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Title: Crustal structure and sedimentation history over the Alleppey platform, southwest continental margin of India: Constraints from multichannel seismic and gravity data

Authors:
; ;
Publication Date:
Sponsoring Org.:
USDOE Office of Fossil Energy (FE), Oil and Natural Gas (FE-30)
OSTI Identifier:
1367749
Resource Type:
Journal Article: Published Article
Journal Name:
Geoscience Frontiers
Additional Journal Information:
Journal Volume: 9; Journal Issue: 2; Related Information: CHORUS Timestamp: 2018-02-15 02:11:30; Journal ID: ISSN 1674-9871
Publisher:
Elsevier
Country of Publication:
Country unknown/Code not available
Language:
English

Citation Formats

Unnikrishnan, P., Radhakrishna, M., and Prasad, G. K. Crustal structure and sedimentation history over the Alleppey platform, southwest continental margin of India: Constraints from multichannel seismic and gravity data. Country unknown/Code not available: N. p., 2018. Web. doi:10.1016/j.gsf.2017.06.002.
Unnikrishnan, P., Radhakrishna, M., & Prasad, G. K. Crustal structure and sedimentation history over the Alleppey platform, southwest continental margin of India: Constraints from multichannel seismic and gravity data. Country unknown/Code not available. doi:10.1016/j.gsf.2017.06.002.
Unnikrishnan, P., Radhakrishna, M., and Prasad, G. K. 2018. "Crustal structure and sedimentation history over the Alleppey platform, southwest continental margin of India: Constraints from multichannel seismic and gravity data". Country unknown/Code not available. doi:10.1016/j.gsf.2017.06.002.
@article{osti_1367749,
title = {Crustal structure and sedimentation history over the Alleppey platform, southwest continental margin of India: Constraints from multichannel seismic and gravity data},
author = {Unnikrishnan, P. and Radhakrishna, M. and Prasad, G. K.},
abstractNote = {},
doi = {10.1016/j.gsf.2017.06.002},
journal = {Geoscience Frontiers},
number = 2,
volume = 9,
place = {Country unknown/Code not available},
year = 2018,
month = 3
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1016/j.gsf.2017.06.002

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  • New deep-penetration multichannel seismic reflection data, combined with refraction results and magnetics modeling, support a hypothesis that the Carolina trough is a Mesozoic volcanic passive margin exhibiting a seaward-dipping wedge and associated underplating. The structure of Carolina platform continental crust is consistent with the late Paleozoic continental collision that produced the Appalachians, but imbrication has had no obvious effect on shallower structures produced by Mesozoic extension and volcanism. The origin of prominent magnetic anomalies crossing the Southeast Georgia embayment can be explained by processes attending Mesozoic separation of Africa and North America, and is not related to a Paleozoic continentalmore » suture, as previously postulated.« less
  • As eustasy, subsidence, and sediment accumulation vary, a 2D computer-based graphical simulation generates on-lapping and off-lapping geometries of both marine and near coastal alluvial deposits, reproducing timelines within sediment-bodies at basin margins. In the simulation, deposition is expressed by creation of new surfaces above previous ones. Thicknesses of layers are reduced by both erosion and compaction while their surfaces move vertically in response to tectonic change and loading. Simulation is divided into a series of equal time steps in which sediment is deposited as an array of en-echelon columns that mark the top of the previous depositional surface. The volumemore » of sediment deposited in each time step is expressed as a 2D cross section and is derived from two right-angle triangles (sand and shale), whose areas are a 2D expression of the quantity of sediment deposited at that time step and whose length matches the width of the offshore sediment wedge seaward of the shoreline. Each column in the array is filled by both marine sediments up to sea level, and alluvial sediments to a surface determined by an alluvial angle that is projected landward from the shore to its intersection with the previous surface. Each time the area representing the sediment column is subtracted from the triangles, the triangle heights are reduced correspondingly. This process is repeated until the triangle heights match the position of sea level above the sediment surface, at which time the remaining area of the sediment triangle is deposited seaward as a single wedge of offshore sediments. This simulation is designed to aid interpretation of stratigraphic sequences. It can be used as a complement to seismic stratigraphy or can be used alone as an inexpensive test of stratigraphic models.« less
  • Approximately 2,100 km of 24-fold multichannel seismic reflection data reveal much about the subsurface geology for a large part of the continental margin east of Florida. Discordance between the westward-dipping pre-breakup sediments and the eastward-sloping basement along the edge of the Blake Plateau is interpreted as an effect of a splinter of continental margin derived from the African plate by a spreading-center jump in the Middle Jurassic. Early rifting centered under the main part of the Blake Plateau became inactive, as a spreading-center jump shifted the active rift to east of the present Blake Escarpment along the Blake Spur magneticmore » anomaly. In the northern Florida Straits the data reveal that the breakup unconformity, underlain by Triassic-Lower Jurassic arkosic volcaniclastics, extends from southern Florida to the western Bahama Banks Back-reef platform deposits of limestones, dolomites, and evaporites of Late Jurassic to Albian age extend from the Blake-Bahama Escarpment westward beneath Florida. These deposits formed what once was a megabank extending over a wider area than the present smaller isolated Bahama Banks. Evidence of recurring scour by current erosion is found in the Florida Straits. Erosional events apparently occurred in the middle Cenomanian, middle Paleocene, early-middle Eocene, and Eocene-Oligocene, which coincidentally are times of lower eustatic sea level according to Vail et al (1977a). This evidence of Florida current scour indicates that the current was present as far back as the Cenomanian. Major faulting appears to have dropped the Northeast Providence Channel relative to the western Bahamas after the Albian. Submarine erosion and bank buildup created the channels and smaller relief features like Great Abaco Knoll beginning in about the Cenomanian. A carbonate bank margin and reef complex was present along the Bahama Escarpment since the Middle Jurassic. 22 figures.« less
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