The stratigraphy and structure of the Laurentian Cone region

1979 ◽  
Vol 16 (9) ◽  
pp. 1726-1752 ◽  
Author(s):  
Elazar Uchupi ◽  
James A. Austin Jr.
Keyword(s):  
Late Eocene ◽  
Climatic Conditions ◽  
Early Jurassic ◽  
Turbidity Currents ◽  
Sea Floor ◽  
Grand Banks ◽  
Oceanic Basement ◽  
Well Data ◽  
Seismic Reflection Profiles ◽  
Continental Glaciation

A series of single and multichannel seismic reflection profiles combined with well data from the adjacent shelves and deep sea and published geophysical profiles permit the reconstruction of the geologic development of the Laurentian Cone. The cone's sediments can be divided into two megasequences, a lower one of Early Jurassic to Eocene age, which extends from a transitional and oceanic basement to horizon AT, and an upper sequence of early-middle Miocene to Holocene age extending from horizon AT to the sea floor. Plastic flow of Early Jurassic salt at the base of the lower megasequence has resulted in the deformation of the strata above, and the formation of a ridge that extends along the continental rise from Georges Bank to the Grand Banks. Horizon AT, separating the two sequences, is the surface of a fan deposited by turbidity currents during a latest Cretaceous and a late Eocene–Oligocene regression; these regressions may be due to the onset of continental glaciation. Deposition of this regressive wedge initiated the emplacement of the Laurentian Cone. The upper terrigenous megasequence, composed of three coalescing fans, was emplaced through the action of turbidity currents, and reflects the rapidly fluctuating climatic conditions associated with the waxing and waning of continental glaciers from latest Miocene to Holocene. The cone is not being supplied with sediments from the continent at present, but sediment continues to move down-cone in response to sporadic seismic activity.

scholarly journals Characterizing Seismo-stratigraphic and Structural Framework of Late Cretaceous-Recent succession of offshore Indus Pakistan

2018 ◽  
Vol 10 (1) ◽  
pp. 174-191 ◽  
Author(s):  
Majid Khan ◽  
Yike Liu ◽  
Asam Farid ◽  
Muhammad Owais
Keyword(s):  
Seismic Data ◽  
Late Eocene ◽  
Indian Plate ◽  
Processing Scheme ◽  
Structural Growth ◽  
Seismic Records ◽  
Exploratory Wells ◽  
Well Data ◽  
Seismic Reflection Profiles ◽  
Push Up

Abstract Regional seismic reflection profiles and deep exploratory wells have been used to characterize the subsurface structural trends and seismo-stratigraphic architecture of the sedimentary successions in offshore Indus Pakistan. To improve the data quality, we have reprocessed the seismic data by applying signal processing scheme to enhance the reflection continuity for obtaining better results. Synthetic seismograms have been used to identify and tie the seismic reflections to the well data. The seismic data revealed tectonically controlled, distinct episodes of normal faulting representing rifting during Mesozoic and transpression at Late Eocene time. A SW-NE oriented anticlinal type push up structure is observed resulted from the basement reactivation and recent transpression along Indian Plate margin. The structural growth of this particular pushup geometry was computed. Six mappable seismic sequences have been identified on seismic records. In general, geological formations are at shallow depths towards northwest due to basement blocks uplift. A paleoshelf is also identified on seismic records overlain by Cretaceous sediments, which is indicative of Indian-African Plates rifting at Jurassic time. The seismic interpretation reveals that the structural styles and stratigraphy of the region were significantly affected by the northward drift of the Indian Plate, post-rifting, and sedimentation along its western margin during Middle Cenozoic. A considerable structural growth along the push up geometry indicates present day transpression in the margin sediments. The present comprehensive interpretation can help in understanding the complex structures in passive continental margins worldwide that display similar characteristics but are considered to be dominated by rifting and drifting tectonics.

Shallow Deformation Along the Crittenden County Fault Zone Near the Southeastern Boundary of the Reelfoot Rift, Northeast Arkansas

1992 ◽  
Vol 63 (3) ◽  
pp. 263-275 ◽  
Author(s):  
E. A. Luzietti ◽  
L. R. Kanter ◽  
E. S. Schweig ◽  
K. M. Shedlock ◽  
R. B. VanArsdale
Keyword(s):  
Fault Zone ◽  
Seismic Reflection ◽  
Vertical Displacement ◽  
Surface Expression ◽  
Late Eocene ◽  
Seismic Reflection Data ◽  
Reflection Data ◽  
Structural Relief ◽  
Well Data ◽  
Seismic Reflection Profiles

Abstract The Crittenden County fault zone (CCFZ) is located near the southeast boundary of the Reelfoot rift in northeastern Arkansas. The southeastern boundary of the rift has been characterized as an 8-km-wide zone of down-to-the-northwest displacement. The CCFZ, however, shows significant down-to-the-southeast reverse faulting of Paleozoic and Cretaceous rocks and flexure and thinning within the Tertiary sedimentary section. We discuss four of nine Mini-Sosie seismic reflection profiles, each 1 to 2 km long, acquired over the surface projection of the CCFZ and Reelfoot rift boundary. One second of two-way traveltime data was recorded, which corresponds to a maximum depth of approximately 1.2 km. Sedimentary layers between 50 and 800 m are well imaged; deeper strata are evident but not well imaged. Well data at one site on the CCFZ indicate approximately 63 and 82 m of vertical displacement of Cretaceous and Paleozoic rocks, respectively. Proprietary seismic-reflection data show reverse displacement of these rock units, indicating compressional tectonics. From the Mini-Sosie profiles, we estimate structural relief across the CCFZ at the Paleocene (Fort Pillow Sand) level to range between 14 and 70 m. The overlying middle-to-late Eocene section shows a similar or slightly smaller amount of thinning, indicating that much of the movement on the CCFZ dates mid-to-late Eocene. Displacement, flexure, and thinning in the geologic section increases as the CCFZ converges with the Reelfoot rift boundary, in the southwest part of the area studied. Surface expression of the CCFZ has not been identified. Reflections from the Quaternary-Eocene unconformity, however, show warping, dip, or interruptions in places over the CCFZ, suggesting that the CCFZ may have experienced Quaternary or Holocene movement as well.

Unconformities on the Scotian Shelf

1974 ◽  
Vol 11 (1) ◽  
pp. 89-100 ◽  
Author(s):  
Lewis H. King ◽  
Brian MacLean ◽  
Gordon B. Fader
Keyword(s):  
High Resolution ◽  
Seismic Reflection ◽  
Upper Cretaceous ◽  
Scotian Shelf ◽  
Early Tertiary ◽  
Late Tertiary ◽  
Glacial Processes ◽  
Well Data ◽  
Seismic Reflection Profiles ◽  
Cut And Fill

Four erosional unconformities have been recognized within the Mesozoic-Cenozoic succession on the Scotian Shelf, on the basis of data from high resolution seismic reflection profiles. Older unconformities are known from well data and others may be revealed by detailed biostratigraphic studies.The oldest of the four unconformities discussed in this paper is of Early Cretaceous age and appears to mark, with discordance, the boundary between Jurassic and Cretaceous strata on the western part of the shelf. A second angular unconformity, of Late Cretaceous age, has been recognized on the central part of the shelf where the basal part of the Banquereau Formation (Tertiary and uppermost Cretaceous) oversteps the zero-edge of the Wyandot Formation (Upper Cretaceous) and lies upon truncated beds of the Dawson Canyon Formation (Upper Cretaceous). Cut-and-fill relationships characterize a third unconformity developed during Early Tertiary time. A fourth unconformity was developed in Late Tertiary – Pleistocene time by fluvial processes and later by glacial processes. Although in many areas the latest unconformity appears to be the most conspicuous one on the shelf, its configuration closely follows the geomorphic expression developed during the previous period of erosion. The regional extent of the Cretaceous unconformities is not known, and they might only occur near basin margins and on structural and basement highs.

Mesozoic sequence of Fuerteventura (Canary Islands): Witness of Early Jurassic sea-floor spreading in the central Atlantic

1998 ◽  
Vol 110 (10) ◽  
pp. 1304-1317 ◽  
Author(s):  
Christian Steiner ◽  
Alice Hobson ◽  
Philippe Favre ◽  
Gérard M. Stampfli ◽  
Jean Hernandez
Keyword(s):  
Canary Islands ◽  
Early Jurassic ◽  
Sea Floor ◽  
Sea Floor Spreading ◽  
Central Atlantic

scholarly journals The marine record of the Russell Fiord outburst flood, Alaska, U.S.A.

1996 ◽  
Vol 22 ◽  
pp. 194-199 ◽  
Author(s):  
Ellen A. Cowan ◽  
Paul R. Carlson ◽  
Ross D. Powell
Keyword(s):  
High Resolution ◽  
Debris Flow ◽  
Seismic Reflection ◽  
Seismic Facies ◽  
Turbidity Currents ◽  
Outburst Flood ◽  
Gravity Core ◽  
Channel System ◽  
Seismic Reflection Profiles ◽  
Long Channel

The advance of Hubbard Glacier, near Yakutat, Alaska, U.S.A., in spring 1986 blocked the entrance to Russell Fiord with an ice-and-sediment dam, behind which a lake formed. The water level in Russell Lake rose to 25.5 m a.s.l. The dam catastrophically failed in October 1986, releasing 5.4 km3of water into Disenchantment Bay. High-resolution seismic-reflection profiles show a 7.5 km long channel system cut into and buried by glacimarine sediment, represented by continuous, parallel reflections. The chaotic seismic facies filling the channel is interpreted to be debris flow deposits. A gravity core from channel-overbank deposits contained sandy diamicton with mud clasts. Above the channel a 1–2 m thick sediment drape extends across the bay. Laminated mud, fining-upward sand beds and diamicton were recovered from this unit. The sediment-drape deposits were produced by suspension settling from turbid plumes and non-channelized turbidity currents generated by the outburst flood.

Remnants of a submerged pre-Jurassic (Devonian?) landscape on Orphan Knoll, offshore eastern Canada

1984 ◽  
Vol 21 (1) ◽  
pp. 61-66 ◽  
Author(s):  
L. M. Parson ◽  
D. G. Masson ◽  
R. G. Rothwell ◽  
A. C. Grant
Keyword(s):  
Long Range ◽  
Seismic Reflection ◽  
Alternative Explanation ◽  
Random Distribution ◽  
Eastern Canada ◽  
Sea Floor ◽  
Large Group ◽  
Seismic Reflection Profiles ◽  
Conical Form ◽  
Water Depths

A large group of discrete peaks occurs on the northeastern surface of Orphan Knoll at water depths between 1800 and 2800 m. Long-range side-scan sonographs are used in conjunction with seismic reflection profiles to establish their flattened conical form. They commonly rise to 300 m above the sea floor and occupy basal areas up to 2 km in diameter at that level. Inclusion of the buried lower parts of these mounds may double estimates of both the height and diameter. The sonographs indicate that the mounds have a random distribution within an elongate northwesterly trending belt. Previous suggestions of their possible origin, such as remnants of dykes or ridges of resistant sedimentary strata, are rejected and an alternative explanation of a zone of partially buried Devonian reef knolls is proposed.

Occurrence and regional geological setting of Paleozoic rocks on the Grand Banks of Newfoundland

1986 ◽  
Vol 23 (4) ◽  
pp. 504-526 ◽  
Author(s):  
Lewis H. King ◽  
Gordon B. J. Fader ◽  
W. A. M. Jenkins ◽  
Edward L. King
Keyword(s):  
Oil And Gas ◽  
Black Shales ◽  
Source Rocks ◽  
Upper Ordovician ◽  
Acoustic Basement ◽  
Lower Paleozoic ◽  
Shallow Marine ◽  
Grand Banks ◽  
Younger Age ◽  
Seismic Reflection Profiles

Analyses of seismic reflection profiles supported by lithological and palynological studies of core samples from submarine outcrops indicate that the lower Paleozoic succession of the Avalon Terrane, southeast Newfoundland, is continuous offshore. The succession crops out over an area greater than 30 000 km2 and is approximately 8 km thick. The sequence is dominantly siltstone and is of Late Cambrian to ?Devonian or younger age. It is relatively unmetamorphosed, underlain by Hadrynian acoustic basement, and overlain along its eastern and southern margins by a Mesozoic–Cenozoic succession that is economically important from an oil and gas perspective.Lithofacies studies indicate that in Early Ordovician time restricted shallow-marine conditions probably prevailed over a vast area of the Avalon Terrane. Upper Ordovician and Silurian siltstones show evidence of deposition under more-dynamic and well-oxygenated conditions and probably represent a normal shallow-marine environment. Redbeds of possible Devonian or younger age are interpreted to be of continental origin. Black shales of Ordovician age are potential source rocks for the generation of hydrocarbons.

Lithofacies and fluvial–lacustrine environments of the Palaeogene Sevkhuul and Ergil members (Ergiliin Zoo Formation, South Gobi, Mongolia)

2006 ◽  
Vol 143 (2) ◽  
pp. 165-179 ◽  
Author(s):  
H. G. DILL ◽  
S. KHISHIGSUREN ◽  
J. BULGAMAA ◽  
KH. BOLORMA ◽  
F. MELCHER
Keyword(s):  
Source Area ◽  
Field Work ◽  
Late Eocene ◽  
Climatic Conditions ◽  
Heavy Minerals ◽  
Gobi Desert ◽  
Carbonate Minerals ◽  
Delta Front ◽  
Delta Plain ◽  
Sheet Silicates

The clastic sequence of the Ergiliin Zoo Formation stretches along the Mongolian–Chinese border in the southern Gobi Desert, Mongolia. Its members (Sevkhuul, Ergil) exposed in the Erdene Sum region are well known for their vertebrate remains of Late Eocene and Oligocene age. Based upon field work, the continental red beds were subdivided into four units described as (I) prodelta/mud-sand flat, (II) delta front, (III) delta plain and (IV) calcretes. All sub-environments are in a fluvial–lacustrine setting. Electronmicroprobe analysis, in addition to conventional thin-section examination, was applied to shed some light on the complex mineral association made up of light minerals (quartz, plagioclase, ternary feldspar, orthoclase, smectite, illite, rare palygorskite), heavy minerals (almandine–pyrope solid solution series, zoisite–epidote s.s.s.) and abundant goethite and carbonate minerals (calcite, dolomite). Igneous rocks being exposed in the source area have contributed to the formation of carbonate minerals and Mg-bearing sheet silicates during diagenesis. Higher up on the delta plain transitional between distal alluvial and deltaic deposits, fluids emerged from the distal alluvial–fluvial deposits and formed calcareous duricrusts. Drawing conclusions from the rock colour, the mineral assemblage and the palaeoecological data, the climatic conditions may be described as alternating wet and dry seasons, closely resembling those conditions of a modern savannah.

Seismic stratigraphy and structure of the east Canadian continental margin between 41 and 52°N

1985 ◽  
Vol 22 (5) ◽  
pp. 686-703 ◽  
Author(s):  
L. M. Parson ◽  
D. G. Masson ◽  
C. D. Pelton ◽  
A. C. Grant
Keyword(s):  
Early Cretaceous ◽  
Continental Margin ◽  
Magnetic Anomalies ◽  
Seismic Stratigraphy ◽  
Sedimentary Sequence ◽  
The West ◽  
Grand Banks ◽  
Late Precambrian ◽  
Oceanic Basement ◽  
Iberian Margin

The seismic stratigraphy of the eastern Grand Banks continental margin is examined, and a five-fold division of the sedimentary sequence overlying basement is proposed. Oceanic basement of Cretaceous age underlies the eastern part of the study area; to the west, continental basement ranging in age from Late Precambrian to ?Jurassic underlies the Grand Banks. The sediment units, ranging in age from Early Cretaceous to Recent, have been dated by extrapolation of both commercial and DSDP drilling results from the Grand Banks and from the formerly conjugate Iberian margin. Identification of oceanic magnetic anomalies in the Newfoundland Basin agrees with the proposed age of the two oldest, Early Cretaceous units.

High-velocity turbidity currents, a discussion

1954 ◽  
Vol 222 (1150) ◽  
pp. 323-326 ◽  
Keyword(s):  
High Velocity ◽  
Turbidity Currents ◽  
Grand Banks ◽  
Coarse Material

The possibility of the transport of coarse material by turbidity currents is discussed. The difficulties in regarding such currents as responsible for the cable breaks following the 1929 Grand Banks earthquake are pointed out.

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