Coeval extension and shortening above and below salt canopies on an uplifted, continental margin: Application to the northern Gulf of Mexico

Dooley, Tim P.; Jackson, Martin P. A.; Hudec, Michael R.

doi:10.1306/03271312072

Cited by 50 publications

(22 citation statements)

References 45 publications

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“…For lack of any better constraint, Dutton (1987) assumed that the rate of erosion was linear from the time that the eroded interval was fi nished being deposited at 42 Ma to the present day. The scenario 2 thermal history, however, is geologically plausible given that its assumed onset of erosion in the Miocene is compatible with several lines of evidence that suggest regional uplift of the Gulf Coast beginning in the Oligocene and accelerating in the Miocene (Jackson et al, 2011;Dooley et al, 2013).…”

Section: Comparison Of a Simulated Bridge With A Natural Examplesupporting

confidence: 53%

Insights into rates of fracture growth and sealing from a model for quartz cementation in fractured sandstones

Lander¹,

Laubach

2014

Geological Society of America Bulletin

168

194

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A new model accounts for crystal growth patterns and internal textures in quartz cement in sandstone fractures, including massive sealing deposits, thin rinds or veneers that line open fracture surfaces, and bridge structures that span otherwise open fractures. High-resolution cathodoluminescence imaging of bridge structures and massive sealing deposits indicates that they form in association with repeated micron-scale fracturing of growing quartz crystals, whereas thin rinds do not. Model results indicate that the three morphology types develop in response to (1) the ratio of the rates of quartz growth to fracture opening and (2) the substantially faster growth rate that occurs on noneuhedral surfaces in certain crystallographic orientations compared to euhedral crystal faces. Rind morphologies develop when the fracture opening rate exceeds two times the fastest rate of quartz growth (along the c axis on noneuhedral surfaces) because growing crystals develop slow-growing euhedral faces. Massive sealing, on the other hand, develops where the net rate of fracture opening is less than twice the rate of quartz growth on euhedral faces because all quartz growth surfaces along the fracture wall seal the fracture between fracturing events. Bridge structures form at fracture opening rates that are intermediate between the massive sealing and rind cases and are associated with crystallographic orientations that allow growth to span the fracture between fracturing events. Subsequent fractures break the spanned crystal, introducing new, fastgrowing noneuhedral growth surfaces where quartz grows more rapidly compared to the euhedral faces of nonspanning crystals. As the ratio of fracture opening to quartz growth rate increases, the proportion of overgrowths that span the fracture decreases, and the range in c-axis orientations for these crystals comes progressively closer to perpendicular to the fracture wall until the maximum spanning limit is reached. Simulation results also reproduce "stretched crystal," "radiator structure," and "elongate blocky" textures in metamorphic quartz veins.The model replicates a well-characterized quartz bridge from the Cretaceous Travis Peak Formation as well as quartz cement abundances, internal textures, and morphologies in the sandstone host rock and fracture zone using the same kinetic parameters while honoring fl uid-inclusion and thermal-history constraints. The same fundamental driving forces, in both in the host rock and fracture system, are responsible for quartz cementation, with the only signifi cant difference within the fracture zone being the creation of new pore space as well as new noneuhedral surfaces for cases where overgrowths span fractures between fracturing events. Rates of fracture growth and sealing may be inferred from fracture cement textures using model results.

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Section: Comparison Of a Simulated Bridge With A Natural Examplesupporting

confidence: 53%

Insights into rates of fracture growth and sealing from a model for quartz cementation in fractured sandstones

Lander¹,

Laubach

2014

Geological Society of America Bulletin

168

194

View full text Add to dashboard Cite

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“…Peel et al, 1995;Rowan et al, 2004;Fort & Brun, 2012) or due to stretching of the salt and its cover during ongoing crustal extension . Worrall & Snelson, 1989;Peel et al, 1995;Rowan et al, 2004Rowan et al, , 2012a, although some gravity gliding was caused by proximal uplift of the margin (Jackson et al, 2011;Dooley et al, 2013). 14;Imbert & Philippe, 2005;Pindell & Kennan, 2007), a distance of up to greater than 500 km.…”

Section: Gulf Of Mexicomentioning

confidence: 99%

Passive‐margin salt basins: hyperextension, evaporite deposition, and salt tectonics

2014

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Passive-margin salt basins are classified as prerift, syn-stretching, syn-thinning, and syn-exhumation. Prerift salt, such as the Triassic Keuper in the Western Pyrenees, undergoes thick-skinned extension, first decoupled and then coupled, along with its substrate and cover. The base salt develops significant relief, is attenuated on the largest faults, and ends up distributed across the entire margin. Syn-stretching salt, such as along the Iberian and Newfoundland margins, is deposited during early rifting and is thus concentrated in proximal areas with variable thickness and extent, with decoupled and coupled thick-skinned deformation dominant. Syn-thinning salt, such as in the northern Red Sea, is also deposited during extension, with the base salt unconformably above proximal stretching faults but offset by distal thinning faults. Both thick-skinned and gravity-driven thinskinned deformation occur, with the latter strongly influenced by the ramp-flat geometry of the base salt. Syn-exhumation salt, such as in the Gulf of Mexico and South Atlantic salt basins, is deposited as part of the sag basin with broad distribution and a generally unfaulted base. Conjugate syn-exhumation salt basins are originally contiguous, form partly over exhumed mantle on magma-poor margin segments, and are commonly flanked by magma-rich segments with volcanic highs (seawarddipping reflectors) that isolate the salt basin from marine water. Salt tectonics is characterized by gravitational failure of the salt and overburden, with proximal extension and distal contraction, and the development of allochthonous salt that includes frontal nappes that advance over newly formed oceanic crust.

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“…Detachment at the allochthonous level and continuous folding of the underlying strata may even have occurred coevally (Dooley et al . ).…”

Section: Comparison Of Modelled Canopy Emplacement Mechanisms With Thmentioning

confidence: 99%

“…Nevertheless, both time period and salt volume are generally comparable to the values proposed for the Eocene canopy evolution. Detachment at the allochthonous level and continuous folding of the underlying strata may even have occurred coevally (Dooley et al 2013).…”

Section: Duration Of Evolution and Extent Of Canopymentioning

confidence: 99%

Numerical modelling study of mechanisms of mid‐basin salt canopy evolution and their potential applications to the Northwestern Gulf of Mexico

Gradmann

Beaumont

2016

Basin Research

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Salt canopies are present in many of the worldwide large salt basins and are key players in the basins' structural evolution as well as in the development of associated hydrocarbon systems. This study employs 2D finite-element models which incorporate the dynamical interaction of viscous salt and frictional-plastic sediments in a gravity-spreading system. We investigate the general emplacement of salt canopies that form in the centre of a large, autochthonous salt basin. This is motivated by the potential application to a mid-basin canopy in the NW Gulf of Mexico (GoM) that developed in the late Eocene. Three different salt expulsion and canopy formation concepts that have been proposed in the salt-tectonic literature for the GoM are tested. Two of these mechanisms require pre-existing diapirs as precursory structures. We include their evolution in the models to assure a continuous, smooth evolution of the salt-sediment system. The most efficient canopy formation takes place under the squeezed diapir mechanism. Here, shortening of a region containing pre-existing diapirs is absorbed by the salt (the weakest part of the system), which is then expelled onto the seafloor. The expulsion rollover mechanism, which evacuates salt from beneath evolving rollover structures and expels it both laterally and to the surface, was not successfully captured by the numerical models. No rollover structures developed and only minor amounts of allochthonous salt emerged to the seafloor. The breached anticline mechanism requires substantial shortening of salt-cored, pre-weakened folds such that the salt breaches the anticlines and is expelled to the seafloor. The amount of shortening may be too large to occur in the central part of a salt basin, but may explain canopy evolution closer to the distal end of the allochthonous salt. When applying the different concepts to the northwestern GoM, none of the models adequately describes the entire system, yet the squeezed diapir mechanism captures most structural features of the Eocene paleocanopy. It is nevertheless possible that different mechanisms have acted in combination or sequentially in the northwestern GoM.

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Coeval extension and shortening above and below salt canopies on an uplifted, continental margin: Application to the northern Gulf of Mexico

Cited by 50 publications

References 45 publications

Insights into rates of fracture growth and sealing from a model for quartz cementation in fractured sandstones

Insights into rates of fracture growth and sealing from a model for quartz cementation in fractured sandstones

Passive‐margin salt basins: hyperextension, evaporite deposition, and salt tectonics

Numerical modelling study of mechanisms of mid‐basin salt canopy evolution and their potential applications to the Northwestern Gulf of Mexico

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