1986 Great Lakes seismic reflection survey, migrated data

Milkereit, B.; Green, A G; Morel-à-l'Huissier, P.; Lee, M W; Agena, W.F.

doi:10.4095/130458

Cited by 8 publications

(1 citation statement)

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“…The GLIMPCE reflection experiment involved the collection of approximately 1350 km of seismic reflection data (Figure 1) using a tuned air gun source array of 127.5 L (7780 inch 3) and a 3-km-long receiving hydrophone array consisting of 120 channels. The experimental configuration, acquisition parameters, original processing strategies, and noise suppression techniques have been discussed elsewhere Milkereit et al, 1988;Hutchinson et al, 1988]. The original processing is called automatic gain control (AGC) processing.…”

Section: Data Acquisition and Processingmentioning

confidence: 99%

Variations in the reflectivity of the moho transition zone beneath the Midcontinent Rift System of North America: Results from true amplitude analysis of GLIMPCE data

Hutchinson¹,

Lee²,

Behrendt³

et al. 1992

J. Geophys. Res.

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True amplitude processing of The Great Lakes International Multidisciplinary Program on Crustal Evolution seismic reflection data from the Midcontinent Rift System of North America shows large differences in the reflectivity of the Moho transition zone beneath the axial rift, beneath the rift flanks, and outside of the rift. The Moho reflection from the axial rift has a discontinuous, diffractive character marginally stronger (several decibels) than an otherwise transparent lower crust and upper mantle. Beneath the axial rift, Moho is interpreted to be a synrift igneous feature. Beneath the rift flanks, the reflectivity of the Moho transition is generally well developed with two identifiable boundaries, although in places it is weakly reflective to nonreflective, similar to Moho outside the rift. The two boundaries are interpreted as the base of essentially intact, although stretched, prerift Archean crust (upper boundary) and new synrift Moho 1–2 s (6–7 km) deeper (lower boundary). Beneath the rift flanks, the layered reflection Moho transition results from the preexisting crustal composition and fabric modified by synrift igneous processes and extensional tectonic/metamorphic processes. The geologic evidence for extensive basaltic magmatism in the rift is the basis for interpreting the Moho signature as a Keweenawan structure that has been preserved for 1.1 b.y. Extension and magmatism appear to enhance reflectivity in the lower crust and Moho transition zone only where stretching factors are moderate (rift flanks) and not where they are extreme (axial rift). This leads to the prediction that the reflectivity across analogous volcanic passive continental margins should be greatest beneath the moderately stretched continental shelves and should decrease towards the ocean‐continent boundary.

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Section: Data Acquisition and Processingmentioning

confidence: 99%

Variations in the reflectivity of the moho transition zone beneath the Midcontinent Rift System of North America: Results from true amplitude analysis of GLIMPCE data

Hutchinson¹,

Lee²,

Behrendt³

et al. 1992

J. Geophys. Res.

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Dereverberation of marine reflection seismic data by a spatial combination of predictive deconvolution and velocity filtering

Samson

West

1995

Mar Geophys Res

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Abstract. Contamination of seismic reflection records at early times by first-order water reverberations can be especially severe during survey operations over hard and flat sea floors on the continental shelf or in lake environments. A new dereverberation scheme based on two classical techniques -predictive deconvolution and velocity filtering -has been developed to address this problem. The techniques are combined spatially to take advantage of their complementary offset-and time-dependent properties. Stage I of the scheme consists of applying predictive deconvolution at short offset. The data are previously conditioned by a normal moveout correction with the water velocity which restores the periodicity of the reverberations in the offset-time plane and enhances the performance ofdeconvolution. Stage II of the scheme involves velocity filtering in the common-midpoint domain which is particularly effective at long offset where the moveout difference between primary reflections and reverberations is largest. The dereverberation scheme is well suited for the initial processing of large volumes of data due to the general availability of costeffective deconvolution and velocity filtering algorithms in seismic processing software packages. Practical implementation issues are illustrated by a field example from the GLIMPCE survey in Lake Superior. Statement of ProblemThe generation of first-order water reverberations during marine reflection seismic operations is illustrated in Figure 1 a using a basic near-surface model comprising a water layer of constant thickness z and velocity vw overlying a half-space rock substratum of velocity v > v~. As a result of the large impedance contrasts at both the air-water and water-rock interfaces, energy is trapped in the water layer which gives rise to a long oscillatory wavetrain on each seismic trace. The two-way travel time curve tn(x) of the nth water reflection is a hyperbola in the shot and common-midpoint (CMP) domains:( 1) whereand x is the source-receiver offset and T the reverberation period at zero offset. The travel time curves of the primary water bottom reflection (n = 1) and of the first four water reverberations (2 _< n _< 5) are shown schematically in Figure lb (solid lines) for a hypothetical shot or CMP gather. In a more realistic multi-layered earth model, the first-order water reverberation wavetrain would mask primary reflections at early times. The goal of water dereverberation is thus to suppress events corresponding to n _> 2. There exists a wealth of techniques for the suppression of multiple energy of which water dereverberation is a more specialized problem. They can be classified into two main categories according to the criterion used to distinguish multiples from primary reflections: (1) moveout difference and (2) predictibility.The simplest multiple suppression operation based on the first criterion is the general stacking operation itself. The most commonly used specialized technique is velocity filtering (Embree et at., 1963), which can be used ...

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Correction for water depth variations of marine crustal reflection seismic data using refraction statics

Samson

West

1992

Mar Geophys Res

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1986 Great Lakes seismic reflection survey, migrated data

Cited by 8 publications

References 0 publications

Variations in the reflectivity of the moho transition zone beneath the Midcontinent Rift System of North America: Results from true amplitude analysis of GLIMPCE data

Variations in the reflectivity of the moho transition zone beneath the Midcontinent Rift System of North America: Results from true amplitude analysis of GLIMPCE data

Dereverberation of marine reflection seismic data by a spatial combination of predictive deconvolution and velocity filtering

Correction for water depth variations of marine crustal reflection seismic data using refraction statics

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