Deep crustal structure of the northeastern Gulf of Mexico: Implications for rift evolution and seafloor spreading

Eddy, Drew; Avendonk, H. J. Van; Christeson, G. L.; Norton, Ian O.; Karner, Garry D.; Johnson, Christopher; Snedden, John W.

doi:10.1002/2014jb011311

Cited by 81 publications

(59 citation statements)

References 84 publications

(223 reference statements)

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“…Furthermore, salt deposits are much less voluminous in the northeastern Gulf of Mexico, indicating that much of the extension and thinning of the crust at that margin took place after Callovian time. In general, the Gulf of Mexico rift appears to have progressed from west to east, which is consistent with plate tectonic reconstructions (e.g., Marton and Buffler, 1994;Eddy et al, 2014).…”

Section: Rifted Margin Evolutionsupporting

confidence: 79%

“…These phases are classified based on the source-receiver offset and travel times at which they are observed, and they have distinct apparent velocities in x-t space. In contrast to seismic-refraction data in the eastern Gulf of Mexico, where salt and sediment cover are relatively thin Eddy et al, 2014), the OBS data along GUMBO Line 2 generally have a lower signal-to-noise ratio. However, the data from GUMBO Line 2 are similar in quality to the seismicrefraction data from GUMBO Line 1 (Van Avendonk et al, 2015).…”

Section: Seismic-refraction Datamentioning

confidence: 61%

“…The 2010 GUMBO study benefitted from a large acoustic array as well as a large number of OBS instruments. The resulting seismic-velocity models for Line 2 and three previously published GUMBO transects Eddy et al, 2014;Van Avendonk et al, 2015) provide full coverage of the crustal structure, even beneath thick salt structures of the Sigsbee Escarpment. Given that the GUMBO seismic-velocity images have good resolution (Fig.…”

Section: Discussion Tectonic Interpretationsmentioning

confidence: 97%

“…Despite this challenge, regional plate tectonic reconstructions that are constrained by basement-stratigraphic relationships offer a consensus on the rifting and seafloor-spreading history of the Gulf of Mexico (Pindell and Dewey, 1982;Salvador, 1987;Marton and Buffler, 1994;Pindell and Kennan, 2009;Hudec et al, 2013;Christeson et al, 2014;Eddy et al, 2014). Kneller and Johnson (2011) have presented an alternative model, where plate kinematics in the Gulf of Mexico are similar, except that opening of the basin started 20-25 million years earlier.…”

Section: Opening the Gulf Of Mexicomentioning

confidence: 99%

“…Seismic-velocity models based on refraction data from GUMBO Line 3 and Line 4 in the northeastern Gulf of Mexico show that the margin has a lower crust with high seismic velocities that may be indicative of a large volume of igneous rock emplaced during rifting Eddy et al, 2014). In contrast, GUMBO Line 1 on the margin of the northwestern Gulf of Mexico exhibits thinner and more heterogeneous crust (Van Avendonk et al, 2015), possibly due to large-scale faulting and sparse magmatism during the Jurassic opening of the basin.…”

Section: Introductionmentioning

confidence: 99%

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Structure and origin of the rifted margin of the northern Gulf of Mexico

et al. 2018

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The wide continental margin of southern Louisiana borders Paleozoic terranes that accreted to Laurentia before Jurassic rifting formed the Gulf of Mexico. It is unclear whether continental rifting here involved widespread or localized crustal extension, or how seafloor spreading in the Gulf of Mexico started. To improve our understanding of this rifting episode, we gathered marine seismic-refraction data along a 396-km-long transect from the continental shelf 50 km off the western Louisiana coast to the central ocean basin as part of the Gulf of Mexico Basin Opening (GUMBO) program. Using travel-time tomography, we imaged the compressional seismic-velocity structure from the shallow sediments to the uppermost mantle. In our geophysical model, the crust tapers in thickness from ~11 km near the Louisiana coast to ~8 km in the deep water of the central Gulf of Mexico. The compressional seismic velocity increases from 5.7 to 5.9 km/s in the shallow basement to 6.8-7.2 km/s above the Moho. The thickness and average wave speed of crust beneath the modern Louisiana coast and continental shelf suggest the presence of uniformly stretched continental crust that was intruded by mantle-derived melts during extension before continental breakup. South of the Sigsbee Escarpment, the crust is thinner with a higher seismic velocity, which is more consistent with thick oceanic crust. A comparison of our seismic-velocity model with coincident seismic-reflection data indicates that the voluminous Louann Salt was likely deposited on rifted continental crust shortly before the onset of seafloor spreading in the Gulf of Mexico.

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Section: Rifted Margin Evolutionsupporting

confidence: 79%

Section: Seismic-refraction Datamentioning

confidence: 61%

Section: Discussion Tectonic Interpretationsmentioning

confidence: 97%

Section: Opening the Gulf Of Mexicomentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Structure and origin of the rifted margin of the northern Gulf of Mexico

et al. 2018

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Deep crustal structure in the eastern Gulf of Mexico

et al. 2014

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We use air gun data recorded by ocean bottom seismometers to constrain the velocity structure along Gulf of Mexico Basin Opening Line 4, a profile extending from the northwestern Florida peninsula across the Florida Escarpment to the central Gulf of Mexico. Moderately thinned continental crust with a Moho depth of 32-33 km, average sediment thickness of 6 km, and an average crustal thickness of 27 km is interpreted on the northeast end of the profile offshore Florida. Thinned and intruded continental crust is identified over a horizontal distance of 225 km where the crustal layer thins from 25 km to 6-7 km; mean seismic velocities of the crust in this region increase from 6.55 km/s to 6.95 km/s from northeast to southwest and are evidence for increased magmatic input as rifting developed. Oceanic crust with an average thickness of 5.6-5.7 km is observed over a distance of 175 km on the southwest end of the profile, with an extinct spreading ridge with an axial valley morphology imaged on a coincident seismic reflection profile. Anomalously high upper oceanic crust velocities of 6.0-6.7 km/s are interpreted as massive basalt flows and could reflect increased temperatures during emplacement. Integrating well, seismic reflection and our seismic refraction data allow us to estimate a full-spreading rate of 2.2 cm/yr for seafloor spreading along the profile; this indicates that oceanic crust was emplaced at a slow-spreading center.

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Distinct crustal isostasy trends east and west of the Rocky Mountain Front

Schmandt

Lin

Karlstrom

2015

Geophysical Research Letters

127

199

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Seismic structure beneath the contiguous U.S. was imaged with multimode receiver function stacking and inversion of Rayleigh wave dispersion and ellipticity measurements. Crust thickness and elevation are weakly correlated across the contiguous U.S., but the correlation is ~3–4 times greater for separate areas east and west of the Rocky Mountain Front (RMF). Greater lower crustal shear velocities east of the RMF, particularly in low‐elevation areas with thick crust, are consistent with deep crustal density as the primary cause of the contrasting crust thickness versus elevation trends. Separate eastern and western trends are best fit by Airy isostasy models that assume lower crust to uppermost mantle density increases of 0.18 g/cm3 and 0.40 g/cm3, respectively. The former value is near the minimum that is plausible for felsic lower crust. Location of the transition at the RMF suggests that Laramide to post‐Laramide processes reduced western U.S. lower crustal density.

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Deep crustal structure of the northeastern Gulf of Mexico: Implications for rift evolution and seafloor spreading

Cited by 81 publications

References 84 publications

Structure and origin of the rifted margin of the northern Gulf of Mexico

Structure and origin of the rifted margin of the northern Gulf of Mexico

Deep crustal structure in the eastern Gulf of Mexico

Distinct crustal isostasy trends east and west of the Rocky Mountain Front

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