Paleocene to Eocene deep-water slope canyons, western Gulf of Mexico: Further insights for the provenance of deep-water offshore Wilcox Group plays

McDonnell, A.; Loucks, Robert G.; Galloway, William E.

doi:10.1306/05150808014

Cited by 50 publications

(20 citation statements)

References 31 publications

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“…; McDonnell et al . ). Reasons for this uniform deposition are only poorly understood but are possibly related to a very wide, salt‐cored marginal wedge that shaped the continental slope (Pindell & Kennan ).…”

Section: Comparison Of Modelled Canopy Emplacement Mechanisms With Thmentioning

confidence: 99%

“…The Late Mesozoic to Paleogene sedimentary succession of the northwestern GoM has a relatively uniform thickness across most of the distal half of the salt basin ( Fig. 2a, Trudgill et al 1999;Meyer et al 2007;McDonnell et al 2008). Reasons for this uniform deposition are only poorly understood but are possibly related to a very wide, salt-cored marginal wedge that shaped the continental slope (Pindell & Kennan 2007).…”

Section: Depositional Historymentioning

confidence: 99%

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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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Section: Comparison Of Modelled Canopy Emplacement Mechanisms With Thmentioning

confidence: 99%

Section: Depositional Historymentioning

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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“…Sandstone was supplied to this area of the Gulf Coast by the Houston delta system throughout Wilcox time, and the interpreted source area in the southern Rocky Mountains, west Texas, and Mexico remained the same during Wilcox deposition (Blakey, 2007;Galloway et al, 2000;McDonnell et al, 2008). The petrographic work confirms that provenance of Wilcox sandstones deposited in the Houston delta system did not change through time.…”

Section: Sandstone Compositionmentioning

confidence: 65%

Reprint of: Diagenetic controls on evolution of porosity and permeability in lower Tertiary Wilcox sandstones from shallow to ultradeep (200–6700m) burial, Gulf of Mexico Basin, U.S.A.

Dutton

Loucks

2010

Marine and Petroleum Geology

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a b s t r a c tReservoir quality is a critical risk factor in deep to ultradeep reservoirs at depths >4.5 km. Analysis of Paleogene Wilcox sandstones on the upper Texas Gulf Coast provides insight into the evolution of reservoir quality during shallow to ultradeep burial diagenesis. Reduction of porosity and permeability with burial in Wilcox sandstones was evaluated using subsurface samples from 200 to 6700 m, at temperatures of 25-230 C. Diagenesis and petrophysical properties were interpreted from petrographic data and core analyses. Wilcox sandstones are mostly lithic arkoses and feldspathic litharenites having an average composition of Q 59 F 22 R 19 . Provenance did not change significantly during Wilcox deposition in this area, nor does average sandstone composition vary among lower, middle, and upper Wilcox sandstones. However, composition does vary with sequence-stratigraphic position; lowstand slope-fan deposits contain more rock fragments than do deposits from highstand or transgressive systems tracts. Given observations from this onshore dataset, Wilcox sandstones deposited in deepwater environments in the Gulf of Mexico are likely to contain more rock fragments than their linked highstand equivalents.Pore types in Wilcox sandstones change from a mix of primary and secondary pores and micropores at shallower depths to predominantly secondary pores and micropores in deeper sandstones. Wilcox sandstones show steady porosity reduction from an average of 33% at 38 C to 12% at 132 C, with little additional loss at higher temperatures. By 132 C, most primary pores have been lost by mechanical compaction or occluded by quartz cementation. Volume of secondary pores remains nearly constant despite dissolution of 3.5% average potassium feldspar during deep burial. Volume of this late dissolution of potassium feldspar is offset by precipitation of ankerite, albite, illite, and minor quartz in secondary pores. The proportion of microporosity, which occurs in authigenic clays, altered grains, and matrix, increases in the deepest sandstones. Change in proportion of pore types and reduction in total porosity with increasing temperature changes porosity-permeability transforms. Because most deep to ultradeep Wilcox sandstones are dominated by secondary pores and micropores, porosity-permeability transforms have lower slopes than those for shallower sandstones.

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“…14). Synkinematic thickness changes show that subtle folding began at least as early as the Paleocene (McDonnell et al, 2008). We therefore infer that subtle salt pillows began forming then and continued through the Paleocene and Eocene.…”

Section: Deep Structure Below the Miocene Detachment And Its Role In mentioning

confidence: 82%

Origin of transverse folds in an extensional growth-fault setting: Evidence from an extensive seismic volume in the western Gulf of Mexico

McDonnell

Jackson

Hudec

2010

Marine and Petroleum Geology

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Paleocene to Eocene deep-water slope canyons, western Gulf of Mexico: Further insights for the provenance of deep-water offshore Wilcox Group plays

Cited by 50 publications

References 31 publications

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

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

Reprint of: Diagenetic controls on evolution of porosity and permeability in lower Tertiary Wilcox sandstones from shallow to ultradeep (200–6700m) burial, Gulf of Mexico Basin, U.S.A.

Origin of transverse folds in an extensional growth-fault setting: Evidence from an extensive seismic volume in the western Gulf of Mexico

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