scholarly journals Uplift, Emergence, and Subsidence of the Gorda Escarpment Basement Ridge Offshore Cape Mendocino, CA

2017 ◽  
Vol 18 (12) ◽  
pp. 4503-4521
Author(s):  
Susan M. Hoover ◽  
Anne M. Tréhu
Keyword(s):  
Basement Ridge

scholarly journals Application of seismo-stratigraphic interpretation techniques to offshore West Greenland

1988 ◽  
Vol 140 ◽  
pp. 64-66
Author(s):  
J.A Chalmers
Keyword(s):  
Pilot Study ◽  
Seismic Data ◽  
Seismic Interpretation ◽  
Shelf Break ◽  
The West ◽  
Regional Geology ◽  
West Greenland ◽  
Oil Companies ◽  
Greenland Basin ◽  
Basement Ridge

A pilot study is being conducted to determine if the use of seismo-stratigraphic interpretation techniques can increase the understanding af the geology of offshore West Greenland in order to reassess the prospectivity of the area. During the period 1975 to 1979, a number of concessions offshore West Greenland were licensed to various consortia of oil companies to search for petroleum. Some 40 000 km of seismic data were acquired, all of which is now released. Five wells were drilled, all of them dry, and all concessions were relinquished by the industry by 1979. The regional geology of offshore West Greenland has been summarised by Manderscheid (1980) and Henderson et al. (1981). They show the West Greenland Basin to consist of fairly uniformly westward dipping sediments bordered near the shelf break by a basement ridge. These authors used what may be termed 'conventional' techniques of seismic interpretation. However, since that time the techniques of seismo-stratigraphy (Vail et al., 1977; Hubbard et al., 1985) have become established. They are now being applied to study seismic data acquired during the mid-1970s.

Geological environment of the Cigar Lake uranium deposit

1993 ◽  
Vol 30 (4) ◽  
pp. 653-673 ◽  
Author(s):  
P. Bruneton
Keyword(s):  
Uranium Deposit ◽  
Transitional Zone ◽  
Uranium Deposits ◽  
Athabasca Basin ◽  
Structural Framework ◽  
Basement Rocks ◽  
Metamorphic Basement ◽  
Basement Ridge ◽  
Archean Basement ◽  
East West

The Cigar Lake uranium deposit occurs within the Athabasca Basin of northern Saskatchewan, Canada. Like other major uranium deposits of the basin, it is located at the unconformity separating Helikian sandstones of the Athabasca Group from Aphebian metasediments and plutonic rocks of the Wollaston Group. The Athabasca Group was deposited in an intra-continental sedimentary basin that was filled by fluviatile terrestrial quartz sandstones and conglomerates. The group appears undeformed and its actual maximum thickness is about 1500 m. On the eastern side of the basin, the detrital units correspond to the Manitou Falls Formations where most of the uranium deposits are located. The Lower Pelitic unit of the Wollaston Group, which lies directly on the Archean basement, is considered to be the most favourable horizon for uranium mineralization. During the Hudsonian orogeny (1800–1900 Ma), the group underwent polyphase deformation and upper amphibolite facies metamorphism. The Hudsonian orogeny was followed by a long period of erosion and weathering and the development of a paleoweathering profile.On the Waterbury Lake property, the Manitou Falls Formation is 250–500 m thick and corresponds to units MFd, MFc, and MFb. The conglomeratic MFb unit hosts the Cigar Lake deposit. However, the basal conglomerate is absent at the deposit, wedging out against an east–west, 20 m high, pre-Athabasca basement ridge, on top of which is located the orebody.Two major lithostructural domains are present in the metamorphic basement of the property: (1) a southern area composed mainly of pelitic metasediments (Wollaston Domain) and (2) a northern area with large lensoid granitic domes (Mudjatik Domain). The Cigar Lake east–west pelitic basin, which contains the deposit, is located in the transitional zone between the two domains. The metamorphic basement rocks in the basin consist mainly of graphitic metapelitic gneisses and calcsilicate gneisses, which are inferred to be part of the Lower Pelitic unit. Graphite- and pyrite-rich "augen gneisses," an unusual facies within the graphitic metapelitic gneisses, occur primarily below the Cigar Lake orebody.The mineralogy and geochemistry of the graphitic metapelitic gneisses suggest that they were originally shales. The abundance of magnesium in the intercalated carbonates layers indicates an evaporitic origin.The structural framework is dominated by large northeast–southwest lineaments and wide east–west mylonitic corridors. These mylonites, which contain the augen gneisses, are considered to be the most favourable features for the concentration of uranium mineralization.Despite the presence of the orebody, large areas of the Waterbury Lake property remain totally unexplored and open for new discoveries.

THE COOPER'S CREEK BASIN

1966 ◽  
Vol 6 (1) ◽  
pp. 71 ◽  
Author(s):  
Adrian Kapel
Keyword(s):  
Sedimentary Basin ◽  
The South ◽  
The North ◽  
Geophysical Surveys ◽  
Lower Palaeozoic ◽  
Basement Ridge

Results of past surface and subsurface geological and geophysical surveys indicate that the Cooper's Creek area has been a sedimentary basin from Lower Palaeozoic time to at least the beginning of Cretaceous time.The Cooper's Creek Basin is bounded to the east by the Canaway Ridge, to the south by a basement ridge that runs from Naryilco to Kopperamanna, to the north by a folded trend that runs from Warbreccan to Kopperamanna.Sediments from Cambrian to Recent age have been encountered in wells drilled by Delhi-Santos. It is postulated that the present basin originated in post-Siluro-Devonian time after the Bowning orogeny.Physiographically the axis of the basin is reflected by the Cooper's Creek.

Hydrothermal seepage patterns above a buried basement ridge, eastern flank of the Juan de Fuca Ridge

2004 ◽  
Vol 109 (B1) ◽  
Author(s):  
G. A. Spinelli ◽  
L. Zühlsdorff ◽  
A. T. Fisher ◽  
C. G. Wheat ◽  
M. Mottl ◽  
...  
Keyword(s):  
Juan De Fuca Ridge ◽  
Fuca Ridge ◽  
Eastern Flank ◽  
Juan De Fuca ◽  
Basement Ridge

Restoration of the Caledonian Baltoscandian margin from balanced cross-sections: the problem of excess continental crust

1987 ◽  
Vol 78 (3) ◽  
pp. 197-217 ◽  
Author(s):  
R. A. Gayer ◽  
A. H. N. Rice ◽  
D. Roberts ◽  
C. Townsend ◽  
A. Welbon
Keyword(s):  
Continental Crust ◽  
Cross Section ◽  
Continental Margin ◽  
Cross Sections ◽  
Branch Line ◽  
Norwegian Coast ◽  
Thrust Sheets ◽  
Thrust System ◽  
Basement Ridge ◽  
The Baltic

ABSTRACTConsideration of six balanced cross-sections through parts of the Finnmark Caledonides, N Norway indicates that shortening varies between 25% and 75%. A restored long cross-section across the width of the orogen, constructed with the aid of a branch line map, demonstrates a foreland propagating thrust system, with earlier formed more internal metamorphic nappes thrust SE 330 km under ductile conditions and then carried piggyback ESE a further 296 km on later brittle thrust sheets. Total shortening is 78·7% with a translation of the most internal thrust sheet of 626 km.The restored section suggests that: (1) the rate of propagation of deformation from hinterland to foreland is c. 2·27 cm y−1; (2) incorporation of basement into the nappes resulted from inversion of extensional faults formed during Iapetus rifting; (3) during rifting a Finnmark basement ridge separated a 220 km wide southeasterly Gaissa basin from the passive Iapetus continental margin which was at least 423 km wide; (4) the Finnmark Caledonides resulted from a continent-microcontinent collision which obducted continental crust at least 600 km across the Baltic margin; and (5) the Caledonian Baltoscandian margin prior to Iapetus suturing extended at least 400 km W of the Norwegian coast. On a Bullard reconstruction this overlaps with Laurentian rocks in Greenland. The excess continental crust is accounted for by shortening of the Baltoscandian margin during collision.

Intraplate shortening and underthrusting of a large basement ridge in the eastern Nankai subduction zone

2002 ◽  
Vol 187 (1-2) ◽  
pp. 63-88 ◽  
Author(s):  
Stéphane Mazzotti ◽  
Siegfried J. Lallemant ◽  
Pierre Henry ◽  
Xavier Le Pichon ◽  
Hidekazu Tokuyama ◽  
...  
Keyword(s):  
Subduction Zone ◽  
Nankai Subduction Zone ◽  
Basement Ridge

ARCTIC OCEAN GEOPHYSICAL STUDIES: THE SOUTHERN HALF OF THE SIBERIA BASIN

Geophysics ◽  
1966 ◽  
Vol 31 (4) ◽  
pp. 683-710 ◽  
Author(s):  
Henry Kutschale
Keyword(s):  
Seismic Reflection ◽  
Magnetic Measurements ◽  
Abyssal Plain ◽  
Turbidity Currents ◽  
The North ◽  
Northern Half ◽  
Gravity Measurements ◽  
Southern Half ◽  
Basement Ridge ◽  
Seismic Reflection Profiles

In 1962, ice island Arlis II drifted over a portion of the southern half of the Siberia Basin. Depth recordings made between 81°N, 170°E and 82°30′N, 160°E show that the ocean floor in this area is an abyssal plain at about 2,825 m depth dissected by several interplain channels. This abyssal plain, here called the Wrangel Abyssal Plain, is bounded on the north by Arlis Gap, which joins it with the Siberia Abyssal Plain at about 3,946 m depth. The Siberia Abyssal Plain occupies the northern half of the Siberia Basin. Seismic reflection profiles show that a prominent subbottom basement ridge exists in the vicinity of Arlis Gap. This ridge strikes in an approximately northwest direction and appears to connect with Alpha Ridge, which bounds the Siberia Basin on the east and north, and with Lomonosov Ridge, which bounds the Siberia Basin on the west. The seismic reflection profiles also show that at least 3.5 km of subhorizontal, stratified sediments underlie Wrangel Abyssal Plain south of the ridge. Each layer within these sediments appears to correspond to a fossil surface of Wrangel Abyssal Plain. This thick sequence of stratified sediments shows the influence of the Asian continent, which bounds the Siberia Basin on the south, on sedimentation within the Siberia Basin. Presumably the buried basement ridge forms a dam which has permitted the accumulation of a thick sequence of sediments under the higher‐level Wrangel Abyssal Plain. Turbidity currents moving through Arlis Gap presumably carried the overflow of sediments from Wrangel Abyssal Plain into the lower‐level Siberia Abyssal Plain. The structure of the sediments suggests that the Siberia Basin has been free from deformation during the deposition of the sediments, except for possible broad crustal down warping. A crustal model based on the water depth measurements, seismic reflection profiles, gravity measurements, and magnetic measurements yields a crustal thickness of 15 km south of the buried ridge and 22 km under the ridge measured from sea level.

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