The thermal maturity of sedimentary basins as revealed by magnetic mineralogy

• Published in: Basin Research
• Main Authors: Abdelmalak, Mohamed Mansour, Polteau, Stephane
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2020
• Subjects: VDP::Mathematics and natural science: 400; VDP::Matematikk og Naturvitenskap: 400; Baffin Bay; Svartenhuk; Baffin
• Online Access: https://hdl.handle.net/10037/21389; https://doi.org/10.1111/bre.12439

This is the peer reviewed version of the following article: Abdelmalak, M. M. & Polteau, S. (2020). The thermal maturity of sedimentary basins as revealed by magnetic mineralogy. Basin Research, 32 (6), 1510-1531., which has been published in final form at https://doi.org/10.1111/bre.12439 . This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. The thermal evolution of sedimentary basins is usually constrained by maturity data, which is interpreted from Rock-Eval pyrolysis and vitrinite reflectance analytical results on field or boreholes samples. However, some thermal evolution models may be inaccurate due to the use of elevated maturities measured in samples collected within an undetected metamorphic contact aureole surrounding a magmatic intrusion. In this context, we investigate the maturity and magnetic mineralogy of 16 claystone samples from Disko-Svartenhuk Basin, part of the SE Baffin Bay volcanic margin. Samples were collected within thermal contact metamorphic aureoles near magma intrusions, as well as equivalent reference samples not affected by intrusions. Rock-Eval pyrolysis (T max ), and vitrinite reflectance (Ro) analysis were performed to assess the thermal maturity, which lies in the oil window when 435°C ≤ T max ≤ 470°C and 0.6%–0.7% ≤ Ro ≤ 1.3%. In addition, we performed low- (<300K) and high-temperature (>300K) investigations of isothermal remanent magnetization to assess the magnetic mineralogy of the selected samples. The maturity results (0.37% ≤ Ro ≤ 2%, 22°C ≤ T max ≤ 604°C) show a predominance of immature to early mature Type III organic matter, but do not reliably identify the contact aureole when compared to the reference samples. The magnetic assemblage of the immature samples consists of iron sulphide (greigite), goethite and oxidized or non-stoichiometric magnetite. The magnetic assemblage of the early mature to mature samples consists of stoichiometric magnetite and fine-grained pyrrhotite ...