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Amplitude blanking in seismic profiles from Lake Baikal

Marine and Petroleum Geology

By:
, , and
DOI: 10.1016/0264-8172(95)00077-1

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Abstract

Imaging of the deepest sedimentary section in Lake Baikal using multichannel seismic profiling was hampered by amplitude blanking that is regionally extensive, is associated with water depths greater than about 900 m and occurs at sub-bottom depths of 1-2 km in association with the first water-bottom multiple. Application of a powerful multiple suppression technique improved the quality of occasional discontinuous, dipping primary reflections, but failed to substantially alter the non-reflective character of the blanking zone. Detailed analysis of amplitudes from original data and synthetic models show that the threshold for detecting primary energy in deep water of Lake Baikal occurs when the primary is about 14-20 dB less than the multiple energy. The blanking occurs because of anomalously low reflectivities of the deep sediments coupled with this 20 dB limitation in real data processing. The blanking cuts across seismic stratal boundaries, and is therefore probably unrelated to depositional lithologies. The deepest, early rift deposits, inferred to come from a mixed fluvial and lacustrine setting, do not easily explain the widespread and uniform character of the blanked deposits. More likely, blanking occurs because of processes or phenomena that physically alter the deposits, causing them to be non-reflective and/or highly attenuating. No single process explains all the observations, but a combination of diagenesis, overpressure, and the presence of dispersed free gas at sub-bottom depths of 1-2 km, offer plausible and possible conditions that contribute to blanking. Copyright ?? 1996 Published by Elsevier Science Ltd.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Amplitude blanking in seismic profiles from Lake Baikal
Series title:
Marine and Petroleum Geology
DOI:
10.1016/0264-8172(95)00077-1
Volume
13
Issue:
5
Year Published:
1996
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Marine and Petroleum Geology
First page:
549
Last page:
563
Number of Pages:
15