Principal facts for gravity data in the Bethel and Russian Mission 1 degree x 3 degrees quadrangles, Alaska

Abstract

Bethel and Russian Mission 1° x 3° quadrangles are located in southwestern Alaska near the mouth of the Kuskokwim River. The Russian Mission quadrangle now has about 266 gravity stations and the Bethel quadrangle has about 485 gravity stations. Riverboat traverses along the Yukon River in the northern part of the Russian Mission quadrangle in 1967 were used to collect the first U.S. Geological Survey (TJSGS) gravity stations in the area of these quadrangles. A float-plane flight through the southeast corner of the Russian Mission quadrangle during the same time period added four stations. In 1969 a float-plane flight added one station to the east central Bethel quadrangle. In 1973 sciff work along the Kuskokwim and some of its sloughs and tributaries was utilized to add many gravity stations to the central part of the Russian Mission quadrangle and some gravity stations near the northern edge of the Bethel quadrangle. Float-plane work that year added about 35 gravity stations throughout the eastern two thirds of the Russian Mission quadrangle. Boat work on the Tikchic Lakes was utilized to establish six gravity stations to the southeast corner of the Bethel quadrangle in 1973. The Alaska Mineral Resource Appraisal Program (AMRAP) of the TJSGS for the Goodnews quadrangle, south of the Bethel quadrangle included the southern 15 minutes of the Bethel quadrangle. About 14 gravity stations were collected in this area during 1975 and 1976 with the use of a helicopter. Several float-plane flights in 1976 added six stations to the Bethel quadrangle. Ski-plane flights added 14 stations in the southwestern corner of the Bethel quadrangle and 12 stations in the southern corner of the Russian Mission quadrangle and the northwestern corner of the Bethel quadrangle in 1977. A total of 16 gravity stations were collected in the eastern Bethel and Russian Mission quadrangles in 1982. About 400 gravity stations were collected as part of the Bethel AMRAP program in the Bethel and Russian Mission quadrangles during 1987, 1988, and 1989. Most of these data were collected with a helicopter, but some were collected by using watercraft