A combined rock-magnetic and EPR study about the effects of hydrocarbon-related diagenesis on the magnetic signature of oil shales (Vaca Muerta formation, southwestern Argentina)

Costanzo-Alvarez, V.; Rapalini, Augusto E.; Aldana, Milagrosa; Díaz, Mónica; Kietzmann, Diego A.; Iglesia-Llanos, María Paula; Cabrera, Ana; Luppo, Tomás; Vallejo, María Dolores Simón; Walther, Ana María

doi:10.1016/j.petrol.2018.10.082

Cited by 10 publications

(3 citation statements)

References 56 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Hydrocarbon occurrence often accompanies the development of authigenic ferromagnetic phases, as observed in various studies (Benthien & Elmore, 1987;McCabe et al, 1987;Font et al, 2006;Aldana et al, 2011;Costanzo-Álvarez et al, 2019;J. Hu et al, 2023).…”

Section: Hydrocarbon Percolation In Carbonates Of the Araras Groupmentioning

confidence: 85%

Clay minerals and continental-scale remagnetisation: a case study of South American Neoproterozoic carbonates

Bellon,

Trindade,

Williams

et al. 2023

Preprint

View full text Add to dashboard Cite

Carbonate rocks frequently undergo remagnetisation events, which can partially/completely erase their primary detrital remanence and introduce a secondary component through thermoviscous and/or chemical processes. Despite belonging to different basins hundreds of kilometres apart, the Neoproterozoic carbonate rocks of South America (over the Amazon and São Francisco cratons) exhibit a statistically indistinguishable single-polarity characteristic direction carried by monoclinic pyrrhotite and magnetite, with paleomagnetic poles far from an expected detrital remanence. We use a combination of classical rock magnetic properties and micro-to-nanoscale imaging/chemical analysis using synchrotron radiation to examine thin sections of these remagnetised carbonate rocks. Magnetic data shows that most of our samples failed to present anomalous hysteresis properties, usually referred to as part of the “fingerprints” of carbonate remagnetisation. Combining scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS), highly sensitive X-ray fluorescence (XRF), and X-ray absorption spectroscopy (XAS) revealed the presence of subhedral/anhedral magnetite, or spherical grains with a core-shell structure of magnetite surrounded by maghemite. These grains are within the pseudo-single domain size range (as well as most of the iron sulphides) and spatially associated with potassium-bearing aluminium silicates. Although fluid percolation and organic matter maturation might play an important role, smectite-illitisation seems a crucial factor controlling the growth of these phases. X-ray diffraction analysis identifies these silicates as predominantly highly crystalline illite, suggesting exposure to epizone temperatures. Therefore, we suggest that the remanence of these rocks should have been thermally reset during the final Gondwana assembly, and locked in a successive cooling event during the Early-Middle Ordovician.

show abstract

Section: Hydrocarbon Percolation In Carbonates Of the Araras Groupmentioning

confidence: 85%

Clay minerals and continental-scale remagnetisation: a case study of South American Neoproterozoic carbonates

Bellon,

Trindade,

Williams

et al. 2023

Preprint

View full text Add to dashboard Cite

show abstract

“…For analysis of IRM curves, a direct signal analysis (DSA) was applied to the experimental IRM. The DSA method has been widely described by Aldana et al (1994, 2011) and has been used to analyse IRM curves obtained from archaeological samples (Rada Torres et al, 2011), sedimentary rocks (Costanzo-Álvarez et al, 2012, 2019), soils (Costanzo-Álvarez et al, 2017a), and synthetic samples (Costanzo-Álvarez et al, 2017b). Figure 3A and B shows the experimental and fitted curves for the shallow sample of core CH04/2, as well as the spectral histogram obtained.…”

Section: Resultsmentioning

confidence: 99%

Testing lake-level reconstructions based on rock magnetic proxies for the sediment record of Laguna Cháltel (Patagonia, Argentina)

Irurzun¹,

Palermo²,

Gogorza³

et al. 2020

Quat. res.

Self Cite

View full text Add to dashboard Cite

This study was carried out on sediment cores collected with a gravity corer from Laguna Cháltel, an almost circular crater lake located in Patagonia, Argentina (49.9°S, 71°W). The main magnetic carrier was Ti-magnetite in the pseudo–single domain range. A model using magnetic grain size and concentration, previously applied to Laguna Potrok Aike to infer lake-level changes, was used for Laguna Cháltel. The main requirement to apply the model is uniform magnetic mineralogy, which is the case for Laguna Cháltel. After magnetic data were compared with previously studied lake levels, it was found that the magnetic proxies that best follow hydrologic changes are ARM/SIRM (anhysteretic remanent magnetisation/saturation of isothermal remanent magnetisation) and ARM. The concentration proxy (ARM measured with a 100 mT alternating field and 0.05 mT direct field) was also used as wind indicator. High wind strength was found at around 3650 cal yr BP, and low wind strength for the last century. ARM/SIRM and ARM were used to infer the strength of fluvial runoff into the lake for a core collected close to the shore and near a tributary. The results show that the magnetic model is promising for inferring lake-level variations, particularly in Patagonian lakes.

show abstract

“…Numerous studies suggest that certain thermochemical conditions (e.g., appropriated redox environments, pressure, temperature, sulfur content, among others) and/or microbial processes trigger diagenetic changes in initially homogeneous soils and sediments (e.g., Machel, 1995;Ellwood and Burkart, B., 1996). Conversely, few works deal with the role played, in the origin of such magnetic anomalies, by the lithology of the rocks affected by the presence of hydrocarbons (e.g., Hall and Evans, 1995;Mena and Walther, 2012;Costanzo-Álvarez et al, 2019). This observable fact is supported by theoretical considerations demonstrating that pressure and concentration gradients appear to be important mechanisms that activate the migration of oil and gas through the porous media (e.g., Matthews, 1996;Brown, 2000).…”

Section: Introductionmentioning

confidence: 99%

Comparing Direct Numerical Modeling Predictions With Field Evidence for Methane Vertical Microseepage in Two Geological Settings

et al. 2022

Self Cite

View full text Add to dashboard Cite

The footprints of petroleum microseepage can be associated with chemical and microbial processes in initially homogeneous strata and/or with the fluid transport properties of the rocks through which oil and gas migrate. This work examines the role of such driving factors in two contrasting geological settings by comparing numerical modeling predictions for upward methane microseepage with some field evidence for hydrocarbons transport and accumulation. The two case studies are a monitoring borehole (BH8) from a landfill in southern Ontario, Canada, and an oil well (Saltarin 1A) from the Eastern Llanos Basin in Colombia. Profiles of relative methane concentrations versus depth were generated using a time-dependent, one-dimensional, simulation of the advection-diffusion equation applied to multiple strata of soils, and sediments. The model employs the layered sequences of these two geological settings. The results obtained hinge on the standard permeability values for the rock types involved and their corresponding flow velocities and diffusion coefficients. Resistivity logs were utilized as direct proxies of hydrocarbon concentrations. As additional evidence for petroleum microseepage, experiments of electron paramagnetic resonance (EPR) were carried out in drilling cuts of Saltarin 1A to measure traces of organic matter free radicals concentrations (OMFRC). Extractable organic matter (EOM) and magnetic susceptibility data were also considered in interpreting the EPR results. Qualitative comparisons between modeled methane profiles and their corresponding resistivity logs suggest that microseepage and hydrocarbon accumulations are conditioned by the fluid transport properties of the rocks contained by BH8 and Saltarin 1A. Moreover, in most of the Saltarin 1A sequence, the OMFRC profiles follow the trends displayed by the resistivity and modeled methane logs. Thus, the EPR data also indicates that hydrocarbon microseepage and accumulation are largely controlled by lithology. Conversely, EOM and magnetic susceptibility appear to be evidence for hydrocarbon-mediated near-surface chemical processes.

show abstract

A combined rock-magnetic and EPR study about the effects of hydrocarbon-related diagenesis on the magnetic signature of oil shales (Vaca Muerta formation, southwestern Argentina)

Cited by 10 publications

References 56 publications

Clay minerals and continental-scale remagnetisation: a case study of South American Neoproterozoic carbonates

Clay minerals and continental-scale remagnetisation: a case study of South American Neoproterozoic carbonates

Testing lake-level reconstructions based on rock magnetic proxies for the sediment record of Laguna Cháltel (Patagonia, Argentina)

Comparing Direct Numerical Modeling Predictions With Field Evidence for Methane Vertical Microseepage in Two Geological Settings

Contact Info

Product

Resources

About