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R. L. Detterman

Publications and source records attributed to R. L. Detterman.

At least 37 records · Page 2Linked to original sources
USGS1981

Gravity anomaly and interpretation map of the Chignik and Sutwik Island quadrangles, Alaska

The gravity field of the Chignik and Sutwik Island quadrangles near the center of the Alaska Peninsula represents a complex series of transitions between probable continental crust on the north, probable oceanic crust on the south, sedimentary basins on each side of the peninsula, and a central structural high and volcanic arc. The resulting gravity field may be generalized as a central southwest- to northeast-trending gravity high bordered on both sides by flanking gravity lows over sedimentary basins underlying the lowlands and continental shelf. All three gravitational features show discontinuities and magnitude variations that reflect the complex geologic setting. Data concerning this complex gravity field have accumulated slowly and intermittently since an initial measurement was made at Port Heiden more than 25 years go (Thiel and others, 1958, 1959). A few reconnaissance measurements by R. V. Allen and an offshore traverse conducted by the U.S. Coast and Geodetic Survey R/V Surveyor were made in the early 1960's (Barnes and others, 1966; Barnes, 1967). At about the same time, Gulf Oil Corp. contracted for a relatively detailed survey of the lowlands on the north shore of the peninsula; the map prepared from this survey is now available (Gulf Oil Corp., Port Moller Development Contract Report, available at U.S. Geological Survey, Anchorage, Alaska). In the early 1970's, a few new land measurements were made by P. L. Dobey, of the Alaska Division of Geological and Geophysical Surveys, and an offshore traverse was completed by the R/V C. Greene on contract to the U.S. Geological Survey (Fisher, 1979, and M. A. Fisher, written commun., 1977). The most recent measurements, the basis for this map, were made by M. E. Yount, D. L. Detra, D. R. Jefferis, and J. E. Case during the mineral assessment of the two quadrangles. D. F. Barnes, R. L. Morin, D. R. Jefferis, and R. F. Sikora have shared in the data compilation. Geologic background for the text was provided by R. L. Detterman, T. P. Miller, E. Young, and F. H. Wilson (1979, 1981).

Alaska↗
USGS1978

A gravity study of the northern part of the Arctic National Wildlife Range, Alaska

Interpretation of all publicly available onshore gravity data provides a basis for outlining regional elements of the basement and overlying structure in the northern part of the Arctic National Wildlife Range. Major post-Carboniferous sedimentary basins whose centers lie offshore on the Beaufort Shelf extend onshore in the northern part of the study area. There is strong evidence that dense basement rocks beneath these onshore extensions rise to relatively shallow depths along the northeast Alaskan coast. Geologic studies and interpretation of the gravity data indicate that the gross structural and stratigraphic framework of this area is similar to that of the Prudhoe Bay region to the west. A high potential for petroleum accumulation in the Wildlife Range is indicated by the surface presence of oil seeps, oil sands, and outcrops of reservoir and source rocks along the southern margins of the onshore basinal areas. Present data suggest that the greatest potential for onshore accumulations of hydrocarbons lies in the area south and east of Barter Island and that possibilities exist there for commercially substantial reserves. The potential of this area cannot be fully assessed, however, until the subsurface extent of several major unconformities is known. Unfortunately, gravity data alone are of little use in such determinations. South of the mountain front, large granitic intrusions are marked by a sharply defined gravity minimum. The subsurface distribution of these bodies could probably be mapped by detailed gravity surveys. Detailed aeromagnetic surveys should serve equally well for such a purpose.

Alaska↗
USGS1975

Post-Carboniferous stratigraphy, northeastern Alaska

Post-Carboniferous sedimentary rocks exposed in northeastern Alaska constitute an almost continuous sequence representing all systems from Permian to Quaternary. Because the rocks are well exposed, only slightly deformed, and very fossiliferous, they comprise an important biostratigraphic reference section. Regional and local unconformities are present, and minor hiatuses can be identified in the stratigraphic record. The rocks are divided into 3 groups, 14 formations, and 16 members; some are newly named, others revised. The Ignek Formation is abandoned, and the Okpikruak Formation is excluded from the stratigraphic sequence in northeastern Alaska. The Sadlerochit Formation is raised to group rank and divided into the Echooka (Permian) and Ivishak (Lower Triassic) Formations. The Echooka includes the Joe Creek and Ikiakpaurak Members (both new), and the Ivishak is divided into the Kavik, Ledge Sandstone, and Fire Creek Siltstone Members (all new). The Shublik Formation (Middle and Upper Triassic) is informally divided into siltstone, limestone and dolomite, and clay shale members; it is separated from the Kingak Shale (Jurrassic) by the (Upper Triassic) Karen Creek Sandstone (new). Lower Cretaceous (Neocomian) rocks are mapped as the Kongakut Formation (new). The Kongakut includes the clay shale, Kemik Sandstone, pebble shale, and siltstone members. The Bathtub Graywacke (new) may be in part equivalent to the Fortress Mountain Formation. The Nanushuk and Colville Groups are extended into northeastern Alaska to replace the Ignek Formation. The Nanushuk includes the Tuktu and Chandler Formations, and the Colville is subdivided into its subordinate Seabee, Prince Creek, and Schrader Bluff Formations. All Tertiary rocks are included in the redefined Sagavanirktok Formation, which is divided into the Sagwon, Franklin Bluffs, and Nuwok Members (new). The Gubik Formation (Pleistocene) is extended into northeastern Alaska. Post-Carboniferous rocks are mainly sandstone, siltstone, shale, and conglomerate, and include both marine and terrestrial deposits with a cumulative thickness of about 8,500 m (28,000 ft). Marine transgressions and regressions are identified in the stratigraphic sequence, and a major shift from a northern source area for the older rocks to a southern source for the younger rocks is demonstrated. This change took place during the Early Cretaceous, and the Bathtub Graywacke is the first unit to clearly reflect a southerly source area. Post-Carboniferous orogeny in northeastern Alaska started during the Aptian Stage of the Lower Cretaceous. Pre-Aptian sandstones are mature, clean, quartz arenites, whereas most post-Aptian sandstones are lithic arenites or graywackes.

Alaska↗
USGS1974

Alaska

No abstract available.

Alaska↗