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Line Bgr 78-19 (24-Fold Stack) from the Continental Margin of Queen Maud Land / Weddell Sea—Antarctica

K. Hinz
K. Hinz
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January 01, 1983


Two units are recognizable on the reflection seismic records within the continental margin of Queen Maud Land, Antarctica: 1) a buried lower unit the top of which is marked by the distinct Weddell Sea "continental margin unconformity"; and 2) an upper sedimentary unit.

The dominant features of the lower unit beneath the "Weddell Sea unconformity" are a suite of oceanward-dipping reflectors (sequence WS-4 and called "EXPLORA Wedge,") which has a similar seismic pattern and velocity distribution as the wedge of oceanward-dipping subacoustic base ment reflectors off Norway and an outer basement high.

Four depositional sequences (sequence WS-1 to WS-3A) are recognizable within the upper unit. Since no boreholes have been drilled on the continental margin of Queen Maud Land, an attempt was made to assess the age of the regional unconformities by assuming that the Antarctic glacification was the dominant short-period mechanism in the Neogene which causes relative changes of eustatic sea level. Under this assumption, the lower boundary of sequence WS-1 has been correlated with the middle Miocene Antarctic ice cap formation. The lower boundary of sequence WS-2 was correlated with the development of an unrestricted Circum Antarctic Current in the late Oligocene.

The erosional unconformity between sequence WS-3B and WS-3A is thought to represent a major climatic-glacial threshold at the Oligocene/Eocene boundary.

The "Weddell Sea unconformity" is interpreted to mark the end of the Jurassic tectonicmagmatic/volcanic regime, which preceded the opening of the Weddell Sea.

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AAPG Studies in Geology

Seismic Expression of Structural Styles: A Picture and Work Atlas. Volume 1–The Layered Earth, Volume 2–Tectonics Of Extensional Provinces, & Volume 3–Tectonics Of Compressional Provinces

A. W. Bally
A. W. Bally
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American Association of Petroleum Geologists
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Publication date:
January 01, 1983




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