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Geology topics

Paul R. Carlson

Publications and source records attributed to Paul R. Carlson.

At least 37 records · Page 2Linked to original sources
USGS1984

Discovery of two new large submarine canyons in the Bering Sea

The Beringian continental margin is incised by some of the world's largest submarine canyons. Two newly discovered canyons, St. Matthew and Middle, are hereby added to the roster of Bering Sea canyons. Although these canyons are smaller and not cut back into the Bering shelf like the five very large canyons, they are nonetheless comparable in size to most of the canyons that have been cut into the U.S. eastern continental margin and much larger than the well-known southern California canyons. Both igneous and sedimentary rocks of Eocene to Pliocene age have been dredged from the walls of St. Matthew and Middle Canyons as well as from the walls of several of the other Beringian margin canyons, thus suggesting a late Tertiary to Quaternary genesis of the canyons. We speculate that the ancestral Yukon and possibly Anadyr Rivers were instrumental in initiating the canyon-cutting processes, but that, due to restrictions imposed by island and subsea bedrock barriers, cutting of the two newly discovered canyons may have begun later and been slower than for the other five canyons.

Bering Sea↗
USGS1982

Geologic hazards in Navarin Basin Province, Northern Bering Sea

Navarin Basin, scheduled for leasing in 1984 (OCS sale 83), may contain vast accumulations of oil and gas. Several geologic and oceanographic processes that may be active in and around Navarin Basin province could be hazardous to commercial development. These potential hazards include submarine slides; sea-floor instability resulting from disturbance of gas-charged sediment; sediment transport and erosion caused by storm waves, tsunamis, internal waves, or bottom currents; pack ice; and active faults and ground motion.

Bering Sea, Navarin Basin↗
USGS1982

Submarine valleys in the northeastern Gulf of Alaska: Characteristics and probable origin

The continental shelf of the northeastern Gulf of Alaska Between Prince William Sound and Cross Sound is cut by at least eight major valleys. From west to east, these are Hinchinbrook Seavalley, Egg Island Trough, Kayak Trough, Bering Trough, Pamplona Troughs, Yakutat Valley, Alsek Valley and Yakobi Valley. Evidence common to most of these troughs or valleys indicating that the present morphology is due to glacial processes includes: (1) a pre-Holocene subbottom erosional surface incised into the underlying lithified strata of the shelf; (2) U-shaped cross sections, both at the sea floor and at the pre-Holocene erosional surface; (3) concave longitudinal sections, commonly shoaling at the seaward end; (4) till-like sediments collected from the walls or outer shelf adjacent to the troughs; and (5) seismic stratigraphy that can be correlated with bottom samples indicative of glacially derived strata. Depressions with tens of meters of relief are present on the pre-Holocene subbottom erosional surface beneath most of these valleys. These depressions have been partially filled by a seaward-thinning wedge of Holocene glacial flour (clayey silt) that is filling the valleys and blanketing the inner shelf at rates as high as 15 mm/yr (based on 210 Pb measurements). Although glaciation played a dominant role in the modern morphology of these sea valleys, structural features, including structurally controlled topographic highs on the shelf (e.g. Tarr Bank, Kayak Island, Pamplona Spur and Fairweather Ground) influenced the flow directions of the glacial lobes.

Alaska↗
USGS1978

Geotechnical properties of sediments from the Continental Shelf south of Icy Bay, northeastern Gulf of Alaska

Studies of geotechnical properties of marine sediments have recently intensified as the search for natural resources has expanded on the continental shelf. The U. S. Geological Survey has begun a detailed evaluation of geologic environmental conditions in continental shelf regions in order to facilitate safe development of continental shelf resources. Investigations of geohazards in the northeastern Gulf of Alaska (Fig. 1) began in 1974 when 6500 km of high and medium resolution seismic reflection data were collected from the eastern gulf between Yakutat and Montague Island (Carlson, Bruns and Molnia, 1975; Von Huene and others, 1975). The first extensive sediment sampling program was begun in 1975 when approximately 400 samples of continental shelf sediments were collected from the same area of the gulf (Carlson and others, 1977b). A limited number of geotechnical measurements were made from these samples and samples collected by subsequent programs, however, systematic measurement of geotechnical properties was not started until the 1977 cruise of the NOAA ship DISCOVERER. Once unstable environments or "geohazards", such as slumps and slides, are delineated, geotechnical testing is an important means of quantifying such geologic processes and consequently furthering our understanding of them. The purposes of this report are two-fold: (1) to report variations of physical properties in 1-2 meter gravity cores and (2) to recognize any variations in the areal distribution of these properties within and adjacent to an area of mass movement in the northeastern Gulf of Alaska.

Alaska↗
USGS1978

Geophysical data from the 1975 cruise of the NOAA ship Surveyor in northern Gulf of Alaska

In April and Flay 1975, a U.S. Geological Survey marine geology field party under the leadership of Bruce F. Molnia and Paul R. Carlson collected geophysical data from the N.O.A.A. ship Surveyor. The cruise, which consisted of 3 legs, studied the area between Cross Sound and Seward (Figure 1). Maps 1, 2, and 3 (scale 1:250,000) show the location of track lines and ship positions for the 3 legs.

Alaska↗
USGS1978

Minisparker profiles and sedimentologic data from R/V Acona Cruise (April 1976) in the Gulf of Alaska and Prince William Sound

In April 1976, the U.S. Geological Survey, Office of Marine Geology conducted a geophysical and sediment sampling cruise in the northern Gulf of Alaska between Seward and Kayak Island (Fig. 1) to obtain data on seafloor hazards pertinent to the OCS oil and gas lease sales. Stormy weather interrupted the planned data collection, during which time supplemental profiles and samples were collected in Prince William Sound including Montague Strait, Valdez Arm, Port Valdez, and Columbia Bay (Fig. 1). High resolution seismic profile records were made using a 600 Joule Del Norte Minisparker along 1151 km of track lines as shown on maps 1 and 2. Sediment samples collected with grab samplers (58) and gravity core (3) and bottom camera stations (14) are also shown on the track line maps and on figures 2 and 3. This report indicates the seismic reflection records and shipboard logs that are publicly available and includes track line maps and a text that; (1) shows examples of characteristic seismic profiles, (2) describes geologic hazards observed on specific profiles, and (3) includes summary descriptions of sediment samples and bottom photographs.

Alaska↗
USGS1977

Submarine faults and slides on the continental shelf, northern Gulf of Alaska

Submarine faults and slides or slumps of Quaternary age are potential environmental hazards on the outer continental shelf (OCS) of the northern Gulf of Alaska. Most faults that approach or reach the seafloor cut strata that may be equivalent in age to the upper Yakataga Formation (Pliocene‐Pleistocene). Along several faults, the seafloor is vertically offset from 5 to 20 m. A few faults appear to cut Holocene sediments, but none of these shows displacement at the seafloor. Submarine slides or slumps have been found in two places in the OCS region: (1) seaward of the Malaspina Glacier and Icy Bay, an area of 1200 km 2 with a slope of less than 0.5°, and (2) across the entire span of the Copper river prodelta, an area of 1730 km 2 , having a slope of about 0.5°. Seismic profiles across these areas show disrupted reflectors and irregular topography commonly associated with submarine slides or slumps. Potential slide or slump areas have been delineated in areas of thick sediment accumulation and relatively steep slopes. These areas include (1) Kayak Trough, (2) parts of Hinchinbrook Entrance and Sea Valley, (3) parts of the outer shelf and upper slope between Kayak Island and Yakutat Bay, and (4) Bering Trough.

Alaska↗
USGS1976

Report on the environmental geology OCS area, eastern Gulf of Alaska

In anticipation of oil and gas leasing of the outer continental shelf (OCS lease area 39) in the northeastern Gulf of Alaska, the U. S. Geological Survey began a regional reconnaissance in 1974. The study area, which extends from Prince William Sound on the west to Yakutat Bay on the east, is in a region fraught with natural hazards. The tectonic history of the area suggests that future major earthquakes could pose serious hazards to installations on the continental shelf or along the coast of the Gulf of Alaska. The hazard may be either direct, by ground shaking or fault displacement, or indirect, through ground failure or generation of tsunami waves. Storm waves sometimes are responsible for ground failures, especially in areas of rapid accumulation of sediment.

Alaska↗
USGS1976

Submarine faults and slides that disrupt surficial sedimentary units, northern Gulf of Alaska

Faults and submarine slides or slumps of Quaternary age are potential environmental hazards on the outer continental shelf (OCS) of the northern Gulf of Alaska. Most of the faults that approach or reach the seafloor cut strata that may be equivalent to the upper Yakataga Formation (Pliocene-Pleistocene). Along several faults the seafloor is offset from 5 to 20 m. A few faults appear to cut Holocene sediments, but none of these show offset at the seafloor. Submarine slides or slumps have been found in two places in the OCS region: (1) seaward of the Malaspina Glacier and Icy Bay, an affected area of 1,770 km 2 with a slope of less than one-half degree, and (2) across the entire span of the Copper River prodelta, an area of 1,730 km 2 , having a slope of about one-half degree. Seismic profiles across these slide areas show disrupted reflectors and irregular topography commonly associated with submarine slides or slumps. Potential slide or slump areas have been delineated in areas of thick sediment accumulation and relatively steep slopes. These areas include (1) Kayak Trough, (2) parts of Hinchinbrook Entrance and Sea Valley, (3) parts of the outer shelf and upper slope between Kayak Island and Yakutat Bay and (4) Bering Trough.

Alaska↗