Organic matter maturation in the contact aureole of an igneous sill as a tracer of hydrothermal convection

Wang, Dayong; Manga, Michael

doi:10.1002/2015jb011877

Cited by 23 publications

(18 citation statements)

References 46 publications

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“…Heat transfer in the country rock can be enhanced by hydrothermal convection. Wang and Manga (2015) show that hydrothermal convection induces complexlyshaped thermal aureoles. Diffusivities decrease with temperatures (Robertson, 1988;Whittington et al, 2009).…”

Section: Discussionmentioning

confidence: 99%

Factors Affecting the Thickness of Thermal Aureoles

Annen

2017

Front. Earth Sci.

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Intrusions of magma induce thermal aureoles in the country rock. Analytical solutions predict that the thickness of an aureole is proportional to the thickness of the intrusion. However, in the field, thermal aureoles are often significantly thinner or wider than predicted by simple thermal models. Numerical models show that thermal aureoles are wider if the heat transfer in the magma is faster than in the country rock due to contrasts in thermal diffusivities or the effect of magma convection. Large thermal aureoles can also be caused by repeated injection close to the contact. Aureoles are thin when heat transfer in the country rock is faster than heat transfer within the magma or in case of incrementally, slowly emplaced magma. Absorption of latent heat due to metamorphic reactions or water volatilization also affects thermal aureoles but to a lesser extent. The way these parameters affect the thickness of a thermal aureole depends on the isotherm under consideration, hence on which metamorphic phase is used to draw the limit of the aureole. Thermal aureoles provide insight on the dynamics of intrusions emplacement. Although available examples are limited, asymmetric aureoles point to magma emplacement by over-accretion for mafic cases and by under-accretion for felsic cases, consistent with geochronological data.

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Section: Discussionmentioning

confidence: 99%

Factors Affecting the Thickness of Thermal Aureoles

Annen

2017

Front. Earth Sci.

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“…Water convecting in the vicinity of sill intrusions could significantly modify the temperature and maturity effect of intrusions. Convection of hot fluids from the magma, the host-rock water, and decomposition products of kerogen is dependent on the permeability of porous host rocks or hydrofracturing in less porous host rocks (cf., [60,61,[82][83][84]. How the fluids from magma and host rock affect the fluid pressure and flow is determined by the host-rock porosity, permeability, and amount of fluids present [85].…”

Section: Temperature Modelmentioning

confidence: 99%

“…How the fluids from magma and host rock affect the fluid pressure and flow is determined by the host-rock porosity, permeability, and amount of fluids present [85]. Wang and Manga [83] showed that for rocks with low permeability (<10 mD) symmetrical contact aureoles are produced, implying that conduction is the favorable cooling method for sills and host rocks after emplacement. On the other hand, rocks of high permeability (>50 mD) show maturation asymmetry above the sill, implying occurrence of convection-influenced maturation [83].…”

Section: Temperature Modelmentioning

confidence: 99%

“…Wang and Manga [83] showed that for rocks with low permeability (<10 mD) symmetrical contact aureoles are produced, implying that conduction is the favorable cooling method for sills and host rocks after emplacement. On the other hand, rocks of high permeability (>50 mD) show maturation asymmetry above the sill, implying occurrence of convection-influenced maturation [83]. Annen [84] studied the maximum temperatures of three rocks of different water saturations: dry, hydrated and total water saturated, and found that in close proximity to an intrusion (~10 m) there were no differences in the temperatures, whereas at a distance of 50 m there was a~50 • C maximum temperature difference.…”

Section: Temperature Modelmentioning

confidence: 99%

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Transient Thermal Effects in Sedimentary Basins with Normal Faults and Magmatic Sill Intrusions—A Sensitivity Study

et al. 2019

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Magmatic intrusions affect the basin temperature in their vicinity. Faulting and physical properties of the basin may influence the magnitudes of their thermal effects and the potential source rock maturation. We present results from a sensitivity study of the most important factors affecting the thermal history in structurally complex sedimentary basins with magmatic sill intrusions. These factors are related to faulting, physical properties, and restoration methods: (1) fault displacement, (2) time span of faulting and deposition, (3) fault angle, (4) thermal conductivity and specific heat capacity, (5) basal heat flow and (6) restoration method. All modeling is performed on the same constructed clastic sedimentary profile containing one normal listric fault with one faulting event. Sills are modeled to intrude into either side of the fault zone with a temperature of 1000 • C. The results show that transient thermal effects may last up to several million years after fault slip. Thermal differences up to 40 • C could occur for sills intruding at time of fault slip, to sills intruding 10 million years later. We have shown that omitting the transient thermal effects of structural development in basins with magmatic intrusions may lead to over-or underestimation of the thermal effects of magmatic intrusions and ultimately the estimated maturation.

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“…The presence of lighter components, such as methane, may dissolve in the fluids or migrate as a gas phase during the formation of HTVCs (Svensen and Jamtveit, 2010;Wang and Manga, 2015). The volume of these carbon-bearing gases depends on the total amount of organic carbon in the host rock (Whitaker, 1986).…”

Section: Formation and Source Of Hydrothermal Vent Complexesmentioning

confidence: 99%

3D structure and formation of hydrothermal vent complexes at the Paleocene-Eocene transition, the Møre Basin, mid-Norwegian margin

et al. 2017

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The mid-Norwegian margin is regarded as an example of a volcanic-rifted margin formed prior to and during the Paleogene breakup of the northeast Atlantic. The area is characterized by the presence of voluminous basaltic complexes such as extrusive lava and lava delta sequences, intrusive sills and dikes, and hydrothermal vent complexes. We have developed a detailed 3D seismic analysis of fluid-and gas-induced hydrothermal vent complexes in a 310 km 2 area in the Møre Basin, offshore Norway. We find that formation of hydrothermal vent complexes is accommodated by deformation of the host rock when sills are emplaced. Fluids are generated by metamorphic reactions and pore-fluid expansion around sills and are focused around sill tips due to buoyancy. Hydrothermal vent complexes are associated with doming of the overlying strata, leading to the formation of draping mounds above the vent contemporary surface. The morphological characteristics of the upper part and the underlying feeder structure (conduit zone) are imaged and studied in 3D seismic data. Well data indicate that the complexes formed during the early Eocene, linking their formation to the time of the Paleocene-Eocene thermal maximum at c. 56 Ma. The well data further suggest that the hydrothermal vent complexes were active for a considerable time period, corresponding to a c. 100 m thick transition zone unit with primary Apectodinium augustum and redeposited very mature Cretaceous and Jurassic palynomorphs. The newly derived understanding of age, structure, and formation of hydrothermal vent complexes in the Møre Basin contributes to the general understanding of the igneous plumbing system in volcanic basins and their implications for the paleoclimate and petroleum systems.

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Organic matter maturation in the contact aureole of an igneous sill as a tracer of hydrothermal convection

Cited by 23 publications

References 46 publications

Factors Affecting the Thickness of Thermal Aureoles

Factors Affecting the Thickness of Thermal Aureoles

Transient Thermal Effects in Sedimentary Basins with Normal Faults and Magmatic Sill Intrusions—A Sensitivity Study

3D structure and formation of hydrothermal vent complexes at the Paleocene-Eocene transition, the Møre Basin, mid-Norwegian margin

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