Fault and conduit controlled burial dolomitization of the Devonian west-central Alberta Deep Basin

Green, Darryl G.; Mountjoy, Eric W.

doi:10.2113/53.2.101

Cited by 47 publications

(51 citation statements)

References 32 publications

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“…From a comparison of the established strontium isotope evolution curve of global marine carbonate rocks, from the early Triassic period with the Feixianguan Formation of northeastern Sichuan, the following conclusions can be reached: The Sr contents of shallow burial dolomites from the platform-margin oolitic beach facies lie in the range of 0.008%-0.016%, with an average value of 0.013%, while those of moderate to deep burial dolomite range from 0.012% to 0.016%, with an average of 0.014%. Both rock types from different burial stages have significantly higher Sr contents than that of a HTD from an alpine basin in Canada, which has a range of 0.0037%-0.0122% [73].…”

Section: Strontium Isotopic Signature and Contentmentioning

confidence: 86%

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Origins and Geochemistry of Oolitic Dolomite of the Feixianguan Formation from the Yudongzi Outcrop, Northwest Sichuan Basin, China

et al. 2017

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Abstract:The topic of dolomite formation has long presented a challenge to researchers. In this study, the origin of widely occurring oolitic dolomites from the Yudongzi outcrop in the lower Triassic Feixianguan formation in northwest Sichuan, China, was investigated through petrographic observations, and mineralogical and geochemical analysis. Analytical methods used include cathodoluminescence, X-ray diffraction, stable isotopes, and electronic microprobe characterization. The dolomites were categorized into three major genetic types according to their textural and structural characteristics, which reflect their various origins. The first genetic type of these dolomites, seepage reflux dolomitization, occurs in marly to microcrystalline dolomite during the penecontemporaneous stage, and displays negatively skewed δ 18 O (−2.83‰ Pee Dee Belemnite (PDB)), positively skewed δ 13 C (2.71‰ PDB), a low degree of order (0.48), and 87 Sr/ 86 Sr ratios of 0.707509-0.707634, indicating involvement of a Mg-rich brine fluid in an open evaporative environment. The second type, shallow burial dolomitization, is the most significant genetic type of dolomite reservoir in this area. This process produced dominantly silty to fine crystalline dolomite in a platform-margin oolitic beach facies with negatively skewed δ 18 O (−3.26‰ PDB), positively skewed δ 13 C (1.88‰ PDB), a high degree of order (0.70), and 87 Sr/ 86 Sr ratios of 0.707318-0.707661, which are related to seawater-derived fluids in a shallow burial environment. The third type is moderate to deep burial dolomitization, and is the main process responsible for zoned dolomite and dolomite with cloudy cores and clear rims (CCCR dolomite), which have the most strongly negatively skewed δ 18 O (−7.32‰ PDB), positively skewed δ 13 C (3.02‰ PDB), and 87 Sr/ 86 Sr ratios of 0.707217-0.707855, representing diagenetic alteration and fluid flow in a closed environment. These findings indicate that dolomite was likely affected by various degrees of burial and related marine-derived fluids, which will aid exploration efforts in high-quality hydrocarbon reservoirs in the Sichuan Basin.

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Section: Strontium Isotopic Signature and Contentmentioning

confidence: 86%

“…Both rock types from different burial stages have significantly higher Sr contents than that of a HTD from an alpine basin in Canada, which has a range of 0.0037-0.0122% [73].…”

Section: Fluid Inclusionsmentioning

confidence: 86%

Origins and Geochemistry of Oolitic Dolomite of the Feixianguan Formation from the Yudongzi Outcrop, Northwest Sichuan Basin, China

et al. 2017

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“…Recent studies of injectioninduced seismicity in parts of Western Canada [1][2][3] have highlighted the probable role of pre-existing basement faults in controlling the distribution of induced earthquakes. Although some basement-related faults in this region have been identified using seismic-reflection images (for example, see [4][5][6]), faults that may control the location of induced earthquakes are often challenging to detect using seismic-reflection images alone. Problematic cases include faults with a geometry that is unfavourable for seismic mapping in horizontally stratified rocks, such as sub horizontal thrust faults or vertical strike-slip faults, or brittle faults hosted within crystalline basement rocks that lack clear marker reflections.…”

Section: Introductionmentioning

confidence: 99%

Basement Tectonics and Fault Reactivation in Alberta Based on Seismic and Potential Field Data

Ekpo¹,

Eaton²,

Weir³

2018

Geophysics

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Injection-induced seismicity in Western Canada and elsewhere in North America has drawn considerable recent interest. Current models indicate that induced earthquakes occur on reactivated basement faults, which can be challenging to detect using seismic-reflection data. Here we use regional gravity and magnetic datasets, together with LITHOPROBE crustal seismic profiles, to investigate basement tectonics and crustal structure in an area of Western Canada that is prone to induced seismicity. Previously mapped basement faults that were active during the Paleozoic can be recognized on the basis of pronounced curvature, truncations and/or offsets of stratigraphic marker horizons. Within the Precambrian crystalline basement, however, brittle faults are poorly imaged by seismic data due to various factors such as the obscuring effect of multiples. Regional potential-field fabrics are critical to establish the tectonic setting of basement domains, with complementary information provided by magnetic, Bouguer and isostatic residual gravity anomalies based on 2D modelling constrained by seismic profiles. However, individual faults appear to lack diagnostic expression in regional potential-field anomaly data, since the anomalies are dominated by the effects of larger-scale crustal structures. We show evidence that large-scale basement faults can potentially be recognized on the basis of truncation and offset of distinct horizons within the Winagami Reflection Sequence (WRS), which is interpreted as a regionally-extensive mid-crustal sill complex emplaced during a Proterozoic magmatic pulse. An abundance of caution is necessary to interpret these features, due to complications arising from out-of-plane reflections at long reflection times.

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“…Devonian carbonate is an important oil and gas reservoir bed in the Swan Hills, Alberta Basin, Canada. There is ubiquitous dolomitization near the fracture and fluid channel [18] , the cross range distance of affection is about 2 km near the fluid side of the channel [19] , the filling degree and type of the matrix near the crack impact the reservoir bed properties [20] . Some attention has been paid to the transformation of carbonate reservoir bed by faulting, but it is only focused on a specific aspect, for example, a study showed that faulting obviously controlled the Ordovician paleo-karst in the west of the Lunnan area [21] , hydrothermal fluids carried by a mjor fault caused metasomatism of carbonate to form a secondary fluorite belt and improved reservoir bed performance [22] .…”

mentioning

confidence: 99%

Influence of Ordovician carbonate reservoir beds in Tarim Basin by faulting

Lü

Yang

Zhou³

et al. 2008

Sci. China Ser. D-Earth Sci.

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The quality of the Ordovician carbonate reservoir beds in the Tarim Basin is closely related to the development of secondary pores, fractures and cavities. Karstification is important in improving the properties of reservoir beds, and karstification related to unconformity has caught wide attention. Compared with the recent research on the unconformity karst reservoir bed improvement, this paper shows a new way of carbonate reservoir bed transformation. Based on field survey, core and slices observation, transformation of Ordovician carbonate reservoir beds by faulting can be classified into three types: (1) Secondary faults and fracturs generated by faulting improved carbonate reservoir bed properties, which were named the Lunnan or Tazhong82 model; (2) upflow of deep geothermal fluids caused by faulting, with some components metasomatizing with carbonate and forming some secondary deposit, such as fluorite. It can improve carbonate reservoir bed properties obviously and is named the Tazhong 82 model; and (3) the faulting extending up to the surface increased the depth of supergene karstification and the thickness of reservoir bed. It is named the Hetianhe model. Transformation effect of carbonate reservoir beds by faulting was very significant, mainly distributed on the slopes or on the edge or plunging end of the uplift.

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Fault and conduit controlled burial dolomitization of the Devonian west-central Alberta Deep Basin

Cited by 47 publications

References 32 publications

Origins and Geochemistry of Oolitic Dolomite of the Feixianguan Formation from the Yudongzi Outcrop, Northwest Sichuan Basin, China

Origins and Geochemistry of Oolitic Dolomite of the Feixianguan Formation from the Yudongzi Outcrop, Northwest Sichuan Basin, China

Basement Tectonics and Fault Reactivation in Alberta Based on Seismic and Potential Field Data

Influence of Ordovician carbonate reservoir beds in Tarim Basin by faulting

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