data, the structural features in the basin appear to be generally contractional, as evidenced by the presence of many reverse faults, thrust faults, and folds, with the contraction mainly oriented east-west. This result is contrary to prior inferences of most previous geologic studies that showed normal faults. Several regional reverse faults have been identified in the seismic data and appear to divide the basin into three regions or “sides”: east, west, and south.

The eastern seismic lines show evidence of numerous short-wavelength antiforms that appear to correspond to a series of northeast-trending lineations observed in aeromagnetic data, which have been interpreted as being due to folding of Paleogene volcanic strata. The eastern side of the basin is also cut by a number of reverse faults and thrust faults, the majority of which strike north-south. The western side of the Susitna Basin is cut by a series of regional reverse faults and is characterized by synformal structures in two fault blocks between the Kahiltna River and Skwentna faults. These synforms are progressively deeper to the west in the footwalls of the east-vergent Skwentna and northeast-vergent Beluga Mountain reverse faults. Although the seismic data are limited to the south, we interpret a potential regional south-southeast-directed reverse fault striking east-northeast on the east side of the basin that may cross the entire southern portion of the basin.

## Citation Information

## Related Content

                  -              Connect           

#### Kristen Lewis, PhD

##### Supervisory Geophysicist/USGS Geomagnetism Program Group Leader

Geomagnetism Program

klewis@usgs.gov

303-273-8471

####             Chris Potter (Former Employee)          

##### Research Geologist

Central Energy Resources Science Center

#### Anjana K Shah

##### Research Geophysicist

Geology, Geophysics, and Geochemistry Science Center

ashah@usgs.gov

303-236-1218

#### Richard G Stanley

##### Scientist Emeritus

Geology, Minerals, Energy, and Geophysics Science Center

rstanley@usgs.gov

650-329-4918

#### Peter J Haeussler, Ph.D.

##### Research Geologist

Alaska Science Center

pheuslr@usgs.gov

907-786-7447

## Related Content

#### Kristen Lewis, PhD

##### Supervisory Geophysicist/USGS Geomagnetism Program Group Leader

Geomagnetism Program

klewis@usgs.gov

303-273-8471

####             Chris Potter (Former Employee)          

##### Research Geologist

Central Energy Resources Science Center

#### Anjana K Shah

##### Research Geophysicist

Geology, Geophysics, and Geochemistry Science Center

ashah@usgs.gov

303-236-1218

#### Richard G Stanley

##### Scientist Emeritus

Geology, Minerals, Energy, and Geophysics Science Center

rstanley@usgs.gov

650-329-4918

#### Peter J Haeussler, Ph.D.

##### Research Geologist

Alaska Science Center

pheuslr@usgs.gov

907-786-7447

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####               Central Energy Resources Science Center          

Denver Federal CenterBldg. 25Denver, CO80225United States

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