Deep crustal structure in the eastern Gulf of Mexico

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

doi:10.1002/2014jb011045

Cited by 72 publications

(44 citation statements)

References 79 publications

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“…We interpret the western margin of the Southern Platform from ~160 to 200 km model distance as an isolated block of thicker rifted crust above unusually low‐mantle velocities (7.6–7.8 km/s; Figures , , , and ). Low‐mantle velocities in the Gulf of Mexico are also observed to the southwest at GUMBO Line 4 [ Christeson et al ., ]. Mantle flow can lead to alignment of olivine crystals and anisotropic seismic velocities, with lower velocities perpendicular to the flow direction [ Hess , ].…”

Section: Discussionmentioning

confidence: 99%

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

et al. 2014

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We image deep crustal structure using marine seismic refraction data recorded by a linear array of ocean-bottom seismometers in the Gulf of Mexico Basin Opening project (GUMBO Line 3) in order to provide new constraints on the nature of continental and oceanic crust in the northeastern Gulf of Mexico. GUMBO Line 3 extends~524 km from the continental shelf offshore Pensacola, Florida, across the De Soto Canyon and into the central Gulf basin. Travel times from long offset, wide angle reflections and refractions resolve compressional seismic velocities and layer boundaries for sediment, crystalline crust, and upper mantle. We compare our results with coincident multichannel seismic reflection data. Our velocity model recovers shallow seismic velocities (~2.0-4.5 km/s) that we interpret as evaporites and clastic sediments. A Cretaceous carbonate platform is interpreted beneath the De Soto Canyon with seismic velocities >5.0 km/s. Crystalline continental crust thins seaward along GUMBO Line 3 from 23-10 km across the De Soto Canyon. High seismic velocity lower crust (>7.2 km/s) is interpreted as extensive syn-rift magmatism and possibly mafic underplating, common features at volcanic rift margins with high mantle potential temperatures. In the central Gulf basin we interpret thick oceanic crust (>8 km) emplaced at a slow full-spreading rate (~24 mm/yr). We suggest a sustained thermal anomaly during slow seafloor-spreading conditions led to voluminous basalt flows from a spreading ridge that overprinted seafloor magnetic anomalies in the northeastern Gulf of Mexico.

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Section: Discussionmentioning

confidence: 99%

“…Dashed and solid red and black lines indicate the limit of oceanic crust and spreading ridge proposed by Pindell and Kennan [] and Christeson et al . [], respectively. Red inverted triangles are locations for GUMBO Line 3 instruments 305, 316, 326, and 340.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2014

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“…However, a consequence of the thick overburden in the Gulf of Mexico is that it makes imaging of the underlying crust more challenging than at sediment-starved margins Bayrakci et al, 2016). Potential field data and maps of the top of basement in seismic-reflection data nonetheless agree quite well on the location of the extinct mid-ocean ridge and the landward limit of oceanic crust (LOC) in the Gulf of Mexico (Pindell and Kennan, 2009;Hudec et al, 2013;Christeson et al, 2014;Sandwell et al, 2014) (Fig. 1).…”

Section: Introductionmentioning

confidence: 88%

“…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%

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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“…The Moho is not observable beneath the outer marginal trough, but reappears basinward as an oceanic Moho, 6–8 km below the top of oceanic crust (Figure S1). The limit of oceanic crust (LOC) in the northeastern Gulf of Mexico has been variably identified within ~50 km window (Figure S3; Sawyer et al., ; Marton & Buffler, ; Pindell & Kennan, ; Hudec, Jackson, & Peel, 2013; Christeson et al., ; Sandwell, Müller, Smith, Garcia, & Francis, ).…”

Section: Geologic Settingmentioning

confidence: 99%

Extensional models for the development of passive‐margin salt basins, with application to the Gulf of Mexico

et al. 2018

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Recent subsalt petroleum discoveries associated with rifted‐margin salt basins have piqued interest in the presalt geology of the Gulf of Mexico margin. Available subsurface data does not uniquely constrain the subsalt geometry, so creating an interpretation of the crustal architecture requires the application of geological models for crustal extension and breakup. However, published interpretations of the nature of the transition from continental rifting to seafloor spreading range from magma‐rich to magma‐poor. To address this uncertainty, we present 2D forward kinematic models for crustal configurations generated by diverse models (symmetric extension, depth‐dependent extension, and volcanic extension). Through a series of conceptual balanced cross‐sections grounded in a ~600 km 2D seismic line from the NE Gulf of Mexico, we demonstrate the implications of each model for the limit of oceanic crust, basement morphology, crustal architecture, and hydrocarbon prospectivity. We discuss evidence for the dominant crustal processes, including geodynamic factors and structural and stratigraphic observations. Based on our observations and the geologic history, we favour an asymmetric, magma‐poor to ‐intermediate margin interpretation for the NE Gulf of Mexico, but suggest that the degree of volcanic input and width of the ocean‐continent transition zone may vary along strike. The along‐strike variability highlights the importance of understanding all potential presalt crustal configurations, their key features, and their implications. With increased data availability on the presalt geology in the Gulf of Mexico the relevance of these scenarios can be assessed, allowing development of comprehensive geodynamic and tectonic models of the margin and consideration of petroleum system elements in the presalt sequence.

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Deep crustal structure in the eastern Gulf of Mexico

Cited by 72 publications

References 79 publications

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

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

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

Extensional models for the development of passive‐margin salt basins, with application to the Gulf of Mexico

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