Geology topics
Roland E. von Huene
Publications and source records attributed to Roland E. von Huene.
Map showing the geologic structure of the continental shelf southeast and southwest of Kodiak Island, Alaska, from 24-fold seismic data
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Transverse tectonic boundaries near Kodiak Island, Alaska
Transverse tectonic boundaries exist at the northeast and southwest ends of the Kodiak islands, so that the Aleutian arc-trench system is longitudinally segmented in this area. Evidence for the transverse boundaries includes alignments of such geologic features as offset volcanic lineations, terminations of structural trends, and boundaries of discrete zones of earthquake aftershock sequences. The boundaries appear to be broad zones of disruption that began to form during the late Miocene or Pliocene. Although oceanic fracture zones and seamount chains intersect the continental margin near the boundaries, subduction of these features probably did not cause the tectonic boundaries. The fracture zones and seamount chains have swept northeastward along the margin, at least since the late Pliocene, because of the direction of convergence of the Pacific and North American plates.
Leg 67: the Deep Sea Drilling Project Mid-America Trench transect off Guatemala.
Drilling on the Cocos plate recovered a basal chalk sequence deposited during early and mid-Miocene time, a short interval of abyssal red clay, and an upper sequence of late Miocene and younger sediment deposited within an area influenced by a terrigenous source. In the trench, a mud and sand fill less than 400,000 yr old overlies the oceanic sequence. The entire section shows no evidence of compressive deformation. In contrast, the section cored on the trench's landward slope 3 km from the trench axis is affected by tectonism. The section contains a Cretaceous to Pliocene claystone sequence capped by Pliocene to Quaternary hemipelagic slope deposits.- from Authors
Sedimentary masses and concepts about tectonic processes at underthrust ocean margins
Tectonic processes associated with subduction of oceanic crust, but unrelated to the collision of thick crustal masses or microplates, are presumed by many geologists to significantly affect the formation and deformation of large sedimentary bodies at underthrust ocean margins. More geologists are familiar with the concept of subduction accretion , which describes the tectonic attachment of rock and sediment masses to the margin's bedrock framework, than with other noncollision processes—for example, sediment subduction, subduction erosion , and subduction kneading . These are equally important processes controlling the geologic evolution of underthrust margins, and any one of them may predominate at a given place.
Free-air gravity anomaly map, western Gulf of Alaska
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Map showing near-surface geologic structures of Kodiak Shelf, Alaska
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Maps showing structural interpretation of magnetic lineaments in the northern Gulf of Alaska
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Petroleum potential, environmental geology, and the technology for exploration and development of the Kodiak lease sale area #61
The Kodiak lease area is along a convergent ocean margin where active subduction is probably the greatest single influence on the geology. This influence is indicated by the Aleutian Trench, the Aleutian chain of volcanoes, and a well developed Benioff zone of earthquakes. Crustal structure under the Kodiak Shelf is intermediate between continental and oceanic. The thickness of sedimentary rock is 8 ± 3 km, which is greater than beneath the island. The proposed lease—sale area is on a submerged shelf extending 100 km or more seaward from the Kodiak group of islands, and it is more than 400 km long. The Kodiak Shelf still retains a glacial topography which has been modified by tectonically uplifted banks along the shelf edge and across the shelf. These banks are readily detectable signs of recent tectonism. Not so easily detectable are three deep offshore Neogene basins formed by depression of an unsampled presumed Paleogene sedimentary section. The basin floors have subsided 5 to 7 km since middle (?) Miocene time; the basins are filled with late Miocene and younger sediment that is only gently deformed. A sudden increase in seismic velocity occurs across the contact between the basin fill and the presumed Paleogene rocks that underlie it. This discontinuity in seismic velocity, the smooth character of the basin surface, and the truncation of dipping beds beneath it, are the basis for inferring subaerial erosion of the Paleogene section. If this inference is correct, the structure in some places requires at least 3000 m of subsidence followed by an uplift of even greater magnitude in Neogene time. The vertical tectonism offshore might produce reservoir rock and different source rock than encountered onshore.
Bathymetric map of the western Gulf of Alaska
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Biostratigraphic results of dart-coring in the western Gulf of Alaska, and their tectonic implications
Age determinations are reported for microfossils from 56 dart-cores collected in 1978 from the Kodiak shelf. The ages suggest that rocks cropping out along Albatross Bank, at the shelf edge, are as old as middle or late Miocene, and that the anticline forming Albatross Bank, previously defined with multi- and single-channel seismic records, plunges northeastward in the sampled area. Foraminiferal paleobathymetry further suggests that m.ajor tectonic activity has occurred on the Kodiak shelf since the early or middle Pliocene, including two episodes of vertical movement--first subsidence on the order of 2000 m, then uplift of at least 3000 m. Microfossil ages and paleobathymetric determinations indicate an average uplift rate of 1000- 3000 m/m.y. for the seaward edge of the Kodiak shelf during the Quaternary.
A summary of petroleum potential, environmental geology, and the technology, time frame, and infrastructure for exploration and development of the western Gulf of Alaska
This summary of the regional geology, petroleum potential, geologic hazards and time frame for exploration of the western Gulf of Alaska has been written to aid the Bureau of Land Management in preparing the Draft Environmental Impact Statement. A preliminary version was written in Sept., 1975.(von Huene and others, 1975) in support of the Call for Nominations, Proposed OCS Oil and Gas Lease Sale #46. Since that time, there has been a substantial increase in information as the result of a two-month examination of recent studies of the adjacent Gulf of Alaska Tertiary Province and a preliminary interpretation of some publicly available common depth point (CDP) seismic reflection data recently acquired by the U.S. Geological Survey. The main source of geologic and geophysical data used in the preparation of this summary is published and unpublished information of the U.S. Geological Survey (Plafker and others, 1975,Bruns and Plafker, 1975; Carlson, Bruns and Molnia, 1975; Carlson and Molnia, 1975; Core, Mattick, and Bayer, 1975; Molnia and Carlson, 1975 a & b; von Huene and others, 1975). Prior to 1975, data were gathered mainly for purposes other than for assessment of oil and gas resources and of the environmental consequences of exploration and development. A systematic survey for such an assessment is planned for the summer of 1976 and, therefore, this summary is tentative. Although the major problems and regional setting are discussed in this paper, a great deal more specific data and interpretations will begin to become available in about one year. In this summary we consider the geology of a broad region on the continental shelf off the Kodiak group of islands and the Kenai Peninsula. We will concentrate on the area proposed for leasing in Sale #46. The area lies between about 56°N latitude and 60°N latitude (Fig. 1), and it measures approximately 660 km x 100 km. Water depths are generally less than 200 m.
Seismic reflection profiles November 1972 cruise, USNS Bartlett, offshore Central and southern California
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A preliminary summary of petroleum potential, environmental geology, and the technology, time frame and infrastructure for exploration and development of the western Gulf of Alaska
This preliminary geology summary of the western Gulf of Alaska has been made to aid the Bureau of Land Management in defining an area for which nominations for oil and gas leasing will be solicited. The suggested area is centered about the Kodiak group of islands and is thought to outline the attractive prospects for oil and gas exploration.
Seismic profiles of the offshore Gulf of Alaska Tertiary Province, R/V Thompson, Sept.-Oct. 1974
No abstract available.
Tectonic significance of the Kodiak-Bowie seamount chain, northeastern Pacific
The hypothesis of a fixed melting spot reference frame (M) for relative plate motion is tested in the northeastern Pacific Ocean, where the Kodiak-Bowie seamount chain intersects the northern triple junction between the Pacific, American, and Juan de Fuca plates. Available age determinations on Kodiak and Giacomini Seamounts provide an estimated average rate of volcanic propagation along the chain of 6.5 cm per yr and allow estimates of plate movements relative to the melting spot. The inferred motion of the American plate relative to M is close to that observed along the Yellowstone-Snake River Plain volcanic trend and broadly supports the concept of a fixed melting spot reference frame. However, the convex northward curvature of the Kodiak-Bowie chain and of several chains to the south does not support the hypothesis. The lack of parallelism between these seamounts and the Hawaiian chain suggests slow relative movement between the Kodiak-Bowie and Hawaiian melting spots.
Peru-Chile Trench sediments and sea-floor spreading
The hypotheses of sea-floor spreading and plate tectonics require the removal of sediment from oceanic trenches either by crustal underthrusting or by folding against the base of a continental or insular margin. Accordingly, over a period of time the volume of sediment removed by way of spreading must be equal to the difference between the observable volume of undeformed terrigenous deposits in a trench and the volume contributed to it by continental erosion. To assess possible sediment loss from the central Chilean segment (23°–44° S.) of the Peru-Chile Trench, we have compared the volume of terrigenous deposits overlying the land, the continental margin, and filling the trench with that expected from continental denudation. Our data indicate that an episode of sediment removal occurred at the base of the margin and adjacent deep-sea floor in Late Cretaceous and perhaps earlymost Tertiary time and may imply spreading. Nearly 100 × 10 3 km 3 of deposits of Tertiary age, chiefly Eocene to Pliocene, have accumulated on the margin, and perhaps an additional 5 × 10 3 km 3 in the trench. This amount of offshore sediment could be supplied by fairly low rates (3 cm/10 3 yrs) of Tertiary erosion. However, many uncertainties in our denudation-sedimentation budget make it impossible to determine whether or not sediment reaching the base of the margin was removed tectonically in Tertiary time. Between 27° and 44° S., the trench contains nearly 70 × 10 s km 3 of turbidite deposits that we believe accumulated during late Cenozoic periods of glacially lowered sea level. The volume of turbidites in the trench is virtually equal to that expected from continental erosion, which is estimated to have probably been no greater than 5 cm/10 3 yr for the arid region between 27° and 31°, and 50 cm/10 3 yr for the humid and partially glaciated region from 36° to 42°. During this time of rapid erosion and trench filling, magnetic data indicate that convergence of lithospheric plates was taking place below the trench at a rate between 5 and 10 cm/yr. If turbidite deposits were swept from the trench at these rates, then continental denudation must have been exceedingly rapid: 20–40 cm/10 3 yr for the arid zone, and 110–165 cm/10 3 yr for the partially glaciated region. If more conventional estimates of erosion are valid, then either (1) late Cenozoic underthrusting has not taken place (or at a rate much slower than that implied by geophysical data), or (2) underthrusting at the prescribed rates has not involved the removal of a significant volume of sediment from the trench.
Geologic structure between the Murray fracture zone and the Transverse Ranges
The Murray fracture has been thought to extend ashore into the Transverse Ranges of California, but a geophysical study shows no evidence of structural continuity between these features. Instead, basement morphology typical of the Murray fracture zone ends where its known magnetic and bathymetric expression dies out. Similarly, east-west Transverse Range structures change direction so that they are parallel to the northwest trend of the coast rather than crossing the continental shelf and slope. The lack of continuity suggests an independent development of the Transverse Ranges since at least mid-Tertiary time along an older structural trend continuous with the Murray fracture zone. Possibly a fundamental lineament in the crust, an extension of the Murray, inactive since at least the mid-Tertiary, provided a convenient trend for development of the Transverse Ranges in response to deformation along the San Andreas fault system. The Murray fracture zone is thought by some authors to be a transform-fault. The transform-fault hypothesis alleviates some difficulties that arise in explaining the origin of the zone by transcurrent faulting but equivalent uncertainties seem to accompany the newer explanation.